Heavy duty battery for minivan???

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SternWake said:
Group 65 is a weird apple being shorter and wider and squatter. They also tend to have higher CCA figures than a battery of the same weight but different dimensions. I'll guess due to wider shorter plates. Somebody more knowledgeable than me said the group 65 plate/acid ratio was a weird mix that did not translate well to a dual purpose flooded battery.

Do you have about 2 more inches of height available? If so you can likely squeeze in a group 29/31 for a good amount more capacity..

Check date codes, A reduced price on a 6 month old battery, is not a deal.

SternWake-My "play" house battery is a group 31 marine battery from Oreilly but it's just too tall-the battery cables don't reach that high. Drats! I thought I could swap the group 31 in as the starting (since I haven't killed it yet) and get a better house battery.

The funny thing is the dying group battery is a Napa Legend 75 with a date code from Dec07(!!!). I'm a little hesitant to get rid of it since it still starts the van fine. And it obviously has been a good one. I only took it to be tested because I had alternator issues a couple of weeks ago, and it was already out because I was trying to find a place to mount my continuous duty solenoid.

I will probably just put another group 65 back in, since I don't have the setup you do and I'm not brave enough or knowledgeable enough to even try. Thanks for the info!
 
JewellAnn-
I'm envious of your second battery tray! I've spent hours (OK, not really hours but still time) trying to configure the interior of the van around the battery: Where to put it, how to secure it, how to vent it, how to wire it, how to run the wiring...
 
Minivans don't have under hood room for a second battery. Size of the chassis battery is limited too.
My experience has been that the months rating means nothing. I can't get any battery, of any rating or warranty, to last more than two years. The next battery will be free for the first replacement. My previous battery was warranted for 72 months, it was 22 months old when it died.
I feel the added stress of using one to run accessories will further shorten it's life.
 
LeeRevell said:
Minivans don't have under hood room for a second battery.  Size of the chassis battery is limited too.

I feel the added stress of using one to run accessories will further shorten it's life.

:huh:   Well this Safari Hightop is a whole new critter to me.  Someone said it was a mini van.  Is it?   I don't know.  The starter battery is on the passenger side and there is a battery tray/holder on the driver's side also.  Maybe it's because it's a Glaval Conversion Van and my mom didn't order all the electronic options back in 1998 when she purchased it?  It would be nice to have an alterative source of power when boondocking on short hops like AL to Temple TX.  It's making it's first shop visit this week and I'll ask Lon [super mechanic} about this.  If anyone's around Ft. Rucker and needs work done I reccomend him.  His prices are competitive, he only fixes what NEEDS TO BE FIXED.  The first repair he made on the Ranger was $490 less than the highest estimate I'd been given and still $200 less than the lowest.  Except tires I've used his shop for 3ys.  It's L & K Automotive & Custom Exhaust, Enterprise AL, 334-475-3141. When I can type some more I'll post this in the right forum.

Jewellann
 
MHO on brand names, house labels vs manufacturer

The mass market for automotive starters is mostly driven by low price, combined with deceptive marketing.

A mega maker like Johnson is perfectly capable of making top-notch product, but when their customers like Walmart AutoZone etc spec a line, it will be built to make (a very small) margin against a price point, balanced against warranty returns.

Sometimes a specific SKU will turn out to be an excellent longevity performer, but even with DieHard and Interstate it's a roll of the dice.

I have read that Interstates direct through their in-house distribution can be much better than those sold to big box channels.

Consumer Reports does good reporting.


wrt Deep Cycle usage, that label as well as "Marine" also means next to nothing in a big box mass market context.

True deep cycle batteries are so much more expensive than the pseudo ones you have to go to the specialist channels and pay the big bucks.

But one glaring exception is the Golf Cart market, very demanding bulk purchasers that do their own thorough testing in-house, very competitive market.

The GC 6v sold by Costco and Sam's Club are not top-notch, but VERY good value for most consumer deep cycling applications.
 
LeeRevell said:
Minivans don't have under hood room for a second battery. Size of the chassis battery is limited too.

Most batteries don't die, they're killed by their owner.

If you have big loads and a stock alternator, you're trying to deep-cycle a starter batt, in effect abusive usage. Starter's chemistry is designed to stay between 95-100% all the time. Even a $1000 deep cycle is designed to be drawn below 80% only rarely, 50% occasionally is OK, 20% is abusive.

Even with a more powerful alt, if you're not driving many hours at a time, you're never getting the batt to 100% where it wants to be at least once or twice a week, that takes 6-12 hours.

Try

1 putting it on a good shore power charger at least that often

2 getting as powerful a "hybrid starter deep-cycle" as will fit, plus an upgraded alternator

3 put a separate house battery inside the van, isolate/combiner from the starter, run all big loads off that

Your good starter will then last 7+ years, but you will still need to figure out how to get the House bank back up to 100% as often as possible.

With big loads, an alternator really only does the shortest Bulk phase of the charge cycle, maybe some way into Absorption, need a solar panel or shore power charger overnight to get to Float.

LiFiPo4 banks are much more forgiving of living at partial (80%) charges, but big up-front cost per AH, specialized chargers, don't like the cold. . .
 
Txjaybird said:
Well this Safari Hightop is a whole new critter to me.
> The starter battery is on the passenger side and there is a battery tray/holder on the driver's side also

Sounds like you've at least got room for a dual battery system.


> I'll ask Lon [super mechanic} about this.  If anyone's around Ft. Rucker and needs work done I recommend him.  

Electrical system suppliers for RV and MARINE (especially) markets are really the specialists you want here, normal automotive mechanics no matter how honest usually just don't know their stuff in this arena.

You'll save a LOT of money on a "good enough" system to meet YOUR needs if you learn to figure it out yourself though.

Start by carefully reading my last post and settle in with Google and take detailed notes as you go along.

The sailing sites really have the most helpful authoritative and detailed info, imagine boondocking out at sea, what level of reliability you'd want.

The "Westy" crowd is also very helpful.

But as always, good quality means paying a LOT more than what most people are willing to consider, and lots of the yachting crowd grossly overspend on unnecessarily complex gadgets.
 
We've drifted from helping Kathleen, into bickering, long ago, but the discussion can be informative for others.

Since most vehicle's voltage regulators are so timid, and will drop from 14.x to 13.x relatively quickly after starting, an upgraded alternator is not really going to make much difference, if any, in most applications where recharging a single or perhaps dual depleted battery is concerned.

A depleted battery might accept 40 amps at 14.7v, but only 10 amps at 13.7v.

The 200 amp alternator will charge no faster than a 100 amp alternator when the battery can only accept a certain amount, and the voltage regulator is seeking only a middling float voltage. Yes there are if's and's and Butt's and exception's with a few qualifying asterisk's involved, but most here will be wasting their money on an upgraded alternator, Unless it is a pre 90's vehicle that came with a 60 amp alternator.

Most vehicles since 1988+, come with alternators rated at 90 amps or higher, so if the depleted battery can only accept 25 amps at 14.7, and there are not 65 amps of other loads, then there is likely no benefit, especially when the thermal protections kick in or the voltage regulator's egg timer clicks and drops voltage to 13.7v instead.

A higher rated alternator should be able to better deal with the heat it generates, when heavily loaded, but a higher rated alternator might only achieve those extra amps at high rpms, and might even be less efficient at low rpms where it is likely to spend the most time.

I say Do not replace a functioning alternator with a higher rated one hoping for better battery charging. this can lead to a false confidence and have little or no benefit. If an alternator fails, then consider upgrading to a higher rated unit, but do not expect any better or significantly faster battery charging, unless one is also running huge electrical loads, like 30 amps of forward lighting and their Hvac motor for another 20 amps., and has a battery bank depleted enough that it would require another 50 amps to be brought to 14.4v.

If one really wanted to maximize the ability of their alternator for the purpose of chrging the battery to full as best as possible in the time on is driving, they would have an adjustable voltage regulator that would seek and hold 14.x volts whenever the battery was anything but 100% charged.

Voltage regulators can be a separate device mounted on firewall, It can be inside the alternator, it can be inside the engine computer depending on the vehicle.

Vehicle manufacturers do not ever consider the voltage regulator needing to perfectly recharge a well depleted battery ASAP. They do not care about achieving battery longevity, nor do they market vehicles that never need any maintenance what so ever. The VR's goal is to keep the battery from being depleted when driving, and to replace what was used to start the engine. They were not designed with a Depleted bank of house batteries tacked onto the end of the circuit, and an anxious van dweller wondering if driving from A to B and back again will be able to power their laptop or Cpap overnight.

If a battery is depleted, and the vehicles voltage regulator only allows 13.7, it matters little whether one has a 60 amp alternator or a 300 amp alternator, as the battery will only accept a small amount of amperage at 13.7v. the exception here would be the vehicular loads outside of the depleted battery, like headlights and blower motor, and also what the engine needs to run ignition and fuel pump.

On my 89 dodge it requires 8.2 amps at idle and 12.2 amps at 2000 rpm to run fuel pump and ignition that is with a fully charged battery. if the battery were depleted the field current to alternator could go upto as high as 10 amps on top of the numbers above, and of course the amperage the depleted battery could accept.

What to do about this glaring deficiency of alternator recharging due to timid voltage regulation?

One accepts it. Any charging is better than no charging, While 13.7 is not ideal for a depleted battery it is so much better than driving and not having the house battery charging at all, or worse, still being depleted powering say a 12vDC fridge or inverter loads.

Or one tries to influence the VR, hoping higher voltages are sought and held longer thereby charging the battery faster, to a higher state of charge before engine shutdown.

Or one bypasses it.

Influencing it.....
..... well that it also extremely vehicle specific, but a cooler battery temperature sensor( if present), can influence it. Also a cooler alternator could influence it. Or a cooler engine computer, perhaps. A cold air intake aimed at alternator can not only possibly raise voltages but it will greatly extend alternator longevity when it is regularly asked to work hard.

..... Thick cables between alternator and depleted batteries might allow the VR to see that a higher field current is required to maintain system voltage, thereby allowing it to hold a higher voltage for longer, perhaps. This is one reason why I recommend people take power right from alternator(+) stud for house battery rather than engine battery. The other benefits are a $horter circuit length, and bypassing the too thin OEM cabling between alternator and engine battery which can throttle amperage into depleted house battery(s).

Obviously influencing the voltage regulator to seek higher voltages for longer just for better battery charging, is not so easy, or a sure thing, and is extremely variable depending on the vehicle.

If one has a dedicated house battery there are DC to DC transformers which will attempt to 3 stage charge
batteries,( turn 13.7 into 14.4), but these are pricey and usually limited to X amount of amps. Some are just 20 amps max, others are 50 amps, and these are generally 300+ dollar devices, and another possible failure point.
Some have thought to use a programmable solar controller in between alternator and house battery, but this should be rated for at least the maximum rating of the alternator or risk the magic blue smoke escaping. See many 100 amp solar controllers?

Some others might hook an inverter to engine battery, which then powers a high amp smart charger hooked to house battery. Problems with this are if the alternator can't, at idle, produce enough juice to power inverter charging the house battery, then juice comes from engine battery, robbing Peter to pay Paul. Inverters do not like being mounted in engine compartment, and since they require pretty fat cabling, this copper might be better off in a direct connection between alternator, solenoid and house battery instead.

Another issue with this method is the inverter is likely ony 80% efficient and the charger is likely only 75% efficient, so much of the alternator output to power the Inverter and charger is wasted, turned into heat. Inverter's can also be electrically noisy and 'might' backfeed the DC system and cause issues with the engine computer. I know of one report where the Van would not run properly when the inverter was running and powering a smart charger charging a house battery. Exception rather than the rule, but a possibility to be aware of.

Last February, sick of my bat crap crazy voltage regulator choosing 14.9v when my battery was full, and 13.7v when it was not, I have chose to trick my voltage regulator mounted in my engine computer. In my 89 dodge with an externally regulated alternator, if the engine computer VR is bypassed, the Check Engine Light comes on, and the computer reverts to a preprogrammed air fuel ratio and spark timing. MPG and power take a pretty big hit and engine runs crustier.

But if a 10 ohm 50+ watt resistor is added in between the original wires that originally went to two alternator field connections, the computer thinks the alternator is still there and does not illuminate the CEL and it applies sensor readings to spark timing and AF ratio.

I then used an external voltage regulator, a transpo540HD, that has an internal potentiometer for adjusting voltage. I removed this potentiometer, soldered wires to the legs, and ran them to a larger potentiometer on my dashboard, next to my voltmeters and ammeter. I also added another heatsink to VR backside with a small 60MM computer fan as I noticed it getting to 120+ degrees when it was asking the alternator for everything with 8+ amps of field current.

I can now choose any voltage between 12.8, and 15.3v, by twisting a dial, but allowing over 14.7v can trigger the CEL and 'limp home' mode where the ECM reverts to preset values on A/F ratio and spark timing.

My ammeter is currently wired to read total alternator current, so I can easily see when it is maxed out for a given rpm. I can tell by experience, but also when more rpms do not raise voltage to my setpoint, or if adding more loads does not increase output.

I could benefit from an alternator that can produce more when the engine is hot and idling, but at 800 rpm or more, a higher rated alternator would do nothing for my small capacity battery bank and electrical loads. if I had more battery capacity, then I would benefit from a higher rated alternator more capable in the 550 to 1100 rpm range, but much depends on the amount of battery capacity and the level of depletion and the health of the battery, as healthy batteries require more amperage to be brought to a higher voltage when depleted.

My alternator is a Chrysler rated at 50 amps idle and 120 amps max, and my ammeter reveals this to be mostly accurate, but my engine idles hot at 550 rpm( factory service manual states 750rpm!?), and max amps there is about 43amps, but at 800 rpm this is in the mid 70's.

For those that made it this far and are interested, I have a more detailed write up with some Pics, on my VR modification here:
https://vanlivingforum.com/Thread-Your-Vehicles-voltage-regulator?highlight=voltage+regulator
 
Txjaybird said:
:huh:   Well this Safari Hightop is a whole new critter to me.  Someone said it was a mini van.  Is it?   I don't know.  

**********************************************************************************************************************************************
TO LEEREVELL   YOU WERE RIGHT AND I WAS WRONG.  THERE IS NO 2nd BATTERY TRAY ON SAFARI!!  IF YOU HAVE RECIPE FOR EITHER CROW OR HUMBLE PIE I WILL LET YOU KNOW IF I'M EVER IN YOUR AREA.
 
In my defense I can only say I must of dreamed it.  Really, I'm dealing with a major infected tooth that hurts up to my eye socket, = 2 x differnt antibiotics + heavy duty pain meds & inflamatory meds.  It's a bummer because not only no 2nd battery tray the one in there looks rotten and probably needs replacing.
              
**********************************************************************************************************************************************

 The first repair he made on the Ranger was $490 less than the highest estimate I'd been given and still $200 less than the lowest.  Except tires I've used his shop for 3ys.  It's L & K Automotive & Custom Exhaust, Enterprise AL, 334-475-3141. When I can type some more I'll post this in the right forum.

Jewellann
 
Jewellann,

I take it the urgent need has now passed?

If your battery tray needs re-doing, this is a great opportunity! Staying with the stock holder will greatly limit your capacity.

Take the van to your trusted car repair guy, along with the battery size chart, and see what he can do to give you a tray that will hold as large a deep-cycle size as possible.

Ideally two of the 6v Golf Cart batteries, go down to Costco and/or Sam's Club, and take accurate measurements of what they have in stock. These are by far best value per dollar if you need deep cycling, without paying industrial/true marine channel pricing.

Maybe take a scale too, heavier means more storage capacity within such similar SKUs.

Don't let anyone tell you these "aren't designed for starting", they've got more oomph than that use will ever require.

You will need to figure out (later) how to get/keep them topped up on float on the road, but for now just put them on a decent shore power charger at least overnight once a week.

You may be able to find online a reasonably priced specialist box to hold these, then your mechanic can figure how to bolt it to your new platform, but he should be able to jury-rig something secure maybe for less cost.

You may well be able to avoid running a second big battery/bank inside the van this way.

Just carry one of those small "personal power" jumper packs - and keep it charged in the glove box! for if/when you run down your one "house bank" too far to start your engine.

If you find you're doing this more than you like, then you can get a battery isolator / combiner setup to automate the whole routine, but that is a bit more complex than what you want to deal with at the moment.
 
SternWake said:
We've drifted from helping Kathleen, into bickering, long ago, but the discussion can be informative for others.

Since most vehicle's voltage regulators are so timid, and will drop from 14.x to 13.x relatively quickly after starting, an upgraded alternator is not really going to make much difference, if any, in most applications where recharging a  single or perhaps dual depleted battery is concerned.

 A depleted battery might accept 40 amps at 14.7v, but only 10 amps at 13.7v.

The 200 amp alternator will charge no faster than a 100 amp alternator when the battery can only accept a certain amount, and the voltage regulator is seeking only a middling float voltage. Yes there are if's and's and Butt's and exception's with a few qualifying asterisk's involved, but most here will be wasting their money on an upgraded alternator, Unless it is a pre 90's vehicle that came with a 60 amp alternator.  

Most vehicles  since 1988+, come with alternators rated at 90 amps or higher, so if the depleted battery can only accept 25 amps at 14.7, and there are not 65 amps of other loads, then there is likely no benefit, especially when the thermal protections kick in or the  voltage regulator's egg timer clicks and drops voltage to 13.7v instead.

A higher rated alternator should be able to better deal with the heat it generates, when heavily loaded, but a higher rated alternator might only achieve those extra amps at high rpms, and might even be less efficient at low rpms where it is likely to spend the most time.

I say Do not replace a functioning alternator with a higher rated one hoping for better battery charging.  this can lead to a false confidence and have little or no benefit.  If an alternator fails, then consider upgrading to a higher rated unit, but do not expect any better or significantly faster battery charging, unless one is also running huge electrical loads, like 30 amps of forward lighting and their Hvac motor for another 20 amps., and has a battery bank depleted enough that it would require another 50 amps to be brought to 14.4v.

If one really wanted to maximize the ability of their alternator for the purpose of chrging the battery to full as best as possible in the time on is driving, they would have an adjustable voltage regulator that would seek and hold 14.x volts whenever the battery was anything but 100% charged.

Voltage regulators can be a separate device mounted on firewall, It can be inside the alternator, it can be inside the engine computer depending on the vehicle.

Vehicle manufacturers do not ever consider the voltage regulator needing to perfectly recharge a well depleted battery ASAP. They do not care about achieving battery longevity, nor do they market vehicles that never need any maintenance what so ever.  The VR's goal is to keep the battery from being depleted when driving, and to replace what was used to start the engine.  They were not designed with a Depleted bank of house batteries tacked onto the  end of the circuit, and an anxious van dweller wondering if driving from A to B and back again will be able to power their laptop or Cpap overnight.

If a battery is depleted, and the vehicles voltage regulator only allows 13.7, it matters little whether one has a 60 amp alternator or a 300 amp alternator, as the battery will only accept a small amount of amperage at 13.7v.  the exception here would be the vehicular loads outside of the depleted battery, like headlights and blower motor, and also what the engine needs to run ignition and fuel pump.

On my 89 dodge it requires 8.2 amps at idle and 12.2 amps at 2000 rpm to run fuel pump and ignition  that is with a fully charged battery.  if the battery were depleted the field current to alternator could go upto as high as 10 amps on top of the numbers above, and of course the amperage the depleted battery could accept.

What to do about this glaring deficiency of  alternator recharging due to timid voltage regulation?

One accepts it.  Any charging is better than no charging, While 13.7 is not ideal for a depleted battery it is so much better than driving and not having the house battery charging at all, or worse, still being depleted powering say a 12vDC fridge or inverter loads.

Or one tries to influence the VR, hoping higher voltages are sought and held longer thereby charging the battery faster, to a higher state of charge before engine shutdown.

Or one bypasses it.

Influencing it.....
..... well that it also extremely  vehicle specific, but a cooler battery temperature sensor( if present), can influence it.  Also a cooler alternator could influence it. Or a cooler engine computer, perhaps.  A cold air intake aimed at alternator can not only possibly raise voltages but it will greatly extend alternator longevity when it is regularly asked to work hard.

..... Thick cables between alternator and depleted batteries might allow the VR to see that a higher field current is required to maintain system voltage, thereby allowing it to hold a higher voltage for longer, perhaps.  This is one reason why I recommend people take power right from alternator(+) stud for house battery rather than engine battery.  The other benefits are a $horter circuit length, and bypassing the too thin OEM cabling between alternator and engine battery which can throttle amperage into depleted house battery(s).

 Obviously influencing the voltage regulator  to seek higher voltages for longer just for better battery charging, is not so easy, or a sure thing, and is extremely variable depending on the vehicle.

If one has a dedicated house battery there are DC to DC transformers which will attempt to 3 stage charge
batteries,( turn 13.7 into 14.4),  but these are pricey and usually limited to X amount of amps. Some are just 20 amps max, others are 50 amps, and these are generally 300+ dollar devices, and another possible failure point.
 Some have thought to use a programmable solar controller in between alternator and house battery, but this should be rated for at least the maximum rating of the alternator or risk the magic blue smoke escaping.  See many 100 amp solar controllers?

Some others might hook an inverter to engine battery, which then powers a high amp smart charger hooked to house battery.  Problems with this are if the alternator can't, at idle, produce enough juice to power inverter charging the house battery, then juice comes from engine battery, robbing Peter to pay Paul. Inverters do not like being mounted in engine compartment, and since they require pretty fat cabling, this copper might be better off in a direct connection between alternator, solenoid and house battery instead.

Another issue with this method is the inverter is likely ony 80% efficient and the charger is likely only 75% efficient, so much of the alternator output to power the Inverter and charger is wasted, turned into heat.  Inverter's can also be electrically noisy and 'might' backfeed the DC system and cause issues with the engine computer. I know of one report where the Van would not run properly when the inverter was running and powering a smart charger charging a house battery.  Exception rather than the rule, but a possibility to be aware of.

Last February, sick of my  bat crap crazy voltage regulator choosing 14.9v when my battery was full, and 13.7v when it was not, I  have chose to trick my voltage regulator mounted in my engine computer.  In my 89 dodge with an externally regulated alternator, if the engine computer VR is bypassed, the Check Engine Light comes on, and the computer reverts to a preprogrammed air fuel ratio and spark timing.  MPG and power take a pretty big hit and engine runs crustier.

But if a 10 ohm 50+ watt resistor is added in between the original wires that originally went to two  alternator field connections, the computer thinks the alternator is still there and does not illuminate the CEL and it applies sensor readings to spark timing and AF ratio.

I then used an external voltage regulator, a transpo540HD, that has an internal potentiometer for adjusting voltage.  I removed this potentiometer, soldered wires to the legs, and ran them to a larger potentiometer on my dashboard, next to my voltmeters and ammeter.  I also added another heatsink to VR backside with a small 60MM computer fan as I noticed it getting to 120+ degrees when it was asking the alternator for everything with 8+ amps of field current.

I can now choose any voltage between 12.8, and 15.3v, by twisting a dial, but allowing over 14.7v can trigger the CEL and 'limp home' mode where the ECM reverts to preset values on A/F ratio and spark timing.

My ammeter is currently wired to read total alternator current, so I can easily see when it is maxed out for a given rpm.  I can tell by experience, but also when more rpms do not raise voltage to my setpoint, or if adding more loads does not increase output.

I could benefit from an alternator that can produce more when the engine is hot and idling, but at 800 rpm or more, a higher rated alternator would do nothing for my small capacity battery bank and electrical loads.  if I had more battery capacity, then I would benefit from a higher rated alternator more capable in the 550 to 1100 rpm range, but much depends on the amount of battery capacity and the level of depletion and the health of the battery, as healthy batteries require more amperage to be brought to a higher voltage when depleted.

My alternator is a Chrysler rated at 50 amps idle and 120 amps max, and my ammeter reveals this to be mostly accurate, but my engine idles hot at 550 rpm( factory service manual states 750rpm!?), and max amps there is about 43amps, but at 800 rpm this is in the mid 70's.

For those that made it this far and are interested, I have a more detailed write up with some Pics, on my VR modification here:
https://vanlivingforum.com/Thread-Your-Vehicles-voltage-regulator?highlight=voltage+regulator

I've just been skimming all the responses but imagine I Love Lucy trying to comprehend all this. I'm ready to round up a wagon and team of horses, or just do what the dust bowl hobos did: walk. :-/

Seriously, thanks to all of you who have taken the time to write. I do appreciate all your info. I have an extremely busy colleague with 3 engineering degrees, mechanical, electrical and one other. Everybody has different opinions on the right way to go, but if I could get him to do the install and teach me how not to wreck it, it would probably work.
 
SternWake said:
Sorry about the 6 week thing, I misread the intent, disregard the previous recommendation, unless you cannot find someone local, then just get the jumper pack and go find the person who can.

Way more reliable is a secondary battery as a house battery, and later you can add solar when you possibly get tired of  house battery replacement every few months, a solar panel which might fit between your minivan's roof rack Would pay for itself in extended battery life.

For a Minivan, and your stated usage, I would recommend an group 31 AGM  properly secured somewhere in the back as a house battery.

These 4, are in my opinion,  best group 31 AGMs:
125 Amp hours:
http://www.impactbattery.com/lifeli...battery.html?gclid=CLDxmoamm9ECFQ1ufgodSj8BAg

This one has 20AH less capacity:
https://www.amazon.com/Lifeline-Mar...580&sr=1-1-catcorr&keywords=lifeline+gpl-31xt

https://www.amazon.com/NorthStar-Ul...080301&sr=8-1&keywords=northstar+group+31+agm

https://www.amazon.com/Odyssey-31-P...83080330&sr=8-1&keywords=odyssey+group+31+agm

Mid range quality:
https://www.amazon.com/VMAXMB137-Ba...8&qid=1483080017&sr=8-5&keywords=group+31+agm

This is one of the most budget oriented 12v AGM's. Know someone with a Sams club card?


http://www.samsclub.com/sams/durace...32&selectedTab=allProducts&_requestid=5483729

That battery is a Deka Intimidator AGM. If treated properly, it is only rated at 1/3 (total the cycles to 50% charged) of the Lifeline, BUt if both were to be treated poorly( chronically undercharged), it will likely  last 3/4th the total amount of cycles of the Lifeline.

It is likely about the same quality as this:

https://www.amazon.com/110Ah-Batter...=1483080391&sr=8-1&keywords=UPG++group+31+agm



One should put the battery in a battery box like this, and make sure it is properly secured to floor or seat anchors:

https://www.amazon.com/Camco-55373-...F8&qid=1483079433&sr=1-3&keywords=Battery+Box

https://www.amazon.com/NOCO-HM318BK...rd_wg=rStaZ&psc=1&refRID=VRC46XVPN5GW51XKCHW5


https://www.amazon.com/Newport-Vess...F8&qid=1483080715&sr=8-4&keywords=battery+box

https://www.amazon.com/UPG-40790-Bl...rd_wg=v23LI&psc=1&refRID=GNK42CGPJY003413FP0B

Those 2 or3 accept group 24 and 27, not group 31 batteries. buyer beware.

I would also recommend  the AGM  be fed  with no thinner than 6awg cable from the alternator, through one of the many 'isolating' devices available to protect engine battery from house battery loads.

Hook this harness to alternator (+) and mounting bolt(-)

https://www.amazon.com/Keeper-KTA14...sim_263_1?ie=UTF8&refRID=147ND97WNXYBJX94R5M6

With this connector  on this trailer harness above, you can easily disconnect the whole house battery box from the vehicle's alternator.  You 'could' connect to drive, and disconnect when parked. But there is the human error factor to deal with.

If you wanted the higher$$ AGM batteries, those 'should, ideally' get fatter cable as they have no amperage limits when recharging, but, the les$er AGM's should likely not be allowed to suck on 4awg or thicker cables from alternator at ~10 feet one way distance.  Top quality 4awg or thicker custom cables cables can be acquired here :

http://www.genuinedealz.com/custom-cables


Below, is an Automatic voltage sensing relay.  As soon as it sees charging voltages from alternator, it closes the circuit and charges house battery.  Soon as voltage falls below a certain limit, after engine is turned off, it automatically separates.

http://www.allbatterysalesandservice.com/browse.cfm/4,2705.html

https://www.amazon.com/Bussmann-RB-...=1483081276&sr=1-4&keywords=battery+separator

There are literally dozens of different products and methods for protecting engine battery from house loads and charge while driving. The linked product above requires no tapping of a live 12v ignition circuit which allows the use of a cheaper continuous duty solenoid.

These isolating devices need not be in engine compartment on firewall, or next to alternator, they can be next to house battery, perhaps even mounted on the plastic battery box itself, with a fuse inbetween house battery and solenoid which then goes to the alternator directly.  IF the wire goes instead to engine battery which is the more common method, but causes slower recharging), then another fuse is required next to that battery.
  One of those basic battery boxes above can be customized with USB outlet, 12v  outlets and voltmeter.

YOu could have a mechanic properly mount the battery box in back,  properly run the fused  cables through floor to alternator (+) and mounting bolt(-), and wire up the voltmeter, 12v power port, and USB outlet, and have a pretty reliable system, as long as you drove each day, or generally keeping the house battery above 12.1 volts.

If you ever get to plug into the grid a regular smart charger of 20 amps or higher, would go a long way in extending battery life, as it simply takes so long to get a battery recharged to 100% full, especially one which has not gotten there for a long time.

Which plug in charger I would recommend depends on which battery you get, but any plug in charge is better than no plug in charger.

Later on, if one gets tired of having to drive, or perhaps just Idle when parked, to keep the battery from going much below 12.1v, Solar can easily be incorporated, and take up the slack.  

Any solar is better than no solar, but more is better.  Size panel(s) to roof racks.  Shoot for 2 watts per 1Ah of battery capacity, but the fridge alone will need no less than 60 watts in good sunny shade free weather to break mostly even.
I'd love to run all my accessories off solar but I've been told that's not possible. Supposedly there are folks who designed vehicles that ran on water as the only fuel source, but then as the stories go, those folks suddenly disappeared. I've always thought, we the human race, could come up with better systems of transport and mechanisms to drive them. I mean, how can we be so shallow that we drive vehicles with no invisible shield to prevent one vehicle from crashing into another and then humans get maimed and/or die due to lack of such a vehicle buffer component? I swear I must have landed here from another planet where technology was more advanced. Meanwhile, here now as an Earthling, I try to interpret the info above. I have not priced solar panels but how much can they cost??? One line I understand in the msg above regarding solar is "more is better."

I watched a video about solar recently, can't remember if it was CRVL or a lady who had her own channel. She was a good techie and had a large panel, which she planned to attach to the side of her vehicle so she could park the vehicle in the shade with the panel facing the sun. And she planned to make it detachable so when she needed to she could move it further away from the van so the van got deeper shade. That much I could comprehend and thought was an innovative approach.

Lots of studying to do from these messages, and the forum info on solar panels. How I wish I could run fridge, laptop, cell phone, and any other gadgets I need on panels only. Thanks for the info!
 
Thank you for clarifying the types of batteries in a way that I could understand! Very helpful.
 
You can, just time, knowlege & money, where there's a will there's a way.

Note travelling around regularly gives you lots of free electricity, still a challenge to optimize deep-cycle recharging from stock alternator / regulators.

And stopping in campsites with shore power makes things very painless!

But it's *stationary* boondocking with heavy usage that requires really unusual measures.

Check this guy out, he's the real deal:
https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/
 
Optimistic Paranoid said:
Let's start by defining a charge cycle.  A charge cycle is where you draw a certain amount of power from a battery, and then fully recharge it.  Hold that thought.

There are three types of batteries.  Engine starting batteries, RV/Marine batteries, and true deep cycle batteries.  Engine starting batteries are built with lots of THIN lead plates.  The idea is to get the maximum amount of square inches of lead in contact with the acid.  This provides the maximum cranking amps.  They are designed to start your vehicle - which may take them from 100% charge down to 95% charge.  The alternator then brings them back up to 100% while providing power to run all the electrical/electronic stuff on your car while you are driving.

Deep cycle batteries have much thicker lead plates.  They are designed to maximize the number of charge cycles you get from them.  They are designed to routinely be drawn from 100% down to 50% before being recharged.  Good ones will give you 1,000 or more such cycles.  If you started drawing engine starting batteries down to 50% before recharging, you'd be lucky to get 40 or 50 cycles out of them before the battery fails.

RV/Marine batteries are a hybrid between the two.  They were designed for use on boats, where they not only had to start the engine, they also had to power the anchor lights all night when the engine was off.  They are usually good for 400 to 500 charging cycles.

Bottom line here is that a "heavy duty"engine battery usually just means it has more cranking amps, NOT that it will stand up to more charging cycles than a standard engine battery.  For what you're trying to do, you should get an RV/Marine battery installed.
Thank you for clarifying the various kinds of batteries in a way that my simple mind could understand!
 
John61CT said:
You can, just time, knowlege & money, where there's a will there's a way.

Note travelling around regularly gives you lots of free electricity, still a challenge to optimize deep-cycle recharging from stock alternator / regulators.

And stopping in campsites with shore power makes things very painless!

But  it's *stationary* boondocking with heavy usage that requires really unusual measures.

Check this guy out, he's the real deal:
https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/
Yes, that's just the issue. I want to do a lot of stationary boondocking in beautiful nature without having to run into town a lot. Thanks for summing up the issue. I will check that link.
 

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