Need help connecting a deep cycle battery to Minivan with isolator or a "kill switch"

[CampingOdyssey]

Hi everyone,

I'd like to install a 12v 100AH deep cycle battery in the back of my 2001 Honda Odyssey to power different 12v devices like a few lights (multi color strip led light and other 12v spot led lights), a small fan, a mini fridge (likely the Coleman 40 quart power chill) etc. I would also like to install a 750watt or 1000watt inverter to have the ability to charge up my laptop and be able to use any other 110 volt devices I may need. 

I don't really have much electrical experience but I'd like to install it myself. I've been watching videos and reading up on electrical systems trying to get comfortable with the idea of installing the set up but am still feeling a bit over my head. I'm hoping to get some help from anyone with electrical experience on this site, or possibly get pointed in the right direction to help me figure it all out. 

I plan on placing the deep cycle battery in-between the two front seats in my van. I'm going to go with an AGM battery because there won't be any ventilation other than the two front windows (from what I hear they are safe to have in inclosed spaces so I should be good to go). I found a cheap one on amazon the https://www.amazon.com/gp/product/B00S1RT58C/ref=ask_ql_qh_dp_hza

Initially, I don't plan on setting up a solar panel etc, so in order to charge up the battery I would like to hook it up to my van to charge while the van is running.

I have watched a few videos on installing an isolator (if I went that route I would likely go with the Stinger SGP32), which seems to be the most common method of hooking up a deep cycle battery to the car. However, I have also heard a few people mention that another, easier, option to connect the battery is to simply wire the two batteries together and put a "kill switch" in-between them. That way when the van is running, flip the switch on to charge the deep cycle battery, then when the van is off, flip the switch off so power won't draw from the starter battery when using power in the back. From what I understand the isolator is just a safety precaution to insure you won't forget to flip the kill switch and leave yourself stranded by draining the starter battery while parked and running electronics. I figure I'm pretty ocd so the chance of me forgetting to flip the switch on/off is pretty slim, and even if I do, I have a portable jump start device that I can hook up to my starter battery to jumpstart myself in case it does die.

Problem is, while I've heard a few people mention you can just install the kill switch instead of using an isolator, I haven't been able to find any explanation on how to actually go about installing the kill switch method. 

With my limited electrical knowledge here's how I imagine installing a deep cycle battery to the van using a kill switch instead of an isolator (warning to anyone looking to set up something similar, don't use this method as instructions, I am merely asking if this is correct): 1st step) with the van off, disconnect the negative (ground) wire from the starter battery to insure I won't get shocked. 2nd step) run a wire (2 gauge wire) from the positive terminal on the starter battery to the positive terminal on the deep cycle battery. That wire will have a kill switch https://www.amazon.com/dp/B01E16SGA4?psc=1 placed in the middle with a fuse on either side, one fuse by the starter battery and one fuse by the deep cycle battery (both fuses will be 200 amp, but not sure if that is the correct fuse or if I even need to instal a fuse(s) on this wire). 3rd step) run a ground wire from the negative terminal on the deep cycle battery to the negative terminal on the starter battery (2 gauge wire) I imagine I could also run a ground wire from the deep cycle battery to the frame of my van but not sure which method is ideal. 4th step) reconnect the ground wire to the starter battery to complete the circuit and the van should charge up both while the van is on and the kill switch is on.

Could anyone tell me if that is the correct method to hook up the two batteries? If not, how would I go about doing it? One other question, by connecting the batteries using the kill switch method, do I run the risk of over charging the deep cycle battery, ie: would I have to monitor the charge level and make sure to flip the switch off once the battery is charged while driving, or will it just automatically stop charging once it is full? Are there any other potential problems setting up the deep cycle battery with a kill switch? Could it be dangerous to to it this way? If its too much trouble for what its worth (simply saving the $50 or so on the isolator) than I'll just go ahead and set up the isolator. Any advice on which option is best would be helpful. 

Once I have successfully connected the deep cycle battery to the van (with either an isolator or kill switch) I'm going to then need to hook up all my electronic devices to it. Again, not having much electrical experience, I'm still wrapping my head around this process. I'll try to explain where i'm at with "figured it all out" and if anyone can tell me if I have it all wrong or if I'm heading in the right direction that would be helpful........ I will connect the positive and negative terminals from the deep cycle battery to an inverter using 2 gauge wire with a 200 amp fuse on the positive wire as close to the deep cycle battery as possible. That way I can plug in all of my 110 volt things like laptop and anything else I may use. I will also connect a 12 way fuse box to the positive and negative terminals on my deep cycle battery using 2 gauge wire. On the positive wire going to the fuse box I will install another kill switch https://www.amazon.com/dp/B01E16SGA4?psc=1 in case I need to cut power to all my electronics quickly. I didn't plan on placing a fuse on this wire... but should I?) Then as I start buying all my 12v devices I will connect them to the fuse box using 12 gauge wire or whatever wire comes with the device I am hooking up. As far as the correct fuses to install in the fuse box corresponding to each of my electrical devices, Im not sure what size fuses I should be using. One other thing I'm concerned about is the fact that with the setup I described above I will have 3 different 2 gauge wires hooked up the the deep cycle battery and I'm not sure if that is a bad idea. I saw one guy had a separate terminal box to hook up to my deep cycle battery and then he had the fuse box and inverter to that. 

Only thing I think I'm missing is a device to monitor the level of my deep cycle battery to know how much power I have left. That way I can figure out when I need to recharge (I plan on recharging it to full once the battery hits about 60%). Not sure what that decide is called, were I can find one and how to hook it up.

Anyways that's where I'm at so far. Not sure if I'm heading in the right direction or if maybe I should just contract the work out and have someone wire it up for me. I'm a bit concerned about electrocuting myself while setting it up and possibly starting a fire or electrocuting myself at some point down the road when least expecting it. Any help would be appreciated. Thanks for taking the time to read. Have a good one.

 

[John61CT]

I would also like to install a 750watt or 1000watt inverter to have the ability to charge up my laptop and be able to use any other 110 volt devices I may need.

Most devices with a charger or "power brick" are in fact low-volt DC devices.

Easy to find 12V converter with the right voltage, plug spec and polarity.

Much more efficient than going through an inverter.

Best if at all possible to avoid needing one at all.



Sent from my Nexus 6 using Tapatalk

 

[jonsun]

if you buy a TEC fridge you

a. need more than one battery
b. might as well get a dorm fridge/freezer...it uses about the same
c. are going to need a couple hundred watts of solar

You need to get something like a dometic cf-018, its a real cooler and uses 1/4 the battery

 

[jonsun]

and you need like a 200-400w basic inverter. save your money for a solar panel. You're going to have to run the engine 10hrs a day to fill the battery your way.

 

[highdesertranger]

1st problem I see is the thermo electric cooler. those are energy hogs. it says it draws 5 amps, that's 5 amps contentiously after 10 hours your battery is dead with just the cooler and no other loads. 2nd with only charging off the alternator it's going to take about 7-9 hours of continuous driving to recharge it to 100%. my advice would be to get a 12v refrigerator and a solar set up. what you proposed is not doable IMHO. you need to rethink your system. start reading and asking questions here and we get you on the right road. highdesertranger

 

[CampingOdyssey]

Hey John61CT

Thanks of the input. I was going to use the inverter to power any sort of device I may need, like hair clippers potentially, etc. More or less a safeguard in case I needed to power a device in a jam that I didn't have a converter for. When I wasn't using the inverter I would just turn it off to it wouldn't use any energy (I assume that's how it works). 

To charge up my laptop (macbook pro) it would be a good idea, like you mentioned, to just get a 12v converter. I found one doing a quick google search that comes with a end that can be plugged into a cigarette lighter. I guess I would need to then have a cigarette lighter type adaptor hooked up to the deep cycle battery via the fuse box... could you (or anyone else) recommend a good one? 

bardo

Thanks for the info. I guess the Coleman fridge is a bad idea. I didn't know they used that much energy. I just picked a camper fridge that was priced good and had a lot of good reviews on amazon. 

I have seen a few van dwellers using the domestic brand fridge you mentioned. Do you think I would be able to run that with a 100ah battery, along with a few lights, fans without having to recharge every 15 mins? I was thinking I'd put it on its lowest setting to save energy. Does anyone know how many watts the domestic fridge pulls at its lowest settings?

From what I can gather a led strip light should be around 40 watts (one of the led strips that has a bunch of different color settings, and can be dimmed as well). A Led spot light should be around the same at 40 watts. A fan should be around 35 watts. And the macbook says on the 110 charger I have plugged into the wall that it maxes out at 85 watts (with a converter I'm guessing it would max out at 75 watts). All in all (without the fridge) I was thinking I'd be pulling max 160-170 watts an hour max, that I thought I should be able to run for 10 + hours before I had to recharge. Am I doing the math wrong or am I underestimating how much power I will be using?

Maybe I'm going to have to end up installing a solar panel set up after all. I am trying to hit the road as cheap as possible and sort of test the waters to see if this is something I can actually get into. I'm afraid I'll spend a bunch of money, do it for a couple weeks then give up and thus waste all the money I invested into it.

 

[CampingOdyssey]

highdesertranger

I guess I was over estimating how quickly the alternator would recharge the battery. On the amazon page I read that the stinger isolator said 200 amps. I thought that meant if it would charge up a 100ah battery fully in a half hour. So if that was the case, if I was charging a battery from 50-60% it should take 15 mins. Lol... I guess I'm missing something and or not understanding how an isolator works and how quickly the alternator will recharge a battery.

Maybe I'll just start off with no fridge and use the cooler and ice method while I get my feet wet traveling. Without a fridge, would a 100ah battery be enough power for a couple lights, fan and recharging a few devices from time to time without having to run the car for 7-10 hours a day?

How can I determine the rate in which a alternator will recharge the deep cycle battery? Thanks for your help.

 

[John61CT]

A lead chemistry battery needs to be fully charged - true 100% - as frequently as possible to last a decent lifetime.

Fossil fuel is great for the first hour or two, bulk stage lots of amps needed quickly.

The remaining 4-8 hours is very low amps, total waste to burn fuel, perfect for solar.

Sent from my Nexus 6 using Tapatalk

 

[John61CT]

When I wasn't using the inverter I would just turn it off to it wouldn't use any energy (I assume that's how it works). 

Yes, but IMO at least delay, size it according to what you actually need it for.


> To charge up my laptop (macbook pro) it would be a good idea, like you mentioned, to just get a 12v converter. I found one doing a quick google search that comes with a end that can be plugged into a cigarette lighter. I guess I would need to then have a cigarette lighter type adaptor hooked up to the deep cycle battery via the fuse box... could you (or anyone else) recommend a good one? 


Ciggie lighters are pretty useless IMO, but tons available cheap.

Better to either wire it in place permanently, or use ​Blue Sea twist lock style, Euro style (​Merit, Powerlet, Hella), or a small Anderson plug.


Sent from my Nexus 6 using Tapatalk

 

[jonsun]

"I just picked a camper fridge that was priced good and had a lot of good reviews on amazon. "

so you already bought it? or you bought a different one? amazon reviews are often complete garbage for stuff we're doing. people arent using them to live out of, they're driving a truck down the road 10hrs a day. and frankly TEC coolers just plain suck even if they werent the least efficient crap made.

"I have seen a few van dwellers using the domestic brand fridge you mentioned. Do you think I would be able to run that with a 100ah battery, along with a few lights, fans without having to recharge every 15 mins?"

you'll run it a whole lot longer than you will a "camping fridge" and it will be 3x colder.

"I was thinking I'd put it on its lowest setting to save energy. Does anyone know how many watts the domestic fridge pulls at its lowest settings?"

first stop looking at watts and look at amps. fridges dont work that way. they pull their amp draw when running and then cycle on and off. so you look at average amperage consumption.

the "camping fridge you already bought draws 5-7 amps continuously and has no setting. A $350 dometic unit draws about 3 amps when the compressor is running and cycles on and off depending on your setting. about 1.5amps per hour to keep it around 35-40f.

either way you have to get a solar panel.

"From what I can gather a led strip light should be around 40 watts (one of the led strips that has a bunch of different color settings, and can be dimmed as well). A Led spot light should be around the same at 40 watts. A fan should be around 35 watts. And the macbook says on the 110 charger I have plugged into the wall that it maxes out at 85 watts (with a converter I'm guessing it would max out at 75 watts). All in all (without the fridge) I was thinking I'd be pulling max 160-170 watts an hour max, that I thought I should be able to run for 10 + hours before I had to recharge. Am I doing the math wrong or am I underestimating how much power I will be using?"

if you pull 160 watts you will have 5 hours max. You cant just run a battery all the way down constantly like that. It kills them really fast. LED light strings should pull about 12-24 watts max (1-2 amps). Just scrap the notion of a strand and get a few fixtures that pull about 3-5 watts each.


we've all been through all this. probably everyone here is going to tell you the same.

1. DO NOT use a TEC fridge at all.
2. you cannot run a battery flat every day
3. you cannot rely only on your alternator 

Either get two batteries and at least 140w of solar, or forget an active cooler and use ice.

 

[CampingOdyssey]

bardo

Sorry for the confusion, I have not bought the Coleman fridge. I haven't bought anything yet, I'm just in the information gathering stage at the moment. I'm trying to create a list of everything I'll need including supplies for the trip, as well as components in the electrical system. 

If I do end up getting a fridge, I will be forking over the extra dough and purchasing the domestic thanks to the advice from you and others who have replied.



I am, sadly enough, being to realize my initial thought of running the system solely off my alternator is not possible. I thought the time in which a alternator could recharge the battery was measured in minutes, not hours. I now realize that this sort of system will require multiple charging methods to run effectively.

As I mentioned, this will all be housed in/on my minivan so if I do go with a solar set up, I will likely stick with just 1 panel. In order to keep it as stealthy as possible, I like the idea of the thin flexible panels so I can secure them directly to the roof via tape. I have read that a solar panels efficiency is effected by the operating temperature so doing it this way will cause them to run hotter than a insulated fixed panel, but as long as the sacrifice isn't too great I would take stealth over speed of charge. I did a amazon search and found this one: https://www.amazon.com/DOLSS-120wat...91796062&sr=8-6&keywords=flexible+solar+panel that seemed would be a good fit for my needs.

I'm thinking two batteries to begin with may be my best option. I thought I could get away with one but I guess I was underestimating.


Now with a solar panel added to the mix, my concern is getting through the night with the type of electricity I'll be using. So let me see if I'm understanding it all so far.... A domestic fridge (if I get one) running at 1.5 amps would be 36 amps per day with 18 amps being drawn when the sun is down. A light system that was running at 2 amps for 6 hours a night would be 12 amps per night. A fan at 3 amps (still estimating 30 or so watts for the fan) for 6 hours a night would be 18 amps per night. And recharging my laptop for 2 hours per night at 8.5 amps would be 17 amps per night. That would be a daily use of 83 amps. With 65 of those coming at night when the sun is down. Add another 20 miscellaneous amps at night and that would bring me to 85 amps used when the sun is down. With that set up, two 100ah batteries and a 120watt solar panel running not perfectly efficient due to the heat, along with a isolator connected to the battery (if I still need one with the solar panel) do you all think I'll be good to go? If so what type of charge controller would be good for my solar panel set up? Ideally a charge controller that I could add a second panel to at some point in the future if I had the room and need for it. Thanks for you help.

 

[jonsun]

dometic...not domestic

12v clip type fan from walmart = .8a
laptop = 1-2a (nowhere near 8.5a even full bore processing)
lights = .5a (2 amps of LED is ridiculously bright)

40a fridge + 7 amps on fan + 5 amps on laptop + 2 amps on lights = roughly 55A

Now you use the alternator for a bulk charge and let the panel top the battery off. The issue is as the battery gets full it has to charge slower and slower. So when its around 50% the alternator can easily throw 50A an hour into it. Then you need the panel to top it off from 90-100% so you only need like a 50-80w panel. Someone on here was giving away a 70w one.

there's a whole nother level of charging issues in that you really need 14.8v for charging. Your alternator plus cable run wont get you there. You need a real charger or a variable voltage power supply to really charge the battery.

 

[SternWake]

2 amps consumed for 4 hours = 8Ah consumed from battery.

  Say that a battery has 100Amp Hours capacity.

This means it, when newish and fully charged, it can power a 5 amp load for 20 hours before battery voltage falls to 10.5v, which is considered 100% discharged.  50% under no load, occurs at about 12.2v.  Voltage seems to fall at a more rapid pace under 12v.

A Dometic or Engel or many various other 12v compressor fridges draw anywhere from 0.5 AH each hour, upto 6 AH consumed each hour.  The average consumption lies somewhere in between those extremes, the variables are many, but the big 2 are how hot inside the vehicle it is, and how much warm stuff was just placed inside. Comparing similar Cubic foot 12v compressor fridges, there is not much electrical consumption differences from brand to brand.  The installation/ location of the compressor fridge can make or break its performance.

Mine , 1.8 cubic foot/ 50 Liters vitrifrigo c51is  consumes 0.62 AH each hour average in 75F days low 60 overnight lows, keeping 33.5F interior.  But this is with extra insulation and very good ventilation of the cooling unit.  In hot weather It consumes closer to 1AH per hour average in my usage.

This Simple ON off switch is rated to pass 300 amps continuous.  Overkill=good
 https://www.bluesea.com/products/6006/m-Series_Mini_On-Off_Battery_Switch_with__Knob_-_Red

A battery can only be charged so fast, and the more charged it is, the slower it charges.  True 100% state of charge from 50% is hard to accomplish in less than 4.5 hours, and that is with a source capable of high amps seeking and holding a high voltage, and a still healthy battery.  A battery that has not recently seen a true full charge, charges to 100% even slower.

Often the vehicle's voltage regulator only allows 13.6v to be held once the vehicle is all warmed up, which can greatly slow charging of a depleted battery.  About 2/3 less amps flow into my depleted battery at 13.6volts compared to 14.7v when about 75% charged.

  The voltage allowed is highly variable among different vehicle platforms.  A voltmeter reading voltage at the battery terminals helps one to see the  potential voltage and thus potential battery recharging speed, when driving  their vehicle.  Voltmeters in ciggy plugs stray from actual battery terminal voltage when there are bigger loads on the vehicles electric system, like headlights, blower motor, rear defroster, but are much better than no digital voltmeter at all.

https://www.amazon.com/Universal-Ba...coding=UTF8&psc=1&refRID=B11XFYB315DZVFTRQG98

When driving with a depleted battery, one really wants to see 14's as the higher the voltage, the faster the battery charging will be, especially with thicker cable between alternator(+) stud---->4awg cable----->Blueseas6006mManual ON OFF Switch--4 awg cable--->  100 amp Fuse/Circuit breaker------->House battery (+)

https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A

Cable terminations are very important for performance and longevity of the circuit.  Auto parts cables are overpriced junk.  Figure out the lengths needed, and order:

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

Manipulating the vehicle's maximum voltages can be done, but could be difficult depending on vehicle. Pricey products exist to fast charge at higher voltages when driving.

Easier to have 100+ watts of solar to finish off the 100AH battery over the day after driving early in the morning.
Mo solar mo bettah.  

With the fridge, Keep the vehicle interior cool, somehow.  Reflectix on the sunny side windows. Computer fans exchanging inside air for outside air will make up for the electricity they use by keeping vehicle interior cooler as the fridge will run much less often, and for shorter duration. 

Good Ventilation is pretty key to comfort of both human, and fridge.

 

[John61CT]

I'm thinking two batteries to begin with may be my best option.
....
Ideally a charge controller that I could add a second panel to at some point in the future if I had the room and need for it.

You will want as much solar as fits on your roof, maximize that by the shape of the panel and the watts per sq in efficiency. Yes you can add more later with panels.

But not batteries.

Buy all your consumers first. IMO Engel fridge way to go, or one with a Danfoss compressor, both much more efficient than Dometic.

Use a cheap starter battery, shore power charger, and a good battery monitor to get a handle on what 24 hours conservative usage will be in AH, then multiply that by 5 to get the minimum AH batteries you need.

Use Sams Club or Batteries+ Duracell branded Golf Car 6V pairs and round up.

Make sure this House bank is isolated from Starter batt. except while running the engine.

Ideally rework your Alt to charge House bank directly with voltage and temp sensing there.

Make sure to track its charging so you're getting max amps at proper voltage long into Absorption, after switch from CC to CV.

If you don't want to carry a small genny and your stock alt is lacking, consider beefing up the latter so you can get a fast big-amp charge running at "hot idle".

But a small genny like Honda eu2000 will save wear and tear on your propulsion engine.

 

[highdesertranger]

lets get this straighten out. do you mean a Dometic or domestic? Dometic is an RV appliance manufacturer. highdesertranger

 

[user 37446]

Wow, you've asked a series of questions that are not quickie answered and potentially have several safety and cost considerations for your situation.

I haven't read through all the replies but already I see posters gently trying to get you to abandon the inverter, forget charging your batteries in 15 minutes and be aware of the need to use some other charging sources. All of which are true.

I'll tell you one thing about the stupid Coleman PowerChill, it's almost a waste of money. I bought one thinking that it (and I read a lot of Amazon reviews) might possibly work. Guess what, even inside the house, the POS wouldn't cool more than 20 degrees (from 70 to 50) in even 6 hours. In a car with sunlight and hot days? Forget it.

The other thing I'd recommend to you is go to the electrical subforum and spend a couple evenings/days just reading. Theres hundreds of threads that are very detailed about how to charge batteries. I'm actually amazed at the patience of the experienced posters on this form, you know, the ones with reputation ratings over 50 and thousands of posts, who will try to guide you instead of just rolling their eyes and telling you to search the forum first. 

Since I have a 0 reputation and less than a couple months here, I will tell you what I did - I read the forums for awhile, watched about 20+ hours of UTube videos then I understood a whole lot more.  

Don't take this personally but use the "search" function first. You'll actually be able to "get it" quicker by seeing what and why people did what they did. Then you can come back and fine-tune your questions.