SternWake and other expert advice needed on electrical hookup

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Seeker

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I noticed that SternWake had hydraulic crimping tool. Are either of these worth buying Amazon http://www.amazon.com/Hydraulic-Battery-Terminal-Crimper-Crimping/dp/B00CUQ042Q and harbor freight http://www.harborfreight.com/hydraulic-wire-crimping-tool-66150.html My van has a #4 AWG wire coming up right behind the drivers seat. It is in some kind of box that I think was a winch control. I want to temporarily hook it up to a fuse box that I will test my vent fan and led light installs with and I need to install a ring connector on the hot and ground lines.

Are either worth buying? I would probably get the Harbor Freight even though its more as it is about a mile from me and no wait.
A SEEKER
 
Both kits use the same crimper, the HF unit appears to have the same undersized dies that I have. While they say they can do 0 wag wire, they cannot. The biggest die can only do a medium walled 4 awg ring terminal.

Of the two the Amazon kit appears to have more appropriately sized dies.

I am not very impressed with my HF crimper. I've used it a bunch, certainly it is better than a hammer crimp, but the dies are a joke. Ever hear of 7 awg wire?

Apparently China has.

But if only for 4 awg wire, it should work OK. Crimping can be an art form, and this tool is like having a decrepit paintbrush.

check out this article. This guy really knows his stuff and his opinion of the HF tool is not good:
http://www.pbase.com/mainecruising/battery_cables&page=3


But the marine environment is more demanding than that of RV. This guy would give all my wiring and terminations a complete failing grade.
A proper quality crimp took is seriously expensive
 
Guess I would be just as well off with a hammer crimp for temporary although in tight places may not be easy.

on another note Sternwake. I really like the idea of how you have your batteries separated with the manual switches. I want to be able to use one battery and charging the other totally separate. I also like not depending on some automatic switching devices and would except the risk of not turning the right switch at the right time and the consequences Would you be willing to share info on what kind of switches and how you wire them up. I am familiar with the battery selector switches in boats but can't imagine how your switches are wired. Do they still use some kind of latching solenoids?
 
No, I utilize nothing automatic in my system. I want to direct where current comes and goes, and automatic systems would not allow that. I use no solenoids, latching or otherwise in my battery system.

3 manual Blue seas Mini series switches, one for the ignition. one for all the house loads, and one for the Solar. Turning any of the 3 switches to "both" renders the position of the other 2 switched mute though.

http://www.amazon.com/Blue-Sea-Syst...66989&sr=8-3&keywords=blue+sea+battery+switch

Wiring them is pretty simple. On the Ignition Switch, there are 3 studs. I have the stud marked 1 going to the battery in the engine compartment, stud 2 going to the house battery, and the common stud goes to the original battery post (+) clamp.

I use 2 awg cable on this circuit. I could shorten the circuit going to the original (+) battery terminal from common stud on the ignition BS switch, but easiest was to just run the cable to the original battery terminal and electrical tape the piss out of it. This way it can be returned to stock easily if need be.

The studs on the back of the switch can accept many ring terminals. I use them as power distribution points and to connect the other switches to battery 1 or battery 2 with the common stud going to the fuse block on my load switch, or to the solar controller on the Solar switch.

Do note that one should not turn the ignition switch to off with the engine running, it can fry the alternator. These switches do not run the field wires through the switch, as do some other switches which will protect against this event.
One should not make a habit of turning the solar switch to off during daylight, and if one does, they should not turn it back on for several minutes. Things inside the charge controller might release the magic blue smoke if it is reattached/ connected too quickly, and this goes for many electronic items too.

These BS switches are 'make before break' meaning they will combine the batteries when turning the dial before removing the switch from the single battery.
 
I am only slightly confused on how you are doing this. Don't you have 2 house batteries and a separate starter battery? I do think those switches are a good way to do it though.
 
I have a hammer crimper and have been happy with it, it works, I don't have to worry about it failing and as SW mentioned, the dies were all just slightly off with many of the affordable hydraulic kits. If you look at a cutaway from a properly crimped connection, you can see the side of the individual wires inside are not separate nor are they solid but instead have changed shape and are fused. I had concerns the units you linked wouldn't be able to do that with standard gauge wiring and decided if I was going to compromise anyway I'd just get the hammer style.


SternWake said:
Turning any of the 3 switches to "both" renders the position of the other 2 switched mute though.

I think you mean moot not mute :)
 
I did mean Moot. Wish I could blame the mistake on auto correct too.
---------

I used to have 2 house batteries. Two group 27 flooded deep cycle batteries hardwired in parallel. I also had one group 27 battery in the engine compartment as a starting battery. I found I never needed all the house battery capacity I was carrying, and I wanted to come closer to the manufacturer recommended charging regimen Via my 200 watts of solar. So since I cannot fit anymore solar without tremendous effort and expenditure, I lowered my battery capacity to better meet what the solar can put out.

Far too many people get giant battery banks and only have a small portion of solar, enough perhaps to replace the amp hours used the night before on a good sunny day, but more is needed than that to meet the manufacturer recommended charge rate.

My flooded USbattery recommends 10%, so my 130 amp hour group 31 wants 13 amps initial bulk current. My solar can barely do this, in summertime at high noon, yet this single battery is behaving better being cycled deeper nightly, than my 2 27's did previously, being cycled more shallowly but recharged at a slower rate by the same amount of solar.

Extremely difficult to have too much solar, far too easy to have too much battery for the solar one does have, and this is ok as long as there are other charging sources applied every so often which can meet or exceed the manufacturer bulk current recommendations. A true 100% recharge is very important every so often, and most every charging source will claim a full charge, when the battery is only 90 to 95%. With Flooded batteries, A hydrometer is the only real way to know when a battery is indeed fully 100% charged.

Never trust any automatic charger to fully charge a battery. They are designed to not OVERcharge a battery, and can easily fall well short of a true 100% recharge. Never trust a solar charge controller to do it either. When any charger indicates a full charge, it is not because the battery was tested and is indeed full, it is because it has gone through the programmed algorithm that some bean counter compromised engineer somewhere decided would make the lawyers happy, by not overcharging any particular battery.

The better solar controllers allow the user to change the absorption voltage and duration and float voltage for the battery, have a battery temperature sensor, and will also allow parameters to be set as to how long the battery is held at absorption voltage before being allowed to go into float voltage. Often prematurely, the float voltage is triggered and signs the sulfated deathknell for batteries, as in general they need 2+ hours at absorption voltages, and this ranges from 14.2 to 14.8 volts depending on the manufacturer. So you can see how one size fits all is not going to necessarily fit one particular size and the algorithms chosen by charger manufacturers are a compromise, and could be a bad one.

If you wanted to Split your house bank in half, then you would need a switch just for that task, and have this switch fed from another switch which switched ignition from engine battery to house bank. With all these connections is is important to use quality terminations crimped properly. Most important on the ignition switch as it will pass the most current, but no hammer crimp would pass a detailed ABYC inspection. A proper crimped battery lug, if cut in half mid crimp, would look like a solid wire. Hammer crimps are adequate, and nothing more, but the HF hydraulic crimper done poorly is not much better. One should test all such connections when high charging currents are being passed through them to see if they are getting hot, indicating high resistance. Bad connections have killed many a battery bank. A proper crimp is not just making sure the wire cannot pull out of the lug, but that there is a good low resistance electrical connection.

If you know the exact lengths of cabling needed, i recommend having high quality cables professionally made by those with the 1200$ crimpers and the skills to use them properly

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

Splitting the house bank can be good to increase the charge rate fed any single battery via too little solar. But discharging 2 house batteries in parallel means that Peukert robs less from the overall capacity compared to discharging each house battery by itself.

I have 3 switches so that either of my 2 batteries can be the house battery or the engine starting battery. My flooded 31 needs very high voltages every day, and once every 10 to 14 cycles it needs about an hour at 16 volts for the specific gravity to rise to the baseline maximum. I reset the solar absorption and float voltages to 16v to accomplish this. When i do this I change all the loads to the other battery via my load switch, to protect all the loads from 16 volts, which is in that voltage danger zone for many 12 volt appliances.

My other battery is an AGM which would be damaged if charged daily at the voltages my Flooded battery requires. Generally I cycle the Flooded battery 13 nights out of 14, and the AGM is kept at 99+ % 13 days out of 14. My AGM is a Northstar and has 930 CCA, and turns my engine over so fast it is frightening. And I like that. i don;t always turn the switch to allow my alternator to feed the house battery. I don't want the battery powering my compressor fridge to also see possible surges from the starter motor, so in this case the manual switch location, inside a cabinet behind the driver's seat is not very convenient. but at the same time i want to take full advantage of alternator current when my depleted battery is hungry. i have a fat cable between the alternator(+) and ignition stud on my Ignition battery switch, and this will allow the alternator to send huge currents into the depleted battery. About 2 to 3x what the original OEM/ Stock charging circuit could pass.

the shift key is failing on my laptop causing many of the lower case letters at the beginning so sentences. Apologies.
 
About 2 to 3x what the original OEM/ Stock charging circuit could pass. Is this only because the cable is large enough to pass the higher current? I am still learning. its hard to believe I once knew a lot of electronics. . . had a store and serviced TV,VCR, microwave ovens and some audio. sold my business when VCR's were going for around $400.00 bucks. I have forgotten the vast majority of what I once knew.

I very much appreciate your help and when I get whatever batteries flooded lead acid or AGM I will be seeking input some more. (like best places to mount the switches) It is too bad I can't find Lithium pack small enough for my needs that I can afford as they are the way to go in the very near future. I have been an LED Flashaholic for a number of years and love batteries like the 18650 rechargeables that seem to last forever as long as certain charging parameters are followed. Like how you take care of your batteries. I have to learn about absorption, bulk, float and all this mumbo jumbo that I have never worried about with my starter batteries.
Thanks again
A SEEKER
 
SternWake said:
the shift key is failing on my laptop causing many of the lower case letters at the beginning so sentences. Apologies.

The quality of your information has taught me to not be a crazy grammar nazi regarding your postings. A mis spelled word here, missing cap there. I do not even notice any more. The longer I am out of the higher educational system the more relaxed I get.

I have learned more from your postings than I learned in paid education classes.

On the subject... My 8 ton chinese crimper has served its purpose of getting me on the road. Now I understand the difference.

Thank you/

John
 
A SEEKER said:
About 2 to 3x what the original OEM/ Stock charging circuit could pass. Is this only because the cable is large enough to pass the higher current?

Yes, this is most of it, but fat cabling on the alternator circuit also allows the voltage regulator to 'see' the depleted house battery. Often people take the power for charging the house battery from the starter battery if they use a solenoid or some other automatic type combiner/isolator.

This has two issues.
1. The original alternator to starter battery cable is not very thick. it is as thin as the manufacturer thought they could get away with. It was designed to charge a starting battery which is 90%+ charged( and which will not ask for much current), and power the vehicles electronics/ engine management systems lights, ect.

When a deep cycle battery is tacked onto the end of this circuit, well a depleted deep cycle battery can ask for twice as much current as required by the stock electrical system. One can see how this this original cable is not adequate for passing all the current the extra battery can ask for when depleted.

My depleted 130 amp hour flooded battery can ask for 65 to 70 amps from the alternator.

My depleted 90 amp hour AGM just maxes out the alternator, 90 to 110 amps if there is enough rpm. Big banks of depleted healthy AGM batteries over fat wiring can easily burn out an alternator, and thinner wiring can be utilized to reduce the strain upon it. So busting out the 4/0 gauge wiring pretty much requires an alternator upgrade to one which can handle a higher duty cycle without overheating.

As the batteries charge up they ask for less, require less current to be held at any given voltage. Once the batteries are brought up to the vehicle's voltage regulator maximum allowed voltage, then the current tapers, as more voltage would be required to allow more current to flow and the current required to hold the battery at that voltage becomes less and less.

Number 2 issue, is the issue of the fully charged starting battery. If voltage regulator does not see the depleted house battery as a big load on the starter battery, and it will not if the cabling between starter battery and house battery is thin, then the voltage regulator will believe the starter battery is very close to full, and will drop the maximum voltage down to ~13.6. When this happens, the current flowing into the house battery falls into the low single digits. If it were allowed to be fed at 14.5 volts, much higher charging current would be required to get that battery upto 14.5v and hold it there, and the battery charges significantly faster.

With the blue seas manual switches I utilize, the alternator current first goes to the original battery (+) cable, then to the manual ignition switch, then to either or both batteries. I have added a parallel circuit, basically skipping all the original cabling. It goes right from alternator (+) stud to My manual ignition switch, through a 150 amp Circuit breaker. This makes for a much shorter and much fatter cable for less voltage drop, and allows the voltage regulator in my engine computer to see the depleted house battery, and allows the alternator to make all it can, limited only by available rpm, and what the battery itself can ask for. It also allows 14.9v to be held for longer, in my vehicle, but not long enough. If I remove the fully charged starting battery from the alternator circuit, then the 14.9 v is allowed for longer too. so there is some outwitting of the voltage regulator going on to get the most into the depleted battery.

These parallel circuits can be added to almost any method one uses to separate/ combine their batteries, and will greatly help to charge the depleted batteries much faster. These parallel circuits need to be fused.

The ground path needs to be beefed up too. If one uses the Chassis as a ground path for the house bank, then add another ground strap from chassis to alternator (-) too. Take extra care with chassis grounds. Make sure they are very shiny and clean very tight, and protected from corrosion with grease or liquid electrical tape, as they are prone to develop high resistance which can greatly reduce charging current, and cause other issues as well.

Fatter cabling in the alternator circuit will not have much of an effect with house batteries above 80% state of charge, as at this SOC, batteries cannot accept much current and the original wiring is adequate for this.

When deep cycle batteries are depleted, i want mine to charge up as fast as possible, and the alternator when wired with fat cables, can be very effective at bringing the batteries upto 80% state of charge. It can do in a half hour what might take a 200 watt solar system, in good sun, 5 or 6 hours.

When one can blast the thirsty batteries with some alternator amperage, and let the solar do the low and slow thing for a good 6 hours afterward, the batteries will come very close to that elusive 100% mark which is in fact very difficult to achieve, because it takes so much time.

Those with flooded batteries, need to get a hydrometer and see that when any charging source indicates the battery is fully charged, that the specific gravity of the battery will say otherwise.

Often automatic charging sources indicate a full charge, but are still charging at a fairly good rate. Mine will flash the green light, yet the battery willl still be taking 6 amps. If i did not have tools to count current, if i believed the green light, I'd be unplugging the charger extremely prematurely.

If you suspect your charger is a bald faced liar, load the battery until voltage drops below 12.8, and restart it. It will not restart if it sees battery voltages over 12.8v. I had to do this 10 times in a row on some one else's abused batteries to get the specific gravity approaching the point where it should be. They batteries had lost capacity, but the force starting the charger over and over again got them up to near their maximum capacity.

Really, with abused flooded batteries, one needs to be able to bring them up to 16 volts for a proper equalization charge, and very few chargers can do this.

So a solar controller that allows one to change the voltages can be a thing of beauty.

Last night, I noticed my battery was dropping a bit lower than i was used to seeing. The solar held it 14.9v for 2.5 hours in the early afternoon, then went to 15.3v, where I have set my float voltage. After an hour it was taking 1.6 amps to hold 15.3, and i busted out my hydrometer.

Full charge is 1.285, the 3 easy to check cells were at 1.255 .1260 and 1.270. i reprogrammed for 16 volts and 45 minutes later the lowest cell was 1.275, but then i lost the sun before reaching 1.285.

Right now it is reading 0.15 volts higher than this time last night, and the amp consumption is pretty much the same, but tomorrow I am going to get the SG upto 1.285 on all the cells
 
When using hydrometer to test specific gravity can that be done without resting a flooded battery for a number of hours and still get a fairly close reading or is a long at rest period needed?
 
I have the HF hydrolic crimper. On 1/0 or 2/0 wire, (with the #0 dies) I have to deform the lug to get it to fit in the dies. On small wires, it makes much better crimps than my racheting or regular chrimpers, but it does tend to crush the plastic.
 
specific gravity readings are pretty much directly related to state of charge.

There is a little bit of lag. If one equalizes a battery and lets it rest overnight, the sg can read 0.005 higher the next day.

Also the Sg will be different, lower at full charge after the cells are topped up compared to when the level is just over the plates and need topping up. this range can be 0.015 on a 12v battery, less on a 6v as each cell is bigger and taller.

a hydrometer with a built in thermometer for temperature compensation is pretty important. those plastic hydrometers are not very accurate or precise. the glass turkey baster style with glass float are orders of magnitude better, but obviously more fragile.

IMG_1613copy_zpsae3d76a3.jpg


http://www.amazon.com/OTC-4619-Professional-Battery-Hydrometer/dp/B0050SFVHO


This 5 minute editing rule is extremely annoying. I forget what i added, here is the whole post again
specific gravity readings are pretty much directly related to state of charge.

There is a little bit of lag. If one equalizes a battery and lets it rest overnight, the sg can read 0.005 higher the next day. The lower the state of charge the sg readings are significantly lower so that .005 is not really consequential. the battery does not need to be rested for accuracy.

When doing an eq cycle the sg at some point will just stop rising. daily regular recharges will likely not return the sg back upto the maximum one reads after an eq cycle stopping 0.005 to 0.010 shy of the maximum baseline. A daily EQ cycle would be detrimental. each battery will display a personality as to how SG responds to charging regimens so these numbers are not set in stone. good to establish baselines when the battery is new.

Also the Sg will be different, lower at full charge after the cells are topped up compared to when the level is just over the plates and need topping up. this range can be 0.015 on a 12v battery, less on a 6v as each cell is bigger and taller.

a hydrometer with a built in thermometer for temperature compensation is pretty important. those plastic hydrometers are not very accurate or precise. the glass turkey baster style with glass float are orders of magnitude better, but obviously more fragile.

IMG_1613copy_zpsae3d76a3.jpg


http://www.amazon.com/OTC-4619-Professional-Battery-Hydrometer/dp/B0050SFVHO
 
fat wiring can easily burn out an alternator, and thinner wiring can be utilized to reduce the strain upon it.  So busting out the 4/0 gauge wiring pretty much requires an alternator upgrade to one which can handle a higher duty cycle without overheating.

Stern: If NOT upgrading the alternator, does it make sense to leave the stock wiring between alternator and starter battery (so as to limit strain on alternator), but use fat wire between house and starter battery so that the vehicle's voltage regulator can "see" the depleted house battery as you say?


Take power right from the alternator(+) stud, instead of the engine battery for the solenoid. Fuse properly to protect the thick wire.
I'd use no less than 2awg.


The above (taken from another of your posts about alternator charging) does not sound like the wiring setup you described here.  Is going directly from alternator, through ACR, to house battery, using fat wire, advisable if using stock alternator?

Thanks for your input.
 
How much battery capacity you looking to charge?

I have accumulated more data And experience since the beginning of this thread
 
When my posts are short, I was typing on my phone.


Since 8/2014 I have upgraded my vehicles voltage regulator, which controls the alternator's output in an attempt to seek and hold absorption voltage.  I can now spin a dial and choose the  target voltage.  If the alternator can make enough amperage to maintain that voltage, that is what my voltmeter displays.  If it can't, then voltage does not reach that target I set.

I also have a Alternator temperature sensor, and a battery temperature sensor, and a voltage regulator temperature sensor.  I also now have am Ammeter on my dashboard.  First it was wired to show total alternator output, now it is wired to show amperage into or out of my single 90Ah AGM battery which now does double duty as starter and house battery, since june 2015.

My alternator temperature sensor has revealed it gets hottest when Idling and maxed out producing all it can at idle speed.  This is an 89 dodge van with a chrysler 50/120 alternator, 50 amps idle 120 amps max. Other vehicles will  perform differently and perhaps to a huge degree.

220 F is th etemperature one wants to keep the alternator under, and I found I can achieve this pretty easily when the motor and alternator are hot, and the the motor is idling and I am  asking it to seek and maintain 14.7v, but the electrical loads... blower motor on high, lights on high beam, and depleted battery require more than the 50 amps this alternator can produce at idle.  Temperatures might be 130F whan I put it in park and begin to idle, but in under 30 seconds of being  maxed out it is up at the ~160F level and climbing.  Also the hotter it gets, the less amperage it can make, but still being maxed out, just keeps getting hotter.

When driving on the highway at 65f , it is hard to get the alternator above 140F even if it is producing 110 amps total.  low speed driving maxed out alternator iis pretty hot too.  MyALt temp sensor is on the stator casing, not the Rectifier plate which will show higher temperatures, how much? IDK.

Obviously underhood airflow is having a HUGE effect on alternator temperature in my van.  More engine rpm also means more alternator fan speed too sucking more underhood air through alternator.   Without having data on other vehicles all I can say is it is very possible that a HOt motor, spinning a high amperage alternator at idle speed might be able to overheat and thus reduce the lifespan of the alternator, either drastically or to some unknown degree.

HOw much battery capacity there is plays a big part too.

Lets disregard other electrical loads on the alterantor,  for this example  Say a  healthy group 31 battery is depleted to 50% state of charge. Lets say the alternator  is spinning fast enough that it can make its full output.

The 50% depleted group 31 flooded  marine battery will likely take about 95 amps to  be brought upto 14.7v within 30 seconds and then the amperage will start tapering.  now lets throw  in load of the  headlamps...~15 amps   the amperage required to run the engine, My 89 requires 8.2 amps at idle, 12.2 amps at 2000 rpm .  Hvac blower motor on high speed, ~18 amps.

2 group marine 31 batteries, even a 160 amp alternator maxed out cold spining at 2000+ engine rpm could not bring these healthy yet depleted group31 batteries instantly to absorption voltage.  How hot will it get, IDK, but hot pretty fast is my guess.  




This total load is more than most  stock or even heavy  duty alternator's can produce, even if engine rpm is up in the 3500 rpm range.  it would not be able to maintain 14.7v under all those loads, its voltage regulator will be sending as much current to the alternator field as it can to ask it to make everything it can. and this makes for a hot alternator, one which might blow right past 220F and have its lifespan shortened to some unknown degree.

Another data point, One one 2013 ram power wagon with  a 160 amp (rated) alternator and seeking only low 14's, well it reached 220f in less than 5 minutes producing  whatever it required to run engine, but including about 90 amps into a single brand spanking new 50% depleted  group 31 125AH (GPL-31XT) lifeline AGM battery, but it levelled off at 220f and the voltage dropped, and thus the amperage too, but it stayed 220f never going higher with the hood up and idling.

Another HUGE factor is the voltage the vehicles voltage regulator is asking for.  This can vary widely on different platforms, but the lesser voltage sought, the less amperage the battery will accept.  Most vehicles will seek low to high 14s for a period of time after starting engine, and then revert to mid to high 13's, but with a depleted battery it might require 45 amps to hold it at 14.7c, but only 13 amps to hold it at 13.6v.  It varies fairly widely but in general a depleted battery held at 14.7v will be accepting about 3x as much amperage as one held at 13.6v

How much amperage the battery accepts is determined by the voltage it receives.  The longer the cabling to alternator and the more amperage that flows through it, the more the voltage will drop en route to battery.

Getting the highest voltage possible to battery terminals will yield the best chance of accomplishing the most charging when driving, and makes a fast spinning alternator much more effective at feeding a depleted battery, especially if the vehicles voltage regulator is really seeking 14.5v or higher which generally only happens for a short period of time aftrer starting the engine.

but the voltage the vehicle seeks is not controllable, Except my Van, I can control the voltage, and I can twist a dial rev the engine watch my ammeter, and see instantly what my alternator can make,  What it needs to make to maintain the voltage I choose, what my battery can accept at that voltage, what temperature my alternator achieves under various loads, rpm and  vehicle speed.  And I can change that voltage  at the twist of a wrist, and watch all the other displays change.

Pretty enlightening data, but I do not have data on other vehicles. 

On other vehicles,  I do not know:
 what voltage they seek after starting.
How long they hold that voltage before reverting to a lesser voltage
the amperage possible at idle cold/hot and at idle speed and at highway speed rpm.
The temperature difference when driving vs Idling
The circuit resistance, the battery capacity, or the battery depth of discharge.

Other charging sources, and how and when they are employed.

All of these have HUGE effects on whether  it is worth it to intentionally restrict alternator current with thinner wiring delivering less voltage, or To just go for fat wire as possible to deliver the most possible whenever one drives.

Getting an additional fat cable onto the alterntor (+) stud is not so easy and in some cases likely extremely difficult.

The OEM wiring has a fuse on cable from alternator to engine battery. If one takes power right from the alternator (+) stud, then an additional fuse is not needed at alternator, but one is needed within 7 inches of house battery terminal on this parallel alternator circuit.  

If one takes power for solenoid/isolation device to charge from engine battery, then this wire/cable needs to be fused within 7 inches of both batteries.

In general, my recommendation if the battery is really depleted, is to not  to start the engine and idle to recharge, but to get moving to 45mph plus asap after starting engine.  Keeping the alternator cooler will likely allow its voltage regulator to seek and maintain a higher voltage for longer, and accomplish more charging of a well depleted battery. 

In general I recommend not idling to recharge, but especially if one has a large capacity of depleted battery, like 200AH or more, and if one's alternator might be very capable at low rpms.  AGMs are especially greedy when depleted. 230AH of 12v marine battery in series depleted to 50% is greedier than 220AH of 6v golf cart battery.

My alternator can only make ~50 amps at hot idle maxed out, and its temperature skyrockets quickly to the danger zone. Imagine if it could do 75 amps at idle. That rocket would climb higher faster.

So much depends on the voltage regulator, as it commands the alternator to make as much amperage as required to maintain the target voltage, and decides how long to hold it.

A thick cable between starter battery and house battery will make the starter battery look like one large  depleted battery to the voltage regulator.  A thinner cable might make the voltage regulator look like a much less depleted battery, and one that does not ned to be held in the 14's for very long.

Thick cabling helps, to some unknown degree, to trick the voltage regulator into perhaps, holding a higher voltage for longer.  Thicker cabling delivers higher electrical pressure to depleted battery. higher pressure mean more amps flow, more amps flowing means faster recharging.

So your call.  it is impossible for me to say how much diffeence there will be with all the different unknown variables in your system.  the safe bet is Shortest possible, fat cabling from alternator to depleted house battery, and to achieve at 45mph plus  soon after starting engine to recharge the well depleted battery.  if the battery is only depleted to 80% state of charge it will not really accept much amperage to be broughto and held at 14.5 volts, but at 50% state of charge it will, and it will for however long it takes to get to ~80% state of charge, depending on the voltage sought abd how long it is sought.

Early morning driving and solar all day thereafter can make for a happy long lived battery. Those twwo with the ability to plug in every so often makes it even happier. If one can plug in regularly to recharge then one can get away with less copper on the alternator charge cirucit and less solar.

Driving alone as a rechargign source, well the 100% recharge is very unlikely to ever be achieved and the battery will be lucky to have 1/2 its capacity remaining after 6 months of daily deep cycling

Also keep in mind batteries are rented.  Achieving ideal recharging each and every discharge time is an absorption voltage nazi's pipe dream.

or is it?

I'm getting excellent service from my current battery.  Only have one, it will be 4 years old in november and will bave over 600 deep cycles on it, several dozen of those so far as to as low as 25% state of charge.

It was a 325$ battery. I could likely buy 3 wally world marine group 27's for that.  i can carry 3 group 27 batteries.
 I prefer to carry only one.

Everything is a compromise
 
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