Solar Installation Question

[user 24295]

Here is the layout of the electrical system i plan on installing and will be adding solar later in this operation. the questions are 
A) how do i connect the solar to this system
B) will this 70 amp isolator work for the solar system

I am planning on using 4 battery's in my system. 2 for the 1st and second main battery and 2 for everything that the solar will run.
does any of this seem right?

 

[Seminole Wind]

to just add solar to this circuit, i would wire the panels through a charge controller. then wire the output of the controller to the "auxiliary" batteries. this will allow the solar to charge those batteries without compromising the included isolator. the solar would not charge the "vehicle" battery but that is generally not needed as the loads you use while parked should be run from the auxiliary battery

 

[user 24295]

Thanks for the info, I was afraid that i might have to buy a completely new everything, and since these are new already i would hate to not be able to use them.

What do you recomend for battery's?

 

[tx2sturgis]

I'm not a huge fan of 'isolators' since they introduce about a half a volt drop (of charging voltage) to both battery banks. I used one many years ago and the batteries apparently didnt get a full charge when I thought they were OK.

In some cases, they are the right answer, but not in all cases. A continuous duty solenoid triggered from the ignition or acc port, or a battery-to-battery charging system might be the right answer, but again, not in all cases.

If you can adjust your alternator to compensate, then it should work out for you.

 

[Seminole Wind]

I'm not a huge fan of 'isolators' since they introduce about a half a volt drop (of charging voltage) to both battery banks. I used one many years ago and the batteries apparently didnt get a full charge when I thought they were OK.

In some cases, they are the right answer, but not in all cases. A continuous duty solenoid triggered from the ignition or acc port, or a battery-to-battery charging system might be the right answer, but again, not in all cases.

If you can adjust your alternator to compensate, then it should work out for you.

while your information is reasonably accurate, sure a properly wired solenoid can have a little less voltage drop. they are far from a good way to charge house batteries from the alternator. trying to compare an electronic actuated isolation to a mechanical actuated isolation is miniscule when compared to the lack of decent charging you will get to a house bank by just combining battery banks while engine is running. heck you could just get a big 1-2-both battery switch and do it manual. still just combining or paralleling both battery banks.

yes, any way you combine the battery banks will work to charge while engine running. both the isolator and solenoid, if wired properly will also disconnect or isolate the battery banks when the engine is off so you dont overly drain the starter/vehicle battery while parked and running loads off the house/auxiliary battery.

problem is, typically 2 things detract from proper and timely charging of the auxiliary battery. first the alternator "dumb" regulated charging source and will drop back charging rate considerably before the battery is fully charge(more obvious the larger the capacity of the battery being charge) the second, regardless of how good the isolation device is in passing current and voltage. the house bank is usually farther from the alternator and there is voltage drop in that circuit. in every instalation i have inspected. the house bank even after driving at speed for hours, and the current going to the house bank had tappered off to almost nothing. the house banks are reading a volt or more less than the starting battery. so if the alternator is keeping the starting battery at 14 volts(common and reasonable) the house bank only reaches 13 volts. that is way low to actually bring any lead acid deep cycle or even an rv battery back to full charge. sure it helps replace some used electricity but takes it's toll battery life

the upgrade to be considered that is not just splitting hairs is to go to some sort of boosting 3 stage (bulk absorb float) battery to battery charger. you can put one together your self if of the diy type or you can buy one commercially made like the sterling brand battery to battery chargers. then you get the best of both worlds. quick recharge, fully charged and then not over charged. then you just have to worry if your alternator can handle the extra work load. either upgrading the alternator or derating the battery to battery charge somewhat can prevent the early demise of the alternator.

 

[Seminole Wind]

Thanks for the info, I was afraid that i might have to buy a completely new everything, and since these are new already i would hate to not be able to use them.

What do you recomend for battery's?

for a more detail oriented battery recommendation. i would like to hear more about your rig and intended use. how much room, can you carry the weight. how long do you need the batteries to provide power, what electrical loads do you need to run.

in general, a pair of 6 volt golf cart batteries tend t be the best bang for the buck in terms of power provide vs life time cycles. this is of course if you have a system that charges and maintains your batteries sufficiently. if a subpar charging system is chronically under or over charging the batteries you wont get much more life out of the golf cart batteries than "rv/marine deep cycle" but since a pair of off brand golf cart batteries can usually be had for the same price as 2 rv/marine deep cycle batteries ther really is nothing to lose by getting the better batteries. they are great training batteries.

 

[highdesertranger]

I am not a big fan of the isolators either. I have replace a lot more isolators that went bad then solenoids. I would never recommend one. highdesertranger

 

[Seminole Wind]

HDR, do you distrust them so much that you would have (back in the day when you had your shops) insisted/persuaded a customer to swap out an existing working isolator for a solenoid if that is what they already had. or would you have just recommended upgrading if/when the isolator failed?

Thanks for the info, I was afraid that i might have to buy a completely new everything, and since these are new already i would hate to not be able to use them.

 

[highdesertranger]

depends, if they were a boondocker (or what they call it today expeditioneer) I would have recommended it. if they were a mall cruiser I would have just mentioned it.

don't get me wrong the best most reliable is the manual switches. but everybody(me included) forget to switch them.

highdesertranger

 

[tx2sturgis]

We went off-the-rail a little bit, but since the OP posted a picture of an isolator I think we are still on-topic, if not, so be it.

I would recommend carrying a spare isolator, ready to swap in, if the 70 amp unit poops itself. I would say the same for a solenoid, carry a spare.