a battery conundrum...

So, I'm still mulling over all the numbers and options I have for powering my RV off of solar. The only part of the investment that is troubling me right now are the batteries. my constraint is that they need to be indoors, where they will be better regulated for temperature, but standard lead acid batteries are out due to the ventilation required. At first AGMs sounded like the way to go, but now I wonder if gel batteries are better. do any folks with experiance in the industry have any advice on weighing the benefits of these batteries, or other ideas entirely?

My other large source of unknown is in the wiring of my system. at first I thought it looked fairly simple, panel to junction box, j-box to inverter, inverter to charge controller, charge controller to battery bank. Now having read through some of the other options from the Backwoods systems, I wonder what other costs are going to be involved. for instance, do I need an additional battery charger if I have a charge controller? and If I plan to do my lights and fans off of DC and only use the inverter for AC on occasion, do I need a whole slew of other switches and boxes and fuses for switching back and forth? If I just set the system up to run my lights and fan on DC, should I still have a fuse box to set everything up in or just wire a fuse into the (+) wire in the socket? I may be grasping at too much at once here, and I apologize if its more than any one cares to respond to, I may have just been reading too much into this and need to step back and reevaluate.

but I appreciate any advice...


  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    Re: a battery conundrum...

    As for batteries, go for the AGMs. I have pulled tooooo many swelled gel-cel batteries from computer UPSs that are only 3-5 years old.

    This RV, is it a trailer or a motorhome ???
  • BB.
    BB. Super Moderators, Administrators Posts: 33,468 admin
    Re: a battery conundrum...

    A good brand of AGM batteries (no cheap knockoffs).

    Regarding fusing/breakers... Remember they are needed for safety and a pain in the butt because fuses and breakers are sort of unreliable (if you run near rated current, they will eventually open).

    So, rating wise, you should have a fuse/beaker/wiring at least 125% of the needed current (need 10 amps, rated at least 12.5 amps, wire a 15 amp circuit).

    And, fuses/breakers only protect "down stream" components. You have a length of wire 14 awg wire with a 15 amp fuse in the middle of it. One end on the battery, the other to your socket with 10 amp load... If the load shorts, no problem. If the wire shorts going into the socket (from the fuse), protected. If the wire shorts from the battery to the fuse holder, big problems as the 14 gauge wire is powered by 100% of the battery short circuit output--100's to 1,000's of amps--depending on wire gauge, resistance of short, etc...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • tripster
    tripster Registered Users Posts: 14
    Re: a battery conundrum...

    Not sure if I'm reading your post wrong but it looks like you have your setup order wrong. Panel should go to the charge controler then to the battery bank, of course with the appropriate breaker/fuse/disconnects in between:D
    That is of coarse if by pnale you mean solar panel.

    I'll let the seasoned solar guru's take over from hear.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: a battery conundrum...

    agms are good for rv situations, but just be sure you have all your fuses/breakers with proper wiring and a good controller that has a battery temp sensor. side benefit is higher charge efficiency. higher cost is the negative. your choice though.