Matching Panels to Batteries

[Cliffman]

In my RV I have 4 deep cycle (Golf Cart) 6 cell 200 AH batteries. Setup in 2 banks tied together with a perko switch. I use a Trace Inverter (2512) for charging and dry camping. I hooked up a 15 watt panel with a 10 amp charge controller. I used my inverter to bring the batteries up to float 13.2. I want to use the 15 watt panel just for storage to keep the battery up. When I turn off the Trace 2512 and use the 15 watt panel the batteries drop to 12.7 and will not come up to the CC's float voltage which is 13.2. When I hook the 15 watt panel to a smaller battery it works fine. I'm assuming that my battery bank is too large for the 15 watt panel but this does not make since to me as all I'm looking to do is maintain a battery that is already fully charged. Shoud this setup work?

[Sunking]

Will not likely work. All batteries have a Self Discharge Rate. To keep them fully charged and at float voltage you have to provide enough power to over come the Self Discharge Rate. Think of it like a bucket with a small hole in the bottom and you want to keep it full of water. Only way to do that is to supply a water source with a trickle flow rate that equals or exceeds what is leaking out. If the leak is greater than the supply, you run out of water and left with an empty bucket.

[SunEagle]

In my RV I have 4 deep cycle (Golf Cart) 6 cell 200 AH batteries. Setup in 2 banks tied together with a perko switch. I use a Trace Inverter (2512) for charging and dry camping. I hooked up a 15 watt panel with a 10 amp charge controller. I used my inverter to bring the batteries up to float 13.2. I want to use the 15 watt panel just for storage to keep the battery up. When I turn off the Trace 2512 and use the 15 watt panel the batteries drop to 12.7 and will not come up to the CC's float voltage which is 13.2. When I hook the 15 watt panel to a smaller battery it works fine. I'm assuming that my battery bank is too large for the 15 watt panel but this does not make since to me as all I'm looking to do is maintain a battery that is already fully charged. Shoud this setup work?

You should have a feature that allows you to "disconnect" your coach batteries from just about all sources that will drain them which will allow them to hold a charge longer. Even if you do that I don't think a 15 watt panel is enough for a "trickle" charge for that size battery bank.

Remember your Trace inverter is rated for 2500 watts which is a lot of charging power. Does it tell you how much power it puts out to maintain the float voltage at 13.2?

[Cliffman]

You should have a feature that allows you to "disconnect" your coach batteries from just about all sources that will drain them which will allow them to hold a charge longer. Even if you do that I don't think a 15 watt panel is enough for a "trickle" charge for that size battery bank.

Remember your Trace inverter is rated for 2500 watts which is a lot of charging power. Does it tell you how much power it puts out to maintain the float voltage at 13.2?

Yes, I have a "perko" switch which allows me to switch through the 2 banks or completley shut them off from the coach. I'll check the amp draw while it's being charged with the trace inverter and see with it takes to keep with a t float of 13.2.

[Cliffman]

Okay, figured it out... Turns out that in order to charge both banks with the 15 watt solar panel the Perko switch needs to be set for both batteries which puts them in parallel to charge them both with one panel. Doing that engaged the batteries with the coach and even though it’s in “storage mode” there must be some “phantom” power drain that I was not aware of. So… rigged up a “Quick Connect” jumper wire to put the 2 banks in Parallel without the Perko switch and Waaalaaa, my little 15 watt panel has both banks up to 13.2 in less than 1 day. So now I fell like a dummy not know that!!! LOL!

[SunEagle]

Okay, figured it out... Turns out that in order to charge both banks with the 15 watt solar panel the Perko switch needs to be set for both batteries which puts them in parallel to charge them both with one panel. Doing that engaged the batteries with the coach and even though it’s in “storage mode” there must be some “phantom” power drain that I was not aware of. So… rigged up a “Quick Connect” jumper wire to put the 2 banks in Parallel without the Perko switch and Waaalaaa, my little 15 watt panel has both banks up to 13.2 in less than 1 day. So now I fell like a dummy not know that!!! LOL!

Glad it worked out for you.