Cowdog353 wrote:

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i have 280watts of panels and a controller hooked to two 6v batteries.  So, I have about 100ah usable from the batteries. I think I'm correct on that.  Question is can I put a 12v battery in the mix,  two 6v in series then parallel a 90ah 12v.  Would I boost usable power by 90 ah or ?.  I'm assuming taking the batteries down no further than 50% .  

Thanks 

Jim

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 Echoing Bill J's comments - Can you do this? Yea - but you shouldn't.  Will it increase the AH available? Yea - but who knows exactly how much and you will reduce the life of all of the batteries.  How much? Who knows for sure.  It depends. But a battery bank should be all of the same type - not only voltage - but type, such as lead-acid / AGM and AH rating and age. 

LarryW21 wrote:

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100 amp hours is a bunch of power. I’ve considered powering my TV with a separate battery and solar system. (Or heater, etc.) Would that work?

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 Everyone has different needs and perspectives as to what is a "bunch" of most anything.  For us 100AH is far from a bunch and I am assuming the 100AH is the size of the battery bank.  If so, that means 50AH useable.  If 100AH is the usable amount from a 200AH bank, for us, that is still far from a great deal.  But it does depend.

For those reading along for perspective:  IF one has a residential fridge and plans to do any boondocking at all just be advised that fridge will require at least a 200AH bank just for the fridge not including any other 12 volt use.  Most residential fridges use well over 100AH of power out of the battery bank in a 24 hour day. (Many OEM battery / inverter setups are intended to just run the fridge while on the road over a typical travel day from site-to-site.  Not go boondocking.)

What is plenty for one may be way marginal for others.  We, as do Howard and Linda, have 600AH worth of battery bank and neither of us have a residential fridge. (We both have an LP / Electric "RV" fridges.) 

We find that 600AH (300AH useable) to be adequate without a lot of conservation and we don't have to run the bank down to the 50% point very often which allows the batteries to have a longer life.  We used to have a 300AH bank and just found that to be quite marginal - for us - even with an RV fridge.

My comments, for those reading along, are just for perspective and information.  One needs to realistically evaluate their needs and naturally the physical space available for batteries.  The correct size battery bank is what is correct for you and those who get along happily on less, good for you.  I know some who have 1,200 AH banks.  It does just depend on the rig and the individuals.

Bill

BiggarView wrote:

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Adding on to Bill's comment about requirements and space.... batteries (At least LA or AGM type) are heavy too. Wouldn't want anyone to overload a trailer to the point structural issues occur. Something has to go if you are already at or near your RV's GVWR. (less likely in a class A, B or C but still possible) 

JHMO.

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 Brain, exactly correct and to my point.  There is no one correct answer for everyone.  Weight and space are part of the equation.  So are capacity and AH usage.  So are RVing style.  What is "plenty" for one is "way too much" for another.  That's one reason for expressing different views and solutions.

Bill and Linda wrote: “and I am assuming the 100AH is the size of the battery bank.”

OP clearly stated: “So, I have about 100ah usable from the batteries.”

Few serious RVers much less dry/boondockers have only one 100 ah battery, and a usable 100 ahs IS a bunch of power unless you need a breathing machine.