113 replies to this topic

[Mickey Bitsko]

You are correct, both batteries are fla. And the Dual purpose is about 4yo.
Are you suggesting the inverter charges up to 13.7 and then floats?
However, the charger on the deep cycle after being on the charger for 12hrs was still charging@ 15.5 +/-

[ckent323]

Two questions:

 

1) Are you using a smart charger on the batteries?\

2) Have you looked up the manufacturer specs on each of the batteries (you did not list model numbers and group numbers of the batteries).

 

All AGM batteries are going to have roughly the same charging parameters but there will undoubtedly be minor differences between manufacturers.  

 

So different batteries can have slightly different float values (recommended bulk charge voltage and charge profiles can differ slightly too).  Best to check the specs for the particular battery

Edited by ckent323, 04 March 2019 - 06:22 AM.

[PaulT]

Battery chargers with a float phase will commonly charge at 14+ volts until the charger logic decides it has reached full charge. At that point, the charger switches to float voltage and remains there until indefinitely.

The actual float voltage is set by the charger mfg.
Paul

[Mickey Bitsko]

Thank you both, I will do some research on both batteries and Sears charger.
I have owners manual for inverter, it should answer my questions.

[ckent323]

I added some links to recent posts on batteries and battery chargers  - on page 1 post #2

[ckent323]

I added some additional links to recent posts on batteries and battery monitor electronics  - on page 1 post #2

[craig333]

I just took some batteries down for recycling. I mentioned to the guy I use deep cycle batteries in the camper and he showed me some 150ah used batteries from commercial UPS systems. $150. I assume these are replaced on a cycle and not due to showing any sign of trouble. Hard to say just how much life is left in these but for someone on a budget it might be something to consider. They looked a bit larger than a typical automotive battery though.

[PaulT]

Operating room lights backup power uses 150 aH batteries. Years ago. I had a friend working in facilities at the local hospital.  He saved me seven 150 aH batteries that measured the highest resting voltager when they replaced all of the batteries at once. Only problem was moving 7 batteries weighing 80 lbs each.  I got years out of them as the power supply for ham radio. Kinda wish he hadn't retired.

 

Paul

[ckent323]

My Dad got large batteries for his boat (diesel engine) from a local Fire Department that has a regular replacement cycle for their batteries.  Too big for a camper but the UPS batteries might be OK if one can move an 80 pound battery into the camper. 

 

I put two 6V deep cycle 220 Ah batteries in our camper and they weigh 66 lbs each.  I would not want to lift anything heavier into the camper.  These used UPS batteries might be better purposed for a battery bank in a cabin or something where you can use a hand truck.  ;-)

Interesting source though.

[craig333]

My current batteries are over 80lbs and yes, it was a bit of a struggle to get them in. The cummins doesn't care what I throw in there. The ones I saw would fit where my current batteries are. Taller but not too much so. 

 

Great idea for a cabin. If only I had one