Troubleshooting Help: House Batteries dying quickly

[Richard Davis]

Anand
You say you charged the battery for a "bit" and it quickly came up from 10.9 to 12.8.  What do you mean by "quickly"?  An 8D battery would require 10 to 12 HOURS to recharge from a badly depleted 10.9 volts and finally rest at 12.8 volts.  Do not be confused by the quick surface charge that takes place when you put batteries on a charger.  That surface charge will deplete as quickly as it appears.  The voltage on that battery should be brought up over 14 volts during the "bulk" charge and then allowed to taper down for many hours during the "absorption" and "float" phase in order to be truly charged.  I am wondering if you are not really getting those huge 8D batteries charged at all.
Richard 

[Anand Shah]

Hi Richard

I’ve had them on shore power charging through bulk/absorb  and float cycles for long periods of time (couple of days) during our trip a few weeks ago, this is what got me to wonder because they simply wouldn’t last very long when we stopped and had the engine off and were off shore power / generator., I removed them and put several through individual charging cycles for 12+ hours and none of the ones I tested hold charge for very long.   The individual ones rapidly drop from 12.9V to 11.5 which very little to no load on them.   I’ve load tested them and the load tester says it can’t get more than 200CCA (one of them only gave 16).  I’ve tried the “reconditioning” function on my battery charger and it never finishes its cycle.

The charging circuits seem to work with the Gen Set on and Shore Power, providing 14.2 volts consistently across the batteries.  I do not have power at my storage location at the moment.

Anything else I should be trying to see if there is potential to save these?

Anand

[Richard Davis]

Anand
It sounds like your assumptions are all correct and the batteries are sulfated beyond recovery.  There comes a time when replacement is the only viable option.  I faced that eventuality last Winter in South Texas during February when power was off for a week during freezing weather.  I absolutely killed my bank of AGM batteries cycling between running the generator to charge them and then running my AquaHot furnace from the batteries (I was running low on diesel and could not replenish since all the stations had no power).  Anyway, long story short; I could not find any AGM deep cycle batteries anywhere in the area.  The only deep cycle batteries I could find were the flooded 6 volt golf cart batteries at Sam's.  I detest having to check and water my battery bank since my battery bay is so difficult to access.  Good batteries have been hard to find with limited supply and distribution during the pandemic.  I hope you have better luck finding replacements than I did.  I will use the flooded batteries I bought last Winter while my budget recharges and then I will replace them with AGM.
Good luck.  Richard