When to replace 6v batteries

Get a power supply that will let you equalize them after charging. You need to be able to do 15.x volts. If you are hitting the road and dont want to mess with it, buy new ones, if you want to experiment continue on. I've replaced a set after 3 years that were still good but because of fast charging on a generator and wanting to go to six gc2 and not mix two new ones in I just replaced them. I just consider it another tank of diesel fuel. 5 years is only $75 a year for four gc2. Just for fun I just slapped a gp 27 back in line with my mean well that had sg that would barely raise the needle. It takes some tinkering but....

wantabe351 wrote:
When testing my 5er 6v batteries,I charge them for 12hrs on my home Battery charger,then disconnect them..the surface voltage is 12.8v after 4hrs its down to 12.5 and after 8hrs it sits at 12.2 for 2days..using my hydrometer the cells are just above or in the replace zone..the Batteries are only 5yr old and no mater how long I charge them or do a 14.5 voltage charge, the voltage after a day drops to 12.2v disconnected. is it time for new batteries

There is a lot being unsaid there. How could the batteries be so bad at five years and not be noticed as being almost that bad two years ago? This did not happen in the last few months.

I suspect the OP got the four 6s years ago with off-grid in mind, but never used them and they sat at 13.6 ever since, so here we are. IMO unless there is a change of RVing style, just get one sealed 12v batt as replacement and replace that every year or two. Save money and not have to do battery maintenance.

Quick! CPR!

Are you nuts? He ain't breathing...

They're toast and you may be able to get a little of their capacity back but not much. Time to replace.

Try 15.5 volts. Sulfation can take WEEKS to revert at the voltage you are trying. Take them to a genuine battery distributor and let them charge the batteries with a manual charger. Gee! They recover and give you 5 more years of service? It's not a remote hope. It's "probable".

When you get the new ones, research the charging regimen for them. If you follow it, they will last longer.

Time for new batteries.

Yes.