Battery testing

[pcatterall]

Our domestic batteries are now 3 years old so I decided to do a check of theirs safe usable capacity under load.
1 plan to use 11.8 v as my lower limit.
Is that reasonable,?
I understand that this would be 11.8 when not under load?
So if the volts get down to say 11.6 under load but return to say 12.8 when the load is switched off can I safely continue the test?
Thanks all.

 

[Poecheng]

11.8v is far too low as a bottom usable limit.
That is a point at which you need immediate re-charging and may very well cause damage in the short or long term. I would expect it to use up one of its 'lives'
12.2 or 12.3 would be a more reasonable lower voltage limit.
Others know this area much better and will be along shortly

 

[fredrussell]

I’ve always worked on 12.7v full, 12.0v empty.

 

[PaulRainbow]

I’ve always worked on 12.7v full, 12.0v empty.

That's about right for a max 50% DOD, with no load