Flooded battery recommendations

[idroba]

Originally Posted by alano

After poking around for some time I couldn't find any intrinsic reason why DD flooded batteries should exhibit shorter cycle lifetimes than AGM batteries. Both can happily be discharged to 80% and recover, albeit with some minor degradation.

This was an eye opener to me - that I can safely discharge my flooded lead-acid batteries to 80% every once in a while to stay comfortable without worry. Just last week I was boondocking my my wife and I cranked down the temperature to 50 deg F inside the trailer at night to try and limit my furnace usage. Next time I'll keep warmer and not stress so much.

My feeling is that it is more important to recharge the batteries fully to 100% as soon as possible rather than worry all that much about an occasional discharge to 20% of capacity. (80% discharge) Going all the way down to 0% I don't think is a good idea though. It is a trade off of course, the deeper the discharge and the more often it happens, the shorter the battery life. But even a battery kept at 100% charge, on the shelf without ever being discharged will have a limit to it's life, that is they don't last forever even if never used and kept fully charged.

How quickly they are fully recharged is just as important or more important than how deeply they are discharged.

[mpsgolf]

Check Basic to Advanced Battery Information from Battery University. This and other sites I've been researching say AGM batteries do have a greater capability to discharge to a lower rate than lead acid with less impact on life. You have to get something for the much higher price!

"AGM offers a depth-of-discharge of 80 percent; the flooded, on the other hand, is specified at 50 percent DoD to attain the same cycle life."

Consistently discharging to the max DoD, whether 50% for flooded or 80% for AGM, will shorten the battery life compared to lesser levels of discharge. There are other considerations for battery life too though, as others have said.

[alano]

Battery U offers no references, nor are they clear that they are referring to deep discharge flooded lead-acid batteries. There are even quite a few comments at the end of the article that dispute their claims.