Let 12V battery drop to 50 pct, or top it off daily?

Whewee Trojan's AGM and Concorde's AGM have "slightly" (?) different life cycle estimates.

Shallow discharges, and as frequently as you can top charge it are preferred. See Mexicowander's graph.

A good question deserves good answers...:)

I have found topping off is great if you have a battery bank at 90% charge already.

In my case when my batteries run down to the 50% charge state I have to start charging right away and due to the time restriction I usually only get to the 90% charge in a three hour time frame. If I had solar then the batteries will eventually get to the 100% charge state.

The problem with going all the way down to the 50% charge state first your batteries have put them selves in danger. In my case I start losing battery bank performance if I continually drain them down to the 50% charge state and then bring them back up to their 90% charge state if I don't do a full 100% charge state after 12 or more of these 50% to 90% charge state runs.

I guess crud builds up on the plates of the batteries that only a full charge will burn it off...

I don't think I have ever had a problem with a good full time trickle charge on the batteries if they were at least at the 90% charge state to start off with.

Guess all of this makes sense haha...

Roy Ken

profdant139 wrote:





I should also add that when we are not camping, the batteries are hooked up to a float charger.

Thanks in advance for your advice!

If you are parked outside I see no reason to run a float charger, just let the solar do it's job.

I was reading a article in Home Power Magazine about a electric car owner who did not recharge his car every night, and found that the mileage range was going down.

Their suggestion was that lead acid batteries like to be refilled as soon as they are discharged, and that sulfur build up on the plates can harden, so charging daily will help out a LOT.

I liked to keep my battery full every day as well, and one set lasted 13 years, so I guess it worked! I also kept an eye on the water levels and used only distilled water when required.

Charging from 90% to 100% takes a long time, so that is best done on shore power or with solar power. I would suggest running the generator for about 1 hour every morning and evening.

One RV.Net member described it like a frog jumping toward the end of a log. Where it can take a large leap in the beginning, it must jump smaller jumps as it gets closer to the end.

I have a e-meter that accurately measures my battery amp flow in and out of the battery. When I was down 140 AH, I would run the generator for about 1 hour in the morning, and cook breakfast. It would start out at 50 - 55 amps when I started the generator, but by 30 minutes it would be down to about 40 amps, and I would shut it off at 35 amps after about 1 hour. So alltogether I would put back about 45 AH in 1 hour.

Then I would let my solar system put back the rest of the power during the day. I can collect about 100 AH more than I use during the day. I have a 400 watt solar system.

Fred.

X3

I'm already sensing a trend here, from two very knowledgeable folks . . . . this could be a real short thread.

Agree. You gain nothing by letting it drop.

There is no reason to disconnect solar and let it run down.
The closer you are to 100% the better the battery life will be.