Battery voltage level

I'm wondering what the full charge is on the TM standard battery.

[rvcycleguy]

Originally Posted by jbbernache

I'm wondering what the full charge is on the TM standard battery.

Its either one 12v battery or two 6v in series. A full charged battery should measure on a volt meter at 13.2. That's 6 cells x 2.2 per cell.

[tentcamper]

An hour or so off the charger, my battery is 13.2/13.3 but after it sits a day it's about 12.8/12.7, but it will depend on the outside temp. At 15 degrees it at about 12.4/12.5v in a day.

[Padgett]

Nominal voltage of a lead acid cell (and both wet cell and AGM are lead/acid) is 2.0v but is best to keep at or a little above 2.1v to avoid sulphation so you want it at or above 12.6v.

[tentcamper]

This year I changed how I do my battery tender. I added a timer and have it set to come on 2x per day for an hour each time. That thought can to me as I was setting up my mil's house for her to come and stay with us for the winter. It has seem to working good and the voltage when I check it is always 12.7/12.8 or greater.

Any thoughts on using a timer as I do???

[TrailManorMan]

I unplug and let them rest for a week then put plug back on. I have a digital cheap meter that I leave connected. When I see my number down near 12.7 is when i connect. Depends on garage temperature but usually around a week. By the way my garage never freezes as I have a full kitchen with running water so I have a furnace. Garage temp never below 38 degrees, This works for me, I'm sure others have other ideas also. My two group 31 Interstates are 3 years old, my last pair I got seven years life. By then I was ok with the "life"

Timers would do what I do manually but not forget

[tentcamper]

But getting back to the original question, it depends on the temperature of the battery. I use as a rule of thumb 12.7/12.8 after it's been sitting for 24 hours.

But it depends on the temp.

Several years ago I did some reading. Only because my battery on the camper stored outside would not hold the voltage I was expecting in very cold weather. If interested i'm sure there is a chart you can google. Ideal fully charged voltage most mentioned for a lead acid battery is at 68 degrees 24 hours after charge. Ideal voltages above or below 68 degrees will be difference. Also the highest available amps was at 68 degrees.

Back when I looked at it 12.2/12.3 was a good voltage at 0-F. What I read back then, indicated that colder temps, in the sub zero range was the best for battery storage, but you need a good charger that would adjust to the temps. But if you did it right and stored the battery in a deep freeze you could get 2-4x the life. But at those temp you have a decrease in available amps.

One of my reading back then, talked about chargers and that most did not compensate for temps, and that was the main cause for early life battery failure in the very cold and hot areas.

[tentcamper]

Skip, I use to do it your way and every so often forget about it. About 4-5 years ago I went to the tender, which seems to work will.

But my newest method with the timer and tender is more about conserving electric. 2 hour a day vs 24 hours a day??? I got on a kick to reduce my electric bill. My usage is about the same as 15 years ago, but the bill is almost 2X.

[ShrimpBurrito]

Originally Posted by tentcamper

But my newest method with the timer and tender is more about conserving electric. 2 hour a day vs 24 hours a day??? I got on a kick to reduce my electric bill. My usage is about the same as 15 years ago, but the bill is almost 2X.

Those Battery Tenders charge at what, 2A? That's 24 watts. Assuming they only are actually charging 12 hrs/day (which I think is ALOT), that's abotu 8.6 kWh/month. We pay alot for power here in LA, about 18 cents/kWh including taxes and fees. So even if you got rid of the charger entirely, you'd save about $1.50/mo.

But you're not saving that because it's charging 2 hrs a day. PLUS, that timer consumes power 24 hrs/day.

Dave

If you are really using a "Battery Tender" (Deltran) you should leave it connected 24/7/365. The Battery Tender is a computer controlled battery maintainer that reads the battery voltage and adjusts the charge level accordingly. It will not over charge the battery. I had one connected to a motorcycle battery for over 6 years ( continually when not actually riding it) If the battery needs to have a specific amount of energy replaced, it does not matter if it is replaced in two hour blocks or all at once.