Have had an AGM battery (one) for a year now, not that being AGM necessarily matters. Never dry camp. Also bought a Progressive Dynamics converter/charger upgrade for it. Recently installed an LED voltmeter display to keep tabs on the battery. Voltage normally floats correctly at 13.7. If I shut the charger off, the battery stays at 13.7 volts for a bit then starts to drop slightly. I believe this is normal? Haven't left it overnight to see what it levels off at but assume it should level off at about 12.7?The only time the battery normally gets discharged is from using the tongue jack, putting the stab. jacks down and running the slide out and when I do the charger is correctly putting out 14.4 volts to charge the battery. Does the battery get discharged much and roughly how long does it take to get back to full charge? Does it help to plug back into shore power before operating the jacks and slide so the battery won't get discharged quite as much or does that help at all?

myredracer wrote:Voltage normally floats correctly at 13.7. If I shut the charger off, the battery stays at 13.7 volts for a bit then starts to drop slightly. I believe this is normal? Haven't left it overnight to see what it levels off at but assume it should level off at about 12.7?13.7 sounds a tad high for AGM - which typically prefer a lower float voltage than flooded batteries do. Does your charger have a switch to select flooded or agm? My Magnum charger floats my AGM at 13.3 - 13.5 depending on the temperature.It is normal for the voltage to remain at 13.x and then drop down into the high 12's after a while.myredracer wrote:The only time the battery normally gets discharged is from using the tongue jack, putting the stab. jacks down and running the slide out and when I do the charger is correctly putting out 14.4 volts to charge the battery. Does the battery get discharged much and roughly how long does it take to get back to full charge? Does it help to plug back into shore power before operating the jacks and slide so the battery won't get discharged quite as much or does that help at all?Sounds normal to me. Plug back in when convenient, doesn't have to be right away or while running the jacks or slides. You paid for that battery capacity, might as well use it now and then. It should take an hour or less to read "full" again. It won't stay at 14.4 very long and will likely drop to 13.x again but it will still be charging, just at a lower rate.The 14.4 sounds a little high for AGM, I think I see 14.2 from my Magnum - I would check your instruction manual for the charger and make sure it knows it's working with an AGM and not a flooded battery.AGM tolerate mild "abuse" very well, if there's no adjustment available don't sweat it then.

Mostly sounds normal. After a few days of minimal or no use the converter should drop to 13.2 float mode. Jacks and slide are very minor. Plug in before or after is virtually the same.If you want to exercise or test the battery a bit you can unplug until you see 12.2 on the meter and then plug back in.

Thx for the comments.I don't know how accurate the LED display is. It's an "economically priced" Drok from Amazon which I think supposedly aren't too bad for accuracy but who knows. Could be off a couple of tenths or so? I could check it against my fancy $10 HF multi-meter. :)Charger is a 4-stage PD 4645 or 4655 upgrade (can't recall which) for the original OEM WFCO along with their charge wizard pendant. Specs. are here. Have never monitored battery voltage before. Has been working flawlessly for the past year and just want to make sure it's all looking good and that nothing needs checking.

Because I had good luck with DROK products I ordered 5 LCD voltmeters. Around $40.00Connected to a fully charged utterly disconnected AGM battery ALL FIVE DROK meters hunt exactly the same. Parade constantly up and down four tenths of a volt. Connected to lab power supply exactly the same reading 5 volts to 20 volts.JUNK. USELESS. DROK is now relegated to the YUGO and LUCAS electrical category.The generic 5 digit YELLOW LED meters are dead accurate and less expensive. They have smaller segments tho. Select YELLOW for highest visibility.

My East Penn/ Deka "Duracell" deep cycle AGM batteries say on them Charge-Absorbtion-Equalize 13.8- 14.6Float-Standby between 13.4- 13.6Temperature corrected charging required.Edit, I forgot to add thats at 77 degrees F. 25C

Couple of battery voltage & charging question | Good Sam Community

21 Replies

MEXICOWANDERER
Explorer
Aug 24, 2017
PaulJ2 wrote:
MEXICOWANDERER wrote:
Because I had good luck with DROK products I ordered 5 LCD voltmeters. Around $40.00

Connected to a fully charged utterly disconnected AGM battery ALL FIVE DROK meters hunt exactly the same. Parade constantly up and down four tenths of a volt. Connected to lab power supply exactly the same reading 5 volts to 20 volts.

JUNK. USELESS. DROK is now relegated to the YUGO and LUCAS electrical category.

The generic 5 digit YELLOW LED meters are dead accurate and less expensive. They have smaller segments tho. Select YELLOW for highest visibility.

The Lucas electrical catagory comment struck me funny. Working in the auto mechanic business the saying back then was...if an auto had Lucas electrical system the saying was....Always park on a hill, and never drive at night.

Play Time!

"LUCAS Innovator Of The Interval Wiper"
"LUCAS" 3-Position Switch: Smoke - Smoulder - Ignite"
mike-s
Explorer
Aug 24, 2017
Lucas - Prince of Darkness.
westend
Explorer
Aug 24, 2017
Lucas..., if I only had a dollar for every Lucas starter and voltage reg I've replaced.

Myredracer, you're a knowledgeable guy on electronics and electricity. What are you doing with cheap measuring gear? For less than $75 US, you can buy a good meter that does AC-DC amperage and is accurate.

FWIW, I have three AGM's but not like anything you would use so no comparisons available. Check with the mfg about charging schemes. Also, I'm using an old Simpson analog gauge and have a Victron battery monitor. They measure voltages all the same as my hand-held Fluke.

Suggestion: Get into solar charging. With a good, adjustable controller, worrying about charging will be a thing of the past.
PaulJ2
Explorer
Aug 24, 2017
MEXICOWANDERER wrote:
Because I had good luck with DROK products I ordered 5 LCD voltmeters. Around $40.00

Connected to a fully charged utterly disconnected AGM battery ALL FIVE DROK meters hunt exactly the same. Parade constantly up and down four tenths of a volt. Connected to lab power supply exactly the same reading 5 volts to 20 volts.

JUNK. USELESS. DROK is now relegated to the YUGO and LUCAS electrical category.

The generic 5 digit YELLOW LED meters are dead accurate and less expensive. They have smaller segments tho. Select YELLOW for highest visibility.

The Lucas electrical catagory comment struck me funny. Working in the auto mechanic business the saying back then was...if an auto had Lucas electrical system the saying was....Always park on a hill, and never drive at night.
BFL13
Explorer II
Aug 23, 2017
myredracer wrote:
Update...

After the battery was discharged somewhat from using the tongue jack and slide, the next day the voltage stabilized at 13.2 volts so all is good there.

I disconnected the battery (after voltage read 13.2) and the next day the resting battery voltage read 12.8 volts so okay there too.

Interestingly, the battery voltage using my HF multi-meter read 13.9 volts, waaay off. Junk!!

I don't know what the battery specs are, but IMO you are not in the clear yet from what you have posted.

12.8 is at the bottom of the range for the resting voltage of this battery when full, where 13v is in the middle. See graph bottom right scroll down.

One day does not tell the tale for resting voltage after a full recharge either. You want to check that over a few days and see that it does not self-discharge much (there is a spec for that too, as you can see here for this particular battery)

You could well be undercharged and a bit sulfated, especially if your battery also specifies 14.8ish for a recharge like this one does.

Yes, a multi-meter will start to read high for voltage when its own battery is getting flat. It happens slowly so you might not notice right away.

http://www.wegosolar.com/products.php?product=SKR%252d125AGM-Stark-AGM-12V-Solar-Battery-Sealed-125A

Note the float voltage for this one is 13.6-13.8 at 25C, nowhere near that 13.2. You must know the actual specs for your actual battery.
time2roll
Nomad
Aug 23, 2017
myredracer wrote:
Interestingly, the battery voltage using my HF multi-meter read 13.9 volts, waaay off. Junk!!
A low internal battery can make them read high.
Replace the battery before you chuck the meter.
myredracer
Explorer II
Aug 23, 2017
Update...

After the battery was discharged somewhat from using the tongue jack and slide, the next day the voltage stabilized at 13.2 volts so all is good there.

I disconnected the battery (after voltage read 13.2) and the next day the resting battery voltage read 12.8 volts so okay there too.

Interestingly, the battery voltage using my HF multi-meter read 13.9 volts, waaay off. Junk!!
pianotuna
Nomad III
Aug 18, 2017
myredracer it depends on the particular AGM. 13.7 may be a little high for float, and 13.2 would be adequate to the OP's style of camping. In an ideal world I'd research to find out what the maker requires, and then follow that "to the letter".

What needs to be observed is to keep the voltage lower than the gassing voltage. That is temperature dependent. The PD can't do temperature compensation--so in summer (it is still summer where I am) 13.2 may be safer.
time2roll
Nomad
Aug 18, 2017
pianotuna wrote:
In your shoes I would use the wizard to reduce the voltage to 13.2.
Some call for 13.2 and some ~13.5
Best to know the brand and model.
BFL13
Explorer II
Aug 18, 2017
pianotuna wrote:
In your shoes I would use the wizard to reduce the voltage to 13.2.

PT, you don't even know what AGM he has and its specs, so whyinheck would you tell him that?????? Come on. :(