[19963.4lsr5]

My toy sat 5 days in my unheated garage and my battery voltage was 12.3.

Like stated in my repair thread my parasitic draw is 26ma well low enough that my battery shouldn’t be at 60% after sitting 5 days. Granted it’s low 20’s at night....but still.


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[Washingtonian]

It would be interesting to know the age of your battery. My 2002 has been sitting about 4 weeks since I last started it. Today it turned over a couple of times and just clicked. I put a charger on it for an hour at 12 amps and it was good to go. I put about 20 miles on it today (dump run and to Costco and back for gas), and I expect it will be good for another two or three weeks of sitting without a problem. We are due for snow this weekend, so I might have to use it sooner.

[spartacus]

My one year old battery died because the door ajar light was on due to the back hatch being not closed properly and the truck hadn't been driven for like two weeks. I trickled charged the battery but it had drained so far down that it would not hold charge. Replaced it under warranty.

[spartacus]

Been driving my other vehiciles and just checked the new battery truck hasn't been driven for about 12 days, the battery is at 12.28 so at about 60%. Time to put a battery tender on.

[shadow247]

Originally Posted by 19963.4lsr5

My toy sat 5 days in my unheated garage and my battery voltage was 12.3.

Like stated in my repair thread my parasitic draw is 26ma well low enough that my battery shouldn’t be at 60% after sitting 5 days. Granted it’s low 20’s at night....but still.


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How old is the battery? If you are only drawing down 26ma on a parasitic draw test, that is not enough to pull a battery down that low that fast....

[calimobber]

All depends on your battery for what the volt settle at. I have a shitty autozone platinum agm $200 but it settles at 12.3-12.4 which is too low for my liking since my auto disconnect instantly disconnects the second battery because its too low already.

Miss my Optima yellow sitting at 13.2v when fully charged.

[19963.4lsr5]

My battery is between 3 and 4 years old. And it does seem to like hitting 12.3 settling out. My Saturn with a tiny napa battery at the end of 5 days shows 12.5 normally.

With my headlights and fogs (16amps of load) the battery quickly goes down to 11.5v.


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[19963.4lsr5]

I keep forgetting battery state of charge VS ambient temps. 40f equals 12.3v as 100% state of charge.


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[sportscarfan]

I hadn't driven the '97 in probably 2 months and the battery had slipped to 9.xx volts in my negligence. I managed to recover it by giving it 48 hours of 1A battery tender and then switching to the 4A tender. The 4a smart electronics were too dumb to initiate the charging so I had to start with the dumb 1A.
I have 3 cars that sit in my shop where the temp generally hovers in the 20's (F) 24-7 all winter. Two others (including the '98) sit outside...
I did take the '97 on a 100-mile city round trip and had no issues, and while at Costco, picked up another 4A tender...so now I have 5 Battery Tenders in 3 amperage flavors for 7 vehicles in these Covid times. I used to not really have to worry about any of them through the winter because I'd just rotate what I was driving regularly.
Oh, and the battery in the '97 (from Costco) is at least 7 years old now.

[19963.4lsr5]

I have a 2-8-12a Schumacher speed charger, 8a deltran (battery tender) and a 4 channel 1.2a tender from deltran.


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[Kanoe]

Originally Posted by 19963.4lsr5

My toy sat 5 days in my unheated garage and my battery voltage was 12.3.

Like stated in my repair thread my parasitic draw is 26ma well low enough that my battery shouldn’t be at 60% after sitting 5 days. Granted it’s low 20’s at night....but still.


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I think it depends on the battery type to a point.

Anecdotally, I ran a spiral grid agm for 10 years and it always read low 12s after resting a few hours. I now have a regular agm and it’s higher but still 12.4 ish after resting. The flooded lead acids in my cars sit more at 12.6 to 12.8 as you would expect.

Not sure if there is any truth or logic to this, just my observations.

[19963.4lsr5]

Originally Posted by Kanoe

I think it depends on the battery type to a point.

Anecdotally, I ran a spiral grid agm for 10 years and it always read low 12s after resting a few hours. I now have a regular agm and it’s higher but still 12.4 ish after resting. The flooded lead acids in my cars sit more at 12.6 to 12.8 as you would expect.

Not sure if there is any truth or logic to this, just my observations.

I had megatron plus batteries sit at 13.1v in the summer and 12.5ish in the winter. I attribute that higher rest voltage to more calcium or whatever they add to the electrolyte to have the higher CCA in the winter.

According to the state of charge charts though I shouldn’t complain about 12.3v in the dead of winter. Even though this MTP-24F never passed the CCA test on my MidTronics battery tester as well as the MidTronics tester at Napa. But it passed the Load test twice on the 1000a load tester at the local interstate warehouse. I feel I should have it tested again.

I guess I’m still looking for an excuse to dump this battery because it ain’t close to the 800cca it’s rated at and I can tell the difference on a cold start. I really think I’ll replace it with a 27f when it’s time.

I wish a group 65 came in a F. I’d use that. They are 180RC which reflects a higher Ah rating over a 24 or 27.


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[19963.4lsr5]

Sitting overnight after using the 8a deltran to charge it yesterday morning I had 12.67v sitting 24 hours.

My deltran’s push the battery to 14.2v and holds it there for around 4 hours before it goes to a 13.2v float charge.

My speed charger only charges to 13.1v which to me never fully charges the battery. I should get one more 8a deltran and stop using the Schumacher unless I need it’s desolation mode. Which I don’t need on my toy because I always have one attached. Which reminds me that since it’s always on it is a parasitic load on the battery.


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[brillo_76]

I unfortunately have most of my batteries on tenders that are not in use. I do have one battery that not on a charger and completely disconnected but its outside in the elements in winter. It's been a few months so I check the voltage and report back.

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[19963.4lsr5]

I have a group 27 battery I kept when I put new batteries in my Cummins because it still tested at 650cca and sitting on my work bench it holds 12.7v for a long arse time. I cycle it by putting a 5a load (old headlight bulb) on it and draw it down to around 12v to keep it in a cycling action while it waits to be used as a jump starting battery.


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