Battery Ran Down

[BobsTrail]

New Sears AGM battery, T4 sat in 40 degree shop for 2 weeks and it was dead, no lights, no display. Our 2 other vehicles had old school lead acid batteries and they were fine. One was down to 11.5 volts but both cranked over normally.

After charging I checked current flow with everything off and saw 300 milliamps. I have a CB radio, but it was off as was everything else. I know part of it is the radio memory and on board computers.

Is this too much drain or is my new battery not holding a charge as it should?

 

[vjack]

0.3 amps is too high. Something is still drawing too much current.

A group 34 AGM battery should have a capacity of around 50 amp-hours (it should be printed on the battery if you are curious). 50 amp-hours means 1 amp for 50 hours, 50 amps for 1 hour, or something in between. (It's really just a ballpark number, but good enough for now.)

At a 0.3 amp draw, that battery should last around 150 hours, or 20 days, until dead. I would detach the CB radio and see if you can get the current drain down to something more reasonable, say 20-30 mA. If it's not the CB radio, check any other modifications, and/or start pulling fuses while watching your multimeter.

 

[BobsTrail]

Checked it again today, remembered I had a Telematics transmitter from AAA insurance plugged into the OBD II connector. Unplugged it and the current went down to 125ma.

 

[RonJR]

0.3 amps is too high. Something is still drawing too much current.

A group 34 AGM battery should have a capacity of around 50 amp-hours (it should be printed on the battery if you are curious). 50 amp-hours means 1 amp for 50 hours, 50 amps for 1 hour, or something in between. (It's really just a ballpark number, but good enough for now.)

At a 0.3 amp draw, that battery should last around 150 hours, or 20 days, until dead. I would detach the CB radio and see if you can get the current drain down to something more reasonable, say 20-30 mA. If it's not the CB radio, check any other modifications, and/or start pulling fuses while watching your multimeter.

Math is good, except that 150 hours is about 6 days (24 hours/day), not 20. Current leakage doesn't just work 8 hour days

 

[vjack]

Math is good, except that 150 hours is about 6 days (24 hours/day), not 20. Current leakage doesn't just work 8 hour days

:doh: