JoLin
Vice Admiral
- Joined
- Aug 18, 2007
- Messages
- 5,146
P.O installed a pair of expensive Lifeline Group 31 AGM's in early 2011. They've worked flawlessly for 6 years. A week ago one battery suddenly wouldn't crank the engines. Got only a fast chattering noise from the starters on both engines. Switched to the other battery and they both cranked right over. So, ran some tests the next morning
Both batteries were reading 12.7 - 12.8 volts on my MM
Started the engines off the good battery and put my MM on the bad one- got a reading of 13.97 volts, which tells me the alternator is putting out
Put them on the onboard charger for a few hours and both batts ran up to 14 volts.
Took them off the charger and let them sit overnight. 14 hours later I saw readings of 13.00 and 13.04 volts respectively.
Tried to start the engines off the 'bad' battery again and got the same result- chattering noise, no crank
Went off to WalMart and bought a Schumacher load tester for $35. It was DOA. Grrrr. Returned it, went to Harbor Freight and bought their $22.00 model. Works fine! When I hooked it up, the needle fell smack dab on 13 volts, which is exactly what I saw on my multimeter.
Specs on the batteries call for 880 CCA. Load tested the 'good' battery and the needle fell right where it was supposed to- on the minimum line for 1000 amps, which is also at the top of the 800 amp scale. All in the 'green'
Tested the 'bad' battery and the needle fell on the minimum line of the 800 amp scale, which also put it just into the yellow, 'weak' section of the tester.
Pretty clear to me that one battery simply doesn't have the cranking capacity it needs anymore. The other battery is still good in all respects- no bad cells, no internal shorts, no voltage loss over time. Sooo, I decided to order one replacement (Lifeline again). I'll use the new battery for starting and switch to the old battery for house loads until that one dies.
My .02
Both batteries were reading 12.7 - 12.8 volts on my MM
Started the engines off the good battery and put my MM on the bad one- got a reading of 13.97 volts, which tells me the alternator is putting out
Put them on the onboard charger for a few hours and both batts ran up to 14 volts.
Took them off the charger and let them sit overnight. 14 hours later I saw readings of 13.00 and 13.04 volts respectively.
Tried to start the engines off the 'bad' battery again and got the same result- chattering noise, no crank
Went off to WalMart and bought a Schumacher load tester for $35. It was DOA. Grrrr. Returned it, went to Harbor Freight and bought their $22.00 model. Works fine! When I hooked it up, the needle fell smack dab on 13 volts, which is exactly what I saw on my multimeter.
Specs on the batteries call for 880 CCA. Load tested the 'good' battery and the needle fell right where it was supposed to- on the minimum line for 1000 amps, which is also at the top of the 800 amp scale. All in the 'green'
Tested the 'bad' battery and the needle fell on the minimum line of the 800 amp scale, which also put it just into the yellow, 'weak' section of the tester.
Pretty clear to me that one battery simply doesn't have the cranking capacity it needs anymore. The other battery is still good in all respects- no bad cells, no internal shorts, no voltage loss over time. Sooo, I decided to order one replacement (Lifeline again). I'll use the new battery for starting and switch to the old battery for house loads until that one dies.
My .02
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