Battery condition

[westslope]

I have a 27 Group Trojan lead-acid deep cycle battery that operated for a couple of years in the vehicle and prior to that powered a 52 lb. thrust electric motor for a couple of seasons.

 

I'm not sure about the condition. I recharged it a few days and have watched the voltage reading subside. A new deep-cycle Trojan batter is down to 12.90 volts. The old one has dropped to 12.6. Both of these batteries are sitting on a shed floor. Does this indicate that the old one might be toast?

 

Can I get useful information out of these tea leaves or do I need to hook the battery up to a volt and amp tester?

Edited January 10, 2010 by westslope

[Precise1]

Amp tester is ideal, but here is a down and dirty you can do with a volt meter. Normally it would be in the car and you use the starter, but since you have have a new, strong battery you can do it differently. Hook the battery up to something that will give it a fairly heavy load, hook up your voltmeter, turn the something on and record the voltage drop. Now do the same with the old one. Is there a significantly greater drop on the old battery?? If so it is getting tired. Also a lower voltage is normal in older batterys as the acid gets weaker, electrical surfaces lose some conductivity, etc. I've had car batteries that barely read over 12 volts last another year or more...

 

Now that I have said that, take the old battery to where you bought the new one and ask them to check it for you.

 

B

[westslope]

Thanks B.

 

Haven't bought a new battery yet. Would take the older Trojan deep-cycle battery to the store where I bought it but the trip is over an hour and am not sure I want to spend C$200 on a new Trojan battery when I can get a starter/deep cycle batter at Napa Auto parts for ~C$131 and only about 1/2 hour of driving. (27-RVS East Penn, 650 CCA, 175 minutes @ 23 Amps.)

[Precise1]

You are welcome.

 

You can take the battery to almost any auto parts store for testing, for some reason I misread/misunderstood.

 

B

[westslope]

You probably misunderstood 'cause I was being terse.

 

I use these deep-cycle batteries for powering electric motors and since the early part of the decade have been running "used" deep-cycle batteries in the pathfinder. So when I thought the older Trojan had failed, I switched it out for a newer Trojan.

 

Napa should have a battery tester. Need to go in, I guess.