Battery Tender
Thread Starter
Drifting
Joined: May 2002
Posts: 1,546
Likes: 282
From: Back in Nebraska
Battery Tender
I just bought a “Battery Tender” from a local motorcycle shop. It is rated at 12Volt 750ma. After connecting it to the battery the red light (charging) does not go green (fully charged). The charger itself seemed hotter than it should be after charging for 4 hours. I checked the battery voltage with a voltmeter and it read in excess of 13 volts and the red light still indicates charging. Should I have bought a charger that charges with more than 750ma? Or does it matter?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Mine does the same thing. It gets hot, stay red, and will charge until the battery gets to about 13.30V.
As long as the red light isn't flashing, it's doing it's job and yes it will get hot.
As long as the red light isn't flashing, it's doing it's job and yes it will get hot.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I've seen it take 4 - 6 hours. It's a float charger so you can hook it up indefinitely and it won't ever over charge the battery or harm it. Just connect it before you go to bed, and see if it's green in the morning.
If it's not, you might have a specific problem with either the battery, the car's electrical system, or possibly the Tender.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
I have the small 750ma Battery Tender for my ZO6, as these cars will drain a battery in three or four weeks if left unattended. The red light has been on for 48 hours after not having the tender hooked for a couple of weeks. Today I put the tender on after driving maybe 50 miles. The light went green in about an hour. So it really depends on how discharged the battery is.
Cheers,
Pete
Cheers,
Pete
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
It doersn't take much to put them into charge mode. For laughs, once the light turns green, open a door so the courtesy lights go on. The charger will go back to red and take 5 minutes to recharge. I leave mine on all winter and it does no damage. When I start the car in the spring it starts as though I just shut it down. 
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Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
There is a difference between having 12V+ and having a full charge, depending on the cells in the battery. It would indicate to me that you have a cell or two going bad. I once had a battery that held 12V but barely had enough oomph to put the windows down and up. The cells can go bad, and while the remaining good cells keep a 12V charge, you're capacity is diminished.
I would personally take that battery in to a parts store and have them load test it.
Thread Starter
Drifting
Joined: May 2002
Posts: 1,546
Likes: 282
From: Back in Nebraska
There is a difference between having 12V+ and having a full charge, depending on the cells in the battery. It would indicate to me that you have a cell or two going bad. I once had a battery that held 12V but barely had enough oomph to put the windows down and up. The cells can go bad, and while the remaining good cells keep a 12V charge, you're capacity is diminished.
I would personally take that battery in to a parts store and have them load test it.
I would personally take that battery in to a parts store and have them load test it.