Battery Tender
Thread Starter
Instructor
Joined: May 2012
Posts: 111
Likes: 15
From: Crete Illinois
Battery Tender
I have had a '76 Stingray for a little over a month and I have had a few things done. I have replaced the starter and the flywheel, and replaced the battery and the battery lead cables. If I do not start the car for a few days, the battery is completely discharged. I readily admit that a "battery tender" was a product that I was unfamiliar with, but after researching I would like to inquire with some veteran gear heads on whether or not a battery tender is advisable in my situation. Or should I still take a closer look at the alternator? It's one of the few things left in the charging system that I have not replaced.
Instructor
Joined: Dec 2007
Posts: 184
Likes: 0
From: Crystal Lake IL
If starting the car every few days keeps your battery charged, then I would say your alternator/charging system is working correctly. It sounds to me like you have a battery draw when the car is off, which can be tricky to troubleshoot. To narrow it down, you can use a DMM to find your battery draw...here's how I do it (there may be other ways):
1) Disconnect your negative battery cable.
2) Set your DMM to Amps and bridge the gap between your battery and the black cable.
3) Watch for several minutes to get a baseline of your car. There is going to be some draw on your system from things like your clock, radio memory, etc. If it baselines more than a couple 100 milliamps, I would think something is drawing too much.
4) Start pulling fuses and relays one at a time and watch for a drop. When you narrow down the fuse, get yourself a wiring diagram or post back here and figure out what devices are on the circuit and troubleshoot them.
I had some problem with my reminder buzzer that was drawing enough to drain my battery every 4-5 days. I replaced the buzzer and now I can go several weeks without starting (probably still a small draw somewhere). I actually keep my car on a battery tender at all times just in case.
1) Disconnect your negative battery cable.
2) Set your DMM to Amps and bridge the gap between your battery and the black cable.
3) Watch for several minutes to get a baseline of your car. There is going to be some draw on your system from things like your clock, radio memory, etc. If it baselines more than a couple 100 milliamps, I would think something is drawing too much.
4) Start pulling fuses and relays one at a time and watch for a drop. When you narrow down the fuse, get yourself a wiring diagram or post back here and figure out what devices are on the circuit and troubleshoot them.
I had some problem with my reminder buzzer that was drawing enough to drain my battery every 4-5 days. I replaced the buzzer and now I can go several weeks without starting (probably still a small draw somewhere). I actually keep my car on a battery tender at all times just in case.
Last edited by morleyz; Jul 3, 2012 at 09:48 AM. Reason: Typo
Race Director
Joined: Feb 2006
Posts: 12,239
Likes: 19
From: Chino CA
If starting the car every few days keeps your battery charged, then I would say your alternator/charging system is working correctly. It sounds to me like you have a battery draw when the car is off, which can be tricky to troubleshoot. To narrow it down, you can use a DMM to find your battery draw...here's how I do it (there may be other ways):
1) Disconnect your negative battery cable.
2) Set your DMM to Amps and bridge the gap between your battery and the black cable.
3) Watch for several minutes to get a baseline of your car. There is going to be some draw on your system from things like your clock, battery memory, etc. If it baselines more than a couple 100 milliamps, I would think something is drawing too much.
4) Start pulling fuses and relays one at a time and watch for a drop. When you narrow down the fuse, get yourself a wiring diagram or post back here and figure out what devices are on the circuit and troubleshoot them.
I had some problem with my reminder buzzer that was drawing enough to drain my battery every 4-5 days. I replaced the buzzer and now I can go several weeks without starting (probably still a small draw somewhere). I actually keep my car on a battery tender at all times just in case.
1) Disconnect your negative battery cable.
2) Set your DMM to Amps and bridge the gap between your battery and the black cable.
3) Watch for several minutes to get a baseline of your car. There is going to be some draw on your system from things like your clock, battery memory, etc. If it baselines more than a couple 100 milliamps, I would think something is drawing too much.
4) Start pulling fuses and relays one at a time and watch for a drop. When you narrow down the fuse, get yourself a wiring diagram or post back here and figure out what devices are on the circuit and troubleshoot them.
I had some problem with my reminder buzzer that was drawing enough to drain my battery every 4-5 days. I replaced the buzzer and now I can go several weeks without starting (probably still a small draw somewhere). I actually keep my car on a battery tender at all times just in case.
GREAT advice....I need to do this myself.....thanks for that post!
Thread Starter
Instructor
Joined: May 2012
Posts: 111
Likes: 15
From: Crete Illinois
If starting the car every few days keeps your battery charged, then I would say your alternator/charging system is working correctly. It sounds to me like you have a battery draw when the car is off, which can be tricky to troubleshoot. To narrow it down, you can use a DMM to find your battery draw...here's how I do it (there may be other ways):
1) Disconnect your negative battery cable.
2) Set your DMM to Amps and bridge the gap between your battery and the black cable.
3) Watch for several minutes to get a baseline of your car. There is going to be some draw on your system from things like your clock, radio memory, etc. If it baselines more than a couple 100 milliamps, I would think something is drawing too much.
4) Start pulling fuses and relays one at a time and watch for a drop. When you narrow down the fuse, get yourself a wiring diagram or post back here and figure out what devices are on the circuit and troubleshoot them.
I had some problem with my reminder buzzer that was drawing enough to drain my battery every 4-5 days. I replaced the buzzer and now I can go several weeks without starting (probably still a small draw somewhere). I actually keep my car on a battery tender at all times just in case.
1) Disconnect your negative battery cable.
2) Set your DMM to Amps and bridge the gap between your battery and the black cable.
3) Watch for several minutes to get a baseline of your car. There is going to be some draw on your system from things like your clock, radio memory, etc. If it baselines more than a couple 100 milliamps, I would think something is drawing too much.
4) Start pulling fuses and relays one at a time and watch for a drop. When you narrow down the fuse, get yourself a wiring diagram or post back here and figure out what devices are on the circuit and troubleshoot them.
I had some problem with my reminder buzzer that was drawing enough to drain my battery every 4-5 days. I replaced the buzzer and now I can go several weeks without starting (probably still a small draw somewhere). I actually keep my car on a battery tender at all times just in case.
Race Director
Joined: Feb 2006
Posts: 12,239
Likes: 19
From: Chino CA
Instructor
Joined: Sep 2010
Posts: 236
Likes: 0
I remember reading once about a guy who was having a battery discharge problem like yours. Turned out his trunk light was staying on. I just wondered---my '78 has an underhood light. Could it be staying on and drawing down the battery?
Thread Starter
Instructor
Joined: May 2012
Posts: 111
Likes: 15
From: Crete Illinois
I have given everything (that I can see) the once over. When I insert the key and the door is still closed, I get the door buzzer. If I had to pick a culprit, I would say it was that, but I am going to reserve judgement and go through the steps that morleyz shared. But I will pop the hood once I get the battery juiced up to see if my '76 has an underhood light too.
Pro
Joined: Feb 2012
Posts: 668
Likes: 21
I use a $3 Harbor frieght test (Item #30779)light to check for this. Put the test light in series with the batter terminal and the battery lead. If it lights up you have a short. Start pulling fuses to locate the circuit. Good luck, I hate electrical problems(maybe because I'm an electrician)
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Racer
Joined: Jul 2009
Posts: 338
Likes: 9
From: South Bend IN
NCM Sinkhole Donor
An easier solution if something is draining your battery, would be to put in a battery kill switch to prevent the drain and it is an added security feature if someone ever tried to steal your car. It doesn't fix the drain, but you could work on that as you have time and still enjoy your car. http://www.summitracing.com/parts/HLA-002843011/
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
I agree with the earlier mentioned ammeter inline with the battery, as a test light may come on, but really not show you any actual current draw. If possible, get hold of a DC clamp on ammeter, as really best not disturbing anything.
Thread Starter
Instructor
Joined: May 2012
Posts: 111
Likes: 15
From: Crete Illinois
Just wanted to let you guys know that I brought the Battery Tender Plus (Deltran) from Sears for about $45.00. I was talking to the sales lady and she told me that her Dad used one on his Corvette because the On-Star module was drawing down the battery so I felt pretty good about buying it.
I plugged it up Tuesday night about 6 pm and I was able to crank the car up this morning on the first try! Amazing!!!! I will still perform the testing with a DMM, but it has been about 150 degrees in my garage so I'll wait it out until next week.
Thanks again guys.
I plugged it up Tuesday night about 6 pm and I was able to crank the car up this morning on the first try! Amazing!!!! I will still perform the testing with a DMM, but it has been about 150 degrees in my garage so I'll wait it out until next week.
Thanks again guys.
Melting Slicks
Joined: May 2009
Posts: 2,217
Likes: 638
From: Port St Lucie Florida
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No question it sounds like something is causing a major power drain. That said, I have been using a tender since 2004 - on my 04 'vette which typically was stored from mid November to early April (sold the car in 09) and now on my 69. Nice thing about the tender is that it never cooks the battery. Unlike a trickle charger, the voltage going in is below the boiling point of the water.
Definitely looking into once you've solved your problem.
Definitely looking into once you've solved your problem.
Melting Slicks
Joined: May 2009
Posts: 2,217
Likes: 638
From: Port St Lucie Florida
2025 C6 of the Year Finalist - Modified
2023 C6 of the Year Finalist - Modified
2022 C6 of the Year Finalist - Modified
2021 C6 of the Year Finalist - Modified
Just wanted to let you guys know that I brought the Battery Tender Plus (Deltran) from Sears for about $45.00. I was talking to the sales lady and she told me that her Dad used one on his Corvette because the On-Star module was drawing down the battery so I felt pretty good about buying it.
I plugged it up Tuesday night about 6 pm and I was able to crank the car up this morning on the first try! Amazing!!!! I will still perform the testing with a DMM, but it has been about 150 degrees in my garage so I'll wait it out until next week.
Thanks again guys.
I plugged it up Tuesday night about 6 pm and I was able to crank the car up this morning on the first try! Amazing!!!! I will still perform the testing with a DMM, but it has been about 150 degrees in my garage so I'll wait it out until next week.
Thanks again guys.
Burning Brakes
Joined: May 2009
Posts: 850
Likes: 36
From: Providence RI
I've been very happy with my Battery-Tender; it takes just a second to pop the hood and connect the pigtail to the Tender next to the car (I've got the lead hooked to the charging-stud on the alternator).
Racer
Joined: Dec 2005
Posts: 492
Likes: 31
From: NJ
I had the same problem but installed a battery disconnect and religiously disconnect after I turn the car off. Keeps the pesky draw from affecting the battery. Also looking into tenders.
Last edited by TSAGG; Jul 8, 2012 at 07:33 AM. Reason: Spell error