Battery saver
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 1,137
Likes: 4
From: Indianapolis Indiana
St. Jude Donor '13, '15, ‘18, '21
Battery saver
I have trouble keeping my batteries alive. My cars can sit for a couple of weeks or months just depending on weather and my schedule. I have gone through some optimas so I finally returned the last one and I am now trying a sealed battery from Duracell.
I have seen products that hook onto the battery and disconnect them to keep them from being run down and causing damage.
Is anyone else using one of these devices?
I have seen products that hook onto the battery and disconnect them to keep them from being run down and causing damage.
Is anyone else using one of these devices?
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Most guys go the other way and fit a battery tender to keep it topped off.
If you're constantly running down the battery you need to find out why.
Identifying Battery Problems
The C5 eats batteries unless you take some regular precautions. If your battery continually dies its either the battery which is on its last legs or something on the car.
You also need to look at how you use the car. Is it a daily driver? If so the battery should be getting a good top up every day so you may have a problem.
Is it a DD but you do short trips? If so you'll be taking a lot out of the battery every time you start. For a short trip, say less than about 20 mins, you won’t top it off properly. Eventually it'll drain.
Is it a weekend car. If so, this takes a lot out of your battery. There’s a 20MA drain even dormant. If you don’t drive the car for a reasonable time every week or so, it'll kill the battery. In this case you really do need a battery tender.
You’ll know when your battery is bad. As it gets low you may get strange electrical indications (random warnings and U fault codes). As it gets lower it may drop the memory settings or defaults such as HUD settings. Eventually you’ll get the dreaded chattering relays in the footwell and eventually the lights on the IPC will disappear.
Most batteries can be recharged quite successfully, although AGMs are harder. Start by checking the charge on the battery. Don’t read the DIC when the car is off. The value you see on the DIC is alternator output when the car is running. It will always measure an inaccurately low voltage on the battery when the ignition is off and figures of 11.0V to 11.9V is normal in this case. With the engine on, the voltmeter should show between 13V and 14.5V. You need to measure voltage across the battery terminals using a digital multi meter if possible. A fully charged battery measures 12.7V and a fully discharged battery measures 11.9V. Partially discharged batteries will give a reading somewhere in between.
If the battery is low give it an overnight charge (or put it on a battery tender until you get a fully charged indication) and retest it. A true test is under load and Autozone will do that test for free.
If you have an AGM battery like the Red Top and it has been deeply discharged it's harder to recover it. This might help:
http://www.youtube.com/watch?v=dIoaL3DWWEg
If you’ve recharged it and it still runs down, then you need to start looking for excessive drains. Bill Curlee posted a good method for checking:
http://forums.corvetteforum.com/1567522286-post590.html
There are some common faults which are well known for causing problems:
First to check is the interior lighting rotary switch on the drivers panel. It’s possible for that to be turned on as there’s a setting (fully clockwise) which bypasses the auto off function. Turn it fully counter clockwise and check after about 30 minutes (preferably in the dark) that the interior lights have gone off.
If it’s not the lights something has failed or is badly installed.
Have you fitted an after-market device which draws current? Typically it’s a cellphone charger, radar warner or a similar device that’s the problem.
If still no joy, you need to start pulling fuses to identify the problem.
The power seat switches on the side of both seats are notoriously unreliable. The switch becomes sticky with use and can stick in the “on” position. You shouldn’t damage the motors as they are thermally protected. The fuse may blow so worth checking (Fuse 36 20A in footwell).
The driver’s lumbar motor can also cause issues so check this too (mini fuse 3 15A in footwell). The seat controls connect under the seat. Pull the connector and if the drain stops that’s your problem.
Less common but not unheard of are failures of the headlight motor control module the alternator and the Bose Amplifier under the dash on the driver’s side.
If you're constantly running down the battery you need to find out why.
Identifying Battery Problems
The C5 eats batteries unless you take some regular precautions. If your battery continually dies its either the battery which is on its last legs or something on the car.
You also need to look at how you use the car. Is it a daily driver? If so the battery should be getting a good top up every day so you may have a problem.
Is it a DD but you do short trips? If so you'll be taking a lot out of the battery every time you start. For a short trip, say less than about 20 mins, you won’t top it off properly. Eventually it'll drain.
Is it a weekend car. If so, this takes a lot out of your battery. There’s a 20MA drain even dormant. If you don’t drive the car for a reasonable time every week or so, it'll kill the battery. In this case you really do need a battery tender.
You’ll know when your battery is bad. As it gets low you may get strange electrical indications (random warnings and U fault codes). As it gets lower it may drop the memory settings or defaults such as HUD settings. Eventually you’ll get the dreaded chattering relays in the footwell and eventually the lights on the IPC will disappear.
Most batteries can be recharged quite successfully, although AGMs are harder. Start by checking the charge on the battery. Don’t read the DIC when the car is off. The value you see on the DIC is alternator output when the car is running. It will always measure an inaccurately low voltage on the battery when the ignition is off and figures of 11.0V to 11.9V is normal in this case. With the engine on, the voltmeter should show between 13V and 14.5V. You need to measure voltage across the battery terminals using a digital multi meter if possible. A fully charged battery measures 12.7V and a fully discharged battery measures 11.9V. Partially discharged batteries will give a reading somewhere in between.
If the battery is low give it an overnight charge (or put it on a battery tender until you get a fully charged indication) and retest it. A true test is under load and Autozone will do that test for free.
If you have an AGM battery like the Red Top and it has been deeply discharged it's harder to recover it. This might help:
http://www.youtube.com/watch?v=dIoaL3DWWEg
If you’ve recharged it and it still runs down, then you need to start looking for excessive drains. Bill Curlee posted a good method for checking:
http://forums.corvetteforum.com/1567522286-post590.html
There are some common faults which are well known for causing problems:
First to check is the interior lighting rotary switch on the drivers panel. It’s possible for that to be turned on as there’s a setting (fully clockwise) which bypasses the auto off function. Turn it fully counter clockwise and check after about 30 minutes (preferably in the dark) that the interior lights have gone off.
If it’s not the lights something has failed or is badly installed.
Have you fitted an after-market device which draws current? Typically it’s a cellphone charger, radar warner or a similar device that’s the problem.
If still no joy, you need to start pulling fuses to identify the problem.
The power seat switches on the side of both seats are notoriously unreliable. The switch becomes sticky with use and can stick in the “on” position. You shouldn’t damage the motors as they are thermally protected. The fuse may blow so worth checking (Fuse 36 20A in footwell).
The driver’s lumbar motor can also cause issues so check this too (mini fuse 3 15A in footwell). The seat controls connect under the seat. Pull the connector and if the drain stops that’s your problem.
Less common but not unheard of are failures of the headlight motor control module the alternator and the Bose Amplifier under the dash on the driver’s side.
Last edited by DeeGee; Jul 27, 2011 at 04:12 PM.
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Been using one for years and it works great. These cars do put a draw on the battery even when sitting still. A good battery should last at least a few weeks, perhaps longer, without any worry of being discharged. But if you are going through a lot of batteries, I agree with DeeGee - maybe a check of the car's electrical system is in order.
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
I've used a BATTERY TENDER PLUS (DELTRAN CORP. @ 1.25amp) for several years now. The battery is always charged during six months of hibernation.
Recently, DELTRAN introduced a version that is solar powered...
http://batterytender.com/
Recently, DELTRAN introduced a version that is solar powered...
http://batterytender.com/
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 1,137
Likes: 4
From: Indianapolis Indiana
St. Jude Donor '13, '15, ‘18, '21
I had a batery tender on mine and it still went dead. When I treid to charged it back up with my big unit the battery got warm, so it may have just been shot to begin with.
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Le Mans Master
Joined: Oct 1999
Posts: 8,205
Likes: 40
From: Tucson AZ
I hook mine up if I don't intend to use it for a couple of days, and they have been fine.
Instructor
Joined: Aug 2010
Posts: 219
Likes: 0
From: Tustin CA
Harbor Freight 1.5 amp 3 stage onboard battery charger/maintainer item #99857 on sale $20.00 Works great. Automatic shutoff when charged.
http://www.harborfreight.com/automot...html?hftref=cj
http://www.harborfreight.com/automot...html?hftref=cj
Last edited by 2004c5blackcoupe; Jul 29, 2011 at 04:48 PM.
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St. Jude Donor '12-'13-'14
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From: SE Pennsylvania
St. Jude Donor '03 thru '26
Oldtimer
Optima's and battery float chargers.
An Optima battery like a Red Top, if allowed to discharge below 10.5 volts will need to be charged via a Vampire charge. If you don't know, ask me. I've use a few chargers over the years and I use one called "BatteryMinder" which is a top rated float charger (It will never overcharge your battery) but once charged up, the charger switches over to a pulse de-sulfation/conditioner It removes the plaque that builds up on the plates walls in the battery. Costs $39.95 To me it's cheap considering all that it does. 
Instructor
Joined: Sep 2009
Posts: 150
Likes: 0
From: Albuquerque NM
My Optima red top went dead after a couple years even after buying a "battery Tender". I found out too late that the gel cel batteries do not charge properly with these battery tenders and they will actually damage them. My newest Optima (about a year old now) is doing fine but I now start the car and let it run for 20+ minutes every 10 days or so. I tossed the battery tender.
Burning Brakes
Joined: Sep 2009
Posts: 1,180
Likes: 2
From: Yes it's hot! Arizona
I've used a BATTERY TENDER PLUS (DELTRAN CORP. @ 1.25amp) for several years now. The battery is always charged during six months of hibernation.
Recently, DELTRAN introduced a version that is solar powered...
http://batterytender.com/
Recently, DELTRAN introduced a version that is solar powered...
http://batterytender.com/
Instructor
Joined: Jun 2011
Posts: 167
Likes: 0
From: La
Wow my car must be doing good.. I work 28 on 14 off and I rarely drive it because of rain. I never had a problem. Sounds like yall have battery drain. I know on my previous vehicles my alarm systems drained my batteries. I used to use a remote disconnect on my positive cable to stop the drain also saving my battery life. I would go around 3-6 months without starting them up. Yeah yeah i used to have 6 vehicles so my toys rarely got played with.