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How long is the C4/C5battery life when garaged?

Roadster Guy

Well-known member
Oct 17, 2004
Rolling Hills NE of Toronto
1996 Roadster CE/LT4/F45
Ok, for the last couple of years this has not been an issue for me. During winter storage I kept my 1996 Vette on a battery maintainer (minder). In season I use it at least once a week and it fires up fine. I have never had a problem. A few weeks ago I went away on business for 2 weeks and when I returned and tried to start her up the battery was dead...ok the radio stations were still programmed, but the time was way off and not even a clicking sound from the starter. So, I charged the battery right up and since then all is well. Even left it a few days just to see and it starts fine. Dash indicates charging 14.9 after startup and then slowly works its way down to 14.1. Battery is the stock Delco, one year old. Alarm system is an aftermarket "Crime Stopper", but when garaged it is never set to on. I know the 96 computer's diagnostic codes were up to 140 from 95's 60 codes, so maybe the computer is draining more than I think. The car is stock outside of the alarm system.

I know these computers do drain the battery slowly, but I'm wondering if there is something else that is also very slowly using power. Therefore, it seems the car can sit a week and be fine, but not two weeks. Any 1996 owners who know their battery life while sitting? How about other C4 and C5 owners? Is there such a thing as normal battery life expectancy for a 96 (or other years for that matter)? All feedback appreciated as I'm kind of puzzled by this.:cool
I have a 92 and have to put a charger on it during the winter months also. Mine will not hold a charge if it is not driven for two weeks. I also seem to replace the battery about 2 to 1 what I do in my other vehicles. Just thought that was the nature of the beast.
Battery life can be sort of a crapshoot. A lot depends on how the car is used and how much of a load is placed on it. If you only start the car at night and drive it a couple of miles, then the altenator may not be able to keep the battery fully charged. Temperatures also affect battery life. Cold temps are hard on batteries especially if they are not kept fully charged.

Last year, before heading out on the 50th Anniversary caravan, I decided to replace the original AC Delco battery that was in my 92. I had never had any problems with it but I decided to swap in a new AC Delco as a hedge against potential failure on the road. I had a load test done of the original battery and after 3 successive tests, it never got below 78% of capacity.

I pretty much let the car sit during the winter months unless there are some sunny days or a club function. I use one of the Harbor Freight maintainers on it when it's in the garage. I can usually go 5 weeks without starting it and no maintainer and it will easily start.

In the winter, I usually turn the radio off before stopping the motor and also hit the OFF button on the Climate Control. Don't know it that makes any difference but it can't hurt. There are various processors like the ECM and CCM that continue to draw some current but it should be very low.
My '94 sat for 5 weeks (not even a good excuse) before I fired it up last night. Battery was fine. Unfortunately it sits for weeks at a time quite often but it holds a charge. The battery is a Die Hard Gold, replaced a little more than two years ago.

Thansk guys for the input. So this is interesting. Dburgjohn's 92 like mine won't hold a charge for more than two weeks. JRMaroon's 94 and c4cruiser's 92 will fire up easily after 5 weeks. Two cars at 2 weeks, 2 at 5 weeks.

What you said c4cruiser about shutting off the climate control before stopping the motor caught my eye. My climate control was not shut off last time and maybe that draws power, though you would not think so. Anyway, I have taken to shutting it off now. And I agree, driving times and conditions do impact batterys. But, if a 92 and a 94 can go 5 weeks, I would think mine should be able to also last 5 weeks under reasonable conditions unless my 96 computer draws more power, but 2 weeks is not very long. And the Die Hard is a good battery, but my new Delco should be pretty darn close. I'm not sure dburgjohn if it should be the nature of the beast as you say....I gotta believe I should get more than 2 weeks of battery life out of the car...Or was it like c4cruiser implied, that the car battery maybe was not in top charge when I left it.
By the way, when I hooked up my Sears battery minder today to check something, I noticed it cuts in and out about every 30 seconds to one minute like it always did, so the computer or something is drawing power.
Have you ever checked the electrical system for excessive current draw? There will always be some current draw because some systems need to have power all the time to retain values. The ECM and CCM are two examples.

You might do a search on "current draw" or "battery drain" to find other threads on this subject. By using a digital multimeter in line with the battery positive cable, you can determine current draw to see how much current is being used. You can also pull individual fuses to see if that impacts current draw.

Electrical diagnosis can be a real PITA but if youkeep having problems, you may have to have the electricl system checked out by a qualified and experienced shop or technician.
Thanks c4cruiser. No, I have not checked the electriacal system for excessive current draw. But, I am going to do that as you suggested. I am also going to contact the aftermarket alarm company to find out if their system draws current when it is off.

I tried to find info on this site and different sites on "battery drain" and "computer drain" etc. etc. but could't seem to get anywhere. I will try again searching under "current draw" as you suggest.

It would be nice to know what a "typical" or "standard" current drain is so that when I found out what mine is draining I will know how it compares. The fuse idea makes sense and is relatively easy. This sounds like a good winter storage project for me if I can't sort it out in the near future......
I have had an Interstate Megatron in my car for the last three years. Original Delco lasted five years. I now have almost 80,000 miles. Last winter I put the car in cold storage on December 15 and the car was not started until March 1. Car started right up. This after I installed wiring for a battery charger so that I could charge it at anytime easily. I really like Interstate Batteries. Sold them for nearly 20 years. Very few problems with them. I feel that the battery is the most important part of this equation. Just my .02.
Thanks lt4man. Same year Vette, same engine. If yours can fire right up two and a half months later, then so should mine. It sure tells me something I wanted to know and that was how much down time was possible with the battery still able to fire the engine. I find two and a half months very acceptable. I'm going to take your advice and check out the battery angle for sure. I'm even wondering now if that Delco was the properly rated one...

And I am going to check on what the drain is on the battery at the same time as c4cruiser suggested. It's got to be the battery or current drain or a combination of both. Of course, the battery is the easiest fix if that is the problem. Busy like crazy at work...long days.... will try to get at it on the weekend.
The first winter I had my 94 I disconected the battery but it was still dead.
Bought one of those battery tender/minders and it has worked great
Corvette-Pilot said:
The first winter I had my 94 I disconected the battery but it was still dead.
Bought one of those battery tender/minders and it has worked great
I used a battery minder last winter and it was also great for long term storage.. I was trying to figure out though, why mine went dead in two weeks time...AND...I got some answers this morning!!!! I went to a shop that services crime stopper car alarms. Because neither of us had a service manual for my model (which is old--installed in 1996) we could not sort everything out and we are now trying to track down through the company a service manual which will tell us lots of good stuff I hope.

Anyway, figured out that mine does draw some power when the alarm system is off, but how much we don't know yet. Also, the batttery for the siren draws it's charge from my battery, so in storage I should use the off switch on that siren to save current draw.. There appears to be no power cutoff switch for the alarm system which is unusual, but we hesitated to put one in until we can get a service manual. Appears then that this alarm system draws some current when off. I am going to try and figure out if it seems to draw less or none at all with the siren switch off. And then once we get the manual I think I will put in a switch on the power line to be able to shut it all off when I want to.

The car battery should be ok..it is new and is the exact rated model Delco /cold cranking amps etc. as per GM specs. I think the alarm system is drawing the extra current....just enough to drain the battery in a couple of weeks.
I have an '85 which is my daily driver. Last year I was suddenly hospilized and was out of comission for about 3 months. My Vette sat in the garage for 2 months before I was able to start it up and let it run. It started right up (quite to my surprise) and never had a problem with the time it sat. My CD changer did die however. :(

I also have a '55 Chevy that spends most of it's time sitting in the garage and I have had issues with batteries with it. I finally installed a trickle charger on it and that ended the battery issues with it. But we are now talking about sitting for months and not just weeks. I sometimes don't start it for several months. It was going through batteries before I installed the charger. The Vette however usually does not sit for long except for that one incident.

Good luck with it...............
Thanks for the info bob2lxa. Further tells me 2 to 3 months is the target time for battery life. I am still waiting for more info on the alarm so I can permanently shut it off during down time and rule it out. Battery minder works great on my car too, but I want to know that it can sit a few weeks without the minder. I am going to pick up the multimeter as c4cruiser suggested if I get nowhere with the alarm service people and I have to sort through the current draw myself. I intend to identify and sort out the reason the battery life is only two weeks....sigh...I wish the original owner had left the alarm system stock........:(...
It has been quite a while, but I finally was able to isolate the alarm system I think and with everything shut off, I followed up on c4cruiser's advice about measuring the current draw on the battery.

The result was "71 milliamps". From what I am told by my mechanic that is very low. He feels the battery should hold up at least a month with that small a draw. He thinks that before when the battery went dead after 2 weeks that either the aftermarket alarm and/or something I had not switched off like the climate control may have been drawing more current.

Does anybody know what their current draw reading is or what it should be? Is it true that 71 milliamps is very low?....and low means good.

I will use my battery minder this winter while it is in storage, but I would like to think the car can sit a month without it and fire right up.

Battery Question

If you disconnect a battery terminal on a '92 to eliminate the draw, what problems do you have with the radio or security system?


markone said:
If you disconnect a battery terminal on a '92 to eliminate the draw, what problems do you have with the radio or security system?


I don't think any except that you may have to re-program in your radio stations you had selected and set the clock when you reconnect. There is a gadget (Corvette Central has them) that you can place in the lighter to maintain some settings when the battery is disconnected. If the alarm is stock I am not aware of any problems there. Many owners disconnect the battery for storage, others use a battery minder. The only time my battery was disconnected was to put in a new one and I only had to reset the clock and the radio stations as I recall. Not sure if there is anything unique to a 92 versus a 96.

Someone else can probably verify that and comment on what to look out for.
I have been told by a number of car dealers that they always disconnect alarm systems on used cars because they tend to drain batterys.;shrug
scav said:
I have been told by a number of car dealers that they always disconnect alarm systems on used cars because they tend to drain batterys.;shrug
I believe that...it makes sense. Since I found an on/off toggle switch under my dash that hooks into my aftermarket Crime Stopper alarm, it seems when switched to off position the battery current draw is way down...like I said before only 71 milliamps which I assume is really low (does someone know how low this is?). I don't think the stock alarm draws much current as some earlier posts indicated their cars could sit for months and still start....I may let mine this winter sit without the battery minder hooked up for a few weeks and then try to start it just to see what happens and if it is ok then try it every couple of weeks.....of course that could be a not so smart idea:duh ...I've had them before.
Canuck nieghbor;
If your battery on a C4 won't hold a charge for over 2 weeks, replace it. I went with the Canadian Tire Eliminator. Great warranty, 1000 amps, free replacement. Now I leave the battery in the car for 6 months of winter, I just disconnect the cables. It resets your clock, trip meter and such but no biggie. I unhooked my goddam Viper alarm before I touch the cables though. Noisy!

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