87vette

I recently purchased a new battery because over the winter my battery slowly died for some reason. Eventhough I would come out every week or 2 to start her up to keep the fluid circulating.. the car won't start until i jump start it. Now with the new battery in it... and the weather being warmer.. The car wouldnt start yesterday and the battery voltage was reading from 10.4 to 11.3. Normally when its fine it reads 14+. I'm a little perplexed to whats going on. I have a new starter in it and thats not the issue. I was told that I should replace my positvie and negative battery cables since the negative cable rubbering is dried and cut up. That shouldn't be an issue either. ANy ideas?? :confused:

Strick

Cables are so important to be clean at both ends and not split from swelling. The swelling is a good indication that the wire is corroding on the inside due to a kink or slight separation of the wire. This will cause resistance. To put your mind at ease, check those cables! As far as a Vette sitting for a while, put a battery trickle charger on it a couple of days before you crank it up. Don't rely on your alternator to charge up your battery, one it's not designed for that and two, it will heat up your alternator, which I think is one of the problems with your vintage Vettes' alternator dying so often. Just a thought.

:cheers:

don hall

There is a difference between "starting" and "cranking". I'm not sure from your post if the battery activates the starter, but the engine doesn't run, or, if the new battery doesn't even turn the starter motor. You say that the vette will start and run with a "jump" start. That is good, as it means that all your starting components are working. The trouble points to the battery and the connections. Make sure all the connectors are tight. The voltage is low, as you understand. Charge the battery so that you are reading 12+V and try to start the vette again. If it starts, you want to see a 14+V indicating correct alternator output. If it doesn't start with a fully charged battery, the cables are suspect, although you are able to jump start using the same battery cables. Confusing problem. Keep us posted.

jimswhite92

Did the new battery start your car 2 weeks ago. If so, you may have a drain on the battery that is discharging it (light on, etc.)

87vette

Nothing that I noticed. With the portable jump starter.. when hooked up all the power comes on. I am charging the portable jump starter as we speak and hopefully that will get her up and running again. As everyone else has been saying it looks like I'm in need of getting some new cables just to play it safe.

VetNutJim

87Vette,

Get yourself a "BATTERY TENDER".

I leave mine sitting for weeks sometimes months. BUT, I ALWAYS have the battery tender on it.
This eliminated my battery problems.

There is enough parasitic drain on the battery of a C4 that it is possible to discharge the battery in a couple of weeks.

BATTERY TENDER..... this is what you want.

My 84 has been sitting for 6-7 weeks now and it'll crank right up. The reason?
Battery Tender.
My Z06 has been driven ONE time this year for about 16 miles.
It'll crank right up right now.... The reason?
Battery Tender.

Don't get ANY old charger either. Most will boil the electrolyte out of your battery in a coupl;e of weeks.
You need the "float charger" capability of the Battery Tender.
I'll save you from having to buy a lot of batteries.

Wow, this soundz like an advertisement for Battery Tender, doesn't it?
It's not. I'm just telling you what has worked for me and worked EXCEPTIONALLY well.

Note: I do not own any stock in the BatterY Tender company.

87vette

Hmmm How much do the battery tenders go for ? I never heard of it. :cheers:

jfb

Your battery was discharged, the evidence is the battery voltage. Fully charged, a car battery should read 13 volts, discharged, 12 or below. If you already have a battery charger, you can buy an interval timer and set it to its minimum interval each day (usually 15 min), then you will keep your battery up without overcharging it. Lead acid batteries don't like sitting doing nothing. Under this condition, lead sulphate collects on the plates and you have an expensive door stop. Lead acid batteries self discharge about 1% each day even disconnected!, so they should be periodically charged. The battery tender is a good method to keep your battery charged, but again, if you already have a battery charger, get an interval timer.

pwrful c4

Something is causing the battery to drain,I would have it checked. possibly the alternator. :steering:

VetNutJim

The Battery Tender is 40 bux. There is a forum vender that sells them but I forget at the moment which one. Go to the forum mall and look for it.
It's the best battery charger since sliced bread! :)

There are a couple of things that ARE causing the battery to drain.

Actually maybe three or four:

1) The courtesy light timer
2) The Radio Memory
3) The VATS/Anti-Theft circuit
4) The battery itself as mentioned above

I don't know if I forgot any other "hot" sources.

If ALL your equipment is working (ESPECIALLY the courtesy lights)
then you probably don't have a malfunction you need to look for.
(The courtesy light timer used to drain my battery in three or four days. of course my courtesy lights didn't work either)

If you have a VOM with an amps range (volt/ohm meter) you can take loose one of the battery terminals and actually measure the current drain to find out. It's a very simple procedure.
Put your meter on the highest scale ie; 10 amps. DO NOT TURN ON THE KEY!!!
If you disconnected the positive terminal then put the positive terminal of the meter on the positive battery terminal.
Put the negative lead on the battery wire you disconnected.

If you are getting a reading if it's VERY small then disconnect ONE meter lead then go to the next smaller amp scale on the meter until you get down to 1 amp or lower. Don't burn out your meter by selecting the smaller scale too soon.
Measure the actual static current draw. It will probably be less than 100 ma (milli-amps)
If it reads 1/2 to 1 amp then you have a problem you need to look for.
Leave you meter connected and pull fuses from the fuse panel ONE at a time.
You're looking for the one that makes the current reading drop way down or dissapear. That will be the circuit you'll have to trouble shoot to find the problem.

This "may" sound complicated if you haven't done it before. Actually it's very easy and won't take you more than 30 minutes to isolate the defective circuit, if you have one.

Send your findings back here and myself or some of the other members will advise as to what you need to check next.

Forgot: AS powerful C4 above said you could have a leaky or defective diode in your alternator. If you do the alternator won't be putting out enough current to charge the battery when you do run the engine.
To find out, get the car cranked, jump it if you have to and check the battery voltage on your dash digital gauge. It's pretty accurate.
With the engine running around 1000 to 1200 RPM if the voltage isn't OVER 13.0 then the alternator isn't charging for some reason. If the voltage is 13.8 to 14.2 then the alternator should be ok.

If it's lower you have wiring/connection/alternator trouble.

BTW if you want to check for a bad alternator diode while you do the test described above then disconnect the alternator red lead AND the alternator plug and measure the current drain as I described. If it makes absolutely no difference then the alternator isn't DRAINING the battery. It may still not be charging it up good but you'll know it's not the source of your battery drain.
BE SURE and disconnect the battery BEFORE trying to remove the alterator wires.

........


[Modified by VetNutJim, 8:17 PM 5/8/2003]

froggy47

It's been my experience that even a new battery can be "spoiled" if it goes below 11 volts or so once or twice. My 02 Suburban had that happen. I killed the battery myself by leaving something plugged into an accessory outlet.

It jump started fine but ever since then if I did not start it for 3 or 4 days it would be dead (below 11 volts - not enough to start)

Put in a new batt & now I can let it sit a week or more & it starts right up.

If you get a new batt look at the Optima line - especially the one designed for long storag/deep discharge.

Also the batt tender is a good piece of equipment, go to an RV store like Camping World. They have lots of battery stuff.

Also a disconnect would solve parasitic's.

87vette

Alright I'll check into that. Gonna have to print this out. I've probably went through 3 to 4 batteries since I owned the car for 3 years now. Everytime I let it sit during the winters this is what happens. When I drive it I never have a problem. Hopefully I'll get it done soon. Thanks for your help. I'll let you know what happens. :cheers: