Third Dead Battery in One Year

[Guest rubbercow]

I've run into an interesting anomaly with my '73 SBF 240z, where in the last year three new batteries, from different brands have all failed.

 

All three have failed a recharge test and an attempt to jump. It is a sudden occurrence, no particular circumstances, weather or driving pattern. Two is an unlikely coincidence, but the third failed yesterday and it simply doesn’t seem likely.

 

Has anyone else run into this with any car, and are there any suggestions?

 

Thanks!

[savageskaterkid]

wht kind of batteries were u using, were they the cheapest thing on the self, or where they decent batteries-if i were u, i'd go with an Optima battery-they have good reviews and such, but if ur killing high-dollar batteries, then just buy cheap ones, cuz if enen a godd battery doesn't last, then no use buying a name brand

[Tim240z]

I second the Optima suggestion....I have deep cycle discharged it several time (leaving stuff on for days at a time). It takes a charge every time and keeps it. I mean I have discharged them flat as a pancake!!!!

[datsunlover]

I had a similar problem, and also went through 3 batterys.. in a matter of months! I bought a car used, and the battery in it at time of purchase needed a boost. Seemed fine for a few weeks, and suddenly it was dead. Would not take a recharge, but managed to get a jump start. Drove to parts store, bought new batery. All was fine.. again, for a few weeks. Then one night while I was driving home, the stereo turned off, the lights dimed, and I had to coast into the driveway (what luck I was so close!) as the engine died. Tried a boost from another running car, but got nothing.

 

So I called a few friends, and garages and the general consensus was a bad alternator. I pulled it out, and had it rebuilt. Got another battry (waranty replacement for the 2 week old dead one.. Me; "I dono man.. it just died.. and it wont take a charge" Parts Guy; hmm.. guess it's just a defective one.. I'll get you another.") And voila! Car started and ran perfect for the next 3 years!

 

The rebuilder tried to explain to me but this is about 4 years ago.. things go fuzzy you know... I think it was something to do with a cuircut in the alternator/regulator/? 'sticking' and constantly charging.. Ie; It was basicaly running the engine/electrical system because the FIRST battry was dying, and on its way out. (dead cells, age) My guess is it then killed the NEW battery from overcharging, and by that point the alternator had had enough torture, so It gave out.

Other than that.. maybe a slow drain somewhere in your electrical/charging system may be doing it.. slowly draining it, and after a certain point.. it won't take a charge from the alt OR a boost?

[GabeRoc]

i'll second the alternator statement. if your voltage regulator is on the blink it can ruin a battery in short order. pull it off and have it tested before putting a high dollar battery in it's place.

[Pop N Wood]

... I think it was something to do with a cuircut in the alternator/regulator/? 'sticking' and constantly charging.. Ie; It was basicaly running the engine/electrical system because the FIRST battry was dying, and on its way out. (dead cells, age) My guess is it then killed the NEW battery from overcharging, and by that point the alternator had had enough torture, so It gave out.

 

Exactly. If the voltage regulator is bad it will put too many volts to the battery and even that $165 optima will cook in short order.

 

The old Z's had external, mechanical voltage regulators. If they stick, or if the voltage sensing wire is shorting out, you will get too much voltage. You need to replace the voltage regulator separately from the alternator. The newer alternators have electronic voltage regulators built into the alternator itself.

 

Hook a volt meter up to the car. You can get ones that plug right into the cigarette lighter. Should stay around 14 Volts. The mechanical regulators will jump around a bit, but the average voltage should not go much over 14 volts.

[Guest rubbercow]

One battery was a new Optima, another was an Energizer, and the third was a Prostart. All three were 900-1000 crank and over 70$ each (ie, not crap batteries.)

 

These are all excellent suggestions. Thanks very much, I'll start testing them tonight.

 

Anyone have any suggestions on a specific alternator or brand?

[Hugh]

When my charging system wasn't working at all, I drove my car for about a week on the Optima red-top I put in it. (wasn't new either) I realized after testing the system that I was seeing about 9.5 volts or so while running... and the battery consistently powered all my electronics and the engine without a single charge in a week.

 

Cut off the engine, I saw 12.2 volts or so.

 

I've been using Optimas consistently for about 4 years now, and I'm not willing to stop.

 

 

In my old 180sx, I once left the dome light on all night. When I came out, I turned on the key and the voltmeter on my dash read something like 3 volts. I cut off the light, and turned the key over. The car started. It recharged on the way to work... and I never had a problem after that.

 

I second the over-voltage thing. Over charging won't only kill the battery... it could really cause an unsafe situation.