Issues with Starting (Page 2/2)
ArthurPeale NOV 21, 01:00 PM
I keep a wrench in my truck specifically for disconnecting the battery if it's going to sit for more than a couple days.

It really sounds like you've got a parasitic draw (possibly your headlights, it's very common). I'd disconnect the battery cable between use.

Doesn't have to be both wires, one is sufficient.
Raydar NOV 21, 04:44 PM

quote
Originally posted by Vintage-Nut:
...
BTW: IF the engine/trunk deck is open and the parking brake is 'Off', current will flow even though the ignition is 'Off" which will drain the battery fast.....



Wait... what? This is absolutely the first I've ever heard of this, and I've had at least one Fiero since '97. (First one from 85-88.)
Which years? Which transmissions? (Since the parking brake/trunk interlock is wired completely differently between different trannies.)
Can you explain the "mechanics" of this?

[This message has been edited by Raydar (edited 11-21-2023).]

theogre NOV 21, 05:29 PM

quote
Originally posted by 87PontiacFGT:

After getting the battery up to around 12.5v outside the car, the car now starts without much issue.
I assume what you're saying that since the charger, despite having a "crank" setting, probably messed with the electronics since it lacks the components necessary to smooth out the AC current well enough. Makes sense I guess. Should I be checking for any specific ECM codes?
The ECM and other components killing a battery in only a few weeks seems kinda short, since the "normal" range of draw, is around 30-50 milliamps on most vehicles.

I should say any charger output is 13.5-14.7 DC volts. No AC volts.

If battery is only 12.5v then either the charger is bad or too small or battery is bad.
"trickle" charger just means under ~ 2a charging.
Use a charger that delivers 6-10a for a few hours. Then read battery volts. Then let it discon for 1 hour or more. Read battery volts again.
If disconnected & still drops then the battery is bad.

check temp during charging. If the battery get very warm to hot then Stop Charger because battery is bad. 6-10a charger for a few hours should bare warm the thing if heats up @ all.

If good or you replace it then Do Not let the car w/ some type of problem kill the battery.
Total "Standby" power for ECM Radio etc only allow ~ 35ma (0.035a) & if you see more then will kill the battery.

Suggest you buy a DC Amp Clamp Meter before bothering anything else.
Example: https://www.amazon.com/UNI-...rement/dp/B00O1Q2HOQ

Many Amp Clamps are AC only for the clamp so watch specs before buying/using other meters.

[This message has been edited by theogre (edited 12-17-2023).]

Vintage-Nut NOV 22, 11:36 AM

quote
Raydar:
This is absolutely the first I've ever heard of this {battery drain when engine/trunk deck is open and parking brake is 'Off'} / Which years? Which transmissions? / Can you explain the "mechanics" of this?



I'm sorry Raydar, I spoke briefly without going into any details so please let me rephrase my post.

First Things First: '88 GT with Manual Transaxle

Secondly, I thought my experience with this parasitic draw issue has been reposted previously so maybe I was "wrong".

The "mechanics" is really an electrical issue, and my temporary 'fix' was to disconnect the trunk solenoid in the engine bay which stopped the battery drain.

I won't dive into the circuit now, but I'll merely add 'Check Factory Inline Diode' on my list. One day, I'll start to see if the diode is shorted or not.......
Kookedlex NOV 27, 06:30 AM
I have a similar situation; the battery dies after a week or so. Can you suggest how to identify the specific issue?
theogre NOV 27, 09:50 AM

quote
Originally posted by Kookedlex:
I have a similar situation; the battery dies after a week or so. Can you suggest how to identify the specific issue?

read above.
Test the battery @ a parts store, walmart w/ auto service. The "smart meter" test more then just volts. But even old load testers can slow a "dead" battery.

see https://web.archive.org/web...rocave/bat_leach.htm

Buy DC amp clamp above so don't cut wires etc.
stevep914 NOV 27, 05:45 PM
I had battery drain and went through a battery in less than a year. Never did find out what caused it. Got fed up, and bought a disconnect switch like ones used on race cars from Autozone, installed it, and have never had the problem since. Not bad for theft deterrent either!