battery question

[rudar]

So I had the battery out of my 1991 tracker for some repairs and whatnot. I noticed that when I re-connect the ground cable the *first* time, it sparks a bit. If I remove and poke the ground to the terminal several times, it does not spark *each* time. Is that normal? I guess it reasonable that there'd be some capacitance to the entire circuit. But then I lent my car to my roommate, who just phoned to say it isn't cranking, but he didn't leave the lights on or anything obvious like that to go draining the battery... So not sure if the two observations are in any way connected...

[rudar]

Well, latest update, after push-starting her twice, the roommate made it home. The battery's showing 12.85V open circuit, but less than a volt under load. Some whirring noise (fuel pump, maybe?), but no dash lights, no starter, no headlamps. Do I assume the battery is pining for the fjords and needs replacement, or is there it likely salvageable?

It *does* have two very encouraging stickers, one saying it was manufactured in October 2005, and the other saying it has a 3-year free replacement warranty, so replacing it might be a cheap (for me, if not for Canadian Tire Corp.) proposition...

[kelikran]

There is often a very small draw on a battery, but it shouldn't be a very big "spark" when
you touch the cables. You can actually measure this draw with an ammeter, just be careful how you hook it up and have it on the 10 amp setting if it has one. The draw should only be in the milliamp range, unless you have something drawing too much, which will kill the battery. I suggest getting a new battery too, Cdn tire can well afford it.

[rudar]

Well, they gave me a new battery, but not for free, because I didn't have the original receipt... Considering the battery was probably bought two owners ago, fair enough They did prorate it, so I was only out of pocket $57 including taxes and eco-fees...

Also, their system had no entry for the 1991 Tracker, but *did* have an entry for the 1992 Tracker, which was not the battery I had in there. Their system said the car needed a minimum of 690CCA, but the battery I was returning only had 630CCA. And they could only give me a pro-rated warranty price on the exact same model... Oh, well. I'm theorising that the old battery basically got shaken to death due to there having been no battery tie-down clamp in there, and had bought one but not installed it when the battery died. So I clamped down the new battery, and hopefully the 60-CCA difference is irrelevant?

[garcia]

Originally Posted by rudar

So I had the battery out of my 1991 tracker for some repairs and whatnot. I noticed that when I re-connect the ground cable the *first* time, it sparks a bit. If I remove and poke the ground to the terminal several times, it does not spark *each* time. Is that normal? I guess it reasonable that there'd be some capacitance to the entire circuit. But then I lent my car to my roommate, who just phoned to say it isn't cranking, but he didn't leave the lights on or anything obvious like that to go draining the battery... So not sure if the two observations are in any way connected...

Something is drawing current.
The radio clock (and station memories), draw some (very slight) current.

You can check how bad it is with an ampmeter.
Connect one wire to the battery post, the other to the terminal clamp (with it removed from the battery).

You'll get a reading. Anything beyond 0.5 amp (perhaps even 0.25 amp), will mean a dead battery overnight.

Try removing fuses to see when the current draw stops. When you find the culprit fuse, you now know which circuit to check.

[rudar]

Yeah, I guess I should do that. But it seems more like a capacitative load than a resistive one. Because it only sparks *once* (and it's a small spark), and it *doesn't* drain the battery overnight. So it's like, if the battery's been out long enough for a capacitor (radio memory, maybe? Some RF filters, perhaps?) to discharge slowly, then it re-charges fast, drawing a lot of current for a short amount of time, which is a spark. But then if I take the ground connector away from the post for a few seconds and put it back, there's no spark, because the capacitor's still mostly charged, so it doesn't draw much to top it back up. But I guess I'll put actual numbers to it, to the extent I can, with the multimeter, next time I have the battery out.

[jtgh]

get an amp meter, stop guessing.
( the ECU Caps will in fact make a spark each time as does total system capacitance)
Capacitance is a function of area and dielectric constant of the insulation.
it's real. We call this C(t) total capacitance.
the memory of radio and ECu both have capacitors filters , they add to it too.



if still worried here i my drain page
fast test:
1: pull neg battery lead.
2; KEY OFF, lights off, all accessories OFF.
3: amp meter leads to 20 amp plug holes.
4: meter to 20amp range with switch.
5, connect either lead to neg, battery term and other lead to minus cable end. DMM.
less then 25ma is spec (SAE) 0.025 amps in decimal.

if greater , pull fuses till you find culprit.
my page on DRAIN:
click>>> Phantom battery drain

add 0.010 amps if you have an extra alarm or remote start or other non oem add ons.

[jtgh]

do not turn on anything while testing as you run risk of popping meter AMP fuse.
if old meter, it can fry.