Another Camaro / Battery / Alternator Dilemma !!!

[Roadkill]

Ever since I picked up the 4th gen it's been weak on starting if left a few days and won't if left a couple of weeks . . .

It's been over at my parents for a while but I brought it back last night . . .

The battery came fresh off of charge at 13.8V across the terminals (IIRC).

When connected up and with the engine idling read 14.8V across the terminals and 14.5V with the lights, full beam and heater blower on . . .

After a short journey (7 miles) back to mine the gauge read this :



(Looks like about 14.5-ish) ??

I'll do the checks again tonight but any ideas ?

I was convinced it was the battery at first but know little of these things !?

[Andy]

Whats the problem? That seems perfectly normal. If anything, I'm jealous. Very jealous. You've got more than 13v.

In all seriousness, that's fine, unless it starts boiling the battery fluid, you have a healthy alternator/battery combo!

[Roadkill]

Why is it going flat after a few days, then ?

**note**

My other 4th Gen was exactly the same . . I can't remember what I did, then, if anything . . .

[Andy]

Oh, I thought you were making a comment about how much your alternator was putting out.

Right, had this on my Camaro earlier this year. Get the multi meter and put it into current measuring mode. You should have an ammeter setting with about a 15amp limit. Pop the hood, disconnect the negative, put the meter between the lead and the battery terminal. How much current are you drawing?

You should see a very tiny draw, like a few milliamperes, obviously make sure the door isn't open as the interior light will give a bumph reading. This test shows if your battery is being drained somewhere. If you have got a high reading, then it's time to systematically start pulling some fuses.

If you have a low reading the only thing it could be is your battery is cream crackered and in need of changing. Bear in mind the cold foooks up batteries quickly.

[Roadkill]

Quoting: Andy

Get the multi meter

Uh-huh . . .

Quoting: Andy

and put it into current measuring mode

Ahh, see, there you lost me . . . . What one's that ?

I'll try to have a play later . . . .

[Incursus]

I would say either something is drawing power (boot/glove box light or dodgy alarm system) or your batteries on it's last legs. imho, afaik, tbh.

The alarm system on mine will drain the battery in under a month, the old battery would drain in a week if I didn't use it.

[Rocky]

4th gens are prone to battery draw, You can test the draw like Andy has said. Its normally the main interior light fuse which is sometimes linked to the central locking for the alarm. As its easy to get to alot just remove the fuse when not using the car for a while.

[Andy]

The setting you're looking for on most meters requires you to put the probe lead in a different socket as it needs to put a fairly hefty shunt in line to protect the meter needle should you actually see a high current draw.

We found ours to be draining like crazy and which point it became apparent the fog light had been left on which was wired to a constant live feed. Must admit not my best choice of wiring.

[Roadkill]

Hmm.

So (from an idiots point of view) if the battery is disconnected it won't have a draw so won't lose power ?

Last night (24 hours after coming off charge) it was 12.7V across the terminals - connected.

So that could be down to a draw or a dud battery . . .

If I disconnect the battery and it doesn't drain then it's a power draw somewhere in the car and if it drains while disconnected it's the battery ? - Is that right ?

Cheers, guys.

EDIT - I seem to recall my last 4th gen's glove box light stayed on all the time . . . think I'll check this tonight, too . . . maybe take the bulb out ???

EDIT EDIT - It definitely doesn't sound like the alternator, though, does it ?

[Andy]

Right, a 12v car battery should hold 12v.

If you take one fresh off a charger it could potentially be charged more than 12v however this extra charge may dicipate due to some clever physics stuff.

If you leave a battery disconnected in the car it should maintain a charge of around 12v but that all depends on the environment its located in. Cold nights kill car batteries, and if its anything like a third gen, there's no body warmer or anything else around the battery to insulate it.

If you connect the battery and leave it 24-48 hours and its dead I would be quite confident in saying you have a drain somewhere in the electrical system.

The best way of looking at is as water in a system...

You have a battery, imagine its a water tank, filled with say 12 litres of water. When not connected to any pipe work there are 12 litres in the battery. Now, connect the pipe work up, the whole car has 12 litres potentially around the system / circuits. If you then imagine every device connected is a little tap. Somewhere in that circuit one of them is either dripping or flowing. This is where current comes into the equation as the flow amount is the current (amps). One of these devices is effectively drain the system of water. Now some items like a perimeter alarm or that will have a drain as they need to function. But this will be tiny amounts. Items like light bulbs however use much more and drain a lot quicker.

Hope that isn't teaching you to suck eggs but it's the way I got it explained to me and makes sense.

This is also why an alternator needs to put out much more voltage than the battery can hold as it is replenishing the system with what it is using.

This doesn't sound like an alternator issue at all really.

[Roadkill]

Quoting: Andy

This doesn't sound like an alternator issue at all really.

That's what I thought.

I'll investigate a drain tonight . . . . . May end up keeping her for a bit so want to get it sorted.

[Andy]

See an alternator issue will be like mine. You'll be driving along, lights on etc, then before you know it, stuff starts going down due to low voltage in the system. Lights become dim, radio stops working. That's an alternator issue, where it's not putting enough power back into the system to make up for what it's lost.

[Big Mouse]

Mine used to do that, then I found that it was linked to the light switch. I used to turn it all the way to the left to turn the lights off and it would always drain the battery after a couple of weeks; then found I had to turn it back one click or it left a light on - that I had never noticed.

[Roadkill]

Odd.

Did have a look and couldn't see any lights on (under bonnet, boot, glove box etc . . . )
Also left the doors unlocked so the alarm wasn't active.

The battery had dropped another 0.1V when I checked a couple of nights ago . . . I'll check again tonight - I suspect it will be almost beyond starting this evening.

[Andy]

.1v is negligible considering the weather and the unknown condition of the battery.

Really need to see if there is any sort of drain on the system.

Has it got the original head unit?

[Roadkill]

Quoting: Andy

Has it got the original head unit?

Yup

[Andy]

Ah fair enough, rules out a constant live running the head unit.

If you want to see the effects the temperature will have on a battery just disconnect it and leave it in the car, over the space of a week it'll lose quite a bit.

You could find that battery has been on there for 5+ years, it's having its first look at British Autumn / winter and ain't keen!

[Roadkill]

Put the multimeter across it yesterday (7 days after the charge) and it read 12.2V.

It fired up a bit sluggish, but not too bad.

General consensus in the end was weakish battery and a possible coilpack drain . . .

Not my concern now as the Camaro is sold and gone !