Battery Drain, Anyone measured the amp draw? Options

[Kerrys914]

I have a slow battery drain on my '74. Has anyone measured the amp draw on their teener? I am wondering if a stock FI car would/should have any amp draw?

I have a new battery and it seems to be going dead on me, 3-4 days of no use.

My dam craftsman multimeter is junk.. (IMG:style_emoticons/default/headbang.gif) I set it to read amps and the dam thing keeps climing till it maxes out. I can't measure a thing with it. I am going to buy a new one tonight and try to find the drain with it. Should I expect 0.0 for a reading?

One of the 4 red wires, which connects to the + , gets a nice spark when I reconnect it to the terminal. That tells me I have a nice draw on that circuit, correct?

Thanks
Kerry

Tyring to get ready for my first big road trip...8/8/04 (IMG:style_emoticons/default/beer.gif)

[bondo]

Do you have a car stereo or an alarm? I've had more trouble with those than anything else.. Also, most car cell phone chargers continue to draw with no cell phone attached. Is your ammeter fused? It only takes once measuring directly across the battery to screw it up.. on really expensive meters it trips a self resetting dealie.. on average ones it blows a replaceable fuse.. on cheap ones it hoses the meter permanently.

For anyone that doesn't know, you need to break the ciruit (disconnect a battery cable) and complete the circuit with the meter (set to current mode) to measure current. (connect one lead to the battery terminal, and the other to the cable end that normally connects to that terminal. In a DC circuit the current is the same everywhere, so you can measure it at either terminal. If you get negative numbers just switch the meter leads.

[Kerrys914]

Dam....I did put it across the battery (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif)

It is the $30 craftsman model. It also says UNFUSED 10amp max on it??

Dam Dam Dam

Looks I need to drop a few $$ and get a fused one with an autoreset feature as you mentioned.

Thanks

[bondo]

Doh. Fluke is the brand everyone likes.. about $100 for a basic one. Not sure what the auto-reset thing is called, but it's not really a fuse or a circuit breaker. It's some sort of device that has a low resistance at currents up to it's rating, and if you go above that it very quickly goes to a very high resistance to limit the current. Once the overload is removed it pretty quickly goes back to normal. I think most meters that have this feature will also beep at you to alert you to the overload. Hopefully someone who knows what the device is called will chime in so you can make sure your next meter has one.

[Rider914]

If your charger has an amp meter on the front, charge for a few hours to level it out, then start pulling fuses 'till you see the current drop.

I would try a battery load tester before a high dollar meter. My WAG is that the battery is shot. Three years is about all I ever get on a wet cell.

[Rider914]

Uh, never mind the old battery thing!

[Dr Evil]

A little less complicated to do is to connect your volt meter across the battery and start pulling fuses one by one. When you see a voltage change (should climb a little) then you know what circuit is drawing power. Check to make sure that the circuit is not supposed to be drawing the voltage; i.e. radio, alarm, etc. Once you get it down to the circuit it is easy. Let us know.
HTH,
Mike

[Kerrys914]

Okay guys..

I am getting 15ma draw from each of the two (double red wire) connections.

Is this normal? Should there be any amp draw from a stock 914?

The alt is putting our 13.5-14.5 volts at 1500 RPM

Thanks
Kerry

[bondo]

I'm not sure if that's normal or not, but I don't think it's enough to drain a battery in 3-4 days. Sometimes batteries are defective, try leaving it dicsonnected for a week and see if it still discharges. If it's a wet cell you can check to see if all the cells are equal with a hydrometer, but if it's a wet cell you should ditch it anyways and get a sealed battery before your car rusts to pieces.

[bperry]

Thats about what my draw down was.
(From what I remember when I measured it a few years back mine
was about 20 ma)
It was split between the factory console clock, my radio, and a
control module that is under the passenger seat.
I seem to recall the clock had the most draw.

--- bill

[Carrera916]

It should be drawing no more than 3 mA with only the clock running with everthing off....15 mA is alot...I have the same problem on my Audi and haven't found the damn culprit....

Radio with it's own clock will drawn current on top of VDO clock....anything that is left on with the ignition key off will draw current....that's something you've go to trace it....the red wires that you mentioned...find out what's that for and see if it's being left on....if so, bingo that's the bug you want to stomp on....

j

[bperry]

Ok, so curiosity got the best of me and I decided to actually
take some measurements.
Pulled my clock out of its storage box (I replaced it with a CHT in the console many years ago).

On the bench, I set my variable powersupply to 13volts and
measured the current draw of the clock with my analog VOM.

The current draw of the clock in this controlled environment
was 14.5ma

I remembered from years ago thinking that the VDO console clock was a
power pig. It is purely mecanical driven by a motor so I guess it is
probably not that bad of draw considering what's inside.

BTW, several aftermarket car alarms that I've measured actually
draw more than this at around 15-20ma.

So, if you have the console with the VDO clock, I'd bet on the clock
drawing your 15ma.

--- bill