Thursday, November 20, 2008 - 11:50 am, by: Daniel Jeyes(Danjeyes)
hi my battery is going flat i have put 2 new ones in and in about a week it has trouble even pushing out the solenoid on the starter i took it to a well recommended auto electrician he said he could not fault it at all he said what ever it was doing it isn't doing it now so a week later what do you know it has done it again it obviously isn't my battery so anyone have a clue that would be great thanks
Thursday, November 20, 2008 - 05:09 pm, by: David Vaughan(Davidv)
You need to get hold of a decent multimeter and maybe someone who knows how to use it. An adequate one can be purchased from Jaycar or similar for a few tens of dollars.
Connect it in series with the battery and check the drain with ignition off and key removed. If it is greater than about 30 mA then start pulling fuses until the drain stops. There will be your culprit, if the problem is indeed a steady drain when the car is not running.
If you want a quick and dirty check, find the lowest wattage 12V globe you can (e.g. interior light) and wire it in series with the battery. If it glows, you have a problem and it is worth getting the multimeter. If it does not glow, you may still have the problem but need a more sensitive instrument.
Friday, November 21, 2008 - 04:07 pm, by: Daniel Clarke(Dieseltrain)
I thought disconnecting the Battery would stop everything all together as it then removes power to the ecu and such? IE breaks the circuit? I locked my wifes keys in her car whilst the bonnet was up and trying to Jump the SOarer 1 time... I disconnected the battery to save the fuel while i broke into it,hehe...
If we take it that Daniel has done exactly as he said then the battery is superfluous once the car has started, because it is in parallel with the alternator to the remaining car circuitry and hence not, in a vital sense, part of the circuit.
I have never bothered to test mine but, having been asked to think of it, parallel connection is essential or else how can the alternator charge the battery?
I agree with David Vaughan's method. Try and isolate where the drain on the battery is coming from, you can also use a current clamp meter which makes things even easier.
Also, it could be that your alternator is not charging properly, check these values against your car (measure across battery terminals)
ignition off- 12- 13.8v Car idling battery voltage- 14.4v lower than 10v- collapsed cell. totaly F*$ked
If it is lower when idling, chances are its an alternator problem. The remedy may be as simple as bad connections in the fuse box, battery terminals (remove, clean with sandpaper and re tighten) or the main earth from the engine and battery to the chassis.
I have worked on taxis lots and there's so many things that can go wrong. some rarer problems can be terminals shorting on the bonnet, or the alternator diode blowing and OVER charging the battery... say at 15+V, which will kill a battery really fast.
Friday, November 21, 2008 - 07:35 pm, by: Daniel Jeyes(Danjeyes)
everything sounds like it should at idle its at 14v but i took off the pos battery terminal an put on a multimeter and it was draining 30mah then i took out the 10amp dome fuse then it dropped down to 20mah and my battery was at 12v that was all about 11:30am today then at 4:45pm i jumped in my car to go home and the door chime wasn,t even beeping and my interior light was dull as f@#k im obviously stuck there must be something draining it so much for it to not even turn off my imobiliser after 5 hours what do you think. next week i have me misses car so thats ok but still not good
Saturday, November 22, 2008 - 12:13 pm, by: David Vaughan(Davidv)
If prior to that the battery was charged only by driving, then it sounds like a static drain, and as I said earlier, 30 mA just won't do that in a few hours.
David Henderson mentioned the possibility of shorting to the bonnet. Have you looked for that (there will be marking)?
When you test the drain, do everything you normally would to leave the car, like closing and locking and so on, except that the bonnet is up . Keep an eye on it for a minute or two, or come back in ten minutes to see if it is the same.
If it comes up clear from that then the remaining problem is charging, so far as I can see. Presumably you had to charge the battery externally the last time it was flat. That being the case, go for a few runs. Check battery voltage immediately before and after immediately after each run (engine off in each case) with at least an hour between them. The resulting measurement pattern should tell us whether it is a static drain or charging problem.
After all, disconnecting the battery every time you park the car has its disadvantages.
with ignition on but engine off you will get some drain due to the dash lights etc... even then though, 30mA is nothing. wont drain a battery fast.
As David V said, try popping your bonnet then locking you car, and check the drain. I think the immobiliser may be the problem, they have internal relays which can die and possibly only be a short after the immobiliser is activated. It seems like the drain is only evident when the car is locked.
See if you can find the immobilizer box, find where the power is tapped into the cars harness (12V all the time and a fuse, probably 3A) and pull the fuse. depending on the alarm, you may also need to find the 2 wires which switch the ignition wire and join them to actually start the car. This will prove the alarm the culprit or not.
A few weeks back, My alarm shat itself and wouldnt let me unlock the car to drive it (as my alarm requires an "unlock" beep just before the igition is turned). I could hear the relays in the alarm switching rapidly (click click click) and, not wanting a flat battery, disconnected it at the terminal until the alarm backup battery died (the next morning). it was ok after that but i will install a new one soon.
Another thing to check is your batteries performance under load. This involves loading it with a carbon pile tester (auto elecs have them) or a very large resistor capable of disipating a few hundred watts. This will test the batteries ability to hold a charge. If a lead acid battery is run completely flat a few times, it will be pretty much stuffed.
Monday, November 24, 2008 - 06:29 am, by: Daniel Jeyes(Danjeyes)
i think you are right David H because i was at my mates house all night with the car windows up locked and in the morning without even thinking about it it just started i was amazed so i tried it last night and it was OK this morning as well so its either the immobilizer like you said or the windows i know it is not fixed yet but thanks for every body's help i am really amazed on the people who are helping me if there's any problem with your car in the future ill be trying to help too thanks