Flat battery

[suicide_al]

Hi, having a problem with my Elan, haved seached the forum and have seen several threads about batteries going dead when left for a week but my problem isn't this (well I don't think so).

Recently had my alternator replaced (ouch!) and was looking forward to a maintenance free couple of months. I use the car almost daily but not to go far. The other day I got in and the battery was flat. Stereo is not on (face is off), no alarm, lights not left on, so nothing obvious (well at least to me).

Thought the battery may just be knackered so went to get a new one fitted today. Jumped the car fine and took it to the garage, they tested the battery and it seemed fine. Stopped the car, and started it again no problems, so decided against getting a new battery. Drove it home, went back to work, came back 4-5 hours later, completely dead again, not even enough charge to operate the central locking.

Any suggestions on what this might be, or even how I could go about diagnosing the problem?

Hopefully I haven't missed any obvious post that has already answered this problem.

I'm also interested in a trickle charger, all links I have seen are dead now, so if anyone can point me in the right direction that would be great.

Many Thanks, Al

[Monty]

if it`s not u`r battery, it still could be the alternator. Whats the battery gauge showing?

oh make sure the boot light is working correctly, as these seem to fail and end up staying on even with the boot closed.

[suicide_al]

The battery gauge shows 14 when running so I don't think it is the alternator. It charges when running cause I can start it again straight away once it has been running the problem only occurs after a few hours.

I'll take the bulb out of the boot, to eliminate that possibility tomorrow, then get another jump start.

[Rob-C]

A duff alternator on the old over I used to have did this.

It was draining the battery to earth all the time it was connected, but still managed to push out enough charge to keep the battery topped up while the engine was running.

[NIL8379]

Well just for good measure go to another place and get the battery checked again cos it sounds like a duff battery to me, all the signs.

The volt meter on the dash is a good indication that the alternator is working ok, 14 volts is good and should drop back as the battery gets charged up.

An easy way to see if anything is draining the battery is simply to disconnect it and leave the car for 4 or 5 hours or overnight. If the battery will not turn the engine when you reconnect it I'd say the battery is loosing its charge. This can happen with batteries when they get an internal short circuit. It may test ok when it's charged up but slowly discharge itself.

I think I'm right here but will stand to be corrected.

[Exbury]

A battery place should also be able to test whether you have a drain, relly unless you have an alarm or hard wired radio, there should be nothing taking away charge (possibly clock). However neither of these should use enough to take away the amount of charge in a fully charged battery in just a few hours. The disconnect & overnight test is a good one.

As stated before either you have a duff battery (check this first), a huge drain (check this second), or a duff altenator (last check) which may have over charged the battery and given you a duff battery too!

It may be a slight possibility you have a really bad earth to the starter motor and it needs a huge amount of power from the battery to turn over. With a smallish drain it is a possibility but without seeing the car 1. unlikely and 2. I would need to see the car more.

[suicide_al]

Many thanks for the replys so far, I'm keeping my fingers crossed it is not the alternator, but as NIL8379 says it looks like the alternator is working.

I'm gonna trying some of the suggestions and see if I have any luck, I'll reply when I know more, but if anyone else has any suggestions I'd be more than happy to hear them!

[chrisP]

If you want to find out whats draining the battery properly (maybe a sticking switch or relay) you need to disconnect the positive battery terminal and place a multimeter in between it and the battery, (set to amps if I remember correctly)you can then go round and remove fuses one by one until you find out what one is causing the current drain
Chris

[Dave M]

You also may want to try a simple cleaning of your battery contacts/posts and make sure they are good and tight. I had an issue with a new battery a while back in the Elan where it acted dead. Wouldn't even show a dash light, let alone turn the car over. After pulling and reinstalling the contacts (making sure to tighten them, especially the positive lead), it works fine.

[suicide_al]

Right, think I have made progress, and am ashamed to admit I think it was something very obvious. Jump started it today and drove it around for a while, all the time I was driving the interior lights were on so that sounds like the likely culprit. I disconnected the battery when I stopped just for good measure and I'll leave that over night to see if it holds charge.

Right next question! Why would the interior lights stay on, and how can I fix it. Its not the switches as they are in the off position. its both sides that stay on if that helps.

I also disconnected the boot light as well to eliminate that...

I'll keep people posted as to the battery outcome, but if anyone knows why those darn lights are on.

I feel a bit a stupid, if it is the interior lights, damn these long summer nights. However if this is the problem its one less thing to worry about.

Thanks for all the help so far...
Al

[Monty]

Sounds like u`ve sussed it, don`t know if u know this but if u pull out the knob that controls the head lights/parking lights this switches the interior lights on, so just make sure that it`s pushed in for off.

[NIL8379]

Well I never, you learn something new every day!

Thanx Monty

Now here's a bit of ohms law as I remember it............lol

Volts x Amps = Watts

Amps = Watts
.............-------
.............Volts

0.5A = 6 Watts
...........--------
...........12 Volts

so a 36 amp per hour battery should power a 6 Watt bulb for 72 hours.

Interior light can't be ur problem surely

Is that right guys?????

[Exbury]

Yeah, but divide by three if the two interior lights and boot light are on, reduce it by the fact the terminals might be slightly corroded, a battery is rarely 100% efficient and that the starter motor needs a good battery that could be a problem.

[suicide_al]

Just thought I'd post the happy news (well for me anyway). Monty had it 100% right, the main light switch was out. Reconnected the battery this morning still had full charge, checked it again at lunch and still full charge.

I'm guessing the light thing is in the hand book ... oh well you live and learn.

Thanks all for your help.

A once again happy al

[Doug]

that's why you are a 'Newbie' !!

[NIL8379]

Well done Monty......so much for ohms law