Flat battery, new owner

[fullthrottlehyde]

Hi all,

I've moved here from the classics section after selling my Mseries and taking the plunge and buying a 4.2 Cerb. As I write I'm currently waiting for the AA man lol after the Cerb has completely run out of battery and come to a grinding stop lol
So when I got her I new the battery was dodgy, so bought a new Bosch unit straight away, seem to be getting about 14 volts when running so technically should be charging, however it's stopped and has absolutely nothing left.
Apologies if this has been covered not the easiest to search on the iphone

Cheers Ben

[Tanguero]

Check the big fuse (at the rear of the engine) it tends to crack and is probably the most common cause of charging issues.

Good luck with the AA!

[fullthrottlehyde]

AA man did the job, fired her up and got her home, wiring was a bit loose on the back of the alternator, which has been tightened up. On restart he checked the charge, on tick over was about 12.5 which whent up to 14 with marginal throttle

[QBee]

Make sure you do find out where the 100 amp fuse is. They are prone to failing and AA men often don't know where to look. If you carry a spare, a jack and a small spanner you can even change it yourself.

BTW, your profile needs attention.....

[fullthrottlehyde]

Off to go and check the fuse, found a great thread on that and probably explains a couple of other things. Yep profiles a little old, not an evo x in sight, was my company car and I hated it, it was awful

[sonnylad]

No jack required for fuse, you will find it behind the coil packs just above the bell housing tucked away in a black plastic housing with two big red wires coming off it.

[Tanguero]

QBee said:

Make sure you do find out where the 100 amp fuse is. They are prone to failing and AA men often don't know where to look. If you carry a spare, a jack and a small spanner you can even change it yourself.

A jack?? There have to be easier ways of getting to the top of the engine than lying under the car and giving the bell housing a reach-around!

[Byker28i]

Jack? Remove the top panel that covers the battery, wiper mechanism, throttle linkage etc and just reach down. Handy to have a torch or light available. It's worth checking what's needed to undo the terminals holding the fuse, then get a long shafted tool for it. Mines covered in shrink rubber so it' won't short against the engine.

[QBee]

Ok.....no jack required. Sorry, assumed it was similar to the Chim and Grief

[fullthrottlehyde]

So got to it and reading the link below I do have some of the other issues as well, which points to the fuse. like dodgy rev counter. However after having to go double jointed to get to the little black box I discovered it has the 125 fuse upgrade. Do I need to take this out to check it? As you can see the link below, it's a pink block?

http://www.clever-trevor.net/TVR/Parts_details/M19...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Cheers

Ben

[sonnylad]

If fuse is ok i would just make sure the terminals are clean and nuts are tight

[Byker28i]

Standard indications that the big fuse has gone are the wipers become incredibly slow, and the rev counter jumps around all over the place. That's before you run out of power

Don't assume it's not gone. They crack around the terminals and are very hard to see if they haven't blown. Actually take it out and check it.

[fullthrottlehyde]

Thank you, I have super slow wipers and a dodgy rev counter, so that should be that then!! Ordered a few replacements to Cary in the mini tool kit

[fullthrottlehyde]

After cutting my arm 4 times, I changed the 125 amp fuse, the old one was fine, cleaned all the terminals and the leads and put some nylock nuts on and hey presto everything working. Battery charging, rev counter working and fingers crossed wipers not horrifically slow anymore.So technically dirty wires or loose nuts.

Put it all back together and fired her up and got the multimeter out and on tick over only getting 12.5 volts, is this normal or should I be getting higher?

Cheers

Ben

[QBee]

Where are you measuring it?

[fullthrottlehyde]

Battery positive to the aircon shroud for neg

[N7GTX]

12.5 on tickover is right. Raise the revs a touch and it should jump above 13.5. Assuming all electrical stuff switched off that is.

[QBee]

Try measuring the output from the alternator.
My battery normally reads 12.5 volts with the engine off, but 13.5 at the voltmeter (I have plugged in the fag lighter socket) with the engine running. Can be almost 14 volts at the alternator with the engine revving.
Suggest you get someone to rev it a little while measuring. But if it still reads 12.5 volts at the battery when reading 14 volts at the alternator, you need to do more research, as clearly the juice ain't getting through.