De-charging problem,please help before I find a hammer!

[Jesus325iTouring]

Righty,problem is my battery is decharging..

Scott and I dropped my new lump in at the weekend,all went well until the test drive,i realised the battery was losing charge and the dash lights (the ones that come on with ignition) are staying on,if you let the hand brake off they dull slighty.

We then went through the electrics we had disconnected and reconnected but could find nothing wrong,I've done the same since and can find no problem.

I have however narrowed the problem down to something to do with the altenator,all connections seem to be fine and the wiring to the starter and battery seems to be ok.

If I disconnect the altenator the dash lights return to normal.

I know the altenator is not at fault as it was fine before we changed the engine,I also as a matter of course tried another known good one and it still didn't make any difference.

Thats about the size of it,any ideas anyone?

PS is there any test I can perform without using a multi meter which I don't have?

Cheers people in advance

[m-dtech]

is the engine earth good ??

[tomtomiS]

is there a zoner who lives near just the right side of insanity who you lend you one! seriously tho, does it discharge over night or while ur driving?

[eko]

Stupid question but is the fan belt tight

[Jesus325iTouring]

is there a zoner who lives near just the right side of insanity who you lend you one! seriously tho, does it discharge over night or while ur driving?

LOL! While driving.

is the engine earth good ??

Check,'tis good

Stupid question but is the fan belt tight

Check,'tis also good


Keep suggestions coming fellas,i'm bound to have missed something!

[SPADGE]

What power are you getting at the battery with the engine running?
Are you sure the 'dulling' of the charge light after releasing the handrake isn't just the handbrake on light bleeding across??

[Jesus325iTouring]

What power are you getting at the battery with the engine running?
Are you sure the 'dulling' of the charge light after releasing the handrake isn't just the handbrake on light bleeding across??

All the dash lights dull mate.

[Jesus325iTouring]

What power are you getting at the battery with the engine running?
Are you sure the 'dulling' of the charge light after releasing the handrake isn't just the handbrake on light bleeding across??

Oh,and i'm not sure of what power is at the battery as I haven't got a meter.

[tomtomiS]

sounds like a massive drain if its killing ur battery while u drive. seriously u need to get a multimeter to go about diagnosing it properly. sounds silly but what about unplugging things that draw big current and see if that does anything

[Jesus325iTouring]

sounds like a massive drain if its killing ur battery while u drive. seriously u need to get a multimeter to go about diagnosing it properly. sounds silly but what about unplugging things that draw big current and see if that does anything

Yer right it is a big drain,and doesn't take very long to flatten the battery.

Wish I had a multi meter,might have to see if I can get one at the weekend if there not too expensive.

As for unplugging things,what i did try was to unplug everything in turn from the fuse box,this had no effect,the only time all the lights went out was when i got too the fuse that does the dash lights.

Does this tell me anything?

[e30cossie]

maplins do a multimeter for less than 5 pound

[Jesus325iTouring]

maplins do a multimeter for less than 5 pound

Cheers Cossie,thats the sort of price I like

Trip to Maplins at the W/end then.....

[Brianmoooore]

Disconnect the two wires from the alternator one at a time with the engine off. Is there a spark from either of them if you brush it against its terminal?

[Jesus325iTouring]

Disconnect the two wires from the alternator one at a time with the engine off. Is there a spark from either of them if you brush it against its terminal?

I'll go and find out now...

[Jesus325iTouring]

Disconnect the two wires from the alternator one at a time with the engine off. Is there a spark from either of them if you brush it against its terminal?

Hi Brian,
I have just done what you asked and the result is no spark at the terminals.

What might this tell me?

[Brianmoooore]

If there's no spark at all, then the altenator is probably not the problem.
This is difficult to diagnose because we can't tell if it's something that's gone wrong or something you've done wrong, or possibly now, both!
You should have a thin blue wire to the small terminal of the altenator, and a thick red one to the large terminal.
The other end of the red one should be on the outside large terminal of the starter motor, along with an even thicker black one, which goes to the battery +.
Not fitted an altenator with rubber mounts that needs an earth strap, have you?
What engine swap is this? M20B25 for the same, or something more exotic?

[Jesus325iTouring]

If there's no spark at all, then the altenator is probably not the problem.
This is difficult to diagnose because we can't tell if it's something that's gone wrong or something you've done wrong, or possibly now, both!
You should have a thin blue wire to the small terminal of the altenator, and a thick red one to the large terminal.
The other end of the red one should be on the outside large terminal of the starter motor, along with an even thicker black one, which goes to the battery +.
Not fitted an altenator with rubber mounts that needs an earth strap, have you?
What engine swap is this? M20B25 for the same, or something more exotic?

Brian, I think you have just solved it

Can you confirm the starter motor wiring please,am I right to understand,the outside terminal of the starter motor has the thick red AND the thick black one connected to it,and the inside terminal will have those little earth strap ones connected to it?
If this is right,then thats my problem

As for engine,swap,nothing exotic,Scott and I took an M20 out of a 525i and popped it into mine.
My engine had to many issues to warrant repair......coolant spewing out,oil spewing out,busted manifold connections,the list grows! Shame really though as mechanically nothing wrong with it.

Still,goes like the clappers now,wa suprised at how much power loss I had,and also new engine only got 150k on it,mine was on 230!

[Brianmoooore]

Can you confirm the starter motor wiring please,am I right to understand,the outside terminal of the starter motor has the thick red AND the thick black one connected to it,

Yes.
If you have the red on the inside terminal, then you have no charge, and an unlikely to be successfull attempt at making a perpetual motion machine.

[Morat]

rofl

[Jesus325iTouring]

Can you confirm the starter motor wiring please,am I right to understand,the outside terminal of the starter motor has the thick red AND the thick black one connected to it,

Yes.
If you have the red on the inside terminal, then you have no charge, and an unlikely to be successfull attempt at making a perpetual motion machine.

All hail the Zone Guru








I've put the red on the inside

Looks like I will now have a perpetual motion machine.

Many thanks Brian,I've spent five hours swearing to try and sort that out!

Thanks again

Ps Thanks for everyone elses suggestions too