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Dead electrics


Adrian
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Afternoon chaps, yet another chapter in the saga of the Mini!

Put it all together, turned the key and absolutely nothing, no lights on pod, no fan no ignition. 12.4 V across the battery terminal. Not touched the battery earth - still the pre rebuild condition which looks good and worked before. I'm not getting a flow so the first thing I thought would be earthing, tried the voltmeter (set on 20v) from +ve battery terminal to the earth strap anchor and nothing. Even though the battery was charged and the condition indicator says OK could it be the battery has died over the last 6 moths whilst disconnected and just doesn't want to give up its charge?

Whilst typing this I'm charging another battery for testing.

This is obviously applicable to all cars and could well be a long investigative process so keen on documenting the investigative methodology for future reference.

Thanks

Adrian

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If you turn the ignition on, and nothing happens, it's an ignition fault. Check your ignition switch / key to find out if power is getting that far; if it is, test to see why it's not going any further. It may be something simple such as a connection to the wrong terminal.

 

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Hi Colin, I haven’t stripped the ignition at all although can’t guarantee that something hasn’t come loose. Shouldn’t, Using the voltmeter from the positive battery terminal to the earth fixing result in a circuit and therefore a reading on the meter?

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9 hours ago, Adrian said:

Shouldn’t, Using the voltmeter from the positive battery terminal to the earth fixing result in a circuit and therefore a reading on the meter?

Yes. There are a couple of reasons it may not. The battery may be utterly dead (which you can test for by putting the meter straight across it). The positive terminal may not be making contact (try the post itself). The earth lead may be broken (in which case you'd see voltage from the battery -ve post to the earth fixing).

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There is 12.4v post to post. But nothing +ve post to earth bolt on body

3 minutes ago, NonMember said:

Yes. There are a couple of reasons it may not. The battery may be utterly dead (which you can test for by putting the meter straight across it). The positive terminal may not be making contact (try the post itself). The earth lead may be broken (in which case you'd see voltage from the battery -ve post to the earth fixing).

 

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9 minutes ago, Adrian said:

There is 12.4v post to post. But nothing +ve post to earth bolt on body

What about -ve post to body bolt? If you see 12V across that (which I am expecting) then your battery earth lead is either broken or not properly connected. Don't forget that the battery posts can corrode underneath the terminals and may even develop a complete layer of insulation without the terminal being removed! It worth taking it off for a clean.

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Hi Adrian, On the mini there is only the one earth strap at front (the one you describe) Can you post a pic of the top of the battery with the leads connected. If you have volts across the battery you should have volts at the front even if not enough to start. Just wondering what type of terminal it has on the battery?

Tony.

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8 hours ago, Adrian said:

OK - I am officially an absolute Idiot.

Not only do I need to buy the T-shirt but I think the whole clothing chain is in order.

Battery Isolator switch under the dash!!!!

Doh!

Welcome to the club Adrian, you are not alone mate :) 

Tony.

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Cue stupid things thread?

I fitted an impact switch to the fuel pump for Pi.       I even selected a switch that had a telltale diode light that lit when it triggered.  Racing SofS, I ran the kerb on a critical corner - and on the exit the engine cut out!      No lights on the dash - end of race, I was even towed back to the pits.    Investifation showed that the impact switch had triggered - and the diode was glowing, but had fallen back out of the dash!   Doh!    I could have pressed the button, reset the switch and carried on!   Double Doh!

John

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