Old mini electrical issues

Right thought you lot might help with this, makes a change from dirty Volkswagens

I have installed a later injection engine and loom from a 96 into an 89, it came from my own running driving car.

I have installed a good battery from another car it reads almost 12.80 volts when disconnected and holds the charge.

When I have it connected it I get a slight voltage drop at the battery, low 12s.

At the starter and alternator I am only reading around 9 volts and the dash gauge also shows around the same.

The reading at the alternator which is a brand new unit is fluctuating, jumping up and down

The engine will turn over

The battery is drained to around 10/11 volts after 30 minutes and that's with no cranking over time.

So far I have checked and cleaned all the earth points, tried a different battery checked all my plugs are tight.

Would an earth issue or cross wires cause this?

 

sounds like a short between wires to cause the drop to 9v

 

I think maybe I have something back to front somewhere

 

On old style minis , the battery positive cable ran under the car , and sometimes got damaged and then corroded . Also check the earth connection at the rear and between the body and subframe.

 

Thanks
I cleaned the cable up a bit will give it a check through, i might add an extra earth strap tomorrow and see if that helps

 

If i put my tester on the positive alternator post and body earth i get 12.5 volts which seems ok, if i test between the negative post and an earth i get a 2 volt reading is this normal? I thought it would be 0 volts

 

Doesn't sound right. What's the other end of the batt -ve connected to?

Set your meter to the ohms range and check the resistance between batt -ve and the body of the car.

 

Thanks snots

The battery -v goes straight to the body

The +ve lead goes to the starter solenoid

I only know how to use my meter for volts, it has a ohms sigh by a number on the dial but i cant seem to get it to do anything where do i poke my prongs

What should and shouldn't it say on the screen

 

Seems odd you're getting 2V across it (if you really are).

On your meter, keep the leads in the volts/ohms position, switch it to a low ohms range if it's got one, and touch the leads together. It should read 0 or thereabouts (as a test). Then put one probe on batt -ve, one on a good earth on the bodywork. Should read 0. I'd be surprised if it doesn't

 

Ok, I don't really know what the range is all about I put the dial to 20 in the v section and get volt readings I think the ohm sign had 200m next to it?

Def get 2v when I touch the alternator -v and a bolt on the body

I get 12 if I touch the +v and the body

And if I touch both+v and -v on the alternator I get 10 and bit volts

 

Where is the -ve terminal on the alternator? Can you take a pic.

 

The +ve battery lead rubs through on the exhaust near the front , gearstick area

 

If the positive is connected when you test between the negative and earth, set you meter to amps and see what the current draw is.

 

It's on the rear, just 2 posts with nuts one small one big with corresponding ring terminals, I'll do a pic tomorrow

 

I have had it all out on the rebuild but might pull it out again and check incase I have damaged it putting in back in the channel

Cheers

 

Is the engine earth cable in place and have a good connection?

 

Cheers bud , ok I'll have a look tomorrow, what would this show me?

Sorry still learning this multimeter business, went on YouTube today and found out how to check for continuaty which is a handy one

 

Yes this is something that keeps popping up, the standard ones seem a problem area and is online lots when I'm looking for answers so I bought an extra cable and fitted a second earth but still the same.

Ta

 

I have continuity have I got a live on a negative somewhere?

 

The small terminal is for the warning light on the dash not the -ve