6 replies to this topic

[callum2464]

ok so i was driving along last night typically miles away from my home and then all of a sudden all the electrics went off e.g cd player and lights and then the engine cut out luckly i was doing like 40 so managed to keep up enough momentum to start making it up a hill, i then pushed it up and bump started it while going down the hill, then had to keep the revs up to get me home or it would just die, ( also quite alot i have needed my car jumped when i stop which makes me think that the alternator is needing replaced cause it may not be charging the battery properly, my car is a rover mini enquinox, spi 1275. thanks in advance ( ps the police are no help whatsoever i was at the light s reving a lot so i dont cut out and the come up behind me and pull me over to check the car, tell me to stop reving it, i explaining why and they still said turn it off and it cut out and they wouldnt even help me get it started so the mini is now abandoned in a car park somewhere while i figure this out, any help guys?

[tractor]

easyiest way to check if an alternator is charging right is to get a volt meter and hold the probes onto the negitive and positive of the battery with the engine running, it should read about 14v without the cd player or lights on if your getting a good charge.

sounds pretty much like its the alturnator at fault here, it happened to me once.

you should be able to jump start your car with jump leads but i doubt you'll be able to bump it now because the battery will be so flat it can't run the coil or the injectors.you were lucky to get it to bump last night.

If you do jump it drive ti back wit out the radio ect on, you'll need all available electric to run the engine.

get yourself one of these if the alternator isn't charging http://www.minispare...ssic/alternator .

Hope this helps

Trac

[tiger99]

If the alternator is not charging, the lights etc would have been running from the battery and "should" have dimmed gradually. It seems that you may have a faulty alternator, and battery, if it gave out so suddenly.

However, the symptoms are also those of a shorted main battery cable, and it usually shorts to the exhaust just in front of the toeboard, because one or both of its fixings to the subframe are adrift. If so, the battery will have been ruined, and may have overheated and may have ejected acid in the boot. Take care, and wash it off with lots of sodium bicarbonate solution.

Check that the battery cable is not shorted, then charge the battery and take tractor's advice about checking the voltage with the engine running. Depending on what you find, we will be able to make further suggestions.

[MiniLandy]

If revving the engine keeps it alive, then the alternator is working, and the battery is not.

Could be either a bad connection, knackered engine earth strap, or knackered main battery earth strap.

The earth straps are cheap and easy to replace to start with (probably pick them up from your local petrol station) but bank on it being the battery. The EXACT same symptoms happened to me, turned out to be the battery.

When buying a battery, go to the motor factors with the mini and ask for the biggest one that fits in the mini battery tray!

EDIT: After reading Tiger99's post, i do remember i did replace the battery and alternator at the same time. If the voltage reg in the alternator went, it could have boiled the battery over (boot full of acid).

Have a look into it, and let us know.

Edited by MiniLandy, 15 September 2012 - 10:34 PM.

[callum2464]

Yeah reving it is no longer keeping it alive, and the battery seems new and I have fitted a new earth strap, and the battery is holding its charge, think my best bet is to try the alternator

[ACDodd]

Do measurements after you have charged the battery, and checked that the fanbelt is properly tight. You need to get 14 to 14.5voltas at the alternator, idling (no loads) and similar at the battery. Repeat the test reving at 3krpm and with the headlamps, heater and heated rear screen switched on. If the voltage is not 14volts at the alternator the alternator is faulty. If you find that you have 14 volts at the alternator and less than 13.7volts at the battery during this test you have a resistive charging circuit.

AC

[tiger99]

I should add to what I said that IF it is a shorted battery cable, it tends to be sensitive to engine torque, because the engine obviously shifts on its mounts, so all may be well when revved, sometimes. At other times, they only short when pulling hard, as happened to me.

But you do really need that voltage measurement to know what is really happening. Revved really hard, once the battery reaches full charge, lights etc off, you should see about 14.4 V at the battery, if the alternator is good. If you then switch off, and put on some small electrical load such as sidelights, it should hold up at 12.6V for a while if the battery is good.