battery or alternator?

AdrianC

[quote=[Deleted User];65564013]Well until I tried to connect the battery wrong way.[/QUOTE]
Ah... Always the pertinent details take a while to come out...

Rolandtheroadie

AdrianC wrote: »

Ah... Always the pertinent details take a while to come out...

Post 1 he mentioned it.:)

AdrianC

scotsman4th wrote: »

Post 1 he mentioned it.:)

Ah... Always the pertinent details take a while to sink in...

[Deleted User]

Looks like defo a !!!!!!ed alternator and possibly dead battery as well then.

[Deleted User]

Managed to trickle charge it a week or so ago. Checked it last night and it was still reading 12.7V (Is this good?).

Can I assume battery is ok since it charged ok and appears to be holding charge?

I guess next test it to put it back in car and see if I can get the alternator to charge it.

forgotmyname

12.7 with no load is not a good test.

You need to put the battery under a load and then check the voltage. Recently i got someone to do a test and they said the battery is fine 12.8 volts.

I said pop your headlights on for 5 minutes and then test the voltage again with the lights still on.
10 seconds later. The battery is kaput. He put the lights on and instantly the voltage dropped below 12 volts. No need to wait 5 minutes.

Voltage off load doesnt mean a lot. Just shows each cell is working. But it may have 1% of its original capacity so flattens quickly.

Joe_Horner

As forgotmyname says, a test under load is far better than an off-load one. Although, it's a fair bet that a battery that's maintained 12.7v (effectively full "settled" voltage for a 12v lead acid battery) for a week will be useable even if it's not up to its best.

It's certaily a good enough bet to worry about the alternator first (becaue that will need sorting) and only change the battery if you still have problems once that's done.

Richard53

I would say the alternator is kaput too. Every time you jump start it, you are putting a small amount of charge into the battery from the starter pack/slave battery, and this is lasting long enough to run the car for a few minutes, and then the charge is gone and the engine dies. The alternator is obviously not putting anything back when the engine runs. Get it checked out, and hopefully it's only the diode pack. Perhaps an exchange unit might be the best option in the long run.


And seriously, money-saving and all, a battery that hasn't had use for a year will be on its last legs, if not dead. A good trickle charge might bring it back to life briefly, but I'd be looking to replace it as soon as possible, as it won't be reliable and could kick the bucket at any time - probably in the most inconvenient spot. Leaving a service battery uncharged for even a short period can reduce its capacity considerably.

[Deleted User]

Well latest tests:-

1. 10 mins with lights on still 12.7v on battery.
2. Started car - still 12.7v so I assume nothing coming from alternator?
3. Pulled plug/leads off alternator and started car. Getting 0.2v which I guess is not right either.

To be honest, it looks like alternator (£60) and new battery needed.

Joe_Horner

[quote=[Deleted User];65735126]Well latest tests:-

1. 10 mins with lights on still 12.7v on battery.
2. Started car - still 12.7v so I assume nothing coming from alternator?
3. Pulled plug/leads off alternator and started car. Getting 0.2v which I guess is not right either.

To be honest, it looks like alternator (£60) and new battery needed.[/QUOTE]

With those results, don't waste money on a battery. get the alternator replaced and you'll be good to go with the battery you've got.