Flat battery after giving a jump start

[patch900]

My neighbours car had a flat battery the other day and I gave him a jump start. Couldnt really say no.

Not drove the car for a day or 2 and got in and the battery was totally flat ! Is this a coincidence or have I done something ? The battery has always been OK before this.

[EvilScotsman]

nah thats happened to me mate. It sucks but a dead battery can drain the life out of a good one. Your alternator or battery maybe are past it as well.

Deposits build on the plates and reduce the capacity over time. Try BAT-AID tablets £4 from an accesory shop, 2 tabs each cell then recharge wi a charger and should be good if the battery isnt knacked. Charging voltage from a good alternator is about 14v and when cranking the engine, the battery musnt drop below 10v. Less shows a weak battery.

[patch900]

Cheers evil, it started today but not easily.

Think the battery has had it, will have the alternator checked out as well. Do you know much an alternator is ?

[tommk3cab]

depends if its from a scrappy or not, can usually get them reconditioned anyway, but new, ouch!

[patch900]

cheers tom, will have it checked first. Fingers crossed its just the battery

[chrutchy]

new high power alternator from euro car parts is bout 120 quid
not as much as people think

[monzablue16v]

You can get them rebuilt for about £30 though

[EvilScotsman]

get a reconned exchange one, its quite cheap. As said, around £30 to £40 with your old one returned.

If you go to a breakers, a passat one will do as well if its exactly the same engine.

[patch900]

Cheers mate, will change the battery first and see how I go. If it still acts up get the alternator changed.

Wished I had said no to the jump start but if someone asks you cant really say no.

[EvilScotsman]

well at least its shown up a weakness in the car before you got stranded somewhere.

Kwiksh!t will do an electronic battery and starting / charging current test for free by the way if you just roll up and ask.

If you give a jump start you should always have the donor car running so the alternator gives charge to both batteries then start the other car after 5 mins of running so its easy on the donor battery.