Bad Battery Or Alternator?

[scott1212]

Avensis 1.8 GS VVTI petrol. I am getting engine management light eratic starting and cutting out when driving. Changed fuel, air filters checked sparks and coil packs and earths to no avail. I removed Battery to find it was almost dead and it is a fairly new Battery. I charged it over night until full put it back in car it ran fine for 10 mins then cut out and displayed engine management light, i removed Battery to test it and it was still full. I am totally lost and confused and would appreciate all the help i can get. Thanks. Scott.

[RAV4Len]

I would get the Battery drop tested first.

Do you have a meter to check the Battery voltage when running?

[scott1212]

Not at the moment but i can get a hold of one if you think it will help?

[RAV4Len]

Not at the moment but i can get a hold of one if you think it will help?

It will you an idea as to what is going on.

[scott1212]

Im totally stumped, it started of like a dirty fuel prob it would start to stall and if i gave it gas it would die, so i changed the fuel filter cleaned spark plugs and checked coil packs. The problem remained then i thought it might be the MAF sensor so i cleaned that and replaced the air filter with no change. Then last night the settings on the in car cd player were wiped so i thought Battery, checked it and it was nearlly flat so charged it over night put it in this morning it ran for 10-15 mins with no warning light then it died. I checked the Battery with a smart charger which says the Battery is still fully charged so now i dont know what to try next.

[bestseany]

Could be a bad earth. If the engine management light came on then you should have a fault code stored that may shed some light on it.

[t-spiritpete]

Hi mate, take no notice of what the Battery charger says, a faulty Battery can show fully charged but it is the discharge that shows up a problem! You seem to have a faulty Battery and the only way to test it is a high discharge or drop test as it is known in the trade, you can do this by putting your voltmeter across the battery which should show around 12.5 volts dc after it has been stood off the battery charger for a short while, get someone to start the car with the meter still attached with the headlights on whilst you watch the meter, it should not drop below 9 to10 volts if the battery is any good, if it drops below this or/and the headlights go dim the battery is faulty. OK, now hopefully the engine is running so rev the engine to just over 2000rpm now the meter should show around 14 volts if this is correct then the alternator output is fine. Let the revs drop to tick over and the voltage should now be around 13 volts give or take a few points.Now you have checked both battery and alternator, which ever one is not in the ranges given then that is the problem part, if they are both correct them come back for a more in depth approach but the above is simple and will cost you nothing.;).

Regards .... Pete.

[igormus]

Avensis 1.8 GS VVTI petrol. I am getting engine management light eratic starting and cutting out when driving. Changed fuel, air filters checked sparks and coil packs and earths to no avail. I removed battery to find it was almost dead and it is a fairly new battery. I charged it over night until full put it back in car it ran fine for 10 mins then cut out and displayed engine management light, i removed battery to test it and it was still full. I am totally lost and confused and would appreciate all the help i can get. Thanks. Scott.

hello Scott

i am surprised a new Battery gives you a lot of troubles -- where did you buy it? Were you warrantied for money back???

OK - you'd to test an outcome charging voltage from an alternator as other typed, as well as i have had one Battery issue on my rav when the car could not be started especially when you did not wait it (after refilling by petrol)--the problem was with the (+) terminal inside but the status indicator on the Battery lid was always green (!) -- the alternator has been giving a good charging. May be you have got the same issue. Cheers/Igor

[bmwe30m3]

hi there start your car then disconnect the live wire if stays started then alternater is fine if it cuts of straight away then alternater is faulty u can pick 1 up from breakers yard for about £40 if not then u can get it reconditioned 4 about £50 with 1 years guarantee ......if still in doubt get a reconditioner to test 4 u. they should test 4 free ......hope this helps