Hi

I'm a new member with a problem, and wondered if any one could help please!

Car: Skoda Felicia

Year: 1998

I fitted an alternator about a month ago, as i was told by RAC that it was the reason why my battery kept going flat. But now that i've changed it the battery warning like on

the dash board still stays on and then last night after a month of having a new alternator, the battery died out again.So RAC came out again and said there was only 12

volts going to the battery, where there should be 14 volts.There was a similar topic on here where someone mentioned something had blown which caused the battery

not to get charged properly, if this is so, where and what should i look for?? I would appreciate any ideas, thank you.

Rich

Hi and welcome aboard.

Hello and welcome to Briskoda, not sure on your query but sure someone will be along to help.

Check voltage at the battery terminal with engine running at about 2,000 rpm . Switch on all the lights , heated rear window , blower at full speed , hazards , air con etc. Then measure voltage it should be over 14 Volts . If it's only 12V then there is either a fault with the alternator or its' wiring . More likely to be an alternator fault. But if its a new alternator you've fitted check wiring for any poor connections / lead damage.

Edited 20 November, 201015 yr by vwcabriolet1971

Check voltage at the battery terminal with engine running at about 2,000 rpm . Switch on all the lights , heated rear window , blower at full speed , hazards , air con etc. Then measure voltage it should be over 14 Volts . If it's only 12V then there is either a fault with the alternator or its' wiring . More likely to be an alternator fault. But if its a new alternator you've fitted check wiring for any poor connections / lead damage.

I can't check the voltage due to not having a meter, but the RAC chap did say that there were only 12volts going through. I presume it would be the wiring as it was a brand new alternator last month. Thanks for the advice and will check the wiring.

If the alternator is new (including reconditioned part), and only producing 12v, you have an issue with the place you got it from.

OTOH it's also very common for the regulator/control box on these cars to fail (that usually causes over-charging, not under) and it's effectively a separate part.

Hello there.Is the new alternator the same model as the old one?When you change it,did you connect the wires corectly?Did you check all the conections to be tidy??It will be better if you can borrow a multimeter from somewhere,so you can check things around.You told us that the battery goes flat : maybe you have a load on the system all the time,like a car alarm,a audio power amplifier or something that drains the battery.In this case is also good to have a multimeter so you can check if something is draining a lot of curent .Sometime is the battery that cause low voltage on the system.Try also with a good battery(borow) ,just to see what is happening.I hope this hepls you.Let us now.

There is no way you can fault-find an electrical system without a multimeter. A cheap digital one will cost about £25 (less than another battery, or the inconvenience of a breakdown), and will last a lifetime if you look after it.

You'll need to check that all the earths are OK, between engine and alternator, engine and body as well as battery to engine, plus all the positive connections. By using the meter you'll be able to check the voltage and find it pretty easily - if it's a new alternator (and its not faulty) then the problem must lie with the car/installation.

I can't check the voltage due to not having a meter, but the RAC chap did say that there were only 12volts going through. I presume it would be the wiring as it was a brand new alternator last month. Thanks for the advice and will check the wiring.

Maplin have digital meter from as little as £4.99- both Birmingham stores have more than five . More than good enough for what you want . Only downside is limitation on current measurements ,more on time use of the 10A range, which you shouldn't have to use .( One MAplin in Temple ST ,other in Erdington )

Maplin have digital meter from as little as £4.99- both Birmingham stores have more than five . More than good enough for what you want . Only downside is limitation on current measurements ,more on time use of the 10A range, which you shouldn't have to use .( One MAplin in Temple ST ,other in Erdington )

Thats great, thanks for that info as I am a bit tight on cash ATM.

There is no way you can fault-find an electrical system without a multimeter. A cheap digital one will cost about £25 (less than another battery, or the inconvenience of a breakdown), and will last a lifetime if you look after it.

You'll need to check that all the earths are OK, between engine and alternator, engine and body as well as battery to engine, plus all the positive connections. By using the meter you'll be able to check the voltage and find it pretty easily - if it's a new alternator (and its not faulty) then the problem must lie with the car/installation.

I really don't know how and what to check when comes to this multi meter. I know it sounds a bit stupid but, how would i check all the earths are ok?

I really don't know how and what to check when comes to this multi meter. I know it sounds a bit stupid but, how would i check all the earths are ok?

Use the lowest resistance range on the meter (usually 200 Ohms) and, for example, put one probe on the alternator earth terminal and the other to a bolt head or bit of bare metal on the body/engine block (you may need to scratch them around a little bit to get a good contact) - it should read only a few Ohms, ideally less than 1. If it's substantially higher, you've got a poor earth connection between those two points and should check the relevant wire and it's connections at both ends.

...or use it to check voltages - you can see volt drop across bad connections where there should be none; I've had more success doing this than measuring the resistance in some cases.

I really don't know how and what to check when comes to this multi meter. I know it sounds a bit stupid but, how would i check all the earths are ok?

Possibly better to go looking for volt drops on the earth side - especially with a lot of items switched on .Youre only looking for a couple of volts , and I'd suggest places where the earth lead joins to engine ,etc.The standard ( from memory ) for the loss across a solenoid is at most .5 volt , with the engine cranking .

Or if you're going to do it on ohms , and only using headlamps -that's 160 W = 13.3 A, so you'd only need about .15Ohm to drop a couple of volts .And if you're doing it on OHMS- check the reading with the leads shorted together ( some meters have a zero facility ) ,and subtract that value from any reading you get .e.g -leads shorted =.15ohm, test across a cable connection = .2ohm, loss =.05 ohm .

Edited 26 November, 201015 yr by VWD