Xantia wouldn't start

Unread post by **SteveG** » 14 Oct 2006, 13:51

I'm wondering if anyone here can come up with a suggestion to this little problem -

Car started up fine, as usual this morning. Went off and did a bit of shopping at different stores with no problem. Decided to return some stuff to ECP and left the ignition on (wife wanted to listen to the radio) but engine off while I popped in. When I came back out the engine wouldn't start

It was turning over okay but wouldn't fire - eventually drained the battery!

Waited for my daughter to turn up with the jump start booster (approx 15 mins), connects it up and waited a couple of mins then ... VROOM! started first turn of the key

Any ideas as to what might have prevented the car from starting.
Xantia 1.9TD by the way.

jeremy · Unread post by **jeremy** » 14 Oct 2006, 14:04

Weak battery

What happens is that when the engine is warm the compression rises and it can actually be harder to turn than when cold.

Before jumping to conclusions like I have above start with the easy bits - is the warning light going out and staying out. (does it work? - it is needed as it is part of the charging circuit). If the light flashes slowly when the electrics are under load then the alternator is faulty.

Check the auxilliary drive belt - if its slack the alternator won't charge properly.

measure the voltage at the battery. When the thing has been running for a while it should be between 14 and 14.4 volts - preferably at the top end. After its been standing overnight (assuming its charging properly) the voltage should be 12.6 volts for a healthy battery, 12.4 is weak and 12.5 is adequate.

Is the battery the right size for the car. The diesel ones should be around 55 amp hr or more.

Unread post by **SteveG** » 15 Oct 2006, 12:20

jeremy wrote:Weak battery

What happens is that when the engine is warm the compression rises and it can actually be harder to turn than when cold.

Before jumping to conclusions like I have above start with the easy bits - is the warning light going out and staying out. (does it work? - it is needed as it is part of the charging circuit). If the light flashes slowly when the electrics are under load then the alternator is faulty.

Hi Jeremy, I take it you mean the battery warning light. This goes out as soon as the engine starts and there is no flicker even with all the electrical items turned on.

Check the auxilliary drive belt - if its slack the alternator won't charge properly.

That appears to be okay and the connections on the alternator are alright.

measure the voltage at the battery. When the thing has been running for a while it should be between 14 and 14.4 volts - preferably at the top end. After its been standing overnight (assuming its charging properly) the voltage should be 12.6 volts for a healthy battery, 12.4 is weak and 12.5 is adequate.

Now we may be getting into dodgy territory. With the engine running at about 1500 rpm the voltage across the battery is just above 14V (14.1 to be precise) and with the engine off the battery volts are just about 12.5V. So the battery may be marginal.

Is the battery the right size for the car. The diesel ones should be around 55 amp hr or more.

That's a good question to which I don't have a good answer. I can't find anything on the battery to say what the AH rating is. What sort of CCA do I need for a new battery?

np · Unread post by np » 15 Oct 2006, 18:22

Sorry to hear of your slight problem Steve.
I replaced the battery just after i got the car,in Jan `02.If i recall correctly i got a slightly larger amp hr battery,as the recomended Halfords battery had a smaller amp hr rating to duff battery i was replacing.So the battery is now getting on for 5 yrs old.
One point of interest that may point to a tired battery is that about a month before you got the car i left the side lights on.(the door switch was sticking at the time,hence the lights on buzzer did`nt come on)The side lights were on for about 3 hrs,after which the battery was nearly dead.The car started just as i thought i`d have to get the jump leads out.
After that it was fine up untill you got it.So it may be getting tired.
Hope you get it sorted

Unread post by **SteveG** » 15 Oct 2006, 23:57

np wrote:Sorry to hear of your slight problem Steve.
I replaced the battery just after i got the car,in Jan `02.If i recall correctly i got a slightly larger amp hr battery,as the recomended Halfords battery had a smaller amp hr rating to duff battery i was replacing.So the battery is now getting on for 5 yrs old.
One point of interest that may point to a tired battery is that about a month before you got the car i left the side lights on.(the door switch was sticking at the time,hence the lights on buzzer did`nt come on)The side lights were on for about 3 hrs,after which the battery was nearly dead.The car started just as i thought i`d have to get the jump leads out.
After that it was fine up untill you got it.So it may be getting tired.
Hope you get it sorted

No problemo, Neil. I just need to find the time to get to a battery emporium

BonceChops · Unread post by **BonceChops** » 16 Oct 2006, 00:44

jeremy wrote:measure the voltage at the battery. When the thing has been running for a while it should be between 14 and 14.4 volts - preferably at the top end.

I always do that with lots of electrical load switched on like all lights, heated rear window and heater fan. You are trying to prove that the alternator is supplying enough current to charge the battery and power the cars electrics, which it should be capable of doing.