Starter or battery??
Discussion
Hope someone can help. Car would'nt start again tonight. Engine turns over fine but just does'nt fire. So, thinking it was the battery i went to halfwits earlier and purchased one for £90. Rang the AA who came and basically said that he thinks its the starter. When he tested the battery it was reading over 12v, when reving the engine this went up to over 14v but when turning the engine over the battery drops to just 7v so he thinks ive got a dodgy starter. What does everyone else think?? Should i try the battery anyway or get the starter looked at?
The highest load on the battery is the starter motor, they can take a couple of hundred amps. Everything else in the car, if switched on at the same time, would probably be 1/4 of that at most.
So if it turns over at a reasonable speed, then the battery is definitely good (unless your spark plugs have fallen out).
OK, I don't know what kind of voltage drop you'd get while it's turning over but 7V sounds quite low. Is that measured at the battery terminals, on the leads attached to the battery terminals, or somewhere else?
Here's the obvious questions. When you've tried it for a while, does the exhaust smell of petrol? If not, there's no petrol getting into the engine.
Remove a spark plug cap and put a spare spark plug into it, with the earth electrode (threaded body) connected to earth. Try clipping it to some bare metal on the engine. Do you get a spark? It should be blue-ish and able to jump 5mm no problem. If not, you have an ignition problem.
But you seem to say it runs ok, eventually. So what's the problem, it takes a long time to start it? Or do you have to jump-start it?
So if it turns over at a reasonable speed, then the battery is definitely good (unless your spark plugs have fallen out).
OK, I don't know what kind of voltage drop you'd get while it's turning over but 7V sounds quite low. Is that measured at the battery terminals, on the leads attached to the battery terminals, or somewhere else?
Here's the obvious questions. When you've tried it for a while, does the exhaust smell of petrol? If not, there's no petrol getting into the engine.
Remove a spark plug cap and put a spare spark plug into it, with the earth electrode (threaded body) connected to earth. Try clipping it to some bare metal on the engine. Do you get a spark? It should be blue-ish and able to jump 5mm no problem. If not, you have an ignition problem.
But you seem to say it runs ok, eventually. So what's the problem, it takes a long time to start it? Or do you have to jump-start it?
It first happened a couple of weeks ago. AA guy put a booster on the battery and it started first time so i dont think its a problem with the fueling or spark. Its been fine for two weeks, then when i got in it after work tonight it wouldnt fire - it just kept turning over. I would still say its the battery but he thinks the starter becasuse the voltage dropped to just 7v - he thought maybe a faulty wire?? Bare in mind that i use this car as my daily drive and i only do 4 miles each way to work, so i guess this is putting a heavy strain on the battery.
stevo i had the same happen to me i don't think my battery dropped to as low as 7v on idle but i have heard that unless the engine is revved alot and if you are sitting in traffic for a long time your battery will be drained. Either get a trickle charger or take the car out for a really long drive and i think you should be ok. Apparently they don't charge on idle?
Two possibilities. One - fuel pump is not running through defect, or fuel pump is not running through imobilisation.
The starter is the subject of numerous threads re imobiliser and the imobiliser bypass fix. Could be a similar issue for fuel pump.
There is an outside chance that your car has had the starter circuit bypassed, and the starter turns over without deactivating imobiliser. If so could be your imobiliser is still active and you just need to press fob again.
Either way it sounds like fuel. HT circuit unlikely on AJP8.
The starter is the subject of numerous threads re imobiliser and the imobiliser bypass fix. Could be a similar issue for fuel pump.
There is an outside chance that your car has had the starter circuit bypassed, and the starter turns over without deactivating imobiliser. If so could be your imobiliser is still active and you just need to press fob again.
Either way it sounds like fuel. HT circuit unlikely on AJP8.
Happened to me about ten days ago. Turned but ground to a halt. Battery out and on charge for a couple of days. Back in and it barked into life like an F1 car. These cars don't like sitting in a cold garage at -1. Need to drive them once\twice a week if you can find a dry spell.
Edited by Mr M on Thursday 13th December 12:22
Mr M said:
Happened to me about ten days ago. Turned but ground to a halt. Battery out and on charge for a couple of days. Back in and it barked into life like an F1 car. These cars don't like sitting in a cold garage at -1. Need to drive them once\twice a week if you can find a dry spell.
Also check that you're not draining the battery (accidentally) when not in use. For instance, I found one of my interior lights on one night. Reckon the swich was right on the edge of just being off and a door slam probably caused it to flick to the on position. This was in the summer so I only noticed very late one night when I just happened to peer outside. Could of been on for days.Also, the ciggy socket is always live, so make sure you don't leave any phone/sat nav chargers in there. Alternatively (as they do become loose when constantly plugging and unplugging) buy a extender socket with a switch on the end. You can get them from Halfords.
Finally, get yourself an Accumate. At this time of the year, mine goes on overnight at least once a week.
The car is my daily drive so i guess i wouldnt need an acumate?? Depsite what the AA guy said im gonna stick the new battery in and see what happens - hopefully its just that. Spoke to Ian at Torque RVT and he confirmed what the earlier post said about the battery not charging correctly on tick over. Ill fit the new battery at the weekend - should be fun!! Thanks all.
At the rsik of sounding like a broken record, a second earth strap direct to the housing of the starter motor is, IMO, always a wise move. Both the existing earth connections are in areas vulnerable to corrosion, and the starter draws some serious juice.
At less than a tenner for the cable, connectors and half a tube of solder - how far wrong can you go?
At less than a tenner for the cable, connectors and half a tube of solder - how far wrong can you go?
Edited by Nefarious on Friday 14th December 07:39
I don't own a Cerb (wish I did) but there's any easy way to tell.
1) Before the AA man put on the jump leads, would the starter turn it over reasonably fast (but with jumpleads, starts ok)? Yes: Go to 8, No: Go to 2
2) Charge battery for at least 12 hours. Disconnect it but keep it in the house overnight (=warm). Measure the voltage. >12V Go to 3, <11V Battery's dead (The End). Inbetween is a grey area.
3) Connect battery in car, then with the engine running at tickover, what's the battery voltage at the terminals? >13V: Go to 7, else Go to 4
4) Same test again with a few thousand revs, >13V: Go to 6, else Go to 5)
5) Check battery terminals and wiring between alternator and battery. If it's not these, then it's probably the alternator (The End).
6) As suggested by someone else here, the Cerb needs revs to charge. Find a way to regularly trickle charge it, drive it more often, go everywhere in low gears? (The End)
7) Electrics ok, battery charged and alternator giving >13V, but voltage at terminals drops to 7V when starting. Starter dodgy. (The End) else
8) Check for smell of fuel, spark at spark plugs, as I said in post 2.
1) Before the AA man put on the jump leads, would the starter turn it over reasonably fast (but with jumpleads, starts ok)? Yes: Go to 8, No: Go to 2
2) Charge battery for at least 12 hours. Disconnect it but keep it in the house overnight (=warm). Measure the voltage. >12V Go to 3, <11V Battery's dead (The End). Inbetween is a grey area.
3) Connect battery in car, then with the engine running at tickover, what's the battery voltage at the terminals? >13V: Go to 7, else Go to 4
4) Same test again with a few thousand revs, >13V: Go to 6, else Go to 5)
5) Check battery terminals and wiring between alternator and battery. If it's not these, then it's probably the alternator (The End).
6) As suggested by someone else here, the Cerb needs revs to charge. Find a way to regularly trickle charge it, drive it more often, go everywhere in low gears? (The End)
7) Electrics ok, battery charged and alternator giving >13V, but voltage at terminals drops to 7V when starting. Starter dodgy. (The End) else
8) Check for smell of fuel, spark at spark plugs, as I said in post 2.
Edited by Ordinary Bloke on Friday 14th December 21:34
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