Lights disabled by starter

Lights disabled by starter

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E-bmw

9,102 posts

151 months

Friday 17th January 2020
quotequote all
First thing to do would be ask around & borrow another meter as 13.9v isn't possible from a car battery.

A shade over 12.6v is the absolute best you will ever see unless you are charging it at the time, and that isn't the battery voltage but the charger voltage.

adcossey

Original Poster:

13 posts

58 months

Friday 17th January 2020
quotequote all
paintman said:
When you tested the starter motor off the car did it just spin nicely or try & fling itself across the floor?
Bit of both, it jumped around the first time I tried so I stood on it for the second test and that held it enough to check it engaged and spun

paintman

7,669 posts

189 months

Friday 17th January 2020
quotequote all
Pity.
I was hoping it just span gently. Had that with my RRC after having the gearbox off. Wouldn't turn the engine over & just spun when powered up off the vehicle instead of needing to be forcibly restrained! Was an electrical connectivity fault in the solenoid area.

Last try would be to connect a jump lead from the battery earth to an earth near the starter & another lead direct from the battery live to the starter motor live.
If that doesn't turn it over & the engine is free to turn & the battery is good & fully charged then the starter motor may be duff. Possibly from the oil contamination you mentioned?


Edited by paintman on Friday 17th January 13:53

anonymous-user

53 months

Friday 17th January 2020
quotequote all
E-bmw said:
First thing to do would be ask around & borrow another meter as 13.9v isn't possible from a car battery.

A shade over 12.6v is the absolute best you will ever see unless you are charging it at the time, and that isn't the battery voltage but the charger voltage.
Yep.

After charging it'll be at 13.8v then drop to 12.6v over about an hour. If you meter 13.8v then it's on charge, or, you just unplugged the charger 1 second ago .

adcossey

Original Poster:

13 posts

58 months

Friday 17th January 2020
quotequote all
RogerDodger said:
Yep.

After charging it'll be at 13.8v then drop to 12.6v over about an hour. If you meter 13.8v then it's on charge, or, you just unplugged the charger 1 second ago .
I was testing that straight after charging the battery, that was yesterday evening but now (16 hours later) the battery's still at 13 volts

adcossey

Original Poster:

13 posts

58 months

Friday 17th January 2020
quotequote all
I tried seeing if power was getting to the starter, I got a piece of wire and jumped power from the main terminal to the signal terminal and sure enough a blue spark and the click of the solenoid (but no spinning from the motor). I then tried jumping power to the main power terminal and once again a blue spark and the motor spun. I then went to check the fuse box, it was a bit damp so dried it off with a hairdryer, I then tried starting it and the engine turned over. Wow. I tried again and yes it was working. I then tried a third time and nothing. The lights once again do not work at all, and there are no clicks.

I have no idea why it turned over then but no other time, the battery is showing 12.6 volts so is not dead. This is getting beyond frustrating, does anyone know a mobile mechanic that knows about electrics and could sort this for me in my driveway.

GreenV8S

30,149 posts

283 months

Friday 17th January 2020
quotequote all
To diagnose this you need to measure the voltages at the starter motor. Any competent auto electrician should be able to sort this out within an hour. If you have breakdown cover or are a member of any motoring organisation they may be able to do it for you or recommend somebody local to do it. Otherwise just look for any local garage which doesn't have a terrible reputation and ask them to visit you. This is not something that's going to need any special skills or equipment.

Smiljan

10,772 posts

196 months

Friday 17th January 2020
quotequote all
adcossey said:
I then went to check the fuse box, it was a bit damp so dried it off with a hairdryer, I then tried starting it and the engine turned over. Wow. I tried again and yes it was working. I then tried a third time and nothing. The lights once again do not work at all, and there are no clicks.
Probably worth concentrating on this area next, if you have damp in the fuse box there may well be corroded or even worse rotten connections.

You really need to measure the 12v supply at the starter solenoid with a test lamp, often with poor connection issues a meter (even a good quality meter) will show the full battery voltage but there won't be enough current flowing to light a test lamp. In your case it may be that the connection is poor, the solenoid might be getting enough juice to click a bit or move a bit but not enough to fully extended and make the high current starter connection to turn over the car.

The headlight issue, although seemingly weird needs to be left alone until you sort the starting issue. Maybe in the same area (ie the fusebox) or as you suggested in your original post relay related.


E-bmw

9,102 posts

151 months

Friday 17th January 2020
quotequote all
adcossey said:
RogerDodger said:
Yep.

After charging it'll be at 13.8v then drop to 12.6v over about an hour. If you meter 13.8v then it's on charge, or, you just unplugged the charger 1 second ago .
I was testing that straight after charging the battery, that was yesterday evening but now (16 hours later) the battery's still at 13 volts
As I said you need to borrow/get another meter.

All of your symptoms sound like a barely charged/almost completely flat battery.

You are measuring voltages that are too high and thinking they are good.

Picture this:
Your meter is reading 1 volt high at battery voltage, so "your" 13 is actually 12.

12v is actually flat & will give you your symptom EXACTLY.

I am not saying that this is your problem, but it does explain everything and needs ruling out.

littleredrooster

5,523 posts

195 months

Saturday 18th January 2020
quotequote all
E-bmw said:
As I said you need to borrow/get another meter.

All of your symptoms sound like a barely charged/almost completely flat battery.
Agreed. And, if not already mentioned, the headlight thing could be a red herring - many cars have a 'load-shedding relay' which turns off ancillaries like lights when the starter is operated in order to aid starting.

anonymous-user

53 months

Saturday 18th January 2020
quotequote all
Bear in mind a duff battery can read over 12.6v too.

M_A_S

1,441 posts

184 months

Saturday 18th January 2020
quotequote all
RogerDodger said:
Bear in mind a duff battery can read over 12.6v too.
Zakly. What's the battery voltage when you're trying to start it?

E-bmw

9,102 posts

151 months

Saturday 18th January 2020
quotequote all
RogerDodger said:
Bear in mind a duff battery can read over 12.6v too.
How?

GreenV8S

30,149 posts

283 months

Saturday 18th January 2020
quotequote all
E-bmw said:
How?
By being fully charged and holding voltage in no-load conditions, but having a high internal resistance so that the voltage dips as soon as any load is applied.

E-bmw

9,102 posts

151 months

Saturday 18th January 2020
quotequote all
GreenV8S said:
E-bmw said:
How?
By being fully charged and holding voltage in no-load conditions, but having a high internal resistance so that the voltage dips as soon as any load is applied.
OK, accepted, makes sense, but how likely is that, as that could also explain OPs symptoms.

GreenV8S

30,149 posts

283 months

Saturday 18th January 2020
quotequote all
E-bmw said:
OK, accepted, makes sense, but how likely is that, as that could also explain OPs symptoms.
I don't know how likely it is, but I once had a battery which seemed to have a broken battery post - simply pushing on the post was enough to make the voltage fluctuate and it was useless under load. A sulphated battery could cause similar symptoms if you manage to get it to take a charge.

E-bmw

9,102 posts

151 months

Saturday 18th January 2020
quotequote all
OP, yer battery is fooked.

Gerra new'un.

Just because it is new doesn't mean it is good, it is displaying all of the symptoms of being dead.

Penelope Stopit

11,209 posts

108 months

Saturday 18th January 2020
quotequote all
Deleted a post here

Thought some were suggesting a faulty battery could read as 13 volts when fully charged and cold

anonymous-user

53 months

Sunday 19th January 2020
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Penelope Stopit said:
Deleted a post here

Thought some were suggesting a faulty battery could read as 13 volts when fully charged and cold
I was. I have had LA batteries die and they "charge" from flat in an instant to around 14.8v. disconnect the charger and they read over 13v and stay that way. Put a load on them and they plummet to 5 or 6v instantly.

Auntieroll

543 posts

183 months

Sunday 19th January 2020
quotequote all
Did you actually try earthing the engine block direct to the battery earth terminal as suggested by a couple of posters.?
The meter may read a believable voltage under no load conditions but if the conductor cross sectional area is inadequate under load then exactly these symptoms will occur.

Again ,as mentioned by other posters ,your new battery may be faulty.

Your knowledge is obviously lacking in automotive matters hence your post, there is a wealth of practical experience on here ,my advice would be to take advantage of it and perform the checks EXACTLY as described ,then report back.
The fault finding procedure is simple ,if you follow it.