Electrical fault

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roger68 said:
That was with ending off after a run showing 13.8 v with enging running
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13.8 engine running is too low, it won't be significantly charging the battery, any electrical load is likely to pull that down to point that is unsustainable.

Check all the wiring to and from the Alternator, check engine earth straps etc, you Alternator could be getting tired, or the battery is shot and it is pulling Alternator output down with it!

Engine running, get an able assistant to hold the revs around 2000 and read the voltage, should be over 14.2V, ideally 14.4-5V
 
What year is the car? I have found 2 early P38's fitted with alternators set to 13.8 volts, this is not enough to fully charge modern lead calcium batteries. Either your alternator is faulty or it's an early one, swapping the regulator for one with a 14.2 volt set point is cheap and easy.
As Saint.V8 said, check the voltage at the battery with the engine at about 2K rpm.
 
Datatek said:
What year is the car? I have found 2 early P38's fitted with alternators set to 13.8 volts, this is not enough to fully charge modern lead calcium batteries. Either your alternator is faulty or it's an early one, swapping the regulator for one with a 14.2 volt set point is cheap and easy.
As Saint.V8 said, check the voltage at the battery with the engine at about 2K rpm.
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Or 14.4 would be better for a calcium. Lead/acid 13.8. Gel 14.2. Calcium 14.4. Is the general guide line. :)
 
roger68 said:
Just tried now 11.1 v not running 13.7v running at 2000 revs
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11.1v = battery flat and maybe dead, 13.7v is insufficient to charge the battery and will be the reason the battery has died if in fact it's dead.
Check the voltage at the alternator output, taking care not to get caught on any moving parts. If it's the same, time to refurb the alternator, if it's much higher, look for bad connections, earth strap from engine to chassis for instance.
 
Datatek said:
Here we go again. 14.2 volts is adequate for LC batteries, up to 14.8 is not unusual, my Yuasa GEL battery has 13.8 stamped on the side as max charge voltage.
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No here we go again at all, general rule is 13.5/13.8 for lead/acid. 13.8/14.2 for gel and 14.4/14.8 for calcium. According to bumf i have read from battery makers. According to that Lead/acid/calcium batteries do not charge properly until the charging voltage is above 14.4. And require a controlled charger for recovery from deep discharge. The battery makers could be wrong of course. :D:D
 
wammers said:
No here we go again at all, general rule is 13.5/13.8 for lead/acid. 13.8/14.2 for gel and 14.4/14.8 for calcium. According to bumf i have read from battery makers. According to that Lead/acid/calcium batteries do not charge properly until the charging voltage is above 14.4. And require a controlled charger for recovery from deep discharge. The battery makers could be wrong of course. :D:D
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14.2 to 15.0 for LC batteries using constant voltage charging ie an alternator. On the P38 diesel, 14.2 charges my LC battery with no problems,
For Gel batteries, constant voltage charging is 13.8, with a smart charger operating in constant current mode, 14.1 to 14.5 depending on battery spec during the fast bulk charge period then reverting to 13.8 to finish. Although the voltage set point may be 14.1 to 14.5 in the bulk charge phase, the battery will not see that voltage for most of the phase as the constant current function limits the voltage to control the current.
 
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Datatek said:
14.2 to 15.0 for LC batteries using constant voltage charging ie an alternator. On the P38 diesel, 14.2 charges my LC battery with no problems,
For Gel batteries, constant voltage charging is 13.8, with a smart charger operating in constant current mode, 14.1 to 14.5 depending on battery spec during the fast bulk charge period then reverting to 13.8 to finish. Although the voltage set point may be 14.1 to 14.5 in the bulk charge phase, the battery will not see that voltage for most of the phase as the constant current function limits the voltage to control the current.
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Lead/acid/cad and lead/acid will take a fast boost charge although lead/acid will gas more and may need top up. But gel batteries can be damaged by gassing if fast charged. So fast boost charging should not be used on those.
 
wammers said:
Lead/acid/cad and lead/acid will take a fast boost charge although lead/acid will gas more and may need top up. But gel batteries can be damaged by gassing if fast charged. So fast boost charging should not be used on those.
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Funny that the data sheets say fast charging with a smart constant current charger is OK, of course it could be that the battery manufacturers are wrong and forgot to ask the Wammer god :praise:Font of all knowledge.
 
Datatek said:
Funny that the data sheets say fast charging with a smart constant current charger is OK, of course it could be that the battery manufacturers are wrong and forgot to ask the Wammer god :praise:Font of all knowledge.
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It depends what you mean by fast charging. So if i put a gel battery on my boost charger and stick 20 volts through it is will be fine then? Lead/acid or lead/acid/calcium would stand that, taking appropriate care, gel won't.
 
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