Battery Condition Observations Charge Discharge Voltage Problems

Druim said:

A wee self study over a near two day period P38 1995 4.6 HSE
Battery modified with extra positive & negative cables giving slightly higher voltage

Outdoor temperature 6-8 degrees & near frost overnight
Beginning: Unlocked car measured 12.2 V on Battery, car had stood still for 1 day
Started car measured 14.18 V no matter revs. Stopped engine no driving.
+ 1 Hour 12.6 V
+ 18 Hours 12.2 V
+ 42 Hours 12.2 V - Started measured 14.19 V
after ½ hour drive with 3 stop/starts measured 14.08 V engine running.
+ 44 Hours measured 12.5 V and it will likely drop back to 12.2 V overnight
+ 44 Hours started car measured 14.1 put all lights on voltage dropped to 14.02 V
(+ Hours are from beginning)

Conclusion: Max. charge in present conditions is near 14.2 Volts going down when not so much charge needed or consumers/lights are on.
Voltage on battery drops to 12.6 V over an hour after stop & to 12.2 V overnight
In very cold weather I remember to have seen slightly higher charge voltage

Rangie are happy with these conditions – I think!

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Druim said:

Another experience:
2 days ago the neighbour’s Japanese diesel 4x4 was out of power due to lights left on over night, there was not even a glow in instruments so very flat, battery 5 years old.
Charged up with 13.4 V from portable charger – when finished measured 13.2 V charger off and after 1 hour still 13 Volts – started up no problems.
Next day 12.92 V - measured charge when started to 14.65 Volts – considerably more than the Rangie’s near 14.2 V
My point is had this been a P38 I don’t think it would have been trouble free but needed lots of the Magic wand, SRS reset being one issue – being Japanese not a single problem/issue and it doesn’t discharge the battery rapidly and the battery is tiny compared to mine which is near new.
So a modified alternator with higher Voltage may do the P38 battery good? - Battery suffering from undercharge?

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