Thread: Battery boiling

If you are measuring 14.48 on alternator and 13.89 on battery when battery is fully charged and you have no electrical load then you have bad connection somewhere. Readings should be the same. Was this the case when you took your measurement? If your battery is wet cell (liquid acid) and it's boiling at 14 volts, to me it looks like battery problem. Have you tried measuring ac voltage on the battery?

If you have 2 volts drop when brake applied it means you have lot of current drawn in that circuit somewhere. Again if you have bad connection between alternator and battery, this heavy current will cause the voltage drop.

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Hi Roamer, thank you for your input , yes when I checked the voltage from the alternator at the battery with no electrical load , the lead from the alternator is new & has new terminals both ends good condition although I have not checked where the earth lead is connected to the chassis for resistance (will check) ,both the positive & negative terminals at the battery are clean & have good contact with battery terminals.
I have used light automotive grease on the terminals as I have no electrical grease could this cause the problem???
As for the indicated voltage drop when breaks are applied I have no idea as to where to start looking, so I will try and correct the voltage drop to the battery first, then sort out the break voltage drop, it may even be sorted out if I can correct the battery voltage drop so I will check all chassis earth strap connections for good contact .
once again thank you for your input
Brad

Yup I'd check earthing as well. Bad earthing can cause voltage drops as well. Grease shouldn't be a problem.

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Hi brad, the voltage drop when you apply the brakes will most likely have nothing to do with your battery boiling.

With an alternator voltage of 14.48v, I would not be trying to alter that in any way.

14.48v is well within the PERFECT charging voltage range and will not cause a battery, in good condition, to boil.

You should make sure all 6 cells have enough water in each cell as a dry cell can cause the others to boil, or if you have had a dry cell at any time, it may now be damaged and again, this can cause the others to boil.

If all the cells have sufficient water in them, then you need to get your battery check as it sounds like it's just about to fail.