17-19 volts to battery why

[offroader-rama]

i have a GQ patrol, it has duel battery's (2 x truck tractor 700cca 13 plater's) one is for starting only the other is for everthing else and this has being good for 4 years, battery's where replaced 2 years ago.

now lately i have had problems with my battery going flat while trying to start on lpg ( different problem, not related to this one) and going flat way to quickly for my likeing now i just run a jumper lead from the exilery battery and usally dose the trick and starts straight away instead of just going click click click .

which inturn made me think that maybe the batterey was down so i through a muilty meter on them both and both are reading 14+ volts with car turned off seemed high started car 14.8 from alternater good there put meter back on battery's while running 14.8 at exilery all good put it to start battery and look out 18.5 volts give engine a rev and it was ranging from 17-19 volts pu it back to alternater and it stayed at 14.8 volts.
i checked the soliniod to see if that was causing it and it was thwe same both sides 14.8 volts

I'M LOST, ANY IDEAS WHY THIS IS HAPPENING

[RoldIT]

Regulator in/on your ALT is farked. You charge system should run around 13.8v to 14.2v while charging.

Most probably farked your batteries too, they should not be anywhere near 14+v with the car off. A fully charged battery sits at about 12.6 - 12.8 volts depending on the battery type.

Time to visit the auto elec ...

[drivesafe]

Before you do anything, check to see if you have a loose or disconnected earth strap somewhere.

But failing that, as RaldIT posted, time to go to the AE.

Cheers.

[offroader-rama]

i know its AE time but as funds are very tight at present and i have a night run tomorrow night, i was hoping some one had a easy sulotion now i know 14 volts is high for a battery.but saying that they work!!
but the alt is staying at around 14.8 a touch high but i wound not have thought enough to worry yet and its only one of the battery that reads 17-19v while running the other is the 14.8 from altnater so i rule alternater out as i put multi meter on the wires from the back of it and they stayed around 14.8v

as for an earth strap funny you should mention that as i was looking around and i fund the one that goes from chassis to manifold hanging i put it back on but didn't change anything.
i have a constant battle with dry joints as with anyone that goes through mud but i cant see it upping volts only removing them.

[drivesafe]

Where it can up the volts is where the regulator uses the earth as the voltage reference and if the earth is damaged or missing the regulator has no reference point so it runs wild and can go in either direction but usually goes high.

Cheers

[me3@neuralfibre.com]

With those numbers, I would try another meter. It sounds like it's not telling the truth.

Paul

[RoldIT]

Only reason I said what I did is, I have seen it before on a mates GQ.

Virtually same readings, ALT reg was farked. Batteries died completely with 1 month after reg was replaced ...

[offroader-rama]

i thought the same thing but its brand new and to double check i check 2 other cars and they read 14.4 and 14.2 and i know they dont have a problem i think i'll have to take all earths off sand and crc them then try again. hope fully what drivesafe says has merit.

[offroader-rama]

roldit
i would agree that it was the ALT if it was 18v at the ALT but it is only on the start battery.
its still reading 14.8v at the ALT a touch high yes but not extream i dont understand how i can have 14.8 on 1 battery and 18v on the other at the same time while the car is running as drivesafe said it could be a bad earth on that battery.
will cheak tomorrow and let you know.

thanks all
rama

[me3@neuralfibre.com]

14.2 with engine off on other cars - your meter is telling fibs.

12.6 with engine off is normal. Doubt you'll ever see over 13

Paul

[drivesafe]

Hi offroader, could I make another suggestion, try putting a load on the batteries while you take a voltage reading and do this with the motor running and with it stopped.

Some times a stuffed battery can do some funny things but putting a load on the battery, a load like a 100w driving light globe can some times cause the battery to give a more realistic reading.

BUT.

It is a bit strange to have a higher than alternator reading while the motor is running.

Real mystery that one and don’t forget to let us know how you get on.

[Bluey]

my honda cbr was doing this, 19 odd volts killed 2 batteries. put a voltmeter on the dash so could see while rinding, and yep the voltage was sky high. was a dodgey regulator, so in the end cost me 2 batteries and 1 regulator. expensive

if you are friendly with the local wrecker see if they will lend you a regulator so you can check the charging voltage. or at least let you bring it back or swap

[offroader-rama]

I am happy to say all fixed i took all leads off clean all areas put all back together and 14.4 - 14.6v on both batterys and 14.8 at ALT happy with that.
So I had to double check i loosend the earth on the battery thats WAS reading 18v and as i loosened it, the volts climbed back up to 18 volts tighten it and bingo 14.4v first one for me, but fixed all the same.
but i think in all this its put some damage to the battery as it still goes flat pretty quick i might swap them over before buying a new one though.

thanks to all again
rama