MarkII, overVolting again...

**MarkIIRx12** · 23-07-2007, 06:29 AM

Hi

My 73 markII is being a bad boy and are blowing bulbs and over heating (over charging?) the battery again, i already had a thread about it blowing bulbs, but now its worse. I have a almost brand new battery, but it seems to have fried it, the battery is making sounds like its boiling, and the outside of the battery is getting kinda hot too. this is one of thoose sealed batteries, so i cant refill acid/water on it either, my guess is that the battery have gone empty of water, from the car over charging it. i measured the volts at the battery terminal, and now its charging 18 volts. The alternator and the voltage regulator is almost new too.

the battery seems to be dieing, sometimes its very low on power without reason, but other times its fine, when its almost dead i have tried to charge it with a battery charger, but the charger disconnects and tells me the battery is already full.

what can i do to fix this problem? does the voltage regulator have some kinda adjustments inside it?

Thanks for all ur help

**Mos** · 23-07-2007, 09:10 AM

For starters don't assume that your alternator and reg are fine because they're new

You shouldn't be seeing much more than 14V while the car is running.
What kind of alternator is it? what kind of regulator?

Mos.

**MarkIIRx12** · 23-07-2007, 11:03 AM

Hi

Thanks for ur answer.

I had this problem before i bought new alternator and volt regulator too tho, im not sure what brand they are, but its original toyota parts, so im assuming they should be good.

i have been thinking about the new volt reg, and it could be that its not working like it should, i dont know how to checkt it and see if its fine.

more good ideas is also great

thanks for ur help

**stradlater** · 23-07-2007, 12:16 PM

D00D!! 18 volts is WAYYY to high! Any wonder your boiling your battery!

**maurice c** · 23-07-2007, 01:11 PM

Try changing the parts for known good ones from another car. I know that aftermarket regs like ingrams are adjustable on the back for voltage. Check the connections to the loom. If there is resistance on the ignition sense or a bad earth on the alternator then this could possibly cause a voltage output increase.

**BMWTurbo** · 23-07-2007, 01:31 PM

The only Item in the charging circuit that could possibly allow 18V through is in the alternator, IE internally regulator alternator. I'd be removing these and having them tested.

Should only cost you maybe $30 from an aut elexctricians and they should diagnose the issue for you.

Alternators are hard to test at home for output under loads, but they will have a machine they mount the alt on and can load it to 100% duty.

**MarkIIRx12** · 24-07-2007, 01:53 AM

Hi

Thanks for ur answers

I think my alternator doesnt have a built in regulator, and thats why it have a regulator box mounted in the engine bay? or does it still have a regulator in the alternator?

i always thought it was only the box in the engine bay that was the voltage regulator, but as usual i might be wrong

**Pure_In_Sanity** · 24-07-2007, 10:33 PM

Maybe high resistance in the "s" circuit, or something along those lines. This could be giving a wrong reference voltage to the regulator?

**MarkIIRx12** · 25-07-2007, 03:52 AM

Hi again

i went and bought another new voltage regulator today.

it seems that the other new voltage reggy was broken even tho it was new, now the car is charging about 14,4V, isnt this a good voltage? i dont remember what is normal voltage

hopefully now it will stop blowing bulbs and torturing the battery