High Voltage at the battery

kitesurfer

kitesurfer

Well-Known Forum User
The day started off really well as I had just finished rebuilding all the headers and carbs after removing and blocking up all the anti-smog components and holes. Had a battery connection issue which I needed to check after trying to start up... sorted it. Turned the engine over and to my amazement it fired straight up. Bearing in mind that it originally wouldn't drop below 2000rpm I'm more than pleased that its ticking over at 1000 and sounding fantastic. Now for my question. I thought I would take a voltage reading at the battery and was supprised to see it running at 18.6v I'm wondering if this be a voltage regulator problem as I would expect around 14.6v The car has been in long term storage. Its a 73 240z with an alternator and what appears to be a voltage regulator bolted to the lower inner wing. Are 240z's prone to regulator problems?
 
Don't think they're particularly prone to it, but yeah I think that your regulator is knackered. I think that'll kill your battery
 
jonbills said:
Don't think they're particularly prone to it, but yeah I think that your regulator is knackered. I think that'll kill your battery
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it will definatley kill your battery:eek:
agree with jonbills looks like the voltage regulators not regulating
 
I put a 280 alternator on my 260 which does away with the voltage regulated if I remember correctly so check wot alternator you have on there but I might be wrong
 
Thanks guys.
Just removed the regulator which is an FD Elecman FHBA12-2. Its all really new inside with no obvious burnt wires. The engine is a L28 but the Alternator is an Hitachi LT150 si I'm guessing the electrics are compatible. Any ideas or is it a case of taking the plunge and fitting a new regulator? 18.6v is telling me regulator but it looks like new!!
 

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Even though its externally regulated there is still an internal diode pack in the alternator converting the AC to DC (the regulator just regulates).
If a leg of the pack has gone down it could result in this excessive reading as it could be leaking AC
 
Wot Moriarty says is true,you still need the diode that plugs straight in to the lead that came off the regulated,member on here sells em but can't remember who
 
Paul - I think you are referring to the plug that goes into the loom for when you convert to integral VR alternators. Moriaty was referring to the bridge rectifier within an early alternator.
 
The LT150 has no internal regulator so does require an external one. I seam to recall that you can test the regulator and there may be instructions in the Haynes manual.
 
Thanks again for the advice. I think my course of action is have the alternator checked out. I am starting to suspect a diode. Another clue is that the ignition light no longer works. Didnt spot it before as I was leaning through the window to start it while I was running the meter. I will take it off next weekend for a once over. The regulator just looks so new so I have my doubts it has gone down although I'm probably wrong!! Always the case of fixing things one at a time!!
 
kitesurfer said:
Another clue is that the ignition light no longer works. Didnt spot it before as I was leaning through the window to start it while I was running the meter.
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Which ignition light? is this a later car with the voltmeter and red light showing when it's not charging?
 
Its a may 73 240z with an L28 engine. Voltage regulator with an LT150 alternator. I assumed the red light within the tacho operated as per cars of that era. Went out when the battery charges. Weather permitting this weekend, I will firstly take the bulb out to see if it has blown!!
 
Rob Gaskin said:
Perhaps the previous owner mis-diagnosed the fault?
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Actually Rob we are both suspecting the same thing. The more I delve into the car the more I find things that seem very amateurish in the way they have been replaced. The engine was a classic as it wouldn't drop below 2000 rpm. Sorted now and sounding very sweet. That said I have a big concern that my rocker problem (previous post) is due to someone forgetting to put the 'lash pad' back in. I'm not deterred though as upon close inspection the car is absolutely solid...it just needs a thorough going over!! Plenty of time before late spring to sort it all out!!
 
kitesurfer said:
Its a may 73 240z with an L28 engine. Voltage regulator with an LT150 alternator. I assumed the red light within the tacho operated as per cars of that era. Went out when the battery charges. Weather permitting this weekend, I will firstly take the bulb out to see if it has blown!!
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Oh that's interesting. I don't recall noticing a charging light on a tacho of that era. I'm sure mine doesn't have it (74 260), but, like status, I could be wrong.
Anyone?
 
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