Alternator regulator temporary fix?

Dellquay13

Dellquay13

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The 35a alternator on my 1gm10 is suspect, I think the regulator is beginning to fail, and it seems it’s occasionally going very high output (not measured but guessing around 18v? I found my battery sitting at 16v shortly after I’d been running the engine for half an hour.)
As a very temporary fix can I use my cheap pwm solar controller in series to stop the alternator from boiling my battery? It would only be used until I can get the alternator sorted.
 
Dellquay13 said:
The 35a alternator on my 1gm10 is suspect, I think the regulator is beginning to fail, and it seems it’s occasionally going very high output (not measured but guessing around 18v? I found my battery sitting at 16v shortly after I’d been running the engine for half an hour.)
As a very temporary fix can I use my cheap pwm solar controller in series to stop the alternator from boiling my battery? It would only be used until I can get the alternator sorted.
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Probably not. The solar regulator will be rated for 100-200 watts. Your 35A alternator can put out well over 400 watts - at 18V it's putting out 630 watts! So your solar regulator would probably fail in interesting ways, up to catching fire!
 
Wondering the Charge Controllers designed for Caravans might help ... designed to take charge load - split off to 2 or more batts - or one if that's all you have ... once controller reaches set point - it switches off ...

As AP says though - that's a lot of watts out of an alternator ... but only when batt is very low .. BUT as your regulator is failing ... mmmmm

I'm not so sure about a Solar controller for it ...

You presumably have a diesel engine ... so why not just disconnect alternator ... if you charge from Solar and Shore .... then unlike a petrol engine - the diesel can run happily without a battery. Just make sure alternator is disconnected BEFORE starting engine and don't reconnect unless engine is stopped.
 
I can't help with a temporary solution, but can say it was very easy to change the regulator on my ancient Paris-Rhone alternator. Change it and you will either have solved the problem, or identified that it is something else causing the problem and you'll have a spare regulator. It will likely be much quicker and easier than rigging up some temporary bodge.

I found a suitable replacement regulator easily online (not expensive) and it was delivered a couple of days later. Took a photo of which coloured wire went to which terminal on the back of the alternator before I started disconnecting anything. Switched off electrics. Removed regulator, put new one in place, reconnected wires, checking against photo. Switched electrics back on, restarted engine. Checked and found alternator was still charging but now at the correct voltage, and has never been a problem since. It was one of the easiest and least problematic of any boat job I've ever done.
 
I would check the alternator output and battery volts when charging using a test meter. Check every connection is good and secure.

Assuming all is not well, disconnect the alternator electrically. Your battery will use a very small portion of its charge starting the engine and your solar (assuming you have it?) should maintain the charge. Monitor the battery voltage rested and under load to confirm all is well.

Either get another alternator to swap out or remove and repair.

When I installed a battery monitor, I avoided the Bluetooth model. I now realise that having access to charge and load history is really useful when something like this happens.
 
Thanks for all the suggestions.

I’ve decided against a temporary bodge. I’ve got a week holiday onboard from Saturday and I don’t want to lose three days having to get the part number, order online and fit a new regulator.
I’ve bought a new alternator and it will be waiting for me at the Marina desk when I arrive Saturday afternoon. A relatively expensive option but It buys me 3-4 days sailing for an extra £80 above the cost of a delayed diy repair.
I could repair the old one at my leisure afterwards
 
Dellquay13 said:
Thanks for all the suggestions.

I’ve decided against a temporary bodge. I’ve got a week holiday onboard from Saturday and I don’t want to lose three days having to get the part number, order online and fit a new regulator.
I’ve bought a new alternator and it will be waiting for me at the Marina desk when I arrive Saturday afternoon. A relatively expensive option but It buys me 3-4 days sailing for an extra £80 above the cost of a delayed diy repair.
I could repair the old one at my leisure afterwards
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When mine started playing up last year, took it off and went to auto repair guy, tested and overhauled in just over an hour, could have got me new replacement later that day. Not sure why a marine one is any difference
 
Daverw said:
When mine started playing up last year, took it off and went to auto repair guy, tested and overhauled in just over an hour, could have got me new replacement later that day. Not sure why a marine one is any difference
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Rural West Wales… I contacted the only local auto alternator company to be recommended by the trusted marine engineers based in my boatyard. Their estimated timescale was around 48hrs Monday -Friday, so I would have been looking at refitting it on the 4th or 5th day of my holiday. And two 30 mile round trips to drop it off and collect it.
I now have a reputable replacement alternator waiting for my arrival at the marina office. I’ll be fully working again around Saturday lunchtime this way.
 
fredrussell said:
Hmm, admittedly I’ve only had dealings with the alternator on my boat - but that one (Hitachi) is isolated ground. Same for the Prestolite one I was given. I’ve been doing a fair bit of reading on the subject due to my Hitach alt dying!

Old thread on subject here:
Insulated/isolated alternator
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As identified in the threadf you linked to, some are isolated return, mostly because the boat has a saildrive. Other than boats with saildrives i've very rarely worked on one with isolated ground, but there have been a few.
 
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