Installing an external regulator on a Volvo D2-55

[Jetx]

Originally Posted by Kiwi Dave

Hi - for my catamaran I got the auto electrician to change a pair of Volvo (Mitsubishi) D1-30 115 amp alternators to external regulation

I’m also considering converting our stock 115 amp Volvo/Mitsubishi alternators to external regulation. I’m curious… how much continuous current do you observe coming from your modified alternators while charging the LiFePo battery bank? (I’m wondering how much they’re capable of producing without burning up.)

[CarinaPDX]

I would like to amplify @Dansken's post about using the VRC-200 regulator instead. While I appreciate the integration and information available from using electronics from the same source I don't think in this case that is the best way to go. First off, using the Alpha will void the warranty on the alternator (at the very least) as you are modifying it. By disabling the internal regulator you lose the thermal management that is part of it, which may be ameliorated somewhat by an alternator temperature probe. Personally I think there is an obsession among cruisers for over-instrumenting their systems; a good charging system should just do its job well and not require any human supervision. I use simple analog ammeters on each charging source (alternator, solar, wind gen) which, with battery voltage, tells me all I need to know. I can see having a battery charge display but I got along just fine without it.

The point with the VRC-200 is that it controls the alternator by manipulating the voltage present on the external battery voltage sense (the yellow wire on the Mitsubishi alternator). There are no modifications to the alternator, and should something go wrong with the external regulator then just connect the voltage sense to the battery instead of the external regulator. This should not be a problem for the warranty, and of course leaves in place the internal thermal regulation. It was designed specifically for use with lithium battery systems but works just as well with the various lead technologies.

I suspect the OP is too far down the road to reconsider but for others the VRC-200 should be the first choice.

Greg

[Kiwi Dave]

Hi James

I'm sorry for the delayed reply

"Hi Dave.
The wiring for the Alpha Pro is probably different from the Balmar. Was the red 12V ignition-on wire from the MDI the same as the R10 wire from the harness to the starter motor shown in the attached VP wiring diagram?
For the Alpha Pro the +12V supply wire is also used for the battery voltage sense"

As far as I can remember
It is tapped from Multi Link "6" (Multi link power supply)

[SweareDeep]

Echoing others, I have been extremely pleased with the addition of a VRC-200 to the Mitsubishi 115 A alternator on my D2-75F. The alternator is feeding 600 Ah of LiFePO4 batteries.

The internal thermal regulation on the alternator is arguably better than external thermal regulation via a temperature probe (less latency), at least according to Eric Bretscher the designer of the VRC-200. Earlier versions of the VRC-200 had a temperature probe but it now relies on the internal thermal regulation.

I find my alternator sustains about 80 A over the long haul (a few hours) with no signs so far of any temperature issues -- the varnish on the windings shows no discolouration, for example.

I find being able to force the VRC-200 into float useful for those occasions when I want to leave the batteries at say 60% charge if I won't be using the boat for a while. Hardest part of the change to lithium has been overcoming how we used to do things with lead acid!