Voltage regulator questions - buy it or build it?

[sfchallenger]

Hi there,

Perhaps you folks can help me with this; my voltage regulator is not working properly and is overcharging my batteries with the engine revved up over 2K rpm. At idle it is no problem- charges around 14.5 v or less, however with the engine running over idle it's more like 16. Obviously I don't want to cook the batteries, so for now I've installed a toggle switch between the regulator and the batts and don't charge them unless my motor is at idle (not often). My battery bank is as follows - two huge deepcycle batts wired together as a house bank, and a separate starting battery. I'm in a marina and on a charger most of the time so this isn't an issue for day trips, but a problem for those longer journeys the boat is hoping to take soon.

So - if you needed a new regulator, would you buy one or build one? Anyone have any good or bad experiences with this? Ideally I think I'd like to have as much charging control as possible - I don't have a genset and will have to rely on the engine for power if those longer distance dreams come true.

Thanks for your help!

hugh

[btrayfors]

Hugh,

I'd say there are two choices: (1) have your alternator's regulator fixed at a local repair shop; or (2) adapt it for an external regulator and get a good one, like the Balmar MC-612 or MC-614.

Even with an internal regulator in your alternator, you should NEVER see more than about 14.4V. These are pretty simple devices, and any alternator shop can fix you up.

An external regulator like the MC-612 would give you more efficient, multi-stage charging and would afford a number of refinements, including:

- setting the profile for the type of batteries;
- setting the maximum percentage of alternator output;
- delayed ramp-up when you first start the engine;
- digital readout of the important parameters;
- easy power reduction when needed;
- attaching battery temp sensors and alternator temp sensors;
- etc.

Whether the investment in a smart external regulator is worth it or not depends on your situation: how you're set up now, the size of alternator and battery bank, how you intend to use the boat, etc.

Bill

[donradclife]

Depending on your budget, you can buy a Balmar marine regulator for $280 or a non marine regulator for about a tenth of that http://www.amazon.com/12-VOLT-EXTERN.../dp/B004HIAI9O

The non-marine regulator is not as fancy, but it will keep you from overcharging your batteries.

[sfchallenger]

Thanks to both of you. I'll probably get a Balmar and swap out my existing one. How much of a difference do you think that makes for battery life as opposed to the auto equivalent?

Cheers,
hugh