M643 charging new LifePO4 bank

[Kirbywatson]

We have a Northern Lights M643 (5KW) generator aboard that is about 25 years old (3100 hrs.). We recently replaced out AGM bank with a 1600+ AH bank of LifePO4. We replaced our old magnum charger with a Victron Multiplus II (120 amp), added 2 Victron Phoenix chargers (50 amps each) and one Sterling charger (60 amp).

A few days ago, the regulator failed. We’re replacing it (along with a new alternator) but my questions are:

1. Are we asking too much of the old generator?
2. Would the bank and new chargers be putting too much ‘stress’ on the generator?
3. Should we consider the smoking regulator normal maintenance? How long should they last?

Thanks!

[dkenny64]

I would not worry about the alternator on the generator(12v). the chargers are 120v. unless my math is way off. the generator will need output around 3400w at max charge of all your chargers. so I would think it can handle this. if not shut down some the chargers. it'll just take a little longer to charger the LIFEPO4 bank.



just my 2 cents
-dkenny64
my m643 will run our 16k btu hvac no problem and the water heater but only if the hvac is already on before the water heater.

[CharlieJ]

OP: What model alternator and alternator regulator did you have? What are you replacing them with? You do know that not controlling the output of an alternator that is charging an LFP bank will lead to a quick alternator death, right?

[Kirbywatson]

Replacing the alternator and regulator with original parts.

[CharlieJ]

OP: If you are charging an LFP bank with a stock alternator that has not been derated, it will self-destruct. There are a number of threads on CF discussing this so I won't rehash the concept and protocol again.

[Kirbywatson]

Thanks Charlie - it was my understanding that the generator does not use the alternator for charging. The alternator and regulator are used on the engine side only. Is this not accurate?

If this is the case, shouldn’t the stock regulator and alternator on the generator be fine?

Thanks again.

[CharlieJ]

A stock alternator, no matter how it is driven, will probably not survive charging an LFP battery/bank unless its output is derated so that the alternator temperature is < 100C or the max. temperature spec provided by the alternator manufacturer.
Here is a demo on how to fail an alternator:

https://www.youtube.com/watch?v=jgoIocPgOug

[Sailmonkey]

Are you talking about the regulator on the generators 12v alternator failing? What does this have to do with charging Lifepo4 from AC chargers?

[wholybee]

Some clarification is needed here. A generator works as a diesel motor, that spins an alternator, which has a regulator. Those parts on a generator are not the same as the alternator that charges the 12V system. I mean, they are, and they work the same way, except that in the case of this generator are rated for a 5kW load.

I don't think it out of the ordinary for these parts to fail after 25 years. As for the question of if you are overloading your generator. You have 4 AC chargers, 120A, 50A, 50A, and 60A. That totals 280A. 280A x 14.6V = 4088W. Assuming 80% efficiency, 5110W. That *IS* overloading the generator. And the efficiency might be lower or higher, I'm not sure. You are working that generator very hard in any case. I would run it with just the 120A and 60A chargers, or upgrade to a larger generator.

[smac999]

Originally Posted by Sailmonkey

Are you talking about the regulator on the generators 12v alternator failing? What does this have to do with charging Lifepo4 from AC chargers?

the gen itself has a regulator to maintain voltage / freg. which was my first assumption. But I also don't know what he's talking about at this point.

[smac999]

Originally Posted by Kirbywatson

Thanks Charlie - it was my understanding that the generator does not use the alternator for charging. The alternator and regulator are used on the engine side only. Is this not accurate?

If this is the case, shouldn’t the stock regulator and alternator on the generator be fine?

Thanks again.

if the house bank is starting the gen, then the alt on the gen is going to try to charge the house bank which it is not designed to do. the gen should have it's own starting battery. and the gen battery not should not be connected to the house at all. IE no ACR etc. then the gen alternator will only have to charge the gen battery. and the AC chargers will charge the house.

[tanglewood]

Let’s go back to the beginning.

What regulator failed? One that is controlling the main engine alternator? Or the regulator in the 5kw generator? One should have nothing to do with the other.

[skipperpete]

Indeed, good point Tanglewood. initially I also thought the problem was the belt driven alternator..... the little 14 amp one with the finned remote regulator but as the thread progressed I started to wonder if I was on the same page..... the lithium confused me[emoji848]
At full continuous genset AC output that little alternator should be able to easily supply the field ( via AVR) with enough DC current and not burn out the alternator.

[tanglewood]

Originally Posted by skipperpete

Indeed, good point Tanglewood. initially I also thought the problem was the belt driven alternator..... the little 14 amp one with the finned remote regulator but as the thread progressed I started to wonder if I was on the same page..... the lithium confused me[emoji848]
At full continuous genset AC output that little alternator should be able to easily supply the field ( via AVR) with enough DC current and not burn out the alternator.

Well, you bring up yet a third possible meaning to the initial post. I was thinking of the main engine alternator, but you are of course correct that there is a small alternator that's part of the genset as well for start battery charging.


Anyway, so far we have lots of advice that's good, but based on assumptions that may well be wrong. I.e., we are telling him how to fix it, but we don't know what broke.

[jordanbigel]

I dont get how all this discussion of alternators started - he clearly said he is dealing with a NL genset which puts out AC power. My little 3.5kw genset also puts out AC power, and it has a "regulator" on it - a small potted circuit board (which I know not how it works exactly) but it has nothing to do with an engine driven 12v alternator. I assume the NL has a similar "regulator" - perhaps I and the OP are using the wrong name for this device, but I think whatever you call it, its a component which is part of an AC genset and has nothing to do with a belt driven engine alternator.

My shot in the dark is that these regulators can burn up if overheated (its happened to me) and possibly from old age. As for whether his 5kw AC genset is being overworked with all those battery chargers, I have no idea, but I feel that somewhere someone mis-read what the OP wrote and went off on the Alternator tangent.

Please, proceed.