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Needing to use engine alternator vs. generator

1419 Views 7 Replies 6 Participants Last post by Flint, Mar 4, 2015

Pamlicotraveler

Discussion Starter · Mar 4, 2015 (Edited)

I have never been "at anchor" longer than a week or two, but am now in the Caribbean where anchoring for a long is the norm. As a result I have not had a "full charge" on my batteries in 6 weeks. This is causing some confusion with the battery monitor and the charging systems.

I am finding that the engines alternator puts in a lot more amps than the generator - more or less double the amps. I hate to run the engine at anchor, I don't need the extra hours of running at idle, but with the generator the amps going in gets to be 20 amps or below quickly and I can be getting 40 or 50 at the same time with the alternator from the engine. They alternator has a separate regulator. Here's the setup:

* 90-100, 135 Amp Balamar alternator on Yanmar 4jh - regulated by a separate Xantrex XAR digital alternator regulator (a multistage regulator).

* Westerbeke 6KW generator, regulated by running through a Xantrex a Freedom 20 charger/inverter/(with a multi stage regulator)

My question is this.... Shouldn't a 6kw generator be able to put in as many or more amps than an engine alternator to charge the batteries? I believe somehow the Xantrex Freedom 20 inverter is "throttling down" the amps from the generator to a lower acceptance level than the separate, free standing alternator that the engine alternator uses. I know I want multi stage charging, but why would the Freedom 20 throttle it down to such a low level? I would much rather run my generator for the same amount of time.

As far as I know there is no way to change the allowed charging rate on the Freedom 20 regulator.

So here I am, in a harbor with a perfectly good generator, charging my batteries using the boats engine. That doesn't seem right.

Any ideas?

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Maine Sail

· #5 · Mar 4, 2015 (Edited)

Is this a Link 2000R where the alternator is doing the charging or the inverter/charger is doing the charging?

If you are only getting 20A out of a 100A inverter/charger then it likely does not like your generator power. Many of these older inverters/chargers can not put out full power when driven by a generator. Alternatively it could be in the settings or a temp issue. Try setting it to cool and choosing the highest voltage setting on the unit which IIRC is actually GEL... The charge voltages on these were awfully low for a flooded deep cycle battery.

If it is a Link 200R this is pretty typical. They were rather poor alternator regulator systems....

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Maine Sail

· #7 · Mar 4, 2015 (Edited)

Pamlicotraveler said:
It's not a link 2000r . We had that but replaced it.... Now we have a link-lite battery monitor and I guess a Link 2000. And these are AGM batteries.

By the way, when the batteries are discharged, the generator (through the freedom), will charge at more than 20 Amps....maybe up to 50 Amp for a while, but it is always less than the engine, and it backs down to a low charge rate much quicker than the alternator does making it take many hours to get a good charge. It makes the generator way too inefficient.

You really need to know the battery terminal voltages of both sources at the same or similar SOC.. If both battery terminal voltage readings are the same :eg 14.4V, and one source is only providing 20A, and the other 50A, then the problem is with the source with low current.

With all DC loads off start the engine and measure battery terminal voltage (PHYSICALLY AT THE BATTERY TERMINALS) and note current flowing into batteries on the Link.

Turn off engine:

Start Generator and I/C and do the same. If the battery terminal voltages are the same, and the current flowing into the batteries is a 30A difference then this is an issue with the inverter / charger that needs to get sorted....

Again many of these older Freedom's perform rather horribly under generator power and can not develop full charge current. To test this plug into a dock and then A/B test between shore power I/C output and generator I/C output at the same SOC...

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