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Old 09-07-2015, 19:23   #16
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Re: Does my generator need an alternator?

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Originally Posted by Paul Sampson View Post
If you run your main engine wile the 110 charger is on from either gen or dock side it can damage your reg and or alt
I don't see how that can happen. The dock side charger can only increase the battery voltage and then the generator reg will shut down the generator field. No harm can come from that.
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Old 09-07-2015, 19:25   #17
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Re: Does my generator need an alternator?

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Sorry didn't communicate well. Battery will remain connected. Charger and alternator feeding same battery a problem?
No, they can both charge the battery until float mode is reached. Then whichever one has the highest float voltage will dominate. The other one will just shut down.
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Old 09-07-2015, 20:06   #18
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Re: Does my generator need an alternator?

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If you run your main engine wile the 110 charger is on from either gen or dock side it can damage your reg and or alt

Ah ha. This answers my question if applicable to generator. I really want to be able to maintain the generator starting battery when plugged in to shore power so will connect to my battery charger. But fixing or replacing alternator may be futile if it will get damaged by the charger when I am running the generator.
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Old 10-07-2015, 01:19   #19
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Re: Does my generator need an alternator?

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Originally Posted by Paul Sampson View Post
If you run your main engine wile the 110 charger is on from either gen or dock side it can damage your reg and or alt
Please explain the mechanism that causes your alleged damage. I regularly do this with no issues.

Jim
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Old 10-07-2015, 14:39   #20
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Re: Does my generator need an alternator?

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Originally Posted by Paul Sampson View Post
If you run your main engine wile the 110 charger is on from either gen or dock side it can damage your reg and or alt
I can't imagine how this would be an issue either - the alternator/regulator could care less if there is 14.1V at the battery - that's what they're set to put out anyway. If this was a problem, we'd all have to turn off our solars before starting the engine, which I can pretty much guarantee no one does.

Back to the original question - the alternator on a diesel generator just replaces the small amount of energy used to start the engine and attempts to fully charge the battery. It makes no difference how you do this. There's nothing magical about energy coming from a particular alternator compared to anywhere else - solar, battery charger, whatever. No need to be spinning more stuff than necessary. Commercial boats typically don't have alternators on their propulsion engines, for instance.
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Old 10-07-2015, 20:16   #21
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Re: Does my generator need an alternator?

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I can't imagine how this would be an issue either - the alternator/regulator could care less if there is 14.1V at the battery - that's what they're set to put out anyway. If this was a problem, we'd all have to turn off our solars before starting the engine, which I can pretty much guarantee no one does.



Back to the original question - the alternator on a diesel generator just replaces the small amount of energy used to start the engine and attempts to fully charge the battery. It makes no difference how you do this. There's nothing magical about energy coming from a particular alternator compared to anywhere else - solar, battery charger, whatever. No need to be spinning more stuff than necessary. Commercial boats typically don't have alternators on their propulsion engines, for instance.

Thank you. It seemed logical to me to rely on a more reliable and sophisticated piece of equipment than a cheap low output alternator


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Old 12-07-2015, 16:40   #22
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Re: Does my generator need an alternator?

If you're a daysailer, no you don't need that because it'll always be a quick trip back to the dock, but if you're a cruiser you'll need multiple ways to get amps in the batteries.
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Old 28-07-2015, 18:10   #23
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Re: Does my generator need an alternator?

My old Onan generator does not have an alternator. It has a small charge circuit, that I augment with the echo charge output from my inverter. Works well and I use my generator every few days.

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Old 28-07-2015, 18:35   #24
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Re: Does my generator need an alternator?

SeaSon,
What is a small charge circuit? What echo charge? Echo chargers don't hook up to inverters.
It has me confused.
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Old 28-07-2015, 19:03   #25
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Re: Does my generator need an alternator?

I disconnected my alternator on my onan genset as it kept melting due to the fact I start my engine and gen using the same battery and the gen alternator isn't up to charging a 150Ah battery. Used a lot of belts and 3 alts before comming to this conclusion. Gen when running has a nice 50Ah charger with multiple outputs so all is well .....
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Old 28-07-2015, 21:04   #26
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Re: Does my generator need an alternator?

My onan mdje, has a circuit built into the generator circuits that provides a couple of amps at 12.5 volts. No additional cables other than to the starter. Don't know much about it other than that.

On my xantrex inverter/charger, the charger is primarily for recharging the house batteries, however it also has an 'echo' charge output intended to be connected to the start battery of a generator, and it too puts out only a small current. I have that connected to the start battery also.

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