Alternator vs generator to charge batteries?

[jkim1990]

Question on charging batteries....

I have twin motors and generator with AC convertor.

Don't have shore power this year and want to know quickest way to charge batteries:

1) Is using motor alternators idling (sitting in slip) or generator with AC convertor faster charge?

2) if running both motors and generator, does batteries charge faster or is one taken out of the circuit?

Thanks!!!

 

[bsampica]

With a simple volt meter you should be able to test this by measuring the volts / amps going to te batteries.

Its ran possible that your generator only charges your house batteries and each engine charges it's own battery. I've got my 300 setup this way, with an emergency switch on the dash that ties them together for starting if necessary but otherwise they are all desperate systems. I have shore power though and when on AC shore power all batteries are charged when I have my converter switch turned on.

 

[Bt Doctur]

engine batteries are charged by the engines charging system when running.
generator W/ D C charger should only charge house batteries

 

[jkim1990]

Bsampica - good call on amp meter, good way to test. Figured someone might know which was quicker without testing.


Bt Doctur - I do not have house and engine seperate. Two batteries supply port engine and cabin panel, one battery supplies starboard engine and helm. Not a good setup, can't leave one off and then kick in solenoid cross over when one is dead.


Which is faster, engine alternators or generator?

 

[Lazy Daze]

Not sure which is faster - alternator, probably? Although at idle, there is less amperage being put out. But use the genny with your built-in charger. It's at least a "better" charge than the alternators. Plus, it's kind of silly to run the the big engines (and it's usually not advisable to do a lot of idling-only) just to charge the batteries when you can run the little genny to do the same thing and provide power to other things (fridge, outlets, etc) at the same time.

 

[jkim1990]

Dennis - good logic, run genie instead of big motors. So real question is while I am headed somewhere, does genie add additional charge or don't bother while both motors running?

 

[Lazy Daze]

Dennis - good logic, run genie instead of big motors. So real question is while I am headed somewhere, does genie add additional charge or don't bother while both motors running?

Unless you want the genny on for other purposes, I don't really see the need to run the genny/charger if you're underway. Don't bother.

 

[northern]

We have a total of 14 batteries on the boat. The converter puts out up to 60 AMPS acording to the manual. It seems to draw 2 amps on shore power. So do not get 60 AMPS. Each engine has a 70 AMP alternator. I need 1600 RPM before the main start batteries (4 group 27) start to charge at any rate. It takes us 10 hours on shore power to fully charge all batteries. 3 hours a day on the generator keep them up. On our 21 foot boat the alternator keeps the batteries up but there are no current draw.
If you have draw on the batteries all the time the generator is the way to charge the batteries. My generator uses a gallon an hour at full load the engined 5 gallons an hour at 1600RPM.

 

[jkim1990]

We have a total of 14 batteries on the boat. The converter puts out up to 60 AMPS acording to the manual. It seems to draw 2 amps on shore power. So do not get 60 AMPS. Each engine has a 70 AMP alternator. I need 1600 RPM before the main start batteries (4 group 27) start to charge at any rate. It takes us 10 hours on shore power to fully charge all batteries. 3 hours a day on the generator keep them up. On our 21 foot boat the alternator keeps the batteries up but there are no current draw.
If you have draw on the batteries all the time the generator is the way to charge the batteries. My generator uses a gallon an hour at full load the engined 5 gallons an hour at 1600RPM.

Thanks, this is great data. Off to spend a few nights on the hook and all comments will help my approach to keeping powered up!!!! Thanks to all for the feedback....

 

[rcknecht]

Solar pannel charger... That's what I would do...