T&T: 12 volt Charging options

[Jeff Barfett]

Arild,

Thanks for the explanation - didn't realize that the generator, by design wasn't putting out clean power!

To further expand on the issue - batteries depleted to 50% - when on
shorepower the Trace immediately goes to 'Bulk' mode and provides 14.2
volts at 125 amps (voltage is adjusted for temperature), after a preset
time it moves to absorption and then finally to float at 13.2 (again
adjusted for temperature).



When attempting to use the Trace charger powered from the Westerbeake
generator, it can take 2 hours just to ramp up to 13.2 volts and it
seems like it is struggling to make 35 amps. It seems the Trace can't do 14.2 and 100 + amps in  the bulk mode when running on the generator and Alrild's explanation shines the light on this issue.

So - since the generator's power isn't clean enough and of the right wave to fully power the inverter/charger to move it to the bulk mode, is there a charger available in the 100amp range that would work with the generator's  power?

As Steve stated, the investment in the generator is already there, so need to figure out the next best option. Understand about the tradeoff's moving past the 80% mark and agree that the cruising option is best for bringing the batteries up to 100%.

I've read elsewhere, the formula for horsepower needed to drive an alternator is 1 horsepower per 25 amps - do others agree? In that case, the Westerbeke in question is 8.1 rated HP at 1800RPM - so a Balmar 100-125 would load the gen down to at least 50% - hopefully leaving some room to drive some AC amps. Since others have accomplished the same thing, the next step is to get with Westerbeke and see what they have to say and if any parts are available from them - no sense reinventing the wheel if they have a solution.

On another note - if you have multiple charging sources, couple of 110VAC charges, an alternator or two - can all of these run together to increase the amperage that you could possibly put back into a battery bank (understand - there is a maximum) . If a regulator on say the alternator is seeing 14.2 VDC on the battery sensing circuit that, say the 110VAC unit is putting out, wouldn't the regulator on the alternator keep it from putting big amps back into the mix?

Regards,
Jeff


SNIP

Hi Jeff,

Yeah its the power factor of the Trace that got you.
Simply put the WEstebeke doesn't produce a clean sinewave and the Trace
cannot compensate enough.

Yes the idea of driving the Balmar 120A  from the genset is good.
with a 1800 RPM  setting you need approximately a  2.77 to 1 pulley ratio to
get full amps from the Balmar.
Realistically you will likely end up with 2.5:1 ratio which is good enough.


If the house bank is already charged to 80%, then the Perkins alternator can
finish the charging in a couple of hours cruising.

What you are proposing is in effect the same as the DC genset concept I have
been promoting for many years.

regards
Arild


> -----Original Message-----
> From: trawlers-and-trawlering-bounces@lists.samurai.com
> [mailto:trawlers-and-trawlering-bounces@lists.samurai.com]On Behalf Of
> Jeff Barfett
> Sent: Monday, May 28, 2007 8:18 PM
> To: 'Trawler List'
> Subject: T&T: 12 volt Charging options
>
>
> Helping a friend with his newly purchased previously used boat.
> The electrical system contains:
>
> * 400 + Amp Hours of AGMS -
> *Trace 2.5KW Inverter with internal 125 amp charger that is
> adjusted for the
> AGMS
> *5KW Westerbeake 3cyl 1800 RPM generator - 250 hours
> *Perkins 4-108 main engine with Balmar 120 AH alternator with
> ASCII external
> regulator.
>
> Trace does a nice job of charging and keeping up with the load with
> shorepower.
>
> Westerbeake has a hard time getting the Trace to fully charge the bats
> without running for hours and hours. Think this has to do with
> the peak RMS
> power that it puts out, which is less than commercial power and some
> efficiency numbers. Too bad about this, if the Westerbeake could drive the
> Trace it would make short work of charging the batteries. * Tried
> unloading
> everything but the Trace on the generator and still no joy - Charger has a
> load of 22 amps at full tilt (at least when on shorepower)
>
> Thoughts about the following modifications?
>
> Perkins and the 125 amp Balmar do a good job of charging, but is very
> lightly loaded when using it for charging only. Thought we could refit the
> Westerbeake with a 125AH Balmar and use it when anchored out, could drive
> the alternator and give some number of 110 amps and drive the
> generator at a
> 85% load for efficiency and long life. Heat exchanger for fresh
> hot water is
> on the generator as well.
>
> Thoughts?
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