[RE-wrenches] Additional Battery Charger

[Mick Abraham]

Hello, Benn~

As regards Iota: these deliver a constant voltage...in fact they strongly
resemble a DC power supply. A "45 amp" Iota type charger would deliver that
rated amperage only so long as the battery voltage is low relative to the
charger's output. In my experience these type chargers taper down on the
amps shortly after the recharge begins. That's OK if one has "always on"
utility power but not so OK if one wants big amps so the generator can be
shut off sooner.

***********************

In contrast, the Outback type charger is "constant current" until the
battery reaches approximately 80% state of charge...the point where the
bulk/absorption voltage is seen on the battery. By pulsing with voltage well
above the bulk voltage, the Outback unit strives to pump that 45 amps. When
the battery comes up to the bulk voltage level the Outback type charger
switches to "constant voltage" mode for the absorption phase.

Summary: There's a reason why the Iota type charger is less expensive per
rated amp compared to some other types.

****************************

IBE chargers are oriented to the forklift world and they go way back in off
grid energy. Others could speak better than I about their charge quality &
reliability, but I estimate both to be high. Cost is also high, however.

*******************************

If IBE level funding is seriously on the radar screen, one should compare
the cost of that against one or more additional Outback inverter/chargers.
One could ignore the inverting function and maybe still come out ahead. All
the chargers would work together as a single unit in that event because of
the network capability...and you get the time delay feature where the
chargers wait 30 seconds before they throw the load onto the generator.
Inverting redundancy, too...

The above suggestion (to use an inverter/charger just to replace a high end
charger) pencils out very well for the lower cost modified square wave
inverter/chargers from Magnum Energy, but those are 12v/24v only. 48v Magnum
units are pure sine so the cost goes back up.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675


On Thu, Jun 17, 2010 at 5:21 PM, benn kilburn <benn at daystarsolar.ca> wrote:

>  G'day Wrenches,
>
>  I'm looking for an additional charger(s) to increase the charging capacity
> from the back-up 12 kW Onan generator into the 1200 Ah battery.  Right now
> the generator's full potential output is limited by the charging capacity of
> the two VFX3648's which have a max charge output of 45A each.
>
> The idea here is to use the generator to its full charging capacity when it
> is running, taking in to consideration that the generator will feed any AC
> loads before charging the battery.
>
> Iota and IBE chargers have been suggested.  Any comments on these or other
> makes?
>
> Do all generator types (diesel, propane, LNG, gasoline) run more
> efficiently when fully loaded?  or is this only the case with diesel (so
> i've heard)?
>
> thanks,
> benn
> DayStar Renewable Energy Inc.
> benn at daystarsolar.ca
> 780-906-7807
> HAVE A SUNNY DAY
>
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