[RE-wrenches] Charging with "no contact" systems

Tue Sep 30 09:23:41 PDT 2008

Walt,
It seems to me that the most obvious solution would be to use more Outback inverters, with one or more serving solely as inverter(s) and the other(s) solely as charger(s). Then you get the benefits of sophisticated charging algorithm, isolation for power quality, compatibility on the Flexnet system, and component redundancy in case of partial failure. However, I don't know for sure that it can be set up in this way; that might take a call to Outback.
Allan

-----Original Message-----

Hello all,

We have an application in Haiti (and some African countries as well) where we have inverter /battery systems on a lousy (very lousy) grids.  The grid is good enough to charge batteries, but not sufficient for sensitive electronic loads.

Therefore, the systems we are using are three Outback FX 3648 inverters.  If they are connected with AC IN from the grid and the grid is on and is lousy (but good enough to get through the voltage and frequency limits), then this power will be passed on to the computers.  (The reality is that we have to open the voltage window too wide to let the grid in at all, and thus unacceptable to the electronics.)  So, we DO NOT connect the AC IN to the inverters.  In other words, the FX units become inverters only, and never pass AC current from the grid to the loads.  (This is what we are calling “no contact” system – similar to a double conversion UPS system.)

So – we need to add separate battery charging to the battery bank that will put in roughly equal amphours to what we feel the daily usage will be during the day.

The load is about 8000 watts, which might translate to 140 to 170 amps of discharging.  We might not have to put in the full amount of charge, since our charging can continue in the night hours when the load is not discharging, but we should probably try to charge the batteries at around 100 to 140 Amps DC (48V).

Does anyone have a recommendation as to the type of charger that might work best for this, either bulk, or smart, or a combination?  OR……other suggestions for this system that I am just missing??

We would plan to monitor this system by using the FlexNET DC system, adding a DC shunt on the negatives of the feed going from the charger TO the batteries.

Thanks,

Walt

Walt Ratterman

SunEnergy Power International

11 Laurel Lane South     Washougal, WA   98671

(360)-837-3680   ▪   fax (360)-837-1315   ▪   Skype  Walt-Mobile

 <mailto:wratterman at SunEPI.org> wratterman at SunEPI.org   ▪    <http://www.sunepi.org/> www.SunEPI.org

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