[VAC] Re: Power Inverters

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx>]

Using inverter to run a charger may work or it may not, it depends on
the inverter. A battery charger tends to be an obnoxious load that draws
current from the AC supply only on the peaks of the supply voltage,
twice each cycle. Simple square wave inverters won't give that peak
voltage that the charger needs and sinewave inverters may not handle the
load with current only at the peaks.

If your scooter batteries are wired in parallel (e.g. 12 volt motor)
then the batteries probably can be charged directly from the van
alternator though if they are gel cells they may need a bit of current
limiting so they aren't charged too rapidly.

If the scooter batteries are wired in series (e.g. 24 volt motor) then
you can disconnect them from the scooter and charge them just like the
trailer battery through the vehicle's isolator, one at a time or in
parallel. Since you need the scooter to get about this shuffling may not
be a viable option.

At best using a battery charger with an inverter is not terribly energy
efficient.

You might check with your scooter maker to see if they offer a 12 volt
input mobile charger, or if its made for wheelchair charging or by
companies like Statpower (has a web page) to charge 24 volt batteries
from a 12 volt system.

You could find yourself stranded if the inverter is connected to the
vehicle starting battery and you run that battery down. That's why
trailer batteries are isolated from the starting battery. Its no fun to
run the vehicle battery down with the trailer loads.

Gerald J.