A New Charger/Inverter for Our Elec-Trak


The built in charger that Elec-Traks come with from the factory was missing on our E15, and the external charger that came with it seemed a bit doubtful.  In addition, I wanted to have a setup that would allow me to use the Elec-Trak to battery pack to power 120VAC loads out in the field or during power outages.   So, what I really wanted was a combination charger and inverter. 

inverter charger
The new inverter/charger and its mounting shelf on the Elec-Trak.

Charger/inverters for 36 volt battery packs are not common, and I ended up buying a 3600 watt Tripplite that is larger than what I really need, but appears to do the job well and appears to be well made.  The $800 price was more than I wanted to pay, and a smaller one would have been fine, but just could not find one.  It weighs in at 57 lbs!

Back to the Elec-Trak Table of Contents...


Mounting and Wiring the Charger/Inverter

I did not want the new charger/inverter to be permanently mounted in the Elec-Trak, as is seems like it could be damaged by all the bouncing around.  But, I did want to be able to use the charger/inverter with the Elec-Track out in the field when 120 VAC is needed to run tools etc.  So, normally, the charger/inverter sits in its yellow plywood "cabinet" on the garage floor next to the Elec-Trak parking spot such that the Elec-Track can be easily plugged in and charged when parked. 

The charger/inverter in its home in the garage.

The Tripplite charger charging the Elec-Trak.
Note the 175 amp Anderson SB disconnect
that is hooked up for charging.

For times when the charger/inverter is needed with the Elec-Track to power 120 VAC loads out in the field, I built a platform off the back battery pack housing that supports the charger/inverter when its used with the Elec-Trak.

The inverter/charger in its position on the back of the Elec-Track.
It only takes a minute to mount it.

The same SB disconnect that allows the inverter charger to
charge the battery pack also connects the inverter/charger to
the battery pack to generate 120 VAC in the field.

Since the charger/inverter has to be able to be separated from the Elec-Trak, a heavy duty disconnect is needed to break the cables between the battery pack and the charger.  I used an Ancerson SB disconnect

The charger/inverter and Elec-Trak powering a circular saw.
This is a fairly big startup load, and shows no sign of any problem.

The new DC circuit breaker at the bottom protects the
charger/inverter and wiring. 
(just ignore those extra yellow and green wires -- it was
a quick workaround :)

With the charger/inverter mounted on the back of the Elec-Track, it can be used out in the field to power 120VAC tools as in the picture just above.

The Tripplite charges the 36 volt pack at up to 30 amps, so a half discharged 220 ah battery pack should charge back up in about 4 hours.  The charger does a 3 stage charge and will also do the equalization charge when requested.  It can be set up for a variety of battery types including the flooded ones I use.  The state of charge is indicated on the charger LEDs -- it would have been nice to have a meter or digital readout.

The wires connecting the charger/inverter to the battery pack are protected with a new 150 amp circuit breaker.  This rating is too low to develop the full surge capability of the Tripplite (they recommend a 300 amp for this), but its plenty for the loads I want to serve, and protecting at 150 amps keeps the wire size reasonable.

In case power power outages, the Elec-Trak and the inverter can be used to power loads in the house by using a heavy extension cord between the Elec-Trak and the house.    The plan is to use this to cover a few critical loads like the the fridge, a few lights, a small TV, laptop, ... and, maybe the furnace (but we do have another emergency source of heat).

In addition, for extended power outages, our PV array can be rewired a bit to to charge the Elec-Trak battery pack ...


PV charging elec-trak
PV charging the Elec-Trak battery pack.



December 13, 2011