Battery Switch

After much research, I finally found the right switch.

When the switch is turned to "1", the internal battery will be connected to the booster, bumping the ~12V up to about ~14V, triggering the PWRgate charger to charge an external battery. This "mobile mode" works great if you are out in the field with the pack and want to charge up a smaller pack, but you're away from an external AC / DC charging source.

When the switch is flipped to "2", the charger will charge the internal battery -- and / or an external battery. I call this "normal mode", because this will be its setting 90%+ of the time when the pack is being used.

When the switch is at the "OFF" position, the internal battery will be completely bypassed / disconnected and the pack will take an AC / DC source from one end of the pack, make sure its voltage is high enough to provide a charge, and charge an external battery. It will be also be switched off when the pack is not used -- such as when it's in transit or storage. In order to allow the pack to be completely disabled, I've also added a booster switch and thermal circuit breaker that you can lock away from prying fingers.

front view

Here you can see the entire pack. It will be complete when I install a couple more DC bulkheads, attach the front plate and pop out the meters, switches and thermal circuit breaker.

I found the inflatable orange tires at Harbor Freight for $8, put a couple bushings together to adapt the axle down to 5/16th, and installed some custom struts that have no problem supporting the entire considerable weight of the pack. See below.

lid #1

From left to right...

TOP: ATC fuse holder, PowerPost, shuntless ammeter (plus switch and open loop current sensor), battery switch, volt meter, (plus switch), DualBus busbar, DC out bulkhead.

BOTTOM: AC in bulkhead, N8XJK Marine Booster (plus switch), circuit breaker, PWRgate battery charger, PowerPost, ATC fuse holder.

lid #2

lid #3

volt meter & DualBus

The LED display was washed out by the camera flash and is much brighter than it appears here.

I cut the busbar's cover and drilled two holes in the top that feed though the existing mounting holes on the DualBus.

ammeter & PowerPost

Again, the LED display is much brighter in real life. As you can see, the ammeter uses the common negative on the PowerPost (left). Its positive cable routes through the switch (bottom center), which allows the meter to get power from incoming, outgoing, internal or external sources. The center switch position turns off the meter, but does not affect the flow of current through the system.

I chose this ammeter because of its compact size and open loop current sensor (bottom right). Unlike a traditional shunt, exceeding its current capacity will not burn up the meter, etc.. It's rated for 75A, which is far more than the 25A max that the booster can pass through it.

volts in

Sorry for the dark picture, but I wanted you to get a better look at the LEDs. This was taken while the AC cable was connected; the volt meter shows the DC out voltage from the power supply measured from the left PowerPost (upper right), before it gets sent through and bumped up by the DC booster and charger.

volts out

This shows the slight increase in voltage after passing through the AC to DC power supply, DC booster and charger. All 3 have the ability to independently regulate their voltages.

side view - AC in

AC in #1

AC in #2

Here's a pic of the custom AC connector cable.

AC to DC PS

The Samlex power supply barely squeezed in beside the batteries. I attached the Samlex to the side of the case using industrial velcro -- not that it needs it. The ATC fuse holder was probably unnecessary as well, since the DC booster already has one on its input.

I replaced the rubber bumpers on the bottom of the power supply with slick furniture sliders that will make removing the batteries a little easier.

side view - DC out

DC out #1

DC out #2

back view

struts

Here's a close up view of one of the 1440's 8" pneumatic wheels and the custom struts I made. They consist of a couple heavy duty fender washers that I cut in half and drilled two holes into. I replaced the bolt on the bottom that used to hold the standard tires with a threaded one, and attached the modified washers from it to the new tire bolt on the top.

As a test, the other day I stood on the pack with the heavy batteries, etc. inside. Even enduring a combined weight of about 400lbs (cringe), the wheels did not bow in at all. That's ROCK SOLID engineering. I'm very proud of it.

ski

Here's a pic of the 1440's "ski". Simple, but very functional. I made it stick out slightly farther than the wheels so it's very hard to tip over, and to compensate for sinking a little in grass, etc.. If you lean the pack over the right way, you can use it as a very expensive hoe. ;-)

If you think the ski might make it wobbly, the case originally sat on only 4 little plastic rings with very little total surface area. Now, the case sits on about 3" x 2 of wheel surface, plus another 13" x 2.5" of ski. It's much more stable than it was.