For Sandy WB5MMB

[Michael Chisena]

Sandy,
I decided to take your challenge and see if I could work out something.
One of the nice things about CAD programs is the ability to 'cut and paste'.
Recycled a bunch of old projects into this one.
I so dislike the repetition in re inventing the wheel.

This is simply a project right now. A plaything, or toy.

It has four key features.

The first two are USB chargers that can deliver up to 3A at 5V for phones.
Those draw about 250mA on my depleted phone battery.
I use these things all over and find them to be reliable.

A DC to DC buck converter, for the moment set at 13.8V into a pair of aft mounted banana jacks. 
This converter is supposed to be good for 3A. 
I can run it in constant current mode at 1A and it runs fine. 
More than that it shuts down in over heat.
At one amp the battery draw is 731mA from the bench supply with a one amp load.

It has a little LED that shows positive contact.

No On/Off switches were used. 

Most reputable lithium packs have a supervisor circuit built in, so they can't be over charged or over dissipated. 
This Bauer pack is a good one.

On the mechanical side, it's a good fit. Nearly zero slop.
To insure solid mounting I make use of the latch system (the red /orange part) built into the Bauer Battery, so it can't slide off by accident.

Im please with it as it stands. 
Neat little project.
Going to show it to the ham radio guys here in Norfolk and see what kind of comments I get back.

The photos are a work in progress, so like anything in a development cycle, it's subject to change depending on whim and the price of grapes.

You said this in a recent post....

20v Dewalt pack to 12V at say 1-5 amps general field and power outage use. 

(I do not have any DeWalt packs at the moment. 
Made up a sample using a Bauer (Harbor Freight) 20V 1.5Ah lithium. 
There is a 5Ah Bauer battery but I can't afford one at the moment.
As we used to say, close enough for government work.)

The converter could be the same for most packs ( there are some 60-80 volt packs that might push using common electronics). 
Plastic would be different for each brand of pack. 
(I can't play that game. 
It's a money issue.
I buy PLA plastic as one kilo rolls of 1.75mm wire. 
Each color is about 22 dollars a kilo.
On the other hand a can of spray paint is about $5.00.
So for now, it's a Henry Ford paint job. 
Any color you like as long as it's black.)

I don't see it adding more than 1 inch or so to the thickness of the pack ( on the 20v Dewalt packs, the packs with a pillar that sticks up in the tool handle would be bigger).

(Good guess on the one inch. 
Actually about 29mm, most of that due to the dual bananna jack's Z.

Samudra suggested I use Anderson Power Pole connectors, that can cut this down by about two thirds.

That's the reason I used the Bauer pack. 
It's flat and similar to the DeWalt's I know. 
If there is one with a stem sticking out the top, I am not aware of it.
Give this photo article a try. It shows the assembly and some of the under resolved glitches.

Keep it warm
Mike

Try this link.
https://imgur.com/a/IXC6N9d



Michael F. Chisena KA2ZEV at Yahoo.com Notice the new phone number..... 703 344 8864
"You are, what you do, when it counts" The Masso