Portable chargers are quite handle I believe. Once went on a Sacramento group ride & someone there had one charging his board while we was at a rest stop. I think he used 2 hover board batteries & some other stuff was include. Anyways I’m very interested in this topic, hopefully I learn something from it
So if this works, smaller high discharge batteries just got a whole lot sexier. Like what if lifepo4 cells were used? Those tanks can take a serious beating. Problem being capacity, this could make them super relevant!!!
Not even trying to hide the fact I just got super hard.
I’ve got some downtime waiting at the vet so I’ll expand a bit on my setup.
I’m repurposing an MPPT solar charge controller, it’s intended to take a PV array (solar panel) as input and it’s output is essentially a programmable CV/CV Li-ion charger.
I’m simply using another battery pack in place of the solar panel and using it as a DC to DC charger.
The particular ‘mppt’ model I’m using is step up only, not true MPPT, so you need a 10S to charge 10S-13S, etc, it won’t step down to charge a lower battery voltage. But it’s cheap, compact, and it works.
Wiring setup is simple:
10S5P Backpack Battery (w/ it’s own BMS and charge input) >> MPPT >> Charge cable to board.
This is my “Do Not Try This At Home” picture of my hastily thrown together test setup. I’m currently rebuilding it all with a 10S5P and enclosure.
I think you are on the right track. Steer clear of boost converter option 3. Mine worked for an hour and crapped out under 5A 42v. Option 1 may be your best bet. Keep in mind the amp output will be less than your input. It’s nice to have a voltage display that beeps at a set low voltage so you know when it’s time to disconnect.
And potting. Pot all your components with silicone or E6000. All those coils, capacitors, mosfets, make sure they are surrounded all around and at least some under what you can… Don’t miss one mosfet- especially if mounting all this to your board.
Your boost converter heatsink will need airflow, I wouldn’t enclose it- at least mount it with the heatsink outside something.
In the end, charging while riding is a dream. On my setup I feel like I cant go long before I’m hitting 50-60% charge. But, with 6S power tool batteries I can keep swapping and keep riding all day. At group rides I’ll end the days somewhere between 90-98% depending on how hard and fast we are going with just a few extra packs in my bag. Have fun, enjoy, good luck!
Just got back from a 22 mile test ride over 90 minutes. Based on the charger counter it added about 300Wh to my ride and I still had plenty of board juice left when I came back.
I have not caught fire yet.
@deckoz how retarded am I for trying this out without having a schematic for the MPPT or BMS? Hah
The TL;DR is I’m using a cheap MPPT solar charge controller + a battery in my backpack as a DC to DC CC/CV charger for a really lazy and simple mobile charger. So far it seems to work fine to charge-n-ride.
So that PV charge controller is feeding the battery directly? Or do you have a bms in there?
(like a D140) I’m guessing that you do have a BMS in there, so you have your range extended connected just like you would if you were using a regular charger to charge it?