I am sold now. Picked up the boost converter, a range of high voltage fuses with various amp ratings and fuse holders…
Hesitant to order batteries from China, I checked out Lowe’s. I didn’t expect to find much in terms of price competitiveness, but the portable power tool batteries are actually priced equal to or better than the Chinese batteries per watt hour!
Two of these batteries comes out to 192 watt hours. Add in the quick charger and the price comes out to be cheaper than a “LG/Samsung” 6S4P 211 watt hour battery without charger from China. Not only is it cheaper, I can design it to be 100% modular with 3D printed mounts / boost converter enclosure that all just snaps onto the board… plug and play additional batteries as needed, carry extras in the backpack to hotswap on the road. Sounds so nice! Plus no shipping cost to save $35, and get them today 
I see a fun project on the horizon.
4 Likes
I don’t know if it’s something I did wrong, or if the converter I got was faulty… But it died on me after an hour of charging- screen flickering, power output ceased, unit got very hot, fan turned on and turned off… Now it’s dead. My excitement is dampened. This is the one I got. It was great, charged really fast at 5A when it was working… Got my board from 30 to 60% in relatively little time compared to my standard 2A brick charger.
I’m swapping it for a new one now… Hopefully this one doesn’t just die on me… With the slightly reduced range on my pneumatics, I really could use the extra range now. I’m still trying to think of a clever way to mount the unit and battery holder to my board, rather than just clipping it to the top… But I’ll probably just keep it clipped to the top. Maybe I’ll go for a rear mount to keep it out of the way. Having clip on extra range will be great, I’ll keep dreaming for now until one of these boost converters actually works.
I can vouch for this charger, I use it to charge my 12s build at about 3-5 amps with an input of 24v.
This is making me want to buy a 6s lipo
2 Likes
Okay, burnt out my second boost converter. I think third time will be the key. Made an anti spark switch, no more Sparks… Gonna draw up and print an enclosure for this new boost converter. This thing looks well soldered, and is quite hefty. Thanks for the suggestion @pat.speed. also picked up a watt meter per pats suggestion.
Edit 1:
Wired up to test and working mmmmmm!!! Voltages and amp outputs of the meter are accurate enough 
Edit 2: After some testing, first 4AH battery charged my 10AH battery by about 30%. If second battery charges to 70% before empty… The math in my head says this boost process is about 70% efficient… And I am totally good with that … it will get me back uphill and home from work with greater than 1% battery to spare,which is all I need. I am a happy camper at the moment, none of the wires are overheating and everything seems to work well now.
If anyone in the US is curious, these are the two things I ordered for this from Amazon:. Boost converter… and this fairly accurate enough watt meter.
Now to draw up the final enclosure and dye everything black.
8 Likes
Got it all hooked up and working! Now I just gotta cable manage a bit…
Okay, here’s a photo vlog:
I’ll probably update when I get the cable management down.
7 Likes
nice one! How did you mount the boost converter with the heat sink poking out?
I have mine on the bench testing at the moment, same parts but with a lipo. so far its good
The heatsink mounts to the boost converter on the four corners of the PCB, with four 6mm tall spacers between the heatsink and PCB. I thought this would be a great place to mount everything, in place of those spacers to print a Nylon shell for the PCB, with a cutout in the bottom of the shell for the PCB to make contact with the heatsink, and just let the heatsink hang loose out the bottom (I’ve since secured it to the deck as an additional point of strength for mounting the entire assembly.
Anyways… Here are some pics of the cable management. I ended up running the charge cable under the lips of my enclosure… And the charge port when not in use just wedges securely under the battery enclosure lip… Totally didn’t plan on doing it this way (I had no plans, just winging it).
And a little video of hooking it up as if I were on the road… Such a satisfying click.
https://youtu.be/BmLwvZJj7ac
2 Likes
Got to try this out today. Two batteries, each drained half way… After 4.5 miles only dropped from ~39v to ~38v with 4P 25r charging at around 3.5-4A… the board meter reading somewhere around 80-85%, down to 75% when I got home. This was all while riding my higher power mode pushing 80A battery max with sligly reduced 16A battery min to compensate for the additional continuous charging.
I also notice a volt or two less voltage drop in the higher power modes, and it just feels noticably snappier for the voltage I was riding at.
I thought I would attach the batteries when I needed the extra range, I think I’ll probably just ride with the batteries all the time now.
I need to make a few changes: E6000 to protect the electronics from bumps and vibration, hot glue to better secure the ingoing and outgoing wires to the boost module and for better water sealing around the edges of the boost module enclosure. Also, I need to solder on an extension to the negative output wire from the boost module- it’s just a tad too short for comfort at the moment.
Sorry for bothering you. I just joined this group. How can i post? It does not seem to have any link for post new topic…
Huh, for me there is a new topic button on the main forum page.
Maybe for new users there is a limitation until you have so many posts or something.
Yeah you need to have a certain amount of time on the forum I’m pretty sure, let’s delete these posts after a day as to not clutter this awesome thread
Cool! Does this just plugin directly to your charging port?
So 6s is the minimum battery config to use for this, is there any advantage in using a higher config say, 10s?
And how efficient is it when used while riding? If you have 10% battery left and you plug it in, will it be able to charge it fast enough for the battery not to get empty while you continue to ride?
The problem with 10S is that you would need a DC-DC converter that can step-up and step-down, they exist, but are harder to find
To make simple and only use a step-up the minimum skate battery voltage should be higher than the maximum battery booster voltage with some margin between the two
10S fully discharged = 28~30V
6S fully charged = 25.2V
7S fully charged = 29.4
wouldn’t plugging into the loop key blow something up? the loop key completes the circuit on one rail whether it be positive or negative. if you added another battery it’d essentially need another antispark. wouldn’t it?
1 Like
it will definitely blow up 
we’re using boost converters to charge through the charge port while riding.
3 Likes
If you plug in a 2s battery with the same spec and state of charge as your 10s to expand your pack from 10s to 12s with an antispark connector and changing your vesc settings to suit the new 12s configuration then no problem. (The long battery leads may make for their own problems with regards to blowing up your vesc).
The much more elegant solution as far as I understand it is with the boost converter and charge port. This is the method I’m going for.
2 Likes
yep just got mine