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.
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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.
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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
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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?
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it will definitely blow up
we’re using boost converters to charge through the charge port while riding.
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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.
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I did just that, plugged in a 2s lipo into my loopkey connector (with an antispark XT-90s of course) and It worked like a charm. 10s works great for me most of the time but sometimes I want a little extra power, eg. climbing steep passages. I just tested it for some minutes today, I’ll drive around more tomorrow and keep you updated Btw, it was even FOC with a FSESC 4.12 (oh my :D)
One thing: I thought it would be a good idea to put a lipo low voltage alarm with the booster pack. Strangely the alarm went off just after driving some minutes. It calmed down when I unplugged the XT-90s from my board and when I measured voltage I got 8.3V, so the question is: Why did the alarm go off?
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What voltage did you have the alarm set to?
The alarm is fixed to 3.3V according to Hobbyking https://hobbyking.com/de_de/hobbykingtmlipoly-low-voltage-alarm-2s-3s.html
I have it so I can simply unplug the booster when its too low. Later I want to add a similar thing to my liion pack.