Yeah I know the one you refer to, I was struggling to keep it down while adding solder and reaching for the clamp to hold it down. Do you think I need to redo it?
Does anyone have a recommendation for a 90V to 12V DC-DC buck converter? Looking for something that can do at least 10A. Ive been looking at options on Amazon, but if anyone has something they have tried and would recommend, Iâm all ears 
Wouldnât hurt. If you have a set of tweezers you can hold the wire with that in one hand and the soldering iron in the other, you should be able to hold it down the entire time.
1 Like
Thatâs a crazy voltage range, whatâs it for? I have a nice DROK one but itâs for my workbench and I think the top voltage is like 75
2 Likes
20S ebike battery, powering a 12v light bar
3 Likes
Itâs a bit tricky to do at first for sure. For me, itâs all about the prep. I just use a short, flat head screwdriver to hold the wire down as I find that easier than tweezers or needle nose. I have it adjacent to my work space and easily accessible to my left hand which is the same hand I feed solder with. Once thereâs enough solder and as Iâm waiting for it to go to a completely liquid state, I put down the solder and grab my screwdriver. Hold down the wire and carefully remove my iron so as not to jostle the pool of solder.
Edit: reflowing is easy. I regularly go back and inspect my joints before I kapton everything a reflow anything that looks a bit cold. Just tin your tip, add a bit more solder to the joint and as above, wait until your pool is completely liquid. Carefully remove your iron and voila.
2 Likes
I find using multiple small vs one big much more friendly, it increases my confidence starting out and this always results in better results 
3 Likes
Digikey or mouser are good places to look, you wonât find anything with personal recommendations there but you might find something commercial or industrial grade if you need it to be bulletproof.
2 Likes
You could also check 120VAC-input converters that can accept a low voltage of 90V. The DC should pass through the front end of the converter and after that be handled the same as a rectified/filtered AC voltage input.
For 10A I recommend at least 150W rating unless the converter can be exposed to moving outside air. Check the datasheet for the derating needed in high ambient temps.
ArrgghhhâŚâŚdammitâŚforgot that the pack could drop to 60V or even lowerâŚnvm. 
2 Likes
The one on my bike is only 40W (3.33 amps at 12v), but itâs This one.
The price has gone up very significantly due to the chip shortage unfortunately.
There are other good ones on Digikey and Mouser that do have a higher power rating, like this one or this one.
Unfortunately, youâre going to be paying >$1/watt for most of them, especially right now.
1 Like
For that much you could just build a 12v pack.
2 Likes
How does one go about removing a bad cell from the nickel a p group?
I would say, very carefully, with a dremel cutoff wheel.
2 Likes
True. There are definitely advantages of going either way.
1 Like
- Uninstall the p-group from the pack
- Disassemble the whole p-group
- Remove the nickel from all the cells in the group
- Carefully clean the nickel crumbs off the contacts of each cell
- Replace the bad cell
- Re-weld the whole group
- Re-install the group into the pack
10 Likes
I could physically feel you holding my hand 
9 Likes
This was recommended at some point
Edit: Ah, not 10A sorry
2 Likes
Very safe handling I know.
Tapped the +/- afterward but for now gonna use a military ammo box and cover it in cat litter until we can dispose of it safely. Idk if cat litter is the best but itâs what we had had sand but someone used it 
. Funny to think this litteral bomb was an inch away from his head.
4 Likes
If you give it a firm tap with a hammer I bet youâll get quite the show
6 Likes