I recently blew one of my three remaining HobbyKing sourced 4S 4.2AH LifePo4 batteries by leaving it plugged into my IC-705. I can’t risk blowing another one.
So the plan was to try creating a 4 cell 18650 battery with BMS, but the cases seem to have really thin wire attached. Is there a better way, other than welding cells together?
I’d be grateful for any recommendations, for battery cases and BMS?
The alternative would be a to buy a battery from Component Shop and add a BMS?
Thanks, Mark.
Nice big chunky cell connectors.
Go for the ones with tabs then?
I use this kind of cell holder for 18650 LiPo cells (ex-laptop), 21700 LiPo cells and 26650 LiFePO cells. They make excellent contact with the cells and can carry sufficient current. Not my experience from using the springy wire contacts in NiMH/NiCd holders in years past.
I use those battery holders for some other projects (not amateur radio related) but be very careful. Those spring contacts can slowly abrade the insulating wrap around the battery terminals with repeated insert/removal of the cells, and the battery can get shorted around the + terminal. When that happens, the battery terminal can be “welded” by its own spark (not easy to remove the cell!), and it gets overheated. That actually happened to me once, so I analyzed it, and prevented further occurrence of the same problem, but that limits the way that battery box can be used.
I also use quite a few 26650 cells as well. Before using a new battery box, I always observe the contact structures and minimize the abrasion from repeated insert/removal.
This!
Jaycar sell these in ZL / VK and I have provided this feedbck to them. Not good when it happens.
I’ve not noticed it with mine but the cells tend to stay in for a long time. I have a piece of ribbon that goes under the cells, pull the ribbon and it lifts the cells out.
I have bought new skins for 18650 cells when I recovered them from laptop supplies so they look nice should airport security want to view them and not like a load of scabby old things. That’s when I found you can buy skins and the positive end insulating washers. So I think adding some more washers over the skin will act as a sacrificial covering.
The washers are fine. It’s that the battery box’s contact is large and tall so it can easily bridge the + and the shell (-) once the protective wrap is abraded enough. I had a ribbon below the battery and always careful to remove/insert the cells, but it still happened.
Put second washer over the cover on the +ve and -ve ends.
If you can secure it (glue and tape?) that may help. However, the point is that, that battery box requires caution each time handling the cells to prevent accidents. It is not the same level of carefree operation as typical AA battery boxes.
Maybe read the item description where it says “adhesive” ? 
I think you are underestimating the force from that spring contact.
I use 3 18650 cells in that type of cell holder in Andy’s link. I wired them to a Deans connector plus a JST balance connector for the charger. The cells live in the holder so there is no problem with the insulating wrap wearing. I don’t use a BMS. I never leave the battery plugged in to anything.
I use a pack of 3 lion 18650 batteries in parallel. I put them in a two-unit holder and use a 10-amp or 20-amp BMS.
https://www.amazon.es › soporte-bateria-18650-Electrónica › s?k=soporte+bateria+18650&rh=n:599370031
I used two of those cell holders Andy referred to above. I then built a 4S2P pack in the back of my IC-705 Go Box. Cells are wired in parallel two by two, and all cells connect to a 5 pin DIN connector on the back. The pack also has an 8A polyfuse on the output to the PowerPole lead.
For charging I use this small balanced charger, with an adapter plug. No need to remove cells (but I can easily access them if needed, the battery cover is fixed with velcro strips).
The only thing is that I must remember never to plug in some old audio stuff with DIN connectors into my go box (or it may become a “boom! box”), but luckily I have no such equipment any more
73,
Luc ON7DQ
Nice solution Luc, thanks for sharing.
