White's TDI SL 4x18650 Battery Tray Made Simple

[Jim in Idaho]

It depends on the number of cells. 14.4 volts is the nominal voltage for a 4-cell pack. max voltage for that pack is 16.8. The nominal voltage for a 3-cell pack is 11.1. Max voltage for that pack is 12.6. Using a charger for a 4-cell pack to charge a 3-cell pack is NOT a good idea.

Jim

[Cascade Steven]

Jim:  I want to be certain that I am on the same page with you.  I should have stated my assumption that I would use four of the cells that could be charged to a total of 16.8 volts.  Based on your comment, I assume that I could use this charger successfully if I charged four of the cells and acknowledging that I should NOT charge only three of the cells with this charger.  Am I correct?  Thanks for your reply.

[Jim in Idaho]

That's correct. Another part of this story is that your battery pack will last longer (more charge/discharge cycles) if you don't charge to the max voltage. I use a buck converter to charge my packs. That converter allows me to set the max voltage I charge to. That adjustability also allows me to use the charger to charge both 3-cell and 4-cell packs. In the case of my TDI SL, I like to limit the charge to 16.0 volts. That both protects the detector, and increases the pack life. I get about 4 hours of use, but with both packs I'm good for an entire day.

Jim

[Cascade Steven]

Jim:  Thanks for the info.

[karelian]

Nuggets the flat top batteries work fine, when packed in tight they make a decent connection. Make sure the brass is punched for peace of mind. Protected cells are longer and require slight mods on this design, but can be made to fit.

Simple design but can be a bit messy and requires the sacrifice of a tray. Well worth the effort, keep it at or under 16 volts for the perfect balance of performance and safety. A friends machines makes a humming noise when over 16 volts, no issues when under 16 volts.... something to consider. All the best for 2021.