Re: Ubitx batteries / charger #ubitx

Arv Evans


There seems to be a potential for problems, unless I have misread what you are planning
to do.  If using only a single Li-Po or Li-Ion cell (3.8 to 4.2 volts) you can charge them with
relatively simple chargers but there must be voltage limiting in the charge scheme to insure
that the voltage never exceeds the manufacturer rated voltage (usually 4.0 volts). 

If using multiple 18650 Li-Ion or Li-Po cells you have to manage the voltage on each individual 
cell during charge to insure that no cell exceeds the rated voltage.   While I abhor the "it won't
work" and the "it will explode" scare tactics, this is one place where the nay-sayers may be
justified.  Over-voltage charging of Lithium based cells has been documented as a cause of
overheating and possibly fire. 

The small brick style cell phone auxiliary power banks usually include built-in charge control
circuitry that protects the Lithium cells from abuse.  This makes them relatively safe for most

Most Li-Ion and Li-Po 18650 type cells include built-in FET switching that prevents discharge
to less than 2.0 volts.  If you do manage to discharge your Lithium based cells all the way to
zero they may refuse to accept re-charging current and thus become unusable. 

There are charge management boards available from several vendors.  These are needed
if you want to make up your own Lithium based battery packs that use multiple cells in series.

Maybe this helps...?


On Fri, Apr 19, 2019 at 12:49 PM George Blass via Groups.Io <> wrote:
Hi All

I’m designing my case and have a question. I plan on using 18650 batteries inside the case with this voltage regulator. 

Voltage regulator

Then for charging I’ll have one of these inside the case. 


My plan is to have everything inside the case with just the charging and USB ports exposed. This way to charge up the batteries you would just plug it in like a cell phone. 

Will this work?  Am I missing something?


Join to automatically receive all group messages.