Tuesday, June 14, 2011

Baofeng UV-3R: Charging

If you open up the the supplied charging base, you will find that there is no circuity between the input and the battery. This has lead to much speculation about the wisdom of using the base to charge a battery outside the radio.

Grant, ZL2BK posted the following which appeared to be a definitive answer.
I did a bit of research [on]the battery and it is also used in a number of different products such as cell phones. It appears to have some protection in the battery to prevent overcharging as is common with these batteries (or single cell in this case).

I put my partially discharged battery on the charger and the charge current was 1.1 amp. The voltage across the terminals was 4.25 volts. I checked the current occasionally and it remained close to 1 amp until the voltage rose to almost 4.3 volts at which point it dropped to zero.
As there are only two terminals on the battery, there is no way of controlling an external charger so there has to be some electronics in the battery for safety and this quick test shows that.

I used the supplied wall supply for this quick check. The voltage on no load was 5.09 volts.
I was happy with that bit of detective work until Tom PA2TSL had to muddy the waters again.
I wonder why a charge circuit (with the LTC-4054-L IC) is present in the UV-3R
when it is already build inside the battery.

I can ony imagine an additional protection when a non-standard power supply is used to charge the battery when it is in the UV-3R.

Anyway, it is nice to have a spare battery available that can be charged outside the UV-3R.
I was about to build the same charge circuit in the cradle, but that makes no sense when it is already inside the battery.
Tom PA2TSL later adds:
It should be quite easy to reproduce the charge circuit and put it into the

A few additional components are required when using the LTC-4054L that is used
in the UV-3R.

You can add a LED for the charge status (just connect it between the appropriate
pin of the IC and the supply voltage with a small resistor).

I guess I will assume that the battery is smart enough to prevent over charging (and fires!), but it would make me wary of buying a knock-off battery that might not have the built in brains.


  1. If base has no circuitry, since battery is lithium, use instead a good lithium charger for RC models (can be programmed between LiPo or LiIon). This microprocessor driven chargers are the best solution to charge cells at the best capabilities and they prevent lot of accidents. You can also read how much milliamps battery absorbed during charge

  2. If there is no charging circuit in the cradle, then one can add such a circuit.
    There are both 0.5 & 1A versions, and the output can also be modified by changing the sens resistor