View Full Version : How do LiPo chargers detect the pack capacity?
cholyoake
03-27-2007, 12:53 PM
how does a charger (like the cellpro 4s) detect the pack capacity so it knows how many amps it should charge at?
does it charge it at a certain amps and see how much the voltage rises in a certain time to figure it out or something completely diffrent? also, how reliable is it? i can set my cellpro to charge at 1C, but can i be sure it is actually charging at 1C and not above? or would it just be safest to set the charge at 2 amps (its a 2100 mah capacity pack) so i know it wont charge too fast?
Finless
03-27-2007, 07:23 PM
It does know the pack size.. It only knows how many cells the pack is. You have to set the charge current acordingly!!!!
For instance if it is a 2200ma pack then to charge at 1C you would set the charger to 2.2 amps or 2200ma.
Bob
how does a charger (like the cellpro 4s) detect the pack capacity so it knows how many amps it should charge at?
does it charge it at a certain amps and see how much the voltage rises in a certain time to figure it out or something completely diffrent?
That sounds right. I was thinking it did something like that since it wouldnt' tell you current pack fuel level until a certain amount of time went by. Since you are in a mode to charge Lipos, it must figure how the lipo should react after the Cell Pro puts in a couple mah at a testing current.
You have to set the charge current acordingly!!!!
For instance if it is a 2200ma pack then to charge at 1C you would set the charger to 2.2 amps or 2200ma.
Not with the Cell Pro. It can figure out your pack size and charge current. It is all automatic if you select 1C as the charge mode. It does my 800mah CX2 batts and my 2100mah Trex batts at the right rates without me doing anything. It does have a mode to select amperage manually in .25amp steps up to 3.00amps. But I just use the auto function. The Cell Pro is pretty newbie proof.
peterob
03-28-2007, 05:46 AM
You can see which rate it's charging at if you press the button. The current on the display matches pretty well with the current my power supply shows.
I use auto mode (1C) too and it hasn't been wrong so far.
vapochilled
03-28-2007, 06:01 AM
exactly, it watches the voltage while pumping at a known A, and calculates from that. Mine has not got it wrong on various packs yet, seems pretty reliable
Finless
03-28-2007, 01:04 PM
exactly, it watches the voltage while pumping at a known A, and calculates from that. Mine has not got it wrong on various packs yet, seems pretty reliable
That makes sense but I can see how it could make a mistake doing it this way. I bet it errors on the low side for safety. Personally I would not trust that myself and just set the amperage manually. Plus some of the newer packs can be charged at 1.5 or even 2 C.
Bob
vapochilled
03-28-2007, 07:39 PM
exactly, it watches the voltage while pumping at a known A, and calculates from that. Mine has not got it wrong on various packs yet, seems pretty reliable
That makes sense but I can see how it could make a mistake doing it this way. I bet it errors on the low side for safety. Personally I would not trust that myself and just set the amperage manually. Plus some of the newer packs can be charged at 1.5 or even 2 C.
Bob
Indeed, cellpro even give the option of charging at 1.4C as they are so confident in the safety of the charger.