Originally Posted by
ignishen
Looking at picking up a 2 channel lipo charger, and am wondering how to calculate approximate charging times on a dead battery. Looking to reduce downtime during practice sessions at the track.
I have a few Lectron 2S 4600mAh 100C (5C charge rate) batteries. What would the effective time difference using either the Hitec X2 AC Plus Dual Port AC/DC Multi-Charger (6S/6A/100W) or the ProTek RC Prodigy 625 DUO Touch AC?
In general, charging at 1C = 1hour charge, and 2C=1/2 hour (double amperage)....4C=15min (4x amperage)
You probably already know, but 1C is charging where charging amps = battery amp hours. Your 4600mAh pack = 4.6Ah (amp hours), so if you charge at 4.5A, it will take ~1 hour to charge.
Pay attention to the rated wattage of the charger. This will tell you more about the charger than just the amps. We know that volts*amps=watts. In order for a charger to charge a 4S pack at 20 amps, it needs to have ~300watt capacity. A 200w charger claiming 20A charge rate can charge a 2S pack at 20A, but higher volt packs will charge at lower amps. Charging a 2S pack at 20A requires only 168watts (8.4v*20A=168watts), but the same charger can only charge a 4S pack at 12amps. And a 6S pack will be even less.
Also, pay attention to the fine print. Some AC/DC chargers claim 500watts per channel, but only when running off of a separate DC power source. The output on AC power is lower.
Of your options, I would go with the prodigy 625. It has 200watts, so will speed up charging.
As an alternative I would also recommend this charger:
Thunder 0620AC 300Watt 20Amp Dual Charger w/ Built-n AC Power Supply
I have used it for a few years, and one of it's main benefits is the 300w output. Granted it is a single output, but you can always use a parallel board to charge multiple batteries. The advantage of a single output charger is that 100% of the power goes into a single battery, meaning faster max charging. And it can charge multiple packs at the same time with the use of a parallel board.
(Parallel charging requires all packs have equivalent capacity and to be equally discharged. Running packs 'till LVC leaves them at an equal discharge. If different charge state or different capacity packs are charged together, charging just takes a lot longer...because when one pack is full, the charger must resort to balancing current to continue charging the other packs. So worst case if you parallel charge with mis-matched batteries is that a charge takes a long time. I've done parallel charging for years, and never had a problem.)