Thread indicating wattage of charger needed for batteries

[RicoBanderez]

Hi all, I'm sure I saw a sticky thread recently going into detail about the wattage a charger needed to be per type of battery?
Can anyway help me find it …

 

[WoodiE]

@RicoBanderez are you referring to this article, How to choose an RC LiPo charger

 

[Jerry-Rigged]

My rule of thumb for most surface RC- buy 25w of power per cell you want to charge at the same time.

So one 2s, 50w.
One 4s, 100w
Two 3s, 150w
Two 6s, 300w
Four 2s, 200w

Etc...

This is based on 5000mah cells, if you use larger or smaller cells, you may need to adjust a bit.

 

[olds97_lss]

Watts = V*A

I made a spreadsheet to make it easy/quick to see what it takes for various packs. I have columns for 1C/2C/3C.

One thing I'm not 100% sure on is the V you should use. As the pack charges, the voltage rises and all my chargers drop current considerably towards the end as I'm assuming it's trying to avoid overcharging. So, on my sheet, I have columns for the math at 3.7V and 4.2V. I should check my chargers to see when they drop down current as I think it's higher than 3.7V, closer to 4V. I also added columns to see the current limit for 100W/150W/200W as that's where my chargers max out. One charger is 10A/100W x 4, the other is 12A/150W x 2and the third is 20A/200W x 2.

The rows in blue are packs I have.

 

[Jerry-Rigged]

One thing I would suggest adding to your chart is a safety factor. Our hobby grade equipment is rated for intermittent loads, at room temp (75f). Use it in your garage on a summer day (cuz every says dont charge lipos indoors, right?) Or at the track, and it can't put out full rated wattage.

I use 25% as a safety factor.

 

[olds97_lss]

For my needs, it was just to see the bare minimum I could charge safely in my house. I don't run my 20A x 2/200W x 2 at it's max, but I do run my 100x4/10x4 and 12x2/150x2 at their max usually.