hey just wondering if anyone knows how to work out how many amp my power supply is putting out at 12v while my charger is drawing 16.8v at 7amp

i am assuming that it would be maybe 8.5-9 amp but i have no idea really

Watts are just amps times volts

16.8v times 7 amps = 118 watts

Assuming a 20% loss for charger overheads

Would require a power supply feeding in 144 watts or so

144w / 12v = 12 amps

Cheers

i have a 29 amp/350watt psu and i had 2x 4s lipos charging at 7amp and another 4s charging at 4 amp. meaning it was drawing 18 amp at 16 volt meaning it would have been about 27amp??

the assuming a 20% loss is that just a normal average on chargers

Most chargers lose around 20%

4s @ 18 amp = 302 watts

Would require a supply of 360 watts or so

360 watts @ 12v would be 30 amps

Some chargers will not get to full power output on a 12v input, they require a higher voltage (varies 15v - 28v)

What charger are you using ?

If its a decent charger it will have a screen that tells you how much power it is using at its input

Cheers

There have been few chargers tested on RC Groups and they show inefficiencies at 20-21%. The iChargers seem to do a little better than that, Junsi claims 10%, but I haven't seen that verified independently.

Documentation for the 206b suggests 10%, might try and see how high I can get it

15v / 21 amp (315w) max input with the Junsi 350 watt supply supposed to be good for 280 watts

Cheers

Testing my 3010b was one of the reasons I bought a Powerlog 6, but taxes and my now re-activated part time work and job interviews for full time work and the like keep getting in the way.....


But I will get there!