power supply volt/amps help
 

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!