HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Apr 28, 2011, 11:10 AM
Registered User
Joined Sep 2008
152 Posts
Help!
Of Amps, Volts, and Watts!

I have the Protek 40 power supply which has 4 individually switched 16 amps outputs. (13.8 V, 40 amps, 520 Watts). On each of the four outputs I am plannig to hook up and charge the following batteries:

1. I am planning to use the Hyperion DUO, charging 2 6S 5 Amp LIPO batteries at 4 amps;
2. using a second charger, the Protek DUO again charging 2 6S 5amp LIPO batteres at 4 amps
3. using a single hyperion charger, again putting up one 6S 5amp LIPO at 3 amps
4. and exactly the same as (3) on the 4th output.

By my count, this should put a total load of 22 amps and slightly more than 300 watts on the power supply. Will that work or is that too much?

Any help would be greatly appreciated!
rotorblade400 is offline Find More Posts by rotorblade400
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 28, 2011, 02:33 PM
Registered User
S9coldfire's Avatar
Littleton, CO
Joined Nov 2009
411 Posts
Keep in mind that Power (Watts) = Voltage (Volts) x Current (Amps). And 6S is not the 13.8V of your power supply, but ~25V when charged. By conservation of energy, the V & A can change, but the power has to be the same in the power supply as all of the power in the chargers. So your chargers take some of the current and convert it to a higher voltage (from 13.8V to 25V).

So using your current levels it would be 22A x 25V = 550W, which is greater than the 520W your supply is rated for. You might be able to get away with 3A on each batt (18A x 25V = 450W), but that doesn't account for the power required to run the chargers and the wasted heat. You could give it a try and if you're not reading 3A on each try reducing the current a little more or just don't plug in quite so much at one time.
S9coldfire is offline Find More Posts by S9coldfire
Reply With Quote
Old Apr 28, 2011, 02:52 PM
Rocket Programmer
jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
25,386 Posts
Also, you need to use the fully charged voltages, since you're charging them all the way up. Just before finishing, before it goes into constant-voltage charging stage, the battery is almost fully-charged, and still being hit with the amperage you selected. So, the total wattage input required by your charger goes up as the battery gets closer to being done.

With a 6S pack charging at 4 amps, it's possible to need (25.2V * 4A) = 100.8 watts (+ a little bit for efficiency losses)

Then you also want to have a little breathing room in your power supply, since running it at maximum output for a long time will definitely make it get hot, and the heat can build up and increase the wear rate, eventually causing a failure. The Hyperion chargers will shut down and beep at you, if the power supply starts to fail. So, you can run it up to the limit, wait for one of the chargers to fail, then back off the amperage.
jasmine2501 is offline Find More Posts by jasmine2501
Reply With Quote
Old Apr 28, 2011, 06:51 PM
Registered User
Joined Sep 2008
152 Posts
of volts, amps and watts

Thanks to both of your comments S9coldfire - and to Jasmine, as always, very useful. Of course, the batteries go beyond 22.2 when full - that simply didn't cross my mind.

Thanks again!!
rotorblade400 is offline Find More Posts by rotorblade400
Reply With Quote
Old Apr 28, 2011, 06:56 PM
Rocket Programmer
jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
25,386 Posts
S9 mentioned it, but I missed it when reading because he put your 22 amps right next to the 25 volts, and I reversed it in my head. So I wanted to be sure to mention it. Since you already own your chargers it isn't a big deal, but it's something people often miss when they are choosing a new charger.
jasmine2501 is offline Find More Posts by jasmine2501
Reply With Quote
Old Apr 28, 2011, 09:15 PM
that's gonna leave a scar
KCinNC's Avatar
United States, NC, Mooresville
Joined Aug 2007
3,454 Posts
wooh...if charging lipos were easy.....it wouldn't be any fun
KCinNC is offline Find More Posts by KCinNC
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Yippee! Dual-Range Power Analyzer – Accurately measures Volts, Amps, Watts, Amp-Hrs, Watt-Hrs MRI Medusa Research 123 Mar 23, 2005 04:10 PM
Volts, Amps, Watts ... HELP! :-) wollins Electric Plane Talk 3 Sep 02, 2004 04:23 PM
Dual-Range Power Analyzer – Accurately measures Volts, Amps, Watts, Amp-Hrs, Watt-Hrs MRI Product Announcements 4 Aug 07, 2004 01:46 PM
Question Watts Volts Amps ? BRIANRC Batteries and Chargers 18 Mar 29, 2004 05:45 AM
Motor heat: amps, volts or watts? meteor Power Systems 46 Jan 16, 2004 02:19 PM