Determining needed power supply amps/wattage

[Egnix]

I'm considering purchasing an EOS0610i DUO II charger and I'm trying to determine how big of a power supply I need.

The most load I intend to put on the charger is 2 2s 8000mah LiPos. Does charging 2 packs at 8 amps each (at the same time) mean that I need a power supply of that provided at least 16 amps? Or do I really need to look at wattage instead?

If wattage was the important factor, I'd be looking at 118.4 watts (if a 7.4V pack is charged at 7.4V, that would be a combined (2 packs at 8 amps each) wattage of 118.4 watts). In this case, do I not care about the output amperage (as long as the output volts x output amps > 118.4)?

Thanks!

Disclaimers: 1. Yes, I searched before posting. 2.. I don't know the true charging voltage. I guessed the 7.4. Feel free to say what the true (max) charging voltage is. 3. I know to include some headroom. I'm just trying to learn the basic math. 4. I'm not interested in using PC power supply. 5. No, I'm not planning on putting 2 2s LiPos in a crawler.

[2JSC]

Contact Maxamps.com or CheaperBatteryPacks.com - either will have great advise!

Or HolmesHobbies.com - Great advise as well.

[ohmyCLOD!]

Originally Posted by Egnix

I'm considering purchasing an EOS0610i DUO II charger and I'm trying to determine how big of a power supply I need.

The most load I intend to put on the charger is 2 2s 8000mah LiPos. Does charging 2 packs at 8 amps each (at the same time) mean that I need a power supply of that provided at least 16 amps? Or do I really need to look at wattage instead?

If wattage was the important factor, I'd be looking at 118.4 watts (if a 7.4V pack is charged at 7.4V, that would be a combined (2 packs at 8 amps each) wattage of 118.4 watts). In this case, do I not care about the output amperage (as long as the output volts x output amps > 118.4)?

Thanks!

Disclaimers: 1. Yes, I searched before posting. 2.. I don't know the true charging voltage. I guessed the 7.4. Feel free to say what the true (max) charging voltage is. 3. I know to include some headroom. I'm just trying to learn the basic math. 4. I'm not interested in using PC power supply. 5. No, I'm not planning on putting 2 2s LiPos in a crawler.

Focus on the amount of current needed by the charger. If you are going to charge 2 batteries at 8A, you need a power supply that can handle the current load required by the charger.

[rdtshaw]

Your assumption is correct. Bassically the 16amps, but the charger will also consume ~1 amp while charging as well. I would shoot for a 20-25A power supply. The closer you push a power supply to it's rating, the more punishment you're giving it. A little head room is a good thing, as the charger may surge a little when starting a charge cycle.

Cheers,

Rob