Electrickery question

[Cagey]

Slightly baffled by the Fusion charger blurb stating it to be 120 W d/c power, but only 90W a/c. Not being too lecky versed I wonder how this comes about. Anyone ?

[waveydavey]

Have a look here, a great site.

https://sites.google.com/site/tjingu...e-for-charging

[Cagey]

Have a look here, a great site.

https://sites.google.com/site/tjingu...e-for-charging

Looked. Lost ! Maths fine, the rest gibberish. Ho hum.

[Cagey]

This is only my opinion and may be totally incorrect....

Might be right as well for all I know. Still don't get it though.

[pDidd]

If it has a an a/c plug on it i.e. its own transformer then it can output 90w max but if you have it powered by a seperate 12v supply you can go up to 120w. I think i'm right but not sure, I know some chargers can output more watts using a 15v supply instead of a 12v I'm sure some one can tell you if I'm right????

[BenScoobert]

What are you charging?
For example if you are charging a 3s 2200mah at 1c....
2.2amps x 12.6volts is drawing 27.72 watts add 10% for loss in efficiency from 12vdc and 240vac so 30 watts approx
Don't draw over 90w on ac and you're good.
It may be down to the extra heat generated from the ac-dc conversion, that they rate it down for AC

[cjcj1949]

The limiting factor is the dc driven charger. Think of two units. A basic chargers fed from a dc source, and in front of it an optional ac power supply to provide a dc source. To give the max output you will need to put in enough current at enough volts to achieve this. Efficiency of chargers varies and they work in much the same way as a switching BEC. (A dc voltage is switched on and off to produce ac at high frequency. It is then passed through a transformer to produce the low voltage. By using high frequency the design gets cheaper with smaller transformers and capacitors required. The design is more complicated, but the complicated stuff is put into a chip)To get 120 Watts out you need to put about 140 Watts in. Watts is power and is exacly the same as horse power that was used to rate cars. If you use an ac power supply, you will only get 120 Watts out if you put 140Watts in. Perhaps they fitted a 120 Watts power supply? It isn't a mystery and you don't need to understand anything about electricity, just economics and marketing.

[steve_b]

I would say it's as pDidd said, that on AC it's the AC transformer that's only rated at 90W, either electrically or because of heat output, but when you're running off a DC source then you won't be using the AC input so can run at 120W

[cjcj1949]

I would say it's as pDidd said, that on AC it's the AC transformer that's only rated at 90W, either electrically or because of heat output, but when you're running off a DC source then you won't be using the AC input so can run at 120W

That's what I said.

[Cagey]

Okay I get it now. It's because it bloody does and that's it ! Ho hum. My brain hurts.