hitec x4
 

Hey guys quick question, just bought this charger and put my 4s on it, I could only get it to charge at 3.3a the whole time. I have it saved at 5.0a to charge...any ideas?

That charger is 50w x 4 channels. You need at least a 100w charger for a 4 cell pack, and if you want to charge at more than 6a, you would need a 200w charger.

I'm not sure if that's completely accurate. I have an x4 80 and it charges my batteries at 6A when I have it set accordingly

He didn't say his was the v4 80 so I just figured it was the original x4. Still, it takes at least 100w to charge a 4s @ 6a. VxA=W: 16.8x6=100.8w. That would lead me to believe the 80 is underrated or that it allows you to run over the stated limit of the charger.

or it could just be really run down packs. a 4s at a little over 3 volts per cell will let you for a short time charge above 6 amps on the pack. it will peter off after the voltage rises, and as the pack reaches peak voltage.

though usually it is recommended that at least 100 watts is used on 4 s pack to give optimum current as most chargers over 100 watts can use 10 amp charge rates anyways.

I charge with an x4 for years. I put multiple 4s packs on at the same time and charge at 5-6amps per pack just fine. As the pack voltage gets closer to 16.8 the input drops. Usually I just balance and look at the screen were each cell level is shown and go from there.

Like DRTMI said, even charging just one 4S @ 6A would require a 100W charging system. Yet you can charge multiple 4S lipos at that rate? Amazing...

Because an x4 is 80w per channel. Not 80w entirety.

HiTec has two (2) x4 chargers. The original x4 and the x4-eighty. So unless the OP comes back and specifically says that he has the eighty, those of that say his charger does not have the power, is the charger we are talking about. You are taking it that he has the x4-eighty and not the x4.
There is no way you are getting 7a charging a 4s with an 80w charger.

X4: http://hitecrcd.com/products/charger...harger/product

X4-eighty: http://hitecrcd.com/products/charger...harger/product

I never said I got 7A of charging. All I have are 2s batteries, and I can fast charge 4 batteries at once at 6A, if they're low on charge. There's better chargers out there but this one suits my needs.

... and the OP is talking about his charger not charging a 4s pack, not 2s.

And all I'm saying is, rather it be a 2s or 4s, it should charge at 6A not 3A. Which would lead me to believe there's an issue with the internals of his charger

But it can't if it does not have the power to maintain 6a of charge current.

4s = 14.8v

Watts = Amps x Volts

To charge at 6a and 14.8 volts you need 88.8 watts

Amps therefore = Watts/Volts

So if he has 50w divide by the voltage (14.8v) you get 3.3 Amps

tada!


PS

2s = 7.4v

6a x 7.4v = 44.4w which will work fine as it is under 50w

PPS

Sorry, I am repeating what DRTMI said earlier

Actually the math is with the lipo at full voltage.

A 4S (4 x 4.2V=16.8V) x 6A is 100.8W of current needed.

A 2S is 1/2 of that (50.4W) so the X4 80 should be capable of that but the regular X4 is right on the edge if it can actually achieve a 6A charge with a 4S lipo.

Regarding the X4 80, I cant see a charger advertising 80W per channel (factor in efficiency losses as well) and actually output over 100W per channel. But thats just pessimistic me talking....

Well if we are being precise (or pedantic ;-) ) the max voltage overstates the requirement as the LIPO charge cycle is only done at MAX amps for the early part of the charge as you can see by watching the display during charging. By the time the batteries get over the spec voltage (3.7v per cell) the charger does not dish out the full amperage so in reality calculating as I did is pretty accurate which is why the calc max amps for 4s was the same as the observed - 3.3A

We are kind of splitting hairs here, we agree on the premise that the 50W charger cannot deliver 6 amps into a 4s battery but can into a 2s.