Alternative lipos

[Will]

I used to race RC cars 20 years ago when the Sanyo NiCad packs were popular. Hobby King.com is the new hot place to get cheap lipo batteries for RC cars and airplanes. Here is an example of a larger 4 cell pack 20ah for $103.  Hobby King has warehouses in North America and in China and the prices vary a little bit but they will ship china to USA as well. 

https://hobbyking.com/en_us/multistar-high-capacity-4s-20000mah-multi-rotor-lipo-pack.html

 Just curious what some of you electrical wizards on the group think of this. The discharge rate is 10 C, not sure if this is a hazard to provide too much current to main boards.  

I'm just getting into wheels, I don't even know much about the batteries they are using and the relative cost but seems $.50 to a dollar per watt hour is the going rate and this would be $.33 a watt hour.

 

[esaj]

23 minutes ago, Will said:

I used to race RC cars 20 years ago when the Sanyo NiCad packs were popular. Hobby King.com is the new hot place to get cheap lipo batteries for RC cars and airplanes. Here is an example of a larger 4 cell pack 20ah for $103.  Hobby King has warehouses in North America and in China and the prices vary a little bit but they will ship china to USA as well. 

https://hobbyking.com/en_us/multistar-high-capacity-4s-20000mah-multi-rotor-lipo-pack.html

 Just curious what some of you electrical wizards on the group think of this. The discharge rate is 10 C, not sure if this is a hazard to provide too much current to main boards.  

I'm just getting into wheels, I don't even know much about the batteries they are using and the relative cost but seems $.50 to a dollar per watt hour is the going rate and this would be $.33 a watt hour.

@EUC Extreme uses custom packs built from RC-lipos. You need quite a few in series (4 * 4s = 16s) to get enough voltage out, plus you need separate charger that can handle the balancing of the cells, but they're "usable". He says they give better torque due to higher current output, but the risk is that the mainboard may not take it well. If you look around, you'll find his custom modifications, like very large heatsinks and such, that may be necessary. At least in one case, the mosfet legs exploded mid-ride...

 

 

[EUC Extreme]

Yes. The torque is significantly better than a good quality lipo battery.
The voltage does not drop during exercise, and super-fast charging is possible.
Unfortunately, Hobby King batteries are not of good quality. So, they can not provide the best performance.
But yes, they are better than any of the 18650 cell.

By far, the best I have tested cell is 18650, the LG 3400mAh.

[Keith]

@Will, just to add to what @EUC Extremeand @esaj have said above, I've considered adding 4 off 4s Hobbyking cells to my existing 340Wh 18650 cell battery. The big problem is balancing them, I have suitable chargers as I fly electric helicopters up to 12S and planes. You could take the balance leads out of the side or take the packs out to charge them individually but it would be a pain and they do need balancing, at least every so many charges (say every 10 or so?)  this had been discussed before on several occasions, here for example:

and also here: 

 

 

[EUC Extreme]

Our cells have two 8S installments. So I download them separately, and then connect them in series when I start driving.
A piece of cake.
Poor quality batteries for cell voltage differences come out more easily.
And even more so if it's very empty.
There is preferably less than 3.4-3.5V.

[Will]

Appreciate your info.  In my case it is more for reference and education, to understand these unicycles.  There are so many international users here and I have read so many posts that I find myself using strict english to be best understood.  (laughing)