Does this make sense with Hobbyking packs?

[ebike11]

Hi guys
Thinking on ordering and combining hobbyking packs in the near future. I think Im gonna go with the Panther Graphenes. Since my main concern is top speed on my qs205 for city riding/highway and since Ive never uses these lipos before..would I get the same top speed result if say for example I used 4 x 6s packs @ 5000mah (100V fully charged) but low Ah (5Ah) compared to the same 12 x 6s packs for a 24s pack 15Ah pack (possibly more for range)?
If I liked the power of the 3 packs together then I could purchase more soon after for longer range.
The packs are about 130us each so I wanna make sure i get the correct ones.
What do you think? Thanks!

 

[Hillhater]

Speed (motor rpm) is a direct function of voltage.
Range is a direct function of Ah capacity. ( all other factors and use being the same )
So , NO , you wont go any faster with the 15Ah pack, but you will go further.

 

[Schlafmutze]

How much current will you be drawing? 5Ah sounds very small for a QS205, even for high current lipo.
I'd expect excessive amounts of voltage sag with such a pack.

 

[ebike11]

How much current will you be drawing? 5Ah sounds very small for a QS205, even for high current lipo.
I'd expect excessive amounts of voltage sag with such a pack.

Using a sabvoton 72200...i just wanna do it as a test if i buy 4 packs of 6s @ 5Ah, so 100v, so that i know what im getting if i end up buying more to fet more range...range doesnt matter at the moment though because its just for checking the top speed of a particular branded battery pack. Id be just charging them to 100v and then hitting some straight roads to see how they perform. Sometimes its hard to rely on the continuous C rating of the china packs coz they sometimes vary being under/over rated.

 

[john61ct]

you can't just change the pack voltage willy nilly.

If you want higher voltage like 100V in order to go faster, you need to get a controller designed to work with that input reliably, with longevity.

 

[Schlafmutze]

[/quote]

Using a sabvoton 72200...i just wanna do it as a test if i buy 4 packs of 6s @ 5Ah, so 100v, s.
[/quote]

Your 72200 is going to release the magic smoke if you hook it up to a pack that reads 100.8v fully charged, those controllers max out at 90v for a reason.
Fets die pretty quickly once their max voltage is approached, so I'd back off from the higher voltage.

If you want more speed you can use the flux weakening feature found on those controllers, much better approach than higher voltage packs for shorter bursts of speed.

 

[ebike11]

you can't just change the pack voltage willy nilly.

If you want higher voltage like 100V in order to go faster, you need to get a controller designed to work with that input reliably, with longevity.

Ah sorry...i will be using a different controller. It can handle 120V

 

[bww129]

If you want top speed on a budget and don't mind balance charging multiple packs then try some HobbyKing packs. I just bought three Turnigy 4.5Ah 6S 30C packs from HobbyKing when they were on sale for $40 each because I wanted to try 18S at 67-72V instead of 14S at 52-56V. Add a few sets of XT90 connectors and some 10AWG wire to your order and you can make a series adapter. Even with a controller that limits the battery current to 40A my bike's top speed went from 28-30mph at 56V to 37-39mph at 72V. Acceleration is also a bit better, but the LiPo packs are being held back by the current limit of the controller.

You know those small boxes that are often used to ship PCBs from JLCPCB and PCBWay? They are almost a perfect fit for the three Turnigy packs :lol:

 

[Sunder]

It is possible, but not likely significant, that a trial pack underperforms your desired final pack. The reason for this is internal resistance. By ohm's law, three packs in parallel means one third of the resistance. Less resistance = less voltage drop under load. That means a higher top speed.

The significance of this depends on how close you are to hitting the pack's limitation. In theory, those 5Ah Graphene Panthers can put out 375A each, so a 15Ah version should be able to put out over 1000A. I've heard that they are mildly over-rated, but not fantasy land over rated like many others without a brand name to protect.

If you are nowhere near 375A, then the difference between trial pack and final pack will probably be negligible. If you are pulling 200+ amps, you will probably see much more signifcant voltage sag than if you were using your final desired pack.

As you use the most current while accelerating hard, you will probably notice more difference in your take off and hill climb than cruising top speed.