Adding a LiPo "booster" pack

[joshseitz]

I've decided to shelve a new build for this year, so I am looking for ways to squeeze more fun out of my existing ride [Cannondale Bad Boy, Amped (MXUS?) front geared motor, compact 13A controller, Ping 48V 20Ah LiFe battery].

The Ping was more or less rebuilt last year (thanks again for your help, dnmun), replacing a number of pouches and the BMS). It is still performing well, but I would like to add a little more "punch" and top-end.

I was thinking of adding a 2S or 3S LiPo pack (8000mAh or so) to get me closer to 60V territory. Charging would be handled independently using my RC charger.

My first question: in what order should the LiPo booster pack be added in series? Behind or ahead of the Ping


Additionnaly, since these packs are of dissimilar capacity (8Ah vs 20Ah), what exactly would take place if I deplete the LiPo booster pack, leaving 12Ah of capacity in the Ping (assuming they discharge at the same rate?).

Finally, will my little Amped controller handle the added voltage of the booster pack? Not too worried if it kills it - I wouldn't mind moving to a 20A controller (then I have to worry more about killing the little Amped front geared hub motor!).

 

[agniusm]

You answered your question yourself. You will have unusable 12ah or if you continue you will have damaged 8ah pack.

 

[joshseitz]

So the moral of the story is to install a LiPo alarm on the booster then?

And how about the order of the packs in series?

 

[dnmun]

why not use 14S of lipo in parallel?

 

[DAND214]

why not use 14S of lipo in parallel?

That would work and then the added voltage won't kill the controller.

Oh, I forgot, you wanted more speed!

Just get a new motor and controller. That will solve the problem.

Dan

 

[dnmun]

why not just go to 20S of the 20Ah ping pouches? i have the 20S D167 lifepo4 BMS from bestechpower and some 20Ah pouches from wineboy to get you to 20S. add a meanwell power supply to your charger to get the voltage up there and then see if the controller will handle the 73V. i have a power supply too you could use to add to the 48V charger.

or better yet, go to 20S lifepo4 and then use 17S of lipo in parallel. with a BMS on each pack and some big diodes to tie them together. actually the diodes don't have to be too big since you only need one side. then use the same charger to charge them both up at the same time.

 

[joshseitz]

I'm not looking to spend too much time or money here. I will be building a new ride from the ground-up next year with a larger custom pack. I just figured that I could use a single 2S or 3S pack to add some fun to my existing setup. Should I go that path, which should be wired in series first? The Ping or the LiPo booster? Does it matter?

 

[dnmun]

not really. but if you put the lipo on top it is easier to wire up i guess. the balancing charger and it's power supply will be your biggest expense then.

 

[Hillhater]

What do you mean by "more fun" ?
More speed ? or more acceleration ?
You could just mod the shunt on that controller to give you more amps !
That 8Ahr lipo in series looks like a potential smoke generator if you are not careful !

 

[dogman dan]

Lets keep it simple. Wire it into series, on the positive side. That is , the negative of the new pack to the positive of the ping.

Yeah, you'll have about 7 ah of usable boost, then you must remove the pack to continue riding. If you don't, you will drive it to 0v, and then it will puff and get melty hot, if not catch fire. So yeah, an alarm would be good. On a longer ride, it might be nice to use the boost at the end of the ride, the last 7 ah.

Buy a charger that will be good later on when you have a large lico pack.


I'm assuming your older ping charges to 60v, but then drops to 55v or lower as soon as you touch the throttle. So ride a block, then add 2s for about 8v more. That should work with your 63v caps in the controller. You will get some miles riding closer to 58v. Lico will drop steadily, so the 60v part won't last all that long, but no more having to do short rides at 52v.

 

[joshseitz]

Thanks all. I appreciate the input. It looks like HK sells a reasonably priced 2S 13Ah pack that will allow me to ride quite a bit further at that higher voltage: http://www.hobbyking.com/hobbyking/store/__37353__ZIPPY_Traxxas_13000mAh_2S1P_30C_Lipo_Pack_Suits_TRA2875_.html

 

[dogman dan]

When I saw that thread, I wondered if you had seen it. Just what you need. Since it's bigger, you won't even need to run an alarm or monitor it much. Your 10 ah pack will shut down while your lipo pack still has at least 2 ah left.