Hacker Brushless with LiPo Battery
 

Hi

I didnt know where to post this so this seemed like the right place.

I saw an article in a mag about putting 11 cells together in an Xray T1 and hooking it up to a Hacker Brushless motor. It did 88 Mph!

I thought i would try something similar but try to use LiPo batteries instead.

I am trying to gather info for what i need and also if it might work. I was going to try the C40 brushless motor and a Lio battery that puts out about 11.2 volts. I have been told its equivalent to a 9 cell 3500 mah battery pack but about 1/4 of the weight.

If all goes well I will run it on an open track against some serious nitro competition to see how it fairs.

Any comments?

Re: Hacker Brushless with LiPo Battery
 

I couldn't believe the rear spoiler they ran on that car. It was just the standard one. You would think that having gone to all that trouble they would have replaced it with a more aerodynamic spoiler!

What current draw can the LiPo handle? If it can do what the SubC's can handle. It would be a great solution.

I was just exchanging mails with Billy Fisher at Hacker. He suggests the system might be able to handlle a 3 cell pack (11.2 volts)

LiPo runs great in RC Helecopters

Just be careful as I heard that they have the tendencies to explode.

I thought that LiPo's werent going to be used in cars ? As they couldnt handle the withdraw that our motors need ??

LiPo discharge rates
 

LiPo cannot handle high discharge rates. Check out this site. It has a table at the bottom with the different pack configurations, their capacity and discharge rates.

http://www.electrifly.com/lithpoly.html

The smaller packs (only 350mAh) have a discharge rate of 20C = 7A

The larger packs (1.5Ah) it is 8C = 12A

You need around 75A to get a stock motor off the mark. While running it would draw say 30A.

While the LiPo would run you would notice a lower performance compared to NiMh packs

yer they tend to get too hot and erm.....explode:D

Yeah not really reccommended then ....

I heard they can be abit of a pain to put out if they catch fire aswell :confused:

Lipos are being used with all sorts of high speed brushless projects.
 

45amps burst and 30amps constant is plenty of power to drive a brushless up to some very high speeds.
Cheap Battery Pack link.
People are using the smaller 15/20amp packs to drive 1/18th scale to 60-70mph speeds.

Re: Lipos are being used with all sorts of high speed brushless projects.
 

From the site...
Cool 45A burst - Well I stand corrected :)

Sounds like a goer to me...

http://www.robotcombat.com/marketplace_lipoly.html

There is also the 20C 2100mah Kokam that can put out 42A.

-James

Re: Re: Lipos are being used with all sorts of high speed brushless projects.
 

Yes a LiPo will do fine with a Hacker. The two cell packs are 7.4 and give you insane run time, I am sure a 3 cells unit will work with the hacker, but I think you will have the thermo issue to worry about. Personally I would stick to the 2 cell unit and it blow past any Nitro, remember the track has more that straights.

LiPo are pretty good now as we have learnt how to charge them. 3 stage chargers out now make them prety safe compared to older units.


Coxy.

I have run a 2-cell 6000Mah Li-Po pack on my 6 turn c40 hacker and it ran fine with insane speed and uncontrolable punch. Nothing like doing a back flip with a XXX at half throtle. Or hearing your cars tyres hunt for traction for 600' while easing in to the throtle.



I have yet to thermal my hacker.
Gearing was 24P/84S

amp draw
 

If your amp draw is too much for the rating on a lipo pack, I would assume that you could always go to 3 cells (11.1V) so that you could get the same amount of power for a smaller amp draw. P=VI. This would depend on if your speedy is rated to 10 cells (1.2V cells). but the weight of the extra cell would not be an issue as we all know the power density of lipos. Legality would not be an issue either as they are already as illegal as hell.

Re: amp draw
 

Yo! Thanks guys. Thats what I was thinking. Higher volts less amps for the same speed. so for same amps higher speed!!

Problem now is the ESC. I have been told a Schulze ESC is the only one capable of handling the power. Bit pricy, any alternatives out there?

I will also need a LiPo charger as ordinary chargers dont work with LiPo correct?

Cheers

http://www.electrifly.com/images/gpmm3150big.jpg

Try getting this. It charges just 'bout anything...Nicd, NiMh, LiPo, Lion.....

Bryan :cool::tire::tire::tire:

Most Li-Po can give out sustained amperage of at least five times capacity, meaning 2000 mAh cells can give 10 amps and a bit more for very short time. Should you need more power just buy battery with more capacity, 8000 mAh pack should give you at least 40 amps.
If you handle Li-Po packs with care: Do not short circuit. Do not use regular charger. Do not overheat them. Then it's very unlikely that they'll explode.
The Triton charger from Great Planes (Towerhobbies) can charge any cells, including Li-Po.

Higher volts equals higher speeds
 

Yes, 11.1volts is the way to go for high speed. Not sure which ESC's can handle that. In micro, the Mamba ESC easily handles it but a Mamba 25 ESC would not last long powering a larger motor.

If you are going for speed, and not racing control, you might look into a plane ESC. They have been around longer and are cheaper. For example, this Kontronik controller is only $45 and can handle 12 cells. Not sure if the 45amps it can handle would be enough, though.

Also, I second the Triton recommendation.

Kontronik at Tower

Where did you get this info from???? Not even close.....

One problem I see with the LiPo cells is that if you drop the voltage below 3v they are fooked!! You can get a warning light for them that flashes at 4v

Mamba 25 speed control has Li/Ion protection.
 

I suspect some others do as well. You can set the shutoff voltage of the Mamba 25....think it defaults to around 4 volts.

AMPs draw??
 

Read it in a magazine... What do you think is more accurate?

The peak current draw while getting a sensorless motor off the line will be quite high, could easily hit 200% of running current. I always overrate my controller for a given motor. I run a Schulze U-Force 75 (75A cont., 100 Peak) on a lehner basic 4200 motor (45A cont., 60ish peak). Keeping the peak current of the motor at or below the continuous rating of the controller seeems to give good results.

Are you using LiPo cells?

Cheers