Li-poly mod
 

There was a thread on another forum that discussed using a Li-Poly battery in place of the regular batteries. Well.....


OMG!!! HOLY CRAP!!! SWEET MOTHER OF MARY!!! SPANK MY ARSE AND CALL ME SUZY!!!

I took a ZipZap with the new PCB's and did this mod. It flippin' rolls over on carpet. The car is AMAZINGLY fast. If I hit a wall or chair leg, the body flies off. The run time seems forever. Well over 20 minutes. When I have the time to take some pics, I will. The bad news is, you have to buy a special charger. The good news is, it's a peak charger for only $40.

Has anyone else here tried this?

I hate to refer anyone to the other forum, but johnk has a whole thread detailing every step and purchase. It has pics, descriptions and warnings. The forum is called - micro rc center.com (remove the spaces). Go to the Radio Shack/ZipZap forum and do a search for Li-poly instructions. If you have any questions from there on, I'll be more then happy to answer them.

The Li-Poly mod is most definitely a cool mod...But there's a few not-so-good points...

- Expensive!
The battery itself is only about $6, but you have to use the special Li-Poly charger and that thing costs $40!

- MUST not overdrain voltage
From the info on Li-Poly I've read, letting the 3.6v pack get below 3.0v is VERY bad. That means you have to be very watchful of when to stop running the car

- So-so current output
Unlike NiCads and NiMH, Li-Poly is pretty restrictive with how much current it puts out...Which equates to poor torque(acceleration). Yeah, you can go fast (because of the 3.6v) but it might not be a lightning bolt off the line. Stridex, can you comment on this part?

This mod is definitely not for everyone. It is on the pricey side, but it's also the cheapest setup for those that want a peek charger and the extra oomph.

The overdrain is it's only real downfall. It can be risky. I've run my car for 20 minutes and been able to recharge it successfully a few times now. Not to say that every-time I do that I'm lessening the life of the battery. I'll know soon enough cos' i can't put the car down. :) Luckily it's mod'd so I can just swap it out without any more soldering to do in/on the car.

The off-the-line acceleration is absolutely crazy. At a stand still on pretty thick carpet, I can flip it by turning left and hitting the gas. If I have a few feet before I turn left, the car won't just flip, it'll roll at-least 4 feet in about 5 rotations. Same goes for the hardwoods when I had the sticky tires on. I'm very happy with the results, but in all honesty, this mod would be best served in a monster truck style Zip/Bit. It's just too much power for those little tires. It's fun seeing how fast it'll scoot across the floor, but it's not the greatest thing to control. You put some bigger tires on (which I plan on) and you got a great monster truck. It'll probably still go faster then a Bit with all it's Tomy hop-ups. And because the battery offers way more power, the coil slams against the magnet while turning. This should allow it to finally steer those big monster tires.

Here's my Li-Poly Monster. It's unbelievable on carpet.

pic 2 - Hummer body

Last pic of Hummer

Cool! FYI we have the LiPoly cells and charger on order!

This is good news. I already have the charger, but I'll probably need a few more batts. Do you know what you'll sell them for yet?

When will this store get the batteries & chargers & what will you sell them for?

1-"Expensive"
maybe, but the $40 charger will last a lifetime and will charge many types of li-poly packs (1-3 cells, 100-1000mah) perfectly. and if you want any nicad or nimh powered bit to perform at it's best with the correct charge, i'd recommend a "real" peak charger anyway.

2-"MUST not overdrain voltage"
true, but i take mine down to 2.5V all the time with no damage whatsoever (25-35min runtimes)

3-"So-so current output"
where did you hear that? li-polys can put out 5-6C easily (same as nicads and nimh's). they have tons of torque and power off the line (wheelies are the norm). they seem to have a lower internal resistance which equates to more low-end torque and available power.

just thought that i'd clear up a few misconceptions...........


regards,
johnk

Legendary John.......Perhaps you will sway me after all ( ive been mulling ths mod over since you posted originaly. If i could only break the vice grip off my wallet).

The information I posted was based on information I've been reading about using Li-Poly in R/C cars.

That's great news if it can put out 5-6C! Though now I'm suspicious of why others have said Li-Poly is weak at current output.

Anybody knows the voltage on this things? the site mentions
Current capacity: 400-500ma sustained, 800-900ma max short term.
which seems plenty, with the motor using much less than 100ma!

i build the charger for about $20 and u can let it sit for about one hour then u have to rechage on the cell i use and i run my car with the slowest motor and gear set for and track and nos motor and red setup for drag and it extreamly fast off the start