Howto: install LIPOs, the safe and convenient way!

[re-inferno]

Well, apart from not being sanctioned under legal racing, lipos have many advantages over common NiXX cells:

- higher energy density means lighter batteries OR batteries that provide much more runtime
- electrically more robust: no memory/lazy battery effect, minimal self discharge, higher cycle lifetime

And with our current 20C cells, there's no need to run them in parallel so they could provide the amps necessary for a powerful motor.

But there's one thing that always distracted me from using lipos: they don't fit into conventional battery slots and aren't protected very good. So, one often has to come up with quite a sophisticated mounting mechanism.
Peak/Orion provide lipo cells that are well protected and fit into most battery bays, but they're substantially more expensive than the bulk cells used, and they're not available in Austria (where I live)

So I came up with this:

http://www.offroad-cult.org/Forum/images/20070222/P1.JPG

above is a 2s Kokam 3200mAh cell. It can provide up to 64A continous current with spikes well above 100A and it's less than 200 grams!
below the pack, there's my "lipo-board", cut from 2mm carbon

http://www.offroad-cult.org/Forum/images/20070222/P2.JPG

At first, double sided tape has to be put on the battery ...

http://www.offroad-cult.org/Forum/images/20070222/P3.JPG

... and then, it's sticked to the lipo board.

http://www.offroad-cult.org/Forum/images/20070222/P4.JPG

Those oval openings the wires have to wind through provide some kind of "tension-relief" so that the battery is not damaged in case you pull the wires too hard.

http://www.offroad-cult.org/Forum/images/20070222/P5.JPG

More tape - this battery is going offroad!

http://www.offroad-cult.org/Forum/images/20070222/P6.JPG

A conventional battery bay (of a Team Losi XXX-4G+ in this case)
I removed the battery posts in favor of two 16mm screws since the new battery can sit 5mm lower than conventional NiXX packs.

http://www.offroad-cult.org/Forum/images/20070222/P7.JPG

A piece of fuel tubing (3x6mm) provides a vibration damped battery post, the battery actually "hangs" but

http://www.offroad-cult.org/Forum/images/20070222/P8.JPG

flanged locknuts press against the fuel tubing so the lipo-board actually "bites" into the silicone a bit and doesn't slide up and down any more (no worries, the fuel tubing is thick enough and won't be damaged.

The XXX-4G+ gains a lot from the lipo setup: a much better left to right balance and it's weight drops to a mere 1500 grams (there's a heavy duty one way and some other tuning parts, so my XXX-4 G+ would be quite on the heavy side!)

If you're interested, you can cut your on lipo board from the template below

http://www.offroad-cult.org/Forum/images/20070131/P1.GIF

The 166,2 mm have to be adopted, since it depends on the actual car, how far the battery posts will be apart.

With this, you can mount any Lipo pack up to a 6cell SC size.

[Jayboy]

Very nice info and very clear pics!...Do you have a photography light box or something?
...oh yeah, and what does 'Durchmesser' mean, on your diagram...is it diameter?

[got2bqik]

Pretty slick setup. I would put some sort of grommet in the slots the wires come thru that carbon fibre will eat thru those wires quickly. Think maybe I can adapt it to fit the xxxt/mf2. A tab on 1 end to fit in the stock slot and a hole for the post on the oppposite end to fit over the stock post. Good idea thanks for sharing!
Tim

[re-inferno]

Jayboy,
Thanks! "Durchmesser" means diameter - and the 7mm is only for the fuel tubing setup. The stock battery posts only need ~ 5mm
About the photos; I do some reviews, so I always try to get the "right" pictures. But these photos weren't taken very careful, just a quick how-to ;)

got2bqik,
Good idea about the grommet. Though the carbon has a small rounded edge, some cushioning for the wires can't hurt.
Of course you can do it for the XXX-t/mf2 (or any other 2wd) too, but the battery is generally very well protected anyways in this type of chassis.
Make sure that you use a battery, that is about as heavy as the NiXX cell, otherwise the f/r weight balance would be thrown way off and you'd get some heavy understeering!

[B4 Stealth]

looks nice, quite an improvement

[pinolelst]

That's actually a pretty good idea for side mounted packs to give the edges some protection.I don't see using it in my xxx-t as they sit center but my brushless Cen Matrix and TC3 might get a set cobbled up just for extra insurance
Thanks

Steve