Which 37v LiPo batt/charger/balancer combo do ppl recommend?

Hi all.


I'm looking at various 37v 12ah - 20ah Li-Po options for my project bike. At the moment the choices include packs from battery space.com but these are limited to 40amp so would have to buy two and wire up in parallel. The advantage of these for my need is the bms built into it for over/under charge and current limit with chargers that are resonably priced.

The other option are the 12ah packs from TrueRc.net but being rc packs, there is no battery protection/ balance built in and chargers/balancers cost a fortune. My question is could i protect the batt from under volting when on the bike and over volting/ balancing on the charger? Any one used these or similar rc style packs? Can anyone recommend a bms/ balancer/ charger combo? Any chargers to stay away from?!

I've been designing a compact drive system to be housed along with the battery(s), esc etc in a custom aluminium mtb frame to be fabricated by myself (aluminium fabricator). I have settled on a combination of a C.C. HV110 esc, Exceed RC 245kv 63-64 (2700w) motor linked via a 15mm HTD belt and pulleys to a Rino Mechanical PGC23 40:1 Planetary Gearbox.
On the output shaft of the box will be a 20T/24T granny gears bolted together on an ENO f.w. The motor will drive from the 24T and 20T will connect to the 22T ENO f.w. on the trials cranks via another short chain.

From my rough calcs this gives an effective front chainwheel of 29T for pedalling which is all i want as it will be used for proper mountainbiking ( steep hills etc...) as well as commuting. The geabox output freewheel is essentially used as a jackshaft for pedaling. Frame design at this stage will look similar to my carbon TerraShark which is sort of similar to the optibike i guess. I will try to scan a drawing later to post up.

Cheers guys,

Paul

P.S. Matt - your single and dual stage drives are a work of art!

Sounds like a great project, being able to custom build the frame should make it look pretty neat.

So you are looking at running 9S Lipos? I am running 6S Lipo at the moment and use an Accucel-6 charger from hobbycity for about $60 AUD. It does balance charging, auto-cutoff etc. If you build up the pack yourself you can just recharge in two batches, e.g. 6S + 3S.

The ESC should have a programmable low volt cutoff, so no need to worry there.

Look forward to seeing the sketches.

Welcome aussie Tim. It's great to have a metal fabricator in the mix. If you have not already, you should definately hit up AussieJester's E-trike build.

Dammit man, you took my idea! :wink: I have that exact motor, and am in the process of putting a longer shaft on it. I was also looking into gearhead reduction units, but I never made the plunge. What is the the torque rating on that unit? What kind of efficiency are you expecting?

As for batteries, you are gonna want something that will withstand the kind of jarring it will experience in the frame. Do you plan on removing the battery, or making it permanent without cutting? If you have never worked with Lipo before, I wonder if your bike wouldn't act much like a pipe .... you know what if those packs ever began to swell or catch fire. Anyway, if you don't want to worrying with balancing, then go with Konions, the kind that come with Bosch or Milwaukee toolpacks. But it sounds like you want something already built and ready to go, if battery space is cheap to you, go for it. But these Bosch toolpacks are going for $45 for a 37 volt 2 ah pack (fast charger $50). Also, what kind of range are you looking for, 20 ah is a hella large battery!

Thanks etard - Yeah my trade is going to come in quite handy with the bikes (and a friend's cnc router machine for machining too!). I had a quick look the other week at Aussie Jester's E-trike, might go back and have another squizzy.

Yeah i'm hoping this motor will hold together ok if i'm not using too many rpm all the time or getting it hot, have you used yours yet on your bike? The nominal output torque rating on the PGC23 40:1 gearbox is 60NM with ultimate output torque (their wording) is 1.5 - 2 times the nominal so around 90 - 120NM which should just about cover it... They claim 90% effiency at full load, max input 5000rpm with a body size of L80mm x W65mm x H65mm and weighing 1.4kg so it should be up to the task and hopefully overkill!

Reguarding batteries, i would prefer to get a ready made pack(s) - ive had a few years experience with lipos through rc cars but have never put my own pack together... i did make my own nicad and nimh packs years ago though. The reason i need decent capacity is just wanting a good range for longer mountain biking rides into the bush and i'd like to be able to commute to work on it eventually too depending on distance. Oh and my love of popping wheelies - i'd imagine a brushless assisted wheelie would be a bit of a power drainer...

For the moment the True RC 37v 12ah or two 8ah packs in parallel are getting the nod due to their pysical size (45mm width) and high cont/max discharge capabilitys (120A /180A - 12ah pack, 160A/240A - 2x8ah packs) being more than enough for the motor. Not sure what to use as shock absorbing material between the frame and battery though, any ideas? I would be taking the battery out for charging for sure. Ive seen pics of those lipo sacks but don't know much about them.

This is my rough drawing so far of the layout. Its hand drawn so bear with me! I've just got CAD so will get to learn to use it properly before posting stuff here!
The picture is viewed from the right hand drive side.


Cheers Grinhill, yeah hopefully it'll look ok when its finished!


Paul

P.s. Ive left a few things out of the drawing to keep it simple to look at for the time being. The thick grey and dark lines are 9spd mtb chains. The HTD 5M - 15mm belt drive from motor to gearbox is on the left hand side with the upper belt showing on the pic and will start off with around a 30T/60T combination. The planetary gearbox is behind the 20/24T granny gears freewheel/ jackshaft. The gearbox will also be used as a stressed member for frame/ drivetrain rigidity. I am considering having to machine up some sort of extra external bearing support for the motor and 'box shafts. Might try it without first though. And the crank length isnt to scale!

Paul