4motus / cromotor DH bike build

[madin88]

I'm slightly torn because all the good ebike frames with a ton of space for battery phasor/raptor/4motus/hpc revolution all beg for a high-power cromotor setup and I do like power myself.

you forgot the chaika frame from russia
I also would like to see more frames for high power middrives. The Motoped would be one of these, but it is much work to install an electric motor and a battery box to this frame.
The low kV "Big Block" motor would be a good choice for a middrive.

 

[crea2k]

The chaika frame looks interesting, looks very much like the Raptor, but a bit more boxy.

************* Build Update *************
So....I got a reply just now from Adaptto about the controller, so all good, they have sent me a price list for everything.
The email was in Russian (god bless Google translate), but they said they can communicate in English too, so all good, iv replied in both Russian and English just in case another person answers the next email.

This is the price list they sent me :
Prices in USD
Mini-E controller 3Kw 450
Max-E controller 10Kw 800
BMS kit 28S 155
BMS kit 16S 125
Mini-E controller 3Kw + BMS 28S 575
Max-E controller 10Kw + BMS 28S 905
Charging Coil 30A 35
Charging Coil 70A 50
Auxiliary balancing board (up to 4S) 13

I think im going to order the Max-E controller 10Kw + BMS 28S 905 , I asked them what the function of the Charging coil is, as I wasn't sure, Im not sure if it plugs into the BMS so I can charge them all at once ?, but im not sure if I trust lipos to charge in the bike anyway, even though it says 'works with all battery types', think I would prefer to put them in my steel box so they dont set fire to my bike.

 

[ridethelightning]

made my pack from these spotwelded units

it was just a matter of soldering bits of copper strip across the blocks for series connection in 22s
you can slot em together in a block or cut em up and put em any shape you like really. spotwelding/spacers came free.
spacers reduce overheating at high discharge.

i only used the 20R cause they diddnt have 25R yet then, but they are nearly same price if you get a good bunch.

re prices for adaptto stuff, its all more or less what they quoted me, maybe better.

the charge coil is really cool. its used for fast charging with a powersupply, really handy for sucking huge current from random unsuspecting outdoor power sockets while on the fly
it means i can charge my 1.5kwh pack from empty in less then an hour with the apropriate compact psu.

better get the large one as it can handle more current for large packs :wink:

 

[crea2k]

Where do you buy them from, as I would do this myself but I don't trust 99.9% of suppliers selling batteries.

 

[danjpendleton]

mine was around 1300 shipped from em3ev with his adjustable charger and frame bag. I did the math for lipo and ultimately the samsung frame triangle pack made way more sense. Pay a bit more up front for a better battery then you can literally plug in and go. Lipos are great because of the discharge rate and price but pretty much suck in every other way.

Ive heard mixed reviews on the headway cells. Trying to find a reputable supplier that doesnt sellyou a bunch of dead cells is a challenge. Plus most of those cells are pretty massive

 

[crea2k]

We have forks !, and tyres

 

[ridethelightning]

the real cells come from supower battery.

try emailing Lilian:

supowerbattery@gmail.com

the prices on their site are not what they qote if you say you are from e.s and get 200+ or so cells.
shipping is also reasonable, however ,due to shipping regulations, easier to get paralelle strips and solder series connections yourself.

 

[crea2k]

Whats everyone's opinion on these packs opposed to the Lipos ?

http://www.battery-matrix.com/DIY-72V15Ah-24S1P-LiFePO4-HEADWAY-BATTERY-PACK-KIT-40152S-cell-40152-cells-headway-lithium-battery-40152-headway-lifepo4.html

DIY 72V15Ah(24S1P) HEADWAY BATTERY PACK KIT
DIY Pack Includes:
1:24pcs 40152S 15Ah Headway Cells
2:1pcs 72V/24S Cell BMS constant discharging current:40A,Peak discharging current:120A(you can choose your need of BMS in our shopping BMS select)
3:1pcs 72V3A（87.6V3A) LiFePO4 Charger
4:24pcs Battery Bonnector
5:1pcs Red/Black 50A Anderson Connection (One is Connecting to the AWG 12# Silicone wire that is 50cm, Used for Discharging)
6:One is 45A Anderson used for Small Discharge Current
7:Two lines of AWG 16# silicone ,the length is 50cm(Color is Red,Black )usd for Charging positive,negative
8:One line of AWG12# silicone,The length is 30cm that used BMS to Battery B-
9:3pcs 6-6mm Diameter of the connection terminals,one is connecting to battery B-, One is connecting to P+.the tired one is connecting to the B+
10:1pcs jack female(1+,2-),is connecting to the charger
11:One meter no-lead environmentally solder (enough )
12:25pcs connection terminalsthat used to connect the BMS signal line and Battery
13:A sufficient amount of heat-shrinkable tube

 

[ridethelightning]

i have these on my comuter bike. they are great for short trips to the shops or going to work on a regular basis, but they are HUGE when compared to liion, and maybe 2x the weight.

they will go for 1000s of cycles(so people say)
but can only give 3C realistic continuous discharge.

my pack is 16s2p(48v20ah)13kg+,the size of an extra large shoebox and is only good for say 50 amps max peak. 4065 26"rim good for 45-50kph on the flat

tough ,durable ,heavy ,slow...and steady

 

[MAGICPIE3FOCUSPOWER]

Looking good mate for so far....

Yes I have those lifepo4 batteries (48V pack), heavy, too big, getting very hot....
But durable....

I am suing for daily ride, so it should be fine for on road use

 

[crea2k]

Hmm looks like im probably going with lipos then unless anyone can suggest anything else for a similar price ?. I like the single cell built packs but they are soooooooooo damn expensive.

 

[crea2k]

At present im leaning towards these, as the current rating is a lot more than the 20c's so hopefully wont get as hot as the cromotor drags the power out of them.
http://www.hobbyking.co.uk/hobbyking/store/__9518__Turnigy_5000mAh_6S_30C_Lipo_Pack.html

 

[Tench]

140a from a 20ah pack is only going to be 7c, your set up will only pull these currents momentarily on hard acceleration or very steep full throttle climbs. I don't think you will be riding WOT as much as you think you will, or be able to pull big currents for more than very short periods. So I would go with the cheaper hard case packs and spend the extra on more packs if you can fit them in! can you fit 25ah in there? this would lower your max draw to about 5.5c

Electric motors are very different to petrol power, a 100bhp ic engine will make 100bhp when held flat out whether it is in gear or not, an electric motor held flat out not in gear will pull very little current but driving in gear will pull the required current to get the job done. if your cro is capable of 10kw that is 13+ bhp, the motor will only pull 10kw currents if you put enough load on the motor that requires it to produce 13bhp to do the work you are asking it to do.

So if the power required to climb a hill at 20mph is only 5kw then that is the current it will pull. So you will only be pulling 140a when you are either accelerating very hard or climbing very steep, situations where the motor needs to produce all that power.
If the wheel size and motor KV/battery voltage dictate a top speed of 40mph then the motor will only pull enough current to do that when flat out, about 4kw, it wont produce power like a petrol engine. But yes if it is geared for 60mph then it will try to do that which will require bigger currents.

So choose your motor kv, wheel size and battery voltage with care as these will have more bearing on the performance than the C rate of your cells.

 

[crea2k]

Tench, have you ever tried going up Winnets Pass with an ebike before ?, as I see youre from Derby, im about 50 mins east of Notts. I want to try some trails round Castleton with it and also Sherwood Pines etc. Can you suggest a charger for the batteries, as most people are base in the US, so cant seem to find a lot of the chargers mentioned. The frame can fit up to 18 6s packs apparently.

 

[crea2k]

I just ordered 12 of these !

http://www.hobbyking.co.uk/hobbyking/store/__9176__Turnigy_5000mAh_6S_20C_Lipo_Pack.html
so I now have batteries, just need a decent charger to charge them, as the Max-E has bms and charging but not sure about using it with lipos or not ?.

 

[ridethelightning]

got yourself a tiger with a tail then!!!

short answer. no you dont need a charger, look for a good powersupply

if using the max-e coil and bms, the lipos will be happy.maybe more so than with low qc rc charger

to charge with coil, its best to use a single unit psu, preferably good for1.5-2kw or so.
compact psu around 50v 30A like mine is good for cool, fast charging on the run, about size of max-e and weighs only 1.5kg.

you can use any psu from 12v up to your battery voltage but it may be slower and lower votage at high current will give higher charging temps in controller and coil components. i know this from experience.

Andrey is currently selling suitable compact 1.8kw units at the mo for 300usd, though there may be others available on ebay etc. they are mentioned in adaptto thread.

 

[crea2k]

Are these the correct connectors / size ?, I can make my own, but need to find the correct connector and size of connector first, also what thickness of cable should I be using to parallel / serial these batteries ?

http://www.ebay.co.uk/itm/Lipo-Battery-Parallel-Pack-3-5mm-Shrouded-Bullet-Connector-Lead-14AWG-UK-Sale-/370900750997?pt=UK_ToysGames_RadioControlled_JN&hash=item565b685295

 

[Tench]

Your in the fortunate position to not need a charger with the Max-e system, all you need is a dc power supply, ideally around 48v.

There are plenty of 48v ones on ebay at around 10a which should see your pack fully charged from bone empty in 3 hours ish.
Spend more on one with an higher output if you need to charge quicker.

I have had a Bomber with an X5 that would pull 6.5kw and do 50mph, great fun but off road the motor rpms where too low with a 24x3" wheel/tyre. I am building another bike now with a slow wind motor (HT3525) in a 17" moped rim so it will climb better, more motor rpms for the same distance travelled, which is like using a lower gear. Mine will only be setup for 3.25kw which will be enough to climb up anything, but it wont go up as fast as yours!!

I have done all the peak district, a lot of the lake district, Yorkshire moors and some in wales, it is great fun! Lets go ride when we have them both finished!

 

[Tench]

Are these the correct connectors / size ?, I can make my own, but need to find the correct connector and size of connector first, also what thickness of cable should I be using to parallel / serial these batteries ?

http://www.ebay.co.uk/itm/Lipo-Battery-Parallel-Pack-3-5mm-Shrouded-Bullet-Connector-Lead-14AWG-UK-Sale-/370900750997?pt=UK_ToysGames_RadioControlled_JN&hash=item565b685295

Your packs say they have 4mm plugs, those say 3.5mm so probably not right! you also should be looking to use 10g cable, when you have paralleled some of those packs your cables want to be bigger not smaller.

 

[crea2k]

My challenge for the bike was to make it up Winnets Pass (coming out of Castleton) without bursting into flames lol, as the first / middle part is rather steep !.

I think I made a bit of a balls up and bought spokes for a 20" wheel and tyres and rim for a 24" wheel (for the back), so not sure if 24" is going to be torquey enough or if I should go with 20" on the back, but then thats going to look a bit odd with a 24" up front, as a bit more difference between 24" and 26".

 

[crea2k]

Cool ok thanks, do the connectors have a specific name or are they just bullet connectors ?.

 

[kudos]

Cool ok thanks, do the connectors have a specific name or are they just bullet connectors ?.

They're called HXT connectors:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9283

 

[Tench]

Have you built a big lipo pack before? do you want to come over and see one, I am sure It would benefit you to come have a look and learn a little more before you bought a ton of connectors.

 

[Tench]

My new build is setup to do 30mph flat out on 20s, this will give me good torque for climbing. You need to work out your speeds from the KV, voltage and wheel size, also remember that the Adaptto controller can give you about an extra 30% on top end with the field weakend over rev function which will allow you to choose a smaller wheel for more torque while maintaining a decent speed capability.

If you want a really good bike it needs to be planned well, or you may end up not achieving your aims. Having said that, you are using a cro and a 140a controller so torque will always be abundant. But geared too high will see a lot of heat generated when making it work hard at low speed.

 

[ridethelightning]

iv got 21" moped wheel on the back, 26"dh rim on the front with hookworm. i had to build custom dropout adaptors to drop the rear wheel down 2" or so to keep the correct geometry.
it looks a little odd, but it goes like the clappers, and the larger wheel on front gives a better approach angle and handles bumps really nicely. i wouldnt have it any other way now.

@ wire gage, i just go hobbyking 8gage for everything high current dc, as it means less losses, and lower resistance which= good.
and keep it all short as pos.

the larger hobbyking xt150 connectors are good for lower resistance connections for battery cables/phase wires, as used on max-e
xt90 is good for charger plugs.