GNG Big Block Build Advice

[mr brandon]

Hello All,
I have been reading much of your experiences and learning as much as I can about e-bike building.
Thank you all for your efforts and taking the time to illustrate for others.
I still don't understand how the motors work and everything that goes into battery builds, just a general idea now.

Well, I have decided to build a do-it-all electric bike. it-all consists of 10-20% grades hauling 45 lbs of cargo OR possibly a 100-150 lb passenger. 1500 ft elevation gain over 12 miles and then a return trip is another example what I may use this bike for. Basically I want an electric motorcycle that is reliable and without being too-powerful to avoid snapping chains. Unless someone has an idea for a simple transmission for the big block, I will need at least 3 speeds so a standard 2 speed dogtooth will not be ideal, and a moped transmission would be a massive undertaking for me. I don't have an option to use anything other than standard 7 or 9 speed bicycle drivetrain currently, but if you have any suggestions let me know.

I looked at cromotor, geared hub drives, bafang bb02 mid drive, and others. Hub drives have worse heat issues and geared hubs seem delicate. bb02 I used on a 10 minute test on an xtracycle with no cargo and it got very warm. I'd kill that motor for sure, and the plastic clutch sounds bad too.
I'd thought to order LR's standard belt driven complete kit, but having seen some video on youtube of gng riders having to wait while the heat diminished on mtb rides with no cargo, I'm concerned about heat buildup. About 1/2 mile of 10% grade seperates me from shops, work, etc.

Currently I ride a 26" GT Palomar cro-mo steel hardtail with rigid surly fork and 200mm front disc, rear v brake, schwalbe big ben tires. I'm going to use this as a platform for an electric bike and then transfer the kit to a full suspension bike with around 8" travel later on, once it's reliable.

I'm now looking for a complete build list for this bike, so I'm asking for your advice. Let's assume it's using the GNG Big Block from LR, I think it may be the best option for me - but I am trying to judge if the weight is worth the copper mass (weight) which can take more heat and not overheat at lower amps.

1) One main reason I want a pre-made battery is to help with theft prevention. I can't be hauling batteries around with me when I'm walking around town.
I also don't know how to solder. Anyways. What's the best battery for this motor that I can go out and buy? I have been looking at Em3ev's triangle 50v with the highest capacity option, and I'm wondering if there is anything that is BETTER for the gng big block for better range. I want the battery to not have any issues with the motor as far as smooth throttle and torque is concerned. I have only seen people buy square bricks and chop them up to resolder and wire them to make their own pack as an alternative, which won't work for me. I looked at batteryspace and all-battery but couldnt find a suitable pack, so I'm asking for suggestions, 48v-60v 18+Ah for range.. will the big block work well with 48V batteries? I've found some threads that seem to use it as a test and it's OK, then they ramp it up to 100A later.

2) I need a controller. I am looking at: 12 FET 84-132V Mark II High Voltage Racing LYEN Edition Controller $199
but this controller was suggested when I was going to use 60A battery with big block, so I think it wont work at 50V 40A
I'd go bigger with batteries but high amp batteries drain SO fast and are expensive, and I'm not sure what pre-built packs can give 60A, or what I'm supposed to do with a 30 lb square brick battery (that's why people chop them up i think)

3) i'll need a throttle. I like the magura twist throttle, but there is a mod which needs to be done to it.

Here is more information on the Magura throttle improvement recommendation:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=46891#p686598

Has anyone done this mod or is there a place I can buy a pre-modded magura throttle? Is the only way for me to solder it myself? I don't own a soldering iron or want to have to do this.

4) I'm assuming that cycle analyst is almost a requirement these days. I want to be able to see what's going on with the batteries etc, so I'm assuming I should buy a CA 3.

5) I believe atomic22 locking crankbolts and a pitlock through the motor mounts should help secure the motor enough that people won't be able to pull it off the bike while I'm away for a couple hours. The rest will have security bolts, but I probably won't be leaving this bike out if I am in class anyways, too risky.

6) I need wiring/cables to hook all this stuff together. And any necessary connectors which I won't know exist until this stuff is here in front of me.

OK, assuming I got the modded magura throttle and 48v battery, will this motor throttle smoothly? my main concern is snapping the chain with this big motor, and finding a way to limit torque "snap" - I'd think consistent smooth torque would not be a problem with these power levels but again I really don't know. Would the Lyen controller be the place to limit this torque and how would I go about it?


Any other advice on this motor vs regular gng motor vs the fan cooled standard gng motor which is available, or anything I may have left out please let me know. I need a complete shopping list

 

[speedmd]

I run a GNG 1 with a 30 amp controller 18s lipo up a 1000 foot climb over a few miles distance (some 30mph avg) with no heat issues. No cargo. If your running low motor RPMs or running very hard I would go with the fan. If not, the stock motor should work fine in all but the hottest days if lugging it down.

 

[parajared]

No need to sweat it too much, your bicycle components will bend and break before you can put enough power in a GNG to worry about it overheating. What will happen is either your chain will break or you will wonder why your chain is flopping around so much and you will look at your gears and see that they are bent inward and grabbing the chain. The lower gears, your 11 tooth and 13 tooth will slip and grind themselves bare and your larger teeth bend and hold on to the chain. When it gets really bad it yanks the chain all the way around and breaks the derailer.

My recommendation: limit to 1200 watts, stick a smaller, less expensive esc on it like a Lyen 9 fet, and use lower voltages because at a 20 degree angle you will want your legs helping with the effort too. Keep in mind if you use 72 volts the freewheeling cranks are spinning at like 300rpm; your legs spin at like 100 rpm(ish), so you want 36 or 48 volts, or one heck of a fatty reduction if you use 72 volts otherwise your legs will be paddling away uselessly on those steep hills

My recommendation goes towards hobby lipo batteries as they are light weight and this matters a lot for steep hills

cycle analyst is great but you can get by with a $5 hobbyking cell meter 6. CA v3 is pretty neat, it has temperature monitoring and throttle dampening, and three way toggle power limiting; it's super cool.

GNG isn't as cool as I had hoped it would be; mid-drive hub has worked way better, way more reliably for me. Mid-hub lets you have a 24 speed bike instead of an 8 speed bike and it isn't loud and obnoxious like GNG is.

 

[mr brandon]

Thanks for the advice Parajared. What most people seem intent on is using electric bicycles in order to pedal while climbing. to me, that makes no sense. I have patellar tendinitis and I ride 100 miles a week. I don't need to be pedaling to help my electric bike climb a hill after dropping $2500 on an ebike kit. Pedaling is what prevents me from being able to mountain bike right now, and I don't think buying a car is the way to go here. I know the GNG kit can do what I need. Then I might as well just go slower and forget the whole ebike thing. And there will be zero pedaling assist when I am hauling my friends as passengers, or 45 lbs of cargo, or both when it's party time.. 1200 watts will absolutely not cut it in this application. The bafang I rode has 1200 watts and with that level of power I would be going only slightly faster uphill than a non-electric bike with the cargo I haul on the grade of hill I live on.
As to the mentions of 60V, again that sounds fantastic - but can someone suggest a 60V battery that does NOT consist of 4-8 LIPO cells velcroed to my frame? And would I even need 60V with the big block since the extra voltage to spin up the motor and get more power may be unnecessary if the motor can put out more power (torque) at lower RPM? rc lipo batteries will get stolen, explode while I'm asleep 3 feet from my head, and also I still don't solder. I need a LiFePO4 pack capable of delivering 60V - OR I need to know if the big block will run acceptably on 48V (30-40A), with what controller, and what wiring do I need? And what about that magura throttle mod does anyone sell it? these questions are the main reason I have put this build on hold. I need a battery and controller to go with the big block that will not require Lipo and with only 1 battery unit that has a BMS built in. Am I right in assuming that is the simplest and least maintenance way of battery option for big block? Something I can lock to the bike either with a case or otherwise and won't require pulling 4-8 batteries off of the bike in order to charge them and then reattaching them all the next day. And I really don't think a 30 Lb battery will hurt my hill climbing abilities, it's more about bike handling and how I can attach them without destroying the COG of the bike.

 

[mr brandon]

I think posting a reply bumps the thread. hoping someone can shed some light on this. thanks.

 

[speedmd]

Sounds like a scooter is what you are looking for.

 

[mr brandon]

Good thing I came to the endless-scooter forum then.... Thanks a lot for all your help.