NRS 2 E-Bike Build

[bl4s7er]

So, I have decided it would be fun to build an ebike! This might get a little long winded but I want to provide as much info as possible so ppl can offer valid feedback. I think I am just about there so here goes;

A couple of months ago I realised I was pretty unfit and I also remembered how much fun I had on my bike in my younger years (I practically lived on it). Looking at buying one the first shock was how expensive bikes are these days. Maybe they always were?. So I started looking at 2nd hand. I came across a pretty good deal IMO - $200 for a 2003 Giant NRS 2. But it needed some work..

I turned it into a rebuild project and stripped it down to the last bolt and bearing. Ended up spending another $300 on parts including new tyre and shimano SLX-M675 hydraulic brakes and rotors.

So now I have a nicer bike than I could have bought off the shelf for the same money (I hope!) and I learnt a lot through the process.

So with my bike finished I took to the streets. I get out 5 days a week minimum and end up doing 10-13km in 30min (avg ~22km/h). On the flat without a headwind I can maintain +30km/h. And with a tailwind can push to 40km/h. Top speed (cadance/gearing being the limiting factor) was 54km/h down hill. I have only been on the bike a month now so expect to be able push a bit harder as I go along.

In the back of my mind I was always thinking of converting to an ebike which is why I specifically looked at a MTB - stronger frames and shocks to smooth the ride. The reasoning behind this is to extend the range I can go thus increasing the enjoyment of riding in new areas. I get bored doing the same paths over and over! This opens up opportunities to head out somewhere new (with PAS), have a ride (without assist) and then head back. I will have to be disciplined to make sure I dont become reliant and actually do put in the effort! I may even consider riding to work (25km).

So the main criteria I believe meets my requirements;
- I still want to exercise
- I want to limit additional weight
- I have a limited budget (cheap is good but not so cheap that its likely to fail)

This is where I am at based on the above;

- Q128C 36v 201rpm @ 48v (or 52v?)
(DD resistance and weight doesnt appeal so thinking geared options are best)

- pswpower KT-LCD3 + SW controller (17A or 20A?)

- 26" x 21-24mm Rim (still looking at options.. )

- Schwalbe Energizer Plus tyre (I already have one installed on the front)
https://www.schwalbe.com/en/tour-reader/energizer-plus.html

Lastly.. batteries
Based on the above I dont know if I can push it to 52v or should I stick with 48v?
I am also not sure if I should go with 4p or 5p

using these cells - LG INR18650MH1 3200mAh - 10A, so between 52 to 70 cells depending on output that is recommended.

I am thinking that a triangle battery case would be better as opposed to a dolphin case?

Lastly, I am looking to purchase batteries 1st, build and test before getting everything else. That way I have a working pack to test everything else when it arrives.

phew.. I did say it would be long winded! Look forward to the feedback

 

[eCue]

Hi bl4s7er , I like your idea building the battery they are costly, you will get the bike built and on your own time without going into debt those costs add up fast.

My kit buying experience

After I bought the front wheel found would have to wait two months for the battery to be delivered so if i waited it would be three months.
So spent about the last of my money on it and will have a quiet month ..

the kit was pieced together from various sellers for $600 , $300 for the battery $300 for the front wheel / hub motor and a controller.

The wheel ended up on a flight the battery got the slow boat from China literally as its reported to take 8 to 9 weeks. Could have payed $70 more for faster shipping but did not have it to spare. Once the bikes built everything changes it becomes a penny pincher fuel miser ecologists dream

My understanding is you want your battery to be able to pass high amps as *some* smaller AH batteries won't next you want a controller that is matched to the battery from there you control the amount of time the motor is under high Amps with the throttle. There are user set limit settings in the controller as well.

If the battery cannot pass enough amps it will cause a brief system shut down if the controller is of to of low amps you will not realize the batteries potential.

the more Volts a battery has the further the distance you can travel on it even with the same amount of AHs.

Making a 52 volt system attractive as it gives more watts / power or range depends how you spend that power.

 

[d8veh]

Chosing a higher voltage is not for more power. You can increase power by increasing the current if that's what you want. You need to choose the right voltage for speed and efficiency. AFAIK, there's two versions of the Q128C. 48v 201 rpm maxes out at 19 mph on the road with a 48v battery, which would be very efficient when climbing. 36v 201 rpm is actually 260 rpm at 36v and 328 rpm at 48v, the same as the 48v 328 rpm one, which maxes out at about 28 mph and gives a road speed of about 24 mph. It has pretty good climbing power and efficiency for use on the road. All those comments are in relation to 26" wheels. Those speeds are proportional to voltage, so 14S will make it 14/13 times faster at the cost of a bit of climbing efficiency.

For off-road use, 52v with the 48v 201 rpm version would probably be the best solution, and for on-road use, 48v with the 48v 328 rpm or 36v 201 rpm one. 20A is as high as I'd go. I run mine with only 14A, which is OK for me and keeps the controller cool. 20A for a 6 FET controller is a lot, but would be OK if you use the PAS and only use level 5 occasionally. 20A is the maximum current. They're actually rated at 10Acontinuous.

 

[Raisedeyebrows]

If you want to put a battery in the triangle of the frame you need to measure the area carefully and see what will fit in there. You likely have room for a pretty nice sized triangle battery in there.

I remember reading some previous threads here on ES where members built electric bikes off the NRS platform, there is likely some useful information if you find those.

 

[d8veh]

If you want to put a battery in the triangle of the frame you need to measure the area carefully and see what will fit in there. You likely have room for a pretty nice sized triangle battery in there.

I remember reading some previous threads here on ES where members built electric bikes off the NRS platform, there is likely some useful information if you find those.

I'e built a couple of NRS ebikes. The dolphin and shark batteries don't fit in the medium sized frame.

 

[bl4s7er]

Thanks for the replies. I will keep following up as I progress with the intention of having a complete build thread by the end of this.

I have a 20.5" frame (large?). I've been working on an idea to allow both balance charging individual cells as well as standard full pack charging (more to come on this once I have something together). To pull this off I will not be able to use a dolphin style battery. I have been looking at using a bag instead, something like this.

I've just measured up the triangle and it looks like its going to be a perfect fit. I will be attaching to the top tube (obviously) and the front of the downtube - so it doesn't get in the way of the rear shock.

I did some range calculations using this http://www.electricbikerange.info/Electric_bike_range.html

Based on this I have decided to just go with a 14s4p battery which will give me plenty of range. The batteries I was looking at - LG INR18650MH1 3200mAh are no longer available so I am currently looking at other options.

 

[Voltron]

Many times the normal shark pack won't fit because the bottle cage mounts are too far back and the battery hits the seat tube. But if you can find a bike shop with the rivnut tool you can pre drill your own hole more forward, and have them put in the rivnut, or pay them to drill the hole too. I usually put in two so there's three total holding the battery.

 

[BigJulie]

I'm watching this build with great interest as I'm about to embark on the same journey !! Attempting to fit a Lekkie Summit Pro kit (with the monster 17.5 Ahr battery) to my NRS frame.

My greatest concern at the moment, apart from "will it fit" (just - I think), is "will it stay on" ?? Any thoughts from anyone about the robustness of rivnuts in light alloy downtubes holding a big battery cradle in place ??

 

[bl4s7er]

That's precisely why I opted for a bag that straps to the frame over a dedicated battery case (dolphin).

Having to add additional rivnuts just to secure it properly and even then stress must be quite high. Plus no shock impact since all vibration etc will travel through the frame to the case. Lastly I plan on rigging up the batteries to allow for both balance charging and full pack charging which couldn't be a done easily with a typical battery case. All in all a bag just seems a better option.

Lastly just an update for the build ( it's going to be a long process since I got a limited budget to put towards it)
I have ordered components to build a battery charger and battery pack (cables, connectors, bms, power meter), plus the bag I posted earlier. Once all this is built up and working I will order the cells. Finally I will order the hub and controller.

I also need to get a rim and spokes. Been looking at the SunRingle MTX31. Also a new cassette (CS-HG80) and chain.

So yea still lots to get..

 

[LewTwo]

Many times the normal shark pack won't fit because the bottle cage mounts are too far back and the battery hits the seat tube. But if you can find a bike shop with the rivnut tool you can pre drill your own hole more forward, and have them put in the rivnut, or pay them to drill the hole too. I usually put in two so there's three total holding the battery.

My rivnut tool kit:

Be sure to use STEEL rivnuts not the aluminum ones.

 

[BigJulie]

The underslung battery bag concept looks like it might be a better way to go. I'm bit wary of having a heavy battery hanging off 3 in-line rivnuts that are really designed for a water bottle.

The bag could also be supported with additional velcro straps, big zip ties, or even a "super-circlip"

Thanks for the feedback, forums are the best !!

 

[eCue]

You can use the water bottle mount points to secure a aluminum flat bar frame to that can be designed to securely hold the loose frame bag. My thought is to use rivets and washers to mount the pack material onto the aluminum frame.

In short make a reinforced soft sided battery pack out of a frame pack

The Bushwacker fargo cost 15 to 20 dollars