Self-build bike nearing completion..couple of questions

[morphix]

OK morphix, I bought my Dahon Espresso as a manufactures return. It was a new bike but had problem with the folding being stiff, so it was £100 from Rutland Cycles.

You lucky bugger!

I paid £150 for my bike but I've been selling off all the parts I'm replacing so I will get a bit back.

When I finish this I want to build another folding bike something smaller and more portable with 20" or maybe 16" wheels.

 

[morphix]

2nd Bike Test - Pedal Assist

Quick update on my self-build e-bike...

I installed the pedal assist sensor (was much easier than I thought) and took the bike out this morning for a second test.. Phew, this thing really moves!

I found the highest pedal assist level (there are 6 levels) to be more powerful than full throttle. In fact, I was able to pedal in highest gear (7th) with complete ease from a standing start as though it was 1st gear!

Pedalling in 7th gear I was able to cover a lot of ground very quickly and soon clocked up 3km.. I adjusted the wheel size setting on my speedometer for more accurate speed as last time it seemed inaccurate. I'm still not sure it's accurate. It was showing 36kmph / 26mph going down a very steep hill with full pedal assist and some pedalling. Seemed a lot faster to me, more like 30-33mph. I climbed the very steep hill near my flat and the bike had no trouble at all getting over it in 6th gear with full pedal assist power and some light pedalling. It went up there much quicker than it did last time using full throttle with no pedalling!

I was only out about 20 mins or so as I need to get back for a delivery. The 5Ah battery was fully charged before I left, but very soon one bar, then two bars went out showing the battery was down to 50% power. This was strange because on the first test ride I did using just the throttle at max, the power indicator remained full the whole time, except on a steep hill. As soon as I reduced pedal assist to first level, the power indicator returned to full. I've seen other users describe this behaviour on indicators, so perhaps the indicator is an estimation of how long the battery will last at any given rate of consumption rather than how much power is actually remaining?

I have to say, I much prefer pedal assist to throttle as it just feels more natural to ride this way and I really like the feeling of being "pushed" along! With the 6 levels of assist too, it's great to be able to just set how much assistance you need for different terrains or journey's. The motor is very quiet and you hardly notice it which is a nice bonus.

I decided to keep the battery and controller on the handlebar in the end. I mentioned that I had planned to try moving it to the rear for better weight distribution. I actually bought a rear seat post mounting bag and tried it, but the weight and height of the bag proved to be a problem as it was touching the rear wheel. The only way I can see a rear mount working would be having the bag supported on a rack. I don't like the idea of that as when I install a rack I want to keep it free for luggage!

Besides, I can see no real benefit now to a rear mounting. The front mounting doesn't seem to adversely effect steering and having everything at the front means shorter cabling. I will try to find a handlebar bag that has a quick release mount though as the one I have now is the velcro strap type which is not very easy to remove and put back.

What I need to do next is go out for a proper long test ride and test the limits of the battery for distance, and also do some accurate speed/performance tests. Maybe tomorrow, weather permitting...

 

[flecc]

This was strange because on the first test ride I did using just the throttle at max, the power indicator remained full the whole time, except on a steep hill. As soon as I reduced pedal assist to first level, the power indicator returned to full. I've seen other users describe this behaviour on indicators, so perhaps the indicator is an estimation of how long the battery will last at any given rate of consumption rather than how much power is actually remaining?

It's neither really, the fact is that these simple meters are inaccurate and inconsistent in use, and direct immediate metering of content is impossible anyway, explanation in my article in the Technical Section.
.

 

[Deleted member 4366]

The battery indicator lights only show the battery voltage. When you draw a high current for a long time, the voltage drops because the battery chemistry can't quite keep up (known as "voltage sag"), so when you stop using power it catches up and the voltage increases, although the net direction is downwards as you use up the power from it. I would expect this effect to be more with a smaller battery like yours. It'll be interesting to see how long your battery lasts (life cycle - not charge cycle). Keep us informed. Maybe all the theory will go out the window.

 

[morphix]

The battery indicator lights only show the battery voltage. When you draw a high current for a long time, the voltage drops because the battery chemistry can't quite keep up (known as "voltage sag"), so when you stop using power it catches up and the voltage increases, although the net direction is downwards as you use up the power from it. I would expect this effect to be more with a smaller battery like yours. It'll be interesting to see how long your battery lasts (life cycle - not charge cycle). Keep us informed. Maybe all the theory will go out the window.

Thanks D8veh for that helpful explanation and to flecc for the link.

I have an LCD panel for my controller so the battery is indicated there, but based on what you say I suppose it's not any more accurate than the LED type you normally see.

As you say it will be very interesting to see how well this small battery performs. I have two of them so I could carry the other one in a rucksack or on a rack to get me back home when the first one gives out! Saying that, providing the battery doesn't take me more than 5 miles, I shouldn't have any trouble pedalling home without power as the bike seems to pedal fairly easy.

It's difficult to know how I should go about doing a benchmark test on the battery for range. I mean, do I use the lowest power setting, the highest, or something in the middle? Do I try a flat journey or a normal one with hills etc..

Hmm.. I suppose the ideal way would be to do a benchmark test would be a typical terrain and use pedal assist at a level that makes pedalling comfortable and switch it off when it's not needed on the flat.

Then I could do a variety of separate tests under difference conditions, like throttle-only, full power pedal assist then low power.

 

[piotrmacheta]

Nicely sorted. I tried to get a 5Ah 48v LiPo battery pack and couldn't find one so I ended up buying RC model helicopter packs and series linking them but it means I have to charge them separately which is a bit of a pain. I got some WinForce 30C 5Ah packs and they seem to deliver the current OK (20A max) but I found that really they only give me about 4Ahr till the 3.2V low volt limit.
Can you give me the link to the site where you got yours as this might be a better option for me. Did it come with the charger and BMS? Do you know how many Ah you really get out of it?
Thanks,
Peter

 

[morphix]

Nicely sorted. I tried to get a 5Ah 48v LiPo battery pack and couldn't find one so I ended up buying RC model helicopter packs and series linking them but it means I have to charge them separately which is a bit of a pain. I got some WinForce 30C 5Ah packs and they seem to deliver the current OK (20A max) but I found that really they only give me about 4Ahr till the 3.2V low volt limit.
Can you give me the link to the site where you got yours as this might be a better option for me. Did it come with the charger and BMS? Do you know how many Ah you really get out of it?
Thanks,
Peter

Hi Peter, I ordered my batteries from a Chinese company (YXM) advertising on eBay. He came recommended to me as a few people on the forum have bought batteries from him and said he's reliable. He normally advertises standard size batteries but will supply any size at no extra cost if you ask him for something different.

I paid £167 for two LiFePo4 36V 5AH batteries which included BMS on each battery and a 5A charger and shipping by FedEx. I had to pay import tax and a £10 fee to FedEx which cost £15.88 in total.

Each battery weighs around 1.8kg. I'm not sure about the performance or Ah at this stage as I've only tested the batteries briefly on short distances <30 mins.

Here's the link:

eBay My World - daoji666

 

[morphix]

Rain and more rain..

Plans to go out an extended test ride today have been stalled as it's been raining all morning. Maybe tomorrow....

 

[morphix]

Went for a ride this morning to test 5Ah battery

Checked the weather and there was a 2 hour window this morning between 9 and 12 before rain was forecast so decided to spend a couple of hours out on the bike to see how long the battery would last..

I covered 13 miles and got back feeling exercised a little but not sweaty and not completely cream crackered. As this is a self-build bike (and an untested bike at that as far as conversions go) I was nervous about going too far from home for fear of a mechanical failure and getting stranded, so I stayed in my home town and within a comfortable distance of home...mostly going along bus route lanes and around industrial estates, where there are miles of flat roads and not much traffic.

I rode on pedal assist and tried to stay on the flat, keeping the power fairly low (2/6 power assist level).. I found this not quite enough at times as the road got steeper or on roads where there was busy traffic. I often cranked up the power to 5/6 for large parts of the journey, then took it down to 2 again when coasting along to conserve power.

I found riding in highest gear (7) to be the most comfortable, with 6 being tolerable..7th gear seemed to provide the perfect balance between power assistance and pedalling (with ease) on both the flat and on hills, and so I never needed to touch the gears.

My average speed was 25km/h (15mph) and I rode continuously for just over an hour. The pedal assistance is really smooth and just seems to deliver power when you need it and cuts back when you don't...it seems to reduce down as you approach 15mph, but sometimes I found myself doing 18mph on the flat with moderate pedalling. Going down a steep hill I pedalled like the clappers in 7th gear with power assistance at full, just to see how fast it could go..the speedometer showed 28mph! I think the speedometer is fairly accurate now I have the wheel settings set.

I was a bit later setting off than planned and have Tesco bringing my shopping at 11, plus a load of work to get started on, so I couldn't stay out as long as I would of liked unfortunately and headed back around 10:20

So how did the battery hold up? Difficult to tell.. the power meter on the LCD dropped down to 50% quite a few times, but then would come back to full...when I arrived back it was still showing full power. I didn't notice any drop in performance towards the end of the journey either, the bike felt just as punchy as when I set off. I guess I need to ride it until it actually goes flat which will mean several hours riding.

No problems with the bike itself to report, except some rattling/vibration when the motor accelerates up.. I'm not sure if this is caused by torque force from the motor in the drop-outs (I don't yet have torque washers fitted) or just vibration up the handlebar stem. It's only brief as the motor powers up and goes away once the power is continuous. The manufacturer was correct about this controller not needing brake cut-outs, as the motor does indeed
cut out instantly the second you stop pedalling.

 

[morphix]

Duff camera

I was hoping to have some video from my new camera but it looks like the one I have is dud and doesn't work I've had to send it back for a replacement but 7dayshop have been good about it and even given me a freepost address to return it..

one thing I did notice about this camera, the handlebar mount doesn't fit my handlebar, even when fully tightened. Nowhere near. I guess a bit of velcro underneath should sort that.

 

[morphix]

A little tip..

I had a saddle I'm looking to sell which I removed from my bike, but annoyingly it had the bike sellers logo screen printed onto it. I tried all manner of household products to remove it without any success. Then I thought, I know..nail varnish remover.. and hey presto the printing wiped off easily without damaging the saddle and leaving no trace. I bought the nail varnish remover from Tesco, cheap own-brand stuff only cost a quid for a big bottle.

So there's a handy tip if anyone wants to remove screen-printed logo printing off saddles or other bike gear. Nail varnish remover.

Oh and another handy tip..if you ever have to remove or fit handlebar grips, try using lemon cleaning spray (Tesco's own brand and Ecover work but I think other brands should too), it works a treat. Just spray it under the grips for removing or spray a bit into the grips for fitting..it does something to the rubber and enables them to go on easily, but it doesn't make them loose like using grease or oil does, they stay in place once you got them on.

 

[piotrmacheta]

Hairspray works for fitting and indeed for removing the rubber grips and it magically sticks the grips on when it dries.

 

[flecc]

but you don't need to go looking for hairspray or cleaning fluid when your bike has the ideal stuff with it for fitting handgrips, which also allows subsequent easy removal.

Just a tiny bit of rubber solution in your puncture repair outfit does the job, but push the grip on in one stroke instantly to prevent it sticking halfway. This is what we used to use in the trade.
.

 

[Deleted member 4366]

No problems with the bike itself to report, except some rattling/vibration when the motor accelerates up.. I'm not sure if this is caused by torque force from the motor in the drop-outs (I don't yet have torque washers fitted) or just vibration up the handlebar stem. It's only brief as the motor powers up and goes away once the power is continuous. The manufacturer was correct about this controller not needing brake cut-outs, as the motor does indeed
cut out instantly the second you stop pedalling.

The noise from the motor is normal They make a sort of grinding noise under high load and once you get to about 10mph they go quiet.
Without brake cut-off switches, you can find it difficult to manoeuvre in tight spaces because as soon as you pedal, you get power. The effect can be lessened by just opening the throttle a little bit, but it's much easier if you have the cut-off switches so that you can feather the brake to cut the motor whilst pedalling around bollards or round very tight corners (U-turns).

 

[morphix]

The noise from the motor is normal They make a sort of grinding noise under high load and once you get to about 10mph they go quiet.
Without brake cut-off switches, you can find it difficult to manoeuvre in tight spaces because as soon as you pedal, you get power. The effect can be lessened by just opening the throttle a little bit, but it's much easier if you have the cut-off switches so that you can feather the brake to cut the motor whilst pedalling around bollards or round very tight corners (U-turns).

Thanks for explaining about the noise, I thought it might be just my bike. I didn't realise the noise was coming from the motor itself. I don't suppose you can do anything about that..except perhaps increase speed more gradually but that's not always practically possible is it.

You're absolutely right about the manoeuvre problem in tight spaces. I meant to mention this in my earlier post as I also had problem with power starting at inappropriate times, for example when giving way. I have to consciously remember to either turn the power assist down to zero or switch into throttle mode which I'm not used to doing yet.

I can see what you're saying though and I agree it would be better if you had the flexibility of the brakes to cut out the motor and stop power assist kicking in. It doesn't help either that as efficient as my controller is at stopping power when you stop pedalling, it's equally as efficient at starting it! You only need to half turn the pedal and bam, you're off. And if you're at full power assist, you're really off! Not always good, I had a couple of near misses today so need to concentrate more and keep the power off until it's needed.

 

[morphix]

Can anyone recommend a good place to buy files? I've been trying to find a round file without much luck. I ordered a set of files online but the supplier (Choiceful) sent my order minus the files.."oversold" typical. Just my luck, the one thing I really needed most in the order.

 

[morphix]

Damn. I can't stop thinking about my ride today and I'm yearning to get back out again and go further. I never thought electric bikes would be addictive! Still, if it gets me out the flat more and enjoying the fresh air and exercising a bit, it's going to be a healthy addiction ;-)

I attracted a fair bit of attention today and got looks from quite a few looks from people, pedestrians, cyclists and drivers alike. I haven't seen a single electric bike in my town so far and wonder if I'm the first person who has one.