Dahon Helios SL electric conversion advice

[Sean McGrath]

okey doke, I have my finger on the order button. Q100C kit, SO6S controller, the 12s 5000mAh hobby king batts, no battery pack yet (I want in integrate them into some kind of back back that holds my laptop that I can pull off (weight distribution on trains). I'm hoping when I get my hands on everything to shave a few grams off here and there and end up with one of the lightest foldable ebikes ever. Very excited

The final, and rather insignificant question - I was going to chuck in the S-LCD3 E-Bike LCD Meter they have (why not?). It says on the page, 'Not all parameters can be set by S-LCD3. Please leave us a message on which parameter you want to set.'

What do I want set???

 

[Deleted member 4366]

While I think about it, there is a danger with lipos. If you drop them or otherwise damage them, they can get a short between the cells. It's like you lit the blue touchpaper. They start smoking, then fizzing, and then burst into flames. From smoking, you have about 30 seconds to put them out in the open. All this can be avoided by taping some protection around them - rigid sheet of some sort. If you put them in a rucksack, use a tupperware box or something. Make sure that the wires aren't vulnerable. Keeping them in a rucksack is OK for riding, but don't carry them round with you all day.

 

[trex]

There is already plenty of speed with the Q100C, why make it more complicated with overvolting? You can have a straightforward frog case, front bag or bottle battery with high discharge rate to support your motor.
if this were my first project, I'd keep it simple to a tried and tested recipe.

 

[Sean McGrath]

I have to say, I really like the idea of the bottle batteries but all the ones I've seen weigh upwards of 3kg which seems unnecessary. Which battery would you recommend trex?

 

[Deleted member 4366]

These batteries are also small light and powerful.
http://www.aliexpress.com/item/36V-e-bike-battery-High-discharge-Panasonic-battery-cell-Multi-Fit-10S4P/754740045.html

 

[trex]

I'd look for a front bag first before ordering the battery. If the bike can fold easily with a front bag, then you can think of putting controller and battery inside the front bag - that you can detach and take inside the office for charging the battery. If not, then d8veh's universal bottle battery makes a good choice.
You can buy it from ebay too, in case you worry about warranty.
http://www.ebay.co.uk/itm/Electric-Bike-Battery-Bike-E-Bike-36v-9ah-lithium-battery-Folding-Bike-/310870656937

John Galvin has found an elegant solution to fit a frog battery to the front.

http://www.pedelecs.co.uk/forum/threads/fitting-a-pas.18556/

 

[Sean McGrath]

thanks for the links and input guys. All of these batteries seem to weigh 3.5-4kgs though. Looking at the weight of the LiPos, I could get two 5s 10Ah (not overvolting right?), whack em in a light weigh aluminium case, pop them in my front bag - for less than 2kg. And they cost twice as much. Is there a performance difference or is it simply that I'm more likely to go down in flames (literally)?

 

[trex]

I am sure there are plenty of members who have used cheaper Lipo solutions for years without problem. The risk is possibly only theoretical but sufficient to make sure that none of the e-bike manufacturers wants use them. Trust me, they are interested in its high discharge capability. So Lipo remains in the domain of self builds. If you want to use Lipo, get yourself an empty frog casing (d8veh may have a few kicking about in his shed) - get one 10S brick and see. I've been looking for a ready made protective circuitry to protect Lipo from low voltage and over current dangers but could not find anything. The other issue is the temptation to fast charge Lipo because you can. Of course Lipo can handle that but it's to the detriment of its life.
http://www.hobbyking.com/hobbyking/forum/forum_posts.asp?TID=37017

 

[Sean McGrath]

Forgive my niavity but will I still get the same mileage on a 10s5ma? The highest capacity I can find on hobby king for a 10s is http://www.hobbyking.co.uk/hobbyking/store/__34598__ZIPPY_Compact_5800mAh_10S_25C_Lipo_Pack_UK_Warehouse_.html?strSearch=10s which weighs in at a very respectable 1.2kg. And we all agree I'll be able to get 15mph without pedalling on this?

 

[trex]

36V * 5.8AH = 208WH. The power consumption will depend on how hilly the terrain is, assuming 15WH/mile on flat terrain, using a lot of throttle, you'll get 14 miles max.
you can get the speed, 15mph without pedalling, but for the range, it will depend how low you will want to let your battery drain to.
If you want to be on the safe side, you don't charge too much and don't discharge too much, you end up with using only 50%-60% of the available capacity. If you want to use more, you'll need to install cell alarm. Because you can't use 100% of the battery capacity without sophisticated monitoring, I'd say 8 to 11 miles.

 

[Deleted member 4366]

You can buy it from ebay too, in case you worry about warranty.
http://www.ebay.co.uk/itm/Electric-Bike-Battery-Bike-E-Bike-36v-9ah-lithium-battery-Folding-Bike-/310870656937

Not that one. It has a low discharge rate, so probably crap cells. It's also very expensive for what it is. The one I linked to has high discharge high capacity Panasonic cells and only weighs 2.5kg.

 

[Sean McGrath]

And so it begins. Finally got the bike (woop!). Needs a clean up. Rode it home. Very responsive and fun. I've also ordered my parts from BMS. Slightly concerned though, and this is probably really dumb of me. The wheels are not 20" as far as I can tell (pic below). Nor are they 16". Is it because the tyres are so thin? Have I ordered the wrong wheel size :|

 

[Deleted member 4366]

That looks OK - the same as BMSB 20" rims. There should be a size written on the tyre, like 37-406. It's the 406 that's important.

 

[Sean McGrath]

28-406

 

[Deleted member 4366]

The BMSB one will go straight on once you've squeezed it in and centralised the rim. Start mugging up on how to dish a wheel if you don't already know. There's videos on Youtube, I believe.

 

[Sean McGrath]

So after months of waiting my parts have arrived! Still not chosen a battery but have plenty to be getting on with. I changed the cassette out and squeezed the wheel in, just to see what it would look like. Just like you said d8veh, it fits (JUST!) but man it looks wonky. I'm hoping the dishing will sort that out. I'm keen to get moving on this ASAP so rather than order a dishing gauge and wait - do you think my bike shop will dish the wheel for me? Woop! very exciting..

 

[Sean McGrath]

You can make the rim central by spacing it on the left side which will make the hub even wider. I think that's just about feasible, or you can dish the wheel, or a combination of both.

Can you explain what you mean by spacing it?

 

[cwah]

I advise you to get this sine wave 48v controller with battery integrated with your Q100C:
https://bmsbattery.com/battery/680-bottle-ebike-battery.html

I have the same thing but on my Q100H and it is really quiet and convenient. It a really lovely kit.


Alternatively, if I was you, I would consider getting the BBS01 or BBS02, which is a bit heavier but that doesn't have so much difference with the Q100H because controller is integrated.
Then add a 52 ring chainring:
http://em3ev.com/store/index.php?route=product/product&path=46&product_id=193

And you'll be able to have speed from low to over 25mph speed.


With your super lightweight helios, you'll soon be frustrated to max out at 15mph when you should easily be able to do that on your human power only

 

[Sean McGrath]

Thanks cwah. I can't fork out $400 on a battery at the moment. Open to alternatives. I agree, 15mph will be frustrating so think I'm going to try 44v setup.

 

[Sean McGrath]

Okay, a worrying development. My mate came round - knows a LOT about bikes. He said that the dishing on the wheel was set up for a single speed configuration. That because the spokes were not crossed (I think he said laced) there would not be enough spoke to dish the wheel far enough over. Said it was dished as if it wasn't going to have a cassette on it. Does this sound plausible? Im guessing sending stuff back to China is a no go? Image of wheel... http://postimg.org/image/keezv4nc3/