GM1000W on 20s lipo "re-build" thread

[mike662]

Hello everyone,

So for the past month and a half I've been reading about how to increase the top speed of my bike and things are finally starting to piece together. I've been meaning to start a "re-build" thread for a long time but have been too lazy. I finally have some time to do a write-up of what I've been up to since I started my quest. I've tried PM'ing a mod to see if this is the right section to post in but I've had no replies in the past week so I'll just post here anyway and mods feel free to move it wherever appropriate

So, my current setup is a 1000W Golden Motor rear hub running a 48V12ah li-ion battery and a stock GM controller (not sure how many fets but probably not many as it is TINY).
Here's a pic of my old setup (controller above battery):

And here's a pic of the new setup (controller and extra cables fit into the front tube bag; battery is off for winter storage, hence the previous picture so that you can see the battery):

So top speed with this current setup is around 40-50km/h and acceleration is, well, weak Don't get me wrong, this was a great setup to start with, but as time goes by you end up wishing you had, more...

So when I first started looking for what to do to increase my top speed, I was a total noob and all I knew was that I needed a higher voltage and probably a new controller. After tons of research and help from so many people on this forum, I've come up with a list of stuff to buy:

- 11 hardcase 4s5ah20c lipo packs from hobbyking (USA warehouse) for a 20s2p configuration and one battery as a spare/auxiliary power source for lights. http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack.html

- Hua Tong 72V 1500W controller for $33 from dhgate.com (more info about the controller here: http://endless-sphere.com/forums/viewtopic.php?f=2&t=29469)

- 2 Meanwell (clones) S-350-48 power supplies, connected in series for 82V bulk charging. Bought from ebay from seller anna758595 but I can't find them there anymore. $73 for the two

- 5 balancers from ebay for $18.58 a piece http://www.ebay.ca/itm/260753810568?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

- 6 low voltage buzzers (1 to spare) http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=18987

- Doctorbass's torque arms 8)

- Large screen cycle analyst direct plug-in. I snipped the plug and wired the 6 wires directly to the controller. I'll make my own harness for it eventually, but for now this will do

- low-profile backpack for the batteries ~$21 http://www.ebay.ca/itm/170647357372?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

- downhill full-face helmet http://www.allsportprotection.com/Demon_Ricochet_Helmet_p/dd0003.htm

- body armor http://www.allsportprotection.com/Demon_Proline_Combo_Pack_p/ds9908.htm

- random misc. parts such as turn signals, switches, cables, relays, mud guards, headlight, etc.

Here are HK buddy codes for some of the things I bought, in case you'd like a discount :wink: :

10AWG wire
Red http://www.hobbyking.com/buddy.asp?code=816052C1-91A1-4EA4-8F7C-FF52261EBAEB
Black http://www.hobbyking.com/buddy.asp?code=0EAD8665-01A0-4D12-B389-106E2FB6C53D

16AWG wire
Red http://www.hobbyking.com/buddy.asp?code=07D0110E-9FAB-469A-B045-DEFBEEEC71E3
Black http://www.hobbyking.com/buddy.asp?code=05DE7F0F-392C-4F98-B71D-15C26771D212

10mm heatshrink
Red http://www.hobbyking.com/buddy.asp?code=5F8FCD79-C2F6-46F5-BC97-94D59E3AE151
Black http://www.hobbyking.com/buddy.asp?code=B8AE934C-B37E-49F7-A297-F6FA8F672F22

4mm bullet connectors http://www.hobbyking.com/buddy.asp?code=AA9F236F-F35B-4DD8-B5B0-105737CADA1D

100mah lipo for my mini-helicopter http://www.hobbyking.com/buddy.asp?code=398D2B44-2EA3-4DA9-A042-5818FECC3F7C

So, first I waited what felt like a crazy long time for the batteries to come into stock at any of the HK warehouses as the hardcase are the best bang for the buck lipo. The USA warehouse received stock after a short while but unfortunately they won't ship to me in Canada. So I had them send it down to the border and I picked them up today. That way I got free shipping and all I had to pay was for some gas and a few dollars to pick up the package. To ship from China was ~$86 I also sent my protective gear there as well since they offered free shipping to the US.

(So here's where I get a little ticked off because when I hit preview before posting, it wanted me to log back in to ES and my post got deleted. I had it backed up in notepad only to this point so everything past here is me writing a little angry so I might have missed some stuff)

I was at my parents' house in Hamilton for the Thanksgiving weekend (Hamilton is only about 40 minutes from the USA border) so I went to pick up my batteries and protective gear today. I brought one of my balancers to check the cell voltages and to my great relief/surprise, all the packs had their cells within 0.02v of eachother, except for one. The one pack had readings varying from 3.84 to 3.87 so hopefully after a few cycles it doesn't go bad. I'll just use this pack to power my accessories. I later tried my other 4 balancers and they all read within spec as well, although the voltages were slightly different between the balancers of course.

Here are pics of what I picked up today:

The protective shorts were free so I'll just use them for snowboarding as using them on a bike over regular pants or shorts would just not work very well :?

Here are the Meanwells, both modded with voltage and current limiting pots. Only one needs to be current limited but I put it in for redundancy

The balancers

Controller

Videos of first tests with the controller and Meanwells before I got the batteries:
[youtube]D0WpP6ppzsU[/youtube]
[youtube]KlUjrADl78Q[/youtube]

My goal with this bike is to make it as stealthy as possible, but powerful at the same time. The batteries will be in a backpack, the controller I'll fit in between the pedals at the bottom of the frame (which I'll have to remove the suspension temporarily to get the controller in there). The front tube bag which currently carries my controller and extra wires will probably be gone, but I'm thinking I may need it for my extra hardcase battery that will run my accessories. The hardcase won't fit in the bag itself, but I only need 3 of the cells to get close to 12V so I'll have to take it apart anyway. We'll see what happens 8)

For now I'll have to wait on the post man to bring me my cables and connectors at the very least so that I can get the batteries all hooked up and tested. Hopefully Doc's torque arms will come in tomorrow so I can get those put on ASAP as I'll need them before I do any real testing. I'll update as new things start to come in or are tested.

Any questions/comments/suggestions are happily welcomed

Mike

 

[mike662]

Oh and before anyone tells me to get a sturdier bike, I know that this frame is not the best but it is much better than most walmart bikes but still nowhere near real downhill bikes. I've taken this think up to almost 70km/h downhill and it rides smooth and stable and the v-brakes are great and haven't needed replacing in over 6 years (although ever since I made it into an ebike they have been wearing faster, but still have lots of life surprisingly). I don't plan on riding it fast unless it's a road that I know where all the potholes are and if it's nice and straight and empty. And anyway, a new bike would cost me a few grand, but some good safety gear is only a bill and a half :wink:

 

[iovaykind]

Interested if you can fit 10ah 20s into a slim backpack like that. As you may or may not know, I have the exact same setup (battery, controller, and probably motor) on my second ebike. I had the batteries in the frame and its all nice and dandy, but I decided I probably want something where I can remove the battery. So if you can fit it onto your back, and its not that heavy, I'm all for it and will probably copy you on that respect :]

 

[mike662]

Interested if you can fit 10ah 20s into a slim backpack like that. As you may or may not know, I have the exact same setup (battery, controller, and probably motor) on my second ebike. I had the batteries in the frame and its all nice and dandy, but I decided I probably want something where I can remove the battery. So if you can fit it onto your back, and its not that heavy, I'm all for it and will probably copy you on that respect :]

ES member Karl was the one who originally gave me the idea for the stealth backpack and he took some photos for me to show how his batteries fit. He was using slightly different batteries but it looked like it should work with 10 hardcase as well. I'll take a pic once I get the backpack so you can take a look for yourself.

 

[iovaykind]

I do remember someone else trying to do this too but forgot who it was, you got a link? (edit: never mind found it, sad to see it not work out for him)

Anyway, its really funny..same batteries, controller, and motor, but just realized accommodate same balancers (though I only got two), same power supply haha reading through this thread was like reading through my own.

I think the backpack will work. I put my 20s2p config on the table flat. My 14" laptop covers it. Obviously my laptop is not as thick, but I don't see these being any thicker than my other laptop, in which case the backpack should stretch to accommodate. I'm probably buying a backpack real soon, sounds like a good idea for me to use one (rear rack would be scarier if anything were to break off)

 

[mike662]

I do remember someone else trying to do this too but forgot who it was, you got a link?

Anyway, its really funny..same batteries, controller, and motor, but just realized same balancers (though I only got two), same power supply haha reading through this thread was like reading through my own.

Haha I know, isn't it awesome? What if we had the same frame as well? lol Guess we can help each other out more easily. I just checked your build thread and I totally remember reading through it about a month ago. It was really helpful since it's so similar to the setup I want to do

I'll probably sell most of the balancers after I get everything running well, but for now I wanted 5 so that I can keep the packs balanced on each of the initial cycles. Do you think 1 would be okay just to balance them every once in a while?

Here's a link to the thread with pics of the backpack and batteries overlayed on it: http://endless-sphere.com/forums/viewtopic.php?f=3&t=22831&start=90#p466432

 

[iovaykind]

I have two.. I find that I only use one at any time. And I have a charger that balances also, so that might be why. But for you, I think you should just sell the other four and use one. Balancing is really something that can be done slowly and doesn't need to be done quickly. Also you'll find that you barely balance as good cells stay in balance pretty well by themselves.

One caveat about the backpack, our hardcase packs have the wires coming out the sides rather than the top of the batteries. The picture you showed i've seen before, and our packs will fit just the same, however, our wires will need to be "taped down" so they don't stick out too much. Another thing, even though we have hardcase packs, we may need to build some sort of board, and velcro these packs to them, and then put them into the backpack. I can't see how these would stay in place, but maybe if the neoprene is really strong then a board isn't needed to keep the batteries in place. Just ordered one btw! :lol:

 

[auraslip]

Nice research. It's almost the same as my most recent bike. http://endless-sphere.com/forums/viewtopic.php?f=6&t=29612

Only down side I see is the controller. Why spend so much money for good gear, and then spend pennies on a controller? I dunnu. I guess if you don't know about all the fun features a programable controller has, you don't know what your missing out on

 

[mike662]

I have two.. I find that I only use one at any time. And I have a charger that balances also, so that might be why. But for you, I think you should just sell the other four and use one. Balancing is really something that can be done slowly and doesn't need to be done quickly. Also you'll find that you barely balance as good cells stay in balance pretty well by themselves.

One caveat about the backpack, our hardcase packs have the wires coming out the sides rather than the top of the batteries. The picture you showed i've seen before, and our packs will fit just the same, however, our wires will need to be "taped down" so they don't stick out too much. Another thing, even though we have hardcase packs, we may need to build some sort of board, and velcro these packs to them, and then put them into the backpack. I can't see how these would stay in place, but maybe if the neoprene is really strong then a board isn't needed to keep the batteries in place. Just ordered one btw! :lol:

That's what I thought, that one balancer would be enough. Do you have your balancing wires paralleled or do you just leave them separate?

As for the backpack, it may have arrived today as I got a delivery notice card that I have to go pick up a package at the post office since I was at school when they tried to deliver to the house. I'll go pick it up tomorrow just in case anything else comes in tomorrow as well. It may also be my lvc buzzers from HK. I hope the quality of the ones we bought are good because they seem to be clones of the original (can't remember the manufacturers name right now) but originals cost over $50

I have come up with 3 ways to organize the batteries:

Case 1 (regular backpack in the background for comparison):

Case 2:

Case 3 (the pack on the right of the picture would go below the pack on the left. I just couldn't set it up the right way without the pack falling over):

Case 1 would be best as it gives the smallest width, which would rest on the spine well and fit under a jacket easily. The top right side would be used for any extra cable and a switch that would cut off all the lvc buzzers. The cables would be cut short to be just slightly longer than they need to be. Having the wires to the sides of the pack also creates a little extra padding from the sides and a flat connection between the hardcases since no wires get in the way.

Case 2 is nice because the wires can all be cut down to a super short length. The center area between the two stacks of batteries would help remove any pressure against the spine but it would have to be perfectly aligned. Otherwise, it will probably only hurt the spine even more. The large downside to this configuration is it is super wide and doesn't make use of the backpack's vertical space, so I probably won't be using this setup.

Case 3 has advantages and disadvantages of both case 1 and 2. It is shorter than case 1 and not as wide as case 2. Most of the wires could be clipped but at least three wires would have to be extended to run from the bottom section of the pack to the top.

These are the basic ways I figured of setting up the batteries inside the backpack, but slight variations can be made by flipping individual or stacks of batteries within each configuration. I'd probably duct tape everything together to keep things from moving around but allow the batteries to stay slightly flexible at the same time so the batteries can conform to my back. Any thoughts on other advantages/disadvantages/changes to these different setups is appreciated

Nice research. It's almost the same as my most recent bike. http://endless-sphere.com/forums/viewtopic.php?f=6&t=29612

Only down side I see is the controller. Why spend so much money for good gear, and then spend pennies on a controller? I dunnu. I guess if you don't know about all the fun features a programable controller has, you don't know what your missing out on

Ah yes, I saw your build before. Another thread that helped me plan my build out, thanks And your website helped me tremendously with building the meanwell chargers, much appreciated for putting that together!

I actually wanted to get a Lyen controller initially but wesnewell suggested getting the Hua Tong. After I read through the entire thread about the controller (which was around 20 pages or so at the time, now it's 28 lol), it sounded like an excellent controller for a steal of a price! I was skeptical of purchasing one because of the name brand/cost, but everyone who bought one sounded super impressed. And I've never had a programmable controller nor would I probably ever play with it, so this is pretty much perfect for a student on a budget, like me (hehe, budget. I just compare it to what insurance+gas would cost and it's still pennies. Safety gear has a much higher budget, however). If I need to limit anything I'll just use the CA to do it, even though it's not the best system since it only adjusts the throttle.


Since I'm still waiting for my connectors and cables to come in, I might just wire up the batteries for a 44v configuration and run it on my 48V GM controller for now just to cycle the batteries at a low C. But first I need to find out if the balance wires need to be paralleled or not.

 

[iovaykind]

My packs main discharge plugs are paralleled two by two. Balance plugs I left alone, I couldn't give up INDIVIDUALLY balancing each cell, so I didn't parallel the balance taps (which would also take forever, with no added advantage). My configuration is different from all of yours, I'll take a picture when I get the chance to show what I mean. But mine is basically like this, each line being a pack, I bolded the top right set of two packs to show that there are 10packs total of 4s bricks:

------- | |
------- | |
------- | |
------- | |
------- | |
------- | |

I think the balancers should be fine. I really don't care if packs are a bit off. Honestly, I'm always going to keep it within 3.5-4.1v/cell so these packs will last.

I like your first configuration the best. I'd do the same if my packs weren't permanently stuck together two by two.

 

[auraslip]

I ordered 40x of 4s balance leads. I plan to make 4s4p balance boards out of strip boards. Should be pretty simple. see this thread http://endless-sphere.com/forums/viewtopic.php?f=14&t=32311

The advantage of being able to keep them in parallel is that I can easily monitor the balance of the packs, and they should also stay in balance better. I might make extras once I get the process down.

Programmable controllers are awesome. Cruise control, 3-speed, 120% speed boost mode, not having to mod the LVC - HVC resistors to get everything working, CA functionality already installed. I was one of the first to get those controllers, and while they are a great bang for the buck, I think people are excited about them for mostly that reason alone.

 

[mike662]

I think you may have drawn an extra 2 batteries in your diagram, otherwise I don't understand the drawing lol. But I looked in your build thread and I can see how the batteries are paralleled (I think :lol: )

What a relief, I thought the balance wires needed to be paralleled and I was not enjoying the anticipation of soldering them all together since I would never get the extra connectors in time. This makes things so much easier and ahead of schedule Looks like the only thing stopping me from initial untethered tests of the bike are getting Doc's torque arms put on. They should be arriving in the mail any day now.

Also, you keep your batts between 3.5-4.1? I thought they unbalanced below around 3.7. And what setting do you put your meanwells to? I assume 82V but how long does it take for the batteries to reach that voltage? Or do you set the charger slightly higher and unplug it as the cells reach 4.1v?

 

[mike662]

Ooh I'll have to read through that thread later on as I just had time to browse through it real quick right now. But you reminded me that my balance plugs need to be paralleled since I only have 6 buzzers and 10 packs :x If you get these built soon I'll buy some as I'll need them asap. Otherwise, it's time to get my soldering hands ready

And those are quite the features. I'll probs get a Lyen controller or whatever is recommended at the time and programmable when this one fries. But those features to me are more of a want than a need, so saving the money has been worth it (for now, but we'll see what happens when it's actually on the bike lol). And definitely true, I'm mostly excited because of the price so if I screw something up (first time working on a controller's insides) then I don't lose too much.

 

[iovaykind]

Don't parallel your plugs, trust me. Put lipo buzzers on a few of them and call it a day. You don't need it drawing from every pack and basically being parasites. These packs stay in pretty good balance, and you can always check it once in awhile. It's just not worth the work of paralleling them when it actually makes it harder to monitor individual cell voltage. For reference, I don't put any lipo buzzers on any of my packs. I carry around a little 2s-6s monitor and I check it when I feel like it (most of the time I don't)

My meanwell (clones) are coming in the mail, so I've been charging with RC lipo charger. When it does come though, I'll hook it up so that each cell gets 4.18v. Looking to put a volt gauge on the body, and limit amps to 5 (on a 7.3a system)

My packs have never seen below 3.7v or above 4.2v/cell, but I'm just saying, I won't be running them out of this range so its not a big deal and they won't go out of balance easily, + we prolong their lives.

Glad you understand how my packs are.. the drawing diagram is horrible haha. my arrangement allows for maximum thickness of 46mm and my 14" laptop fits over it so that means it'll fit inside the backpack.

 

[mike662]

I guess you're right about the buzzers. I won't be discharging the batteries past 3.7V/cell so even if a cell manages to drop below 3.3V before all the other ones hit 3.7 then it's probably not going to be worth keeping anyway.

Why will you be charging your lipos at 5A? Since you have them paralleled into two's for 10ah, a 1C charge rate would be 10A, right? 5A is only 0.5C so it would take 2 hours to charge. IIRC, a 1C charge rate is still quite low compared to what the lipos can really take. I guess lower than 1C might slightly improve cycle life, but I would like to have a faster charging rate until I trust my batteries more. Since the two meanwells can produce 700W, at 81V that's 8.6 amps. Is this sound logic or am I going to fry my meanwell? That way, only having to monitor them for ~1.5 hours wouldn't be so bad as I don't want to leave them charging unattended until I know they're acting normal.

 

[rui_fujino]

I had been looking into 72v 1500w Hua Tong controller...but they say it can only take 84v max...but our max voltage is 84v hot so wouldnt it make it risky???
if no one had any prob with it then i might actually get one for fun/spare!
PS: how did u managed to connect CA dircet plug in?!

 

[iovaykind]

Mine are 7.3a meanwell. People say don't run them at full power. So 5a it is at 82v

 

[wesnewell]

I had been looking into 72v 1500w Hua Tong controller...but they say it can only take 84v max...but our max voltage is 84v hot so wouldnt it make it risky???

Depends on which one you get. The single head models I have will both take 24s lipo (100.2V) without a problem. Someone said the double headed model they got only had 75V fets in it. Both of mine have 100V fets.

 

[John in CR]

What kind of current do those balancers balance with? I like the idea of balancing at a chosen voltage instead of at the top of charge. I you decide you have extras, I'll buy at least 2 off of you at cost.

Once you decide to organize those hardpacks, tape them up very well to keep good compression and help stop them from puffing the plastic right at the seam.

edit- Almost forgot...My vote would be no on controller in a bag on any kind of higher power rig. They need to dissipate their heat, not roast in a bag.

 

[mike662]

For anyone who doesn't want to read all this, I made a summary video which can be found at the bottom of this post.

PS: how did u managed to connect CA dircet plug in?!

Look at the bottom right of the picture for the cycle analyst dp pinout.

I cut the connector off and wired each of the pins to spare cables from the Hua Tong controller (ie. I unsoldered the 60/120 degree phase wires and rewired them to areas that I needed on the controller for the CA, and then connected those wires to the CA). Here are pics:

I then connected Vbatt and digital GND to the red and black battery voltage wires, respectively, on the outside of the controller and the Hall wire to the blue hall wire.

To calibrate, I just followed this post (near the bottom) but used my meanwells as a constant current supply instead: http://endless-sphere.com/forums/viewtopic.php?f=16&t=7361&#p110932

Mine are 7.3a meanwell. People say don't run them at full power. So 5a it is at 82v

5A it is then. Are you going to do a fan mod? I don't really see why there is a need to unless you're over-powering the meanwells so I'm not going to.

What kind of current do those balancers balance with? I like the idea of balancing at a chosen voltage instead of at the top of charge. I you decide you have extras, I'll buy at least 2 off of you at cost.

Once you decide to organize those hardpacks, tape them up very well to keep good compression and help stop them from puffing the plastic right at the seam.

edit- Almost forgot...My vote would be no on controller in a bag on any kind of higher power rig. They need to dissipate their heat, not roast in a bag.

The instruction manual doesn't say what they balance with but the same kind on hobbyking are rated for a discharge current of 200~450ma (I don't believe the current is adjustable). I remember reading about a mod you can do to increase the current by replacing one of the resistors on the circuit board. I'll try discharging a few packs with them soon to see more precisely what the amount of current they take is. I'll probably not need more than 1 balancer so PM me with how many you want and what your shipping address is.

Thanks for the tip on the taping. I would have thought the cases would be strong enough but I guess not huh. And I'd never put this controller in a bag. My old one is tiny and has never showed any little bit of heating so it's fine in the bag, but this one is about 4 times as big so there's not even a chance of it fitting inside it anyway. Where I'll be putting it it will get lots of airflow and be well protected from rain as well.


Tonight I may series 3 batteries and try to charge them to 49.2V. I will then hook them up to 1 meanwell set to 49.2V and see what happens. I'll cycle all 11 batteries this way using my golden motor 48V controller so that they experience a nice low current draw to start. I also can't go to full voltage yet as I need to have my torque arms on the bike before that happens.

I also got the lipo buzzers today. Tried one out and they look good and are loud! I won't be needing them anymore though so if anyone would like to buy them, send me a PM. I can also throw in a 4 on-non-on switch if you buy all of them. I was going to use to wire all the ground wires from the buzzers in series with so that I could shut them all off if any one of them goes off. You can see them in action in the summary video below (sorry for the quality, it's recorded on my cell phone camera which doesn't work well for up-close shots):

[youtube]w4DnvJuGFr8[/youtube]

 

[iovaykind]

Nice vid! Wish I had seen this earlier.. the SA cycle analyst not only costs more, but its not aesthetically please because of the magnet and extra tire. May just do what you do since all CA's are technically the same.

Anyway, this is the newer controller right? The one that uses 4710 fets? Have you figured out regen yet? I know that pad x on these newer controllers is wheel lock and not regen, and unfortunately i broke my older hua tong that had regen AND better fets :[

 

[mike662]

This is the new controller with the 4710 fets, unfortunately I haven't played much with the controller yet as my priority is to just get everything running for now and I'll try the different pads after I get all the batteries hooked up. How did you break your Hua Tong?

I tried charging 3 of my lipos in series yesterday and all went successfully. I was worried about getting KFF so I wore some gloves and my new helmet in case stuff went flying Yes, overkill, but I like my fingers and face being un-charred, thank you. The power supply buzzed a little but I don't think it's a big deal. Near the end of the charge cycle the fan started going on and off. When the fan went on, the current dropped and stayed there until the fan shut back off. Near the end of the charge cycle where the current was already low, as the fan turned on the current dropped to -0.01A, the same as it was with the batteries hooked up to the meanwell and the meanwell not plugged into the wall socket. I may do the fan mod to keep the current steady. Is it bad for the current to change like this during charging?

Also, does anyone know why the current rises as time goes by? At the beginning of the charge the current was at 5.04A, then it slowly rised to around 5.20 and then dropped steadily down to almost 0 as the voltage of the batteries neared the set voltage of the meanwells. Again, probably not a big deal but I'd like to find out if it is bad for the charger at all.

I used the balancers to monitor voltage but not to balance at the same time. I later played with them and the balancing function works great and so does the discharge function. The balancers got quite warm when discharging.

In other news, I received Doc's torque arms today along with some off-white DP420 (the black is really hard to find for some reason, and those sources I did find won't ship to Canada). Now I need to go to Walmart to pick up some acetone and clamps! Also, my shipment of wires and connectors from HK has arrived in Mississauga's postal sorting centre tonight, so I'll get the package either tomorrow morning or on Monday.

I have some really big midterms coming up on Monday so I am pretty much stuck studying, working out, eating and sleeping and won't have much time to work on the bike. I may try putting on the torque arms but I don't want to risk messing something up and then being stuck without a bike for a few days.

As usual, here are some vids. I personally like seeing videos of people's stuff as it's easier to see what's going on than having to read it. Plus, you might see something that you didn't think about or had a question about and you can pause and replay to see what's happening. So I try to return the favour by filming what I do. Who knows, maybe we'll catch a live KFF demonstration

[youtube]W_gqcrdm2OQ[/youtube]
[youtube]Gv2xCRCaub0[/youtube]

 

[mike662]

Just a quick update. Wires, heatshrink and connectors came in today. They included about an extra 2ft of 10awg wire of both the red and the black, very kind of HK. Again, I'll be busy until Monday so hopefully Monday afternoon I can get started assembling everything together. I now have all the parts I need to make this baby work!

 

[rui_fujino]

I am so looking forward to your master work! I hope it all pays back in the end!
Have you thought of getting full suspension for the new build??

 

[mike662]

Thanks! The bike I am using is actually a full suspension with a single pivot rear suspension. Maybe one day I can afford getting a real mountain bike but for now this one will do just fine

So my midterms are done (for now) which gives me time to continue the build. I went to the post office to pick up the package that has been waiting there for a week and it was the backpack. So I fit in the batteries really quickly to see what it was like. I used method 1 as shown in my previous post, where the 8 batteries are stacked long side down, and then two stacked short side down beside the first stack. The batteries fit perfectly with room to spare and without stretching the bag at all. The backpack fits well, although it does feel like it hangs kind of low. This is actually ok as it sinks into the lumbar part of the spine, giving the pack an even lower profile look. I could even fit my regular backpack on top of it without a problem. I can't speak much about comfort as I wore it for barely 2 minutes, but during that time it felt very comfortable.

Batteries inside the backpack

Lipo backpack only

Lipo backpack beneath regular backpack

I also tried discharging the 3 lipo's that I previously charged by using the battery ballancers. Here is the data if anyone feels like interpreting the discharge rate of the balancers:

Next up, it's time to create my own paralleling harnesses. I will create 3p harnesses first so that I can use the batteries in a 12s configuration for the first few cycles to break them in. Given all the extra room that I have in the backpack now, I don't mind having some extra cable in there. The only thing to consider is weight but I don't think it will be too much from the cables themselves. Then I will create a harness for the CA-DP to the controller so that I can easily plug and unplug the CA.