Cowardlyducks - E-BikeE builds

Lurkin said:
Is it possible to solder the wire connection on first to nickel strip, then spot weld the nickel to the cells to be joined?
I did think about this, but it's not ideal.
The only way it would work is if enough nickel was still showing after soldering to get enough spots welded on. More possible with thinner wire, but then it's easier to just do it after the fact on the cells.

I'm past the point of experimenting now as the pack is nearing completion. I had another idea to make the another 'hybrid' approach. I will 16awg (x2) for the shorter main discharge positive connection, but for the longer one, I will use 16awg at the cell connection points, then splice to 2 x 14 awg for the long run up to the other end of the pack. I would use 12 or 10awg, but I need to keep the height profile of the pack lower in order to get it to fit in the frame.
I'll just have to hope the heat from using the 14awg on the 2S section doesn't negatively effect the cells. I won't really know until I've cycled them a few times anyway, but at least if it has I can easily enough switch back to 12S while I replace that section.

Cheers
 
Using 20awg wire and pre heating the solder with the butane torch so it's extra hot really seems to be helping.
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I also wrap the cells in a wet wipe to keep them cool which also seems to be helping and so far they only get mildly warm at most. :)

Now after seeing/reading about how non insulating the cell wraps are over here, I'm going to start adding some heat shrink between each series group to protect against shorts.

Cheers
 
I've still been making progress on the pack build, however slower now that I'm back at work.

I've been finding it increasingly hard to keep the pack lined up as it grows in length. I was thinking it would be easy enough to keep it aligned using a flat surface and aligning it by hand, but after removing the glue and re-gluing some sections over 5 times to get it right, I decided I needed some kind of guide.

Well it just so happens that within reach all along on the dining table was a perfectly sized napkin holder. So I put it to use and was able to glue the whole second half of the pack together almost perfectly straight.
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Fingers crossed that once I join the first half to the second it will all be straight enough to fit inside the frame still.

Cheers
 
Allex said:
If your cells heat up or you have difficulties solder a 8-14AWG wire then you dont have a good enough soldering iron or wrong tip(to thin)
I did wonder that, but I use a Hakko 888 soldering station that can go up to 480C and I only just recently replaced the iron/cable section as it wasn't much more cost than a new heating element. I'm using a standard sized tip, and use solder flux also. I am using lead free solder which I know doesn't help, but it's melting point is still 220C, well below the iron. I'm planning on putting together a video of the whole build so will be sure to include some soldering action so you can see how I do it. AFAIK I'm not doing anything wrong, but I do wonder if my Hakko is fake or something else is up with it as it doesn't seem to hold heat very well once it's sinked to a large mass.
Regardless, combining it with my small butane torch does the trick of getting it extra hot and keeping it hot.

The builds almost done. I'm down to 2 x 6S sections that I now need to join together, but do so keeping everything as straight end to end as possible or I risk it not sliding into the frame cleanly.
It looks like my length measurements were spot on and it will fit with a small amount of room to spare. :)
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Now I just hope I haven't build it too tall, but a visual check shows it should be ok. I still have to add the main discharge and balance wires which will add some height. I'm still confident it will fit, but it may mean I can't fit any other wires or cables inside the frame. That's ok, as I was expecting to have to route everything under the frame anyway, but was hoping I could keep some things inside the frame still. We'll see.

I did buy a bunch of stick on cable guides, but they turned out not to hold to well when they get warm which they will definitely do on this frame.
Anyone have any suggestions as to how I might tidily route all my cables/wires under the frame?

I'm still far from finished though. Even once the battery is complete, I still have to mostly strip the bike in order to mount it. When I built this bike nearly 2 and a half years ago, I had to cut all the wiring for my CA, throttle, etc in order to feed it all into an old DVI cable that I then routed through the frame and re-soldered to the cut off connectors. It's not possible to pull those connectors back through the frame holes, so I will have to cut and re-solder everything again in order to re-route it all outside the frame now. :roll:

Cheers
 
It not the temperature but the mass of the tip.
You can go to 1000C with a small tip without doing any action at all.
So you need to have a large tip when doing work on cells and thick wires

If I work with this 2mm tip
http://www.ebay.com/itm/OKI-METCAL-SFV-CH20-SOLDER-TIP-CHISEL-30DEG-2-0MM-/361730562341?hash=item5438d25925
It will only heat up small wires up to maybe 16Awg
if I go to 5mm then I can to some more damage and it will solder wires up to 10AWG
http://www.ebay.com/itm/OKI-METCAL-SFV-CH50-SOLDER-TIP-CHISEL-30DEG-5-0MM-/142113808875?hash=item2116a4a1eb

When doing work with 8AWG then you need something beefy like
150W
ersa_230-150-2.jpg
 
Thanks for the 'tips' Allex. :) It makes sense what you say and I think I do have a slightly larger tip, so I will try that for the main discharge wires and see if it helps. :)

briangv99 said:
Hey CD, I've found that solder doesn't flow/stick well to the area with spot welds, if you solder your wire to clean nickel you should get a much cleaner joint and less heat transfer to the cells.
Thanks mate! I have been hesitant to solder to the area's between the cells for fear of the heat wicking through and damaging the insulation on the positive side.
Using my method with the butane torch and solder flux I found there is always a few area's that still stick the solder well enough to make it work on he spot welds.
However I think I will heed your advise for the main discharge connections as they will be that much more tricky. Thanks!

To potentially answer my own question on how to route the cables/wires under the frame. I think I can still use my little plastic stick on cable guides, but I will replace the sticky stuff with good strong epoxy.
These are the guides if anyone's interested:
https://hobbyking.com/en_us/tie-d-wires-cable-wire-holders-10pc.html
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Failing that, I could stick Velcro along the length of the underside, then sandwich the wires between 2 pieces of Velcro.

Cheers
 
I'm still making progress on my battery built, albeit slower lately after a chaotic few weeks where a large tree branch took out our houses power for 48 hours and our main car was stuck getting serviced for 5 days while it was too unsafe to drive.

Tonight I finished off the balance leads. I've attached 2 x 6S balance wires/plugs using 18awg wire. The wire size is a little overkill, but I like the idea of being able to charge at the full 8A my BC168 is capable of occasionally. I also don't want the balance measurements to be too put off by long runs of thinner cable causing small amounts of voltage drop, but I honestly don't know if this is a factor for voltage checking without load. And apart from all that...I didn't have enough 20awg left to do the job, but have plenty of 18awg as I had (have?) plans to start making/selling 18awg balance wires....still don't know if it's worth the effort. :roll:

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As you can see from the last photo above, I'm building up some hot glue on top of the exposed wire runs and nickel strips. This is an attempt to add a bit of an electrical isolation from the frame. I will also be adding a layer of electrical tape, may add a layer of thermal padding, and then heat-shrink over the whole thing...maybe 2 layers. I have to balance the whole batteries height (or it won't fit) with it's electrical isolation and thermal dissipation properties so it doesn't short out on the frame, but can still keep cool in the heat of summer, or under high load. Mostly, I'm just taking a stab at it based on educated guesses...I haven't even measured the height recently so it may already be too tall. :oops: I need to check that. :lol:

I also have some other, very exiting news about the bike. I'm going to pick it up from a LBS tomorrow with a very special new addition....lets see if anyone can guess what I've added to it. :)

Cheers
 
The fingers said:
Could it be a video rear view camera and screen? 8)
Lol

Nah, it's a Schlumpf ats speed drive. 1:1.65 ratio.
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This thing is now the most expensive piece of kit on this bike...worth even more than my new battery. :roll:
With this in place, there will be no more chains coming off and a shorter chain which means a bit less weight. :)

Now I just hope nothing else serious ever happens with this bike like a cracked frame. :|

Cheers
 
I've been getting increasingly concerned about the height of the battery as posted previously.
Before starting out on this endeavour I had thought I had more than enough room due to the cells only being 65-70mm tall and my previous rough measurements indicating I would be fine as long as I kept everything under 75mm.

Well today after adding my hot glue buffer, I measured everything up and reached 85mm :shock: ...bugger!

So I flattened all the hot glue down as much as possible and completely removed it from the bottom side. I re-added some to the same height as the raised wire sections in order to spread any load and I'll cover over it all with electrical tape.
After all that I re-measured and managed to get it down to 76mm at the tallest point:
DSC_3731.jpg


I still have to add the electrical tape, heat-shrink and some thin padding, but if I can keep it below 80mm tall it should still fit...just. Based on my measurements, I've got about 80mm to play with...so I don't think I'll be fitting any wires inside the frame any more. This is gonna be close!

Cheers
 
Alan B said:
The balance wires don't need to be so large. The BC168 suspends charging when it measures cell voltages, removing the voltage drops through the balance wires.

Best of luck with this, I want to do something similar someday!
Thanks!
I guess it's too late to downsize the balance wires now...although while they may not need to be so large to support accurate voltage checking, they do certainly help when it comes to charging at the full 8A the BC168 supports.
I've found that while 20awg, or even high strand count silicone 24awg, can handle 6-8A, it's the JST balance plugs that become the weak point during high amp charging through the balance plugs. Using 18awg allows all that heat to soak back into the wire leaving the balance plugs only slightly warm. On the other hand using 20 or 24awg lets the balance plugs get mighty hot to the point of failure in some cases.

I'll try and post up some lessons learned once I'm done so you and others can benefit from my venture into the unknown. :)

Cheers
 
Yes, the JST plugs are the weak link, then the wires. The larger balance wires help when balance charging.

But bulk charging most of the time, and when balance charging do a bulk charge to 80% or so and then balance charge the rest of the way at 3A or so works great. I find balance charging is only needed a couple times a year anyway, so it hardly matters how long it takes.
 
Your right Alan...and I follow roughly the same approach, only balance charging once in a blue moon or on the odd occasion I want maximum range possible by charging everything up to 4.2V.

Anyway, the potential sizing issues with making the battery fit inside the frame was really beginning to get to me, so I spent the time to disassemble the bike tonight and test fit what I've got so far.

The rear 2S section that is already complete with thermal padding and 2 layers of heat-shrink only just fits. It's a very tight fit, and kinda just squeezes in there without too much shuffling. This was kind of a fluke, but a good one since this pack will be sitting there with nothing below it...I still need to think of how I'm going to secure it, but probably just zip ties with a bit of padding.
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Next I CAREFULLY test fit the main pack. It's currently only mildly electrically insulated with a layer of hot glue on the top side (the bike and pack are upside down in the shots below) and even less insulation on the bottom side. I was extremely nervous sliding it in, but my desire to know if it actually fits overcame my fear of it shorting out on the frame.
DSC_3738.jpg

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As you can see, it currently does fit. :)
I did have it slid in further, almost all the way, but pulled it back out to take the photo's so you can see how tight it is.
I was planning on putting thermal padding on both sides before heat shrinking over, but now I don't' think I will be able to put any on. I think I will still add a thin layer of 1-2mm padding on the bottom side as I have just enough room for that. Interestingly, it looks like I might still be able to fit my CA and other electrical cables above the pack. I'm not too sure about the brake and gear cables though, and given the tendency for those cables to move under tension, I don't think I want to place them right next to my pack where they could easily rub through the thin layer of heat shrink.

Apart from that...this is the first time in a long time I've taken apart my rear wheel drop-out's/torque arms, etc. I really need to do something about all that as it's a real mess and I fear disaster at some point if I don't put some clamping forces on the twisting axle. The dropouts are spreading, my torque arms aren't holding very well, and the bolt on steel drop-out's I added are starting to rust. :roll:

My recent success with designing and having made some replacement clamping torque blocks for my Stealth Fighter has inspired me to come up with a more permanent solution for the Bike-E. Once I'm done with all this battery stuff, I think I'll get to work designing and getting made some similar clamping drop out's for the BikeE. They will have to be either bolt on, or clamp to the existing drop out's in some way, but I'll worry about that when I start designing it.
Would anyone else with a BikeE also want a set? They would not be cheap...my prototypes for the Fighter clamping torque blocks were about $100USD + shipping each. Unless I could get at least 10 people interested, the price would probably be the same as prototypes for just a handful.

Cheers
 
Made a little bit more progress. I properly electrically insulated the top/bottom and ends of the battery with electrical tape. I taped a small amount of padding to the ends and a thin strip along the bottom, then covered the whole lot with PVC heat shrink and shrunk it down with a hair dryer.
This is the end result:
Top
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Bottom
DSC_3743.jpg

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Next I need to sort out the hole left from the chain guide. When I removed it I discovered it was secured with a large timber screw and the other day when shining a torch down the frame I realised it had left some large burrs on the inside of the frame that would tear my battery to shreds if I just shoved it in.
I'm thinking I might try and angle a file through the hole to see if I can remove the burrs, but if that fails I might be able to drill the hole slightly bigger. I'll try and get some photos if I can, but it's really hard to see.

Cheers
 
Attach your file (or other sanding device) to a broomstick and file it from the open end of the frame. PITA but it'll let you reach it. ;)
 
Thanks for the suggestion AW. It's too far down to reach with any pressure being applied unfortunately.

Well today I decided I would defeat this thing, and set about sizing it up.
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As you can see from the photo's above it's no small obstruction, so I tried using a file angled in from the outside of the hole. That made no difference so then I used a dremel with a small grinding attachment which enlarged the hole slightly allowing me to angle and pull it back through to smooth out the inside edges. I was sure this would work, but was surprised to discover it made no difference either.
DSC_3763.jpg

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It was at this point that it dawned on me that what I was seeing was not actually burrs from the hole at all. :oops: I still wasn't sure what it was, but if you look really closely at the first photo down the frame from above you will see the hole is actually just before and to the left of what ever that thing is.
So next I tried inserting a bunch of different things down there to try and dislodge it, and ended up succeeding with a curtain rod.
DSC_3769.jpg

I actually removed these wet wipes and had to shove at it with some force, but then it came loose....and this is all it was:
DSC_3771.jpg


So all that just to remove a bit of gunk. :| :roll: I'm still not 100% sure what it even was, but it looks like some of that black gummy stuff manufacturers sometimes use for various things. My guess is it was part of the original circular padding around the cables which I removed some time ago.

Anyway, next up is some more cable work. I've got some new brake and gear cables coming, and I want to use thicker gauge wire for my solar panel to reduce losses. I'm considering leaving the existing CA, throttle, power, etc wires in place as it looks like they should fit nicely on either side of the top 'hump' of the battery.
I'm also not quite ready to permanently insert the battery just yet. I've been thinking about redoing the heat shrink with a small strip of thermal padding on either side. This would achieve a better thermal connection with the frame, and also help keep it secured while not making it too wide over all so as to not fit. By only placing a thin strip on either side, not taking up the whole height of the cells I think it should make it easier to slide in/out of the frame also. I'm also still waiting on some thermal silicone grease to arrive. The grease is crucial to me being able to remove the battery with ease as I'm only going to be able to pull it out by the main discharge wires and gravity once it's in there.

Cheers
 
A bit more progress on the battery was made the other day.

I decided I wasn't happy with no side padding, and/or a potentially sloppy fit so I removed the heat-shrink and re did it, this time with thermal padding on both sides.
Then I tried fitting it again and managed to put a decent sized tear right down to the bare metal of one of the cells. :shock:
Apologies for the poor quality photo....it's a still from a video and I held the battery too close to the camera. :oops:
Tear.jpg


I "repaired" the damage by adding another layer of heat shrink over the top. Then I set about figuring out how/why it had happened. It turns out the edges of the frame opening are quite sharp. Most of the way down the tapered section it's 90 degrees, but towards the apex the profile sharpens as the cut conforms to the shape of the frame. This is where I think my battery was snagged up and tore.
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I solved this problem with some light dremel work. I might have been able to use some sand paper, but I don't have any on hand suitable for this kind of work. Now I can run my finger down it with some pressure and it doesn't feel sharp.
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The only down side is the anodising finish is now gone, but I don't mind too much in that area anyway.

The battery now slides in a bit easier and doesn't get snagged up on those edges, but because of the 2 layers of heat shrink + thermal padding, it's quite a tight fit. Tight enough that I didn't want to insert it all the way until my silicone grease lubricant arrives in the mail. The plan is to use ample amounts of it to both conduct the heat better and lubricate the battery so it doesn't get stuck inside the frame.

Cheers
 
Today I epoxied some cable guides on the frame underside and installed all new brake and gear cables.

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I'm glad I didn't cut the other CA, Throttle, etc wires as I've only just got enough room in these guides to run the rear brake and derailleur cable as it is. If I ever do have to re-route the other wires I will need to install additional guides or replace these ones with larger ones.

Cheers
 
Cowardlyduck said:
The plan is to use ample amounts of it to both conduct the heat better and lubricate the battery so it doesn't get stuck inside the frame.
I highly recommend adding a good sturdy strap around the battery in the least-tight dimension (I'd expect that to be around the top and bottom vs the sides) so you can still pull it out even if it does get stuck (from frame flex or pack expansion or unexpected materials bonding).
 
amberwolf said:
I highly recommend adding a good sturdy strap around the battery in the least-tight dimension (I'd expect that to be around the top and bottom vs the sides) so you can still pull it out even if it does get stuck (from frame flex or pack expansion or unexpected materials bonding).
Thanks for the suggestion AW.
My original plan was to use an old leather belt, then when it became clear the fit would be tight I had the idea to use some rope or string. However, now that I'm done, I can't see how I will fit anything like that.
I think worst case, if it does get a bit stuck, I can tip the frame on it's end and jolt/hammer it on it's end using gravity to slide the battery out. I can also insert something thin down the now unused cable holes and push the other end of the battery a bit if needed and if things get really bad, I can heat up the frame to expand it a bit.
So with those removal options in mind, and considering the fact that I've already finished wrapping the battery, do not have enough heat shrink left to do it again, and have practically no space top/bottom, or side to side to work with, I think I'll just leave it and hope for the best.

If I were doing this whole build again from the start, I wouldn't use any copper wire for the series links, and just layer more nickel. I would also thread the balance wires through cell gaps so they could all be on on the top, leaving the bottom of the battery completely flat/flush with the cell bottoms. This would have given me an extra 2-3mm of height to play with allowing all wires/cables to remain in the frame. It might also have allowed some string to be layered under the heat shrink for pulling the battery back out again.
I would also have put more effort into keeping the whole pack straight side to side, which might have given me a bit more wiggle room along the side of the pack.

Cheers
 
Then the best recommendation I can make is to secure a stiff hard plate to the end of the pack that goes into the frame first, so that whatever you have to use to push it out from the inside of the frame will spread it's load across the entire face of the pack, and not just on the one spot (risking damage to stuff inside the pack).

It's probably not going to be used, and probably unimportant...but if you do need to do it you can't do it if you didn't already do it before putting it in there. ;)

I only bring it up at all because I've gone thru this with various projects of different types over the years, where if I had planned ahead to get whatever it was out of the other thing, I wouldn't have ended up cutting up the outer object to get the inner one out, or smashing the crap out of hte inner object to preserve the outer one. :oops:
 
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