Xyster's X5

[xyster]

Images & Stats

[D-Man]

Where did you get the square guages at? How many amps are the batteries good for? I see how low your amp draw numbers are with the speed listed with high voltage. Only 5amps at 20 mph. Nice.....

[xyster]

Thanks. I got the voltmeter and ammeter from allelectronics.com
The batteries used to be good for 1.8c or 59 amps at my 33 amphours. After I damaged some in an overdischarge accident, the pack as a whole only puts out about 36 amps at 60F, and 33amps at 40F.

The x5 really needs 72v and at least 20 amps to really begin to shine. It takes that much to get its 25lb mass rolling quickly.

[Lowell]

Thanks. I got the voltmeter and ammeter from allelectronics.com
The batteries used to be good for 1.8c or 59 amps at my 33 amphours. After I damaged some in an overdischarge accident, the pack as a whole only puts out about 36 amps at 60F, and 33amps at 40F.

The x5 really needs 72v and at least 20 amps to really begin to shine. It takes that much to get its 25lb mass rolling quickly.

From ebikes.ca:

500 Series Threaded Side Cover
0.91 kg (2.01 lbs)

I haven't taken my X5 apart yet, but are the side covers really that heavy?

[xyster]

I haven't taken mine apart either. The covers look pretty hefty don't you think? Are you thinking about getting the threaded cover for disc brakes?

[Lowell]

I haven't taken mine apart either. The covers look pretty hefty don't you think? Are you thinking about getting the threaded cover for disc brakes?

Hadn't really thought about a disc brake on the rear, I was just surprised to see the covers are 2lbs each.

What are you using for rear brakes?

[xyster]

What are you using for rear brakes?

Prayer

No rear brakes in other words...The rear brake lever has been rerouted to an add-on front V brake. There's also the stock front disc brake. There's no mount on the rear for a V type as the bike came with a rear disc, and there was only room in the 135mm drop outs for a three speed freewheel and the hubmotor.

[safe]

So where is the "backhoe"?



You know I'm kidding you of course and I really don't want to generate hostilities because of our different design decisions. Your bike looks like an awesome ride and since it's capable of going into the dirt it's something you could take off road very easily without worry.

It actually makes me ponder making my own off road bike to complement my own road racer concept bikes.

I used to race a little motocross years ago too, so I've loved all kinds of machines. (I managed a 4th place trophy in my one and only race)

You still get the thumbs up by me!

My current mountain bike could be adapted to the 5304 very easily. Hmmmmm... you might actually inspire me to do this... and the 24" rims could be used on either the mountian bike or the road racer... hmmmmm... multi uses... hmmmmmm...

[xyster]

There's no "hostilities" from me. I can appreciate a little heated debate, and some fun at my own expense like the tractor comments without getting all overheated like many/most people (in general, not here) seem to.

My criticisms are that your aero-derived numbers were applied to the geared systems only. To be fair and realistic, if you're deriving stats for a tucked position, you should apply those adjusted numbers to all experimental subjects equally -- in this case the geared system and the hubmotor. Also, don't cherry-pick only the most favorable results to support your case, such as top-speed in a tuck, when the debate covers all areas of performance...after all, we're not running for election or advertising a product we're scientists-of-sorts, trying to uncover and better describe the truth of the matter through theoretical models, emperical experiments, and of course, spirited debate.

[Mathurin]

Woah, no back brake no wonder you were going slow in that vid on ice.
That thing muct be pretty hairy off of paved roads.


Closeup pics of the lights please?

[xyster]

Woah, no back brake no wonder you were going slow in that vid on ice.
That thing muct be pretty hairy off of paved roads.

It brakes much better than I expected with just the front, but yah I do take it extra slow on slick surfaces. This one I always planned as a road bike -- the motor's too heavy for serious off-roading. The off-road beast, with probably the 8lb Puma geared hubmotor, will come later.

Closeup pics of the lights please?

Ye asks, ye receives...

Right now the rear lights are not attached to the bike because the battery box also housing those lights is on the ground upside down because the rack holding it broke. These (3) rear 12V LED pairs are wired in series to that back battery pack containing 150 lithium 18650s in 10s15p (~37V) config. So they can be run independently of the front lights, remaining on at all times main power is on to remind me power is on, and because they draw so little current.

The front string of (6) MR11's are also wired in series, then powered by the total ~72V battery pack including the one's on the back. So it can't work unless the back pack is hooked up. The MR16 in the middle is also on an independent circuit - right now powered by a phantom 12V boost pack of emoli lithium manganese cells that's up next in the ebike project queue after I replace that broken rack.

[Ypedal]

About the 2 lb side cover.. yes.. it does !!!! I've had mine off !

Aluminum side covers would shed some serious weight.... anyone with a CNC with spare time on their hands ??

[xyster]

Good to see you here, buzzz-ypedal.

Free Upskirt Pedal Porn!!!!

To lighten the load on the new back rack, and to provide better balance, today I moved the small box of 2s15p batteries to underneath the midframe box. I rode it around at 30 volts and was surprised to find it'd only pull ~12 amps max. I still don't understand why this should be, but this approximates the results for 24 volts at the ebikes.ca/simulator simulator.

[xyster]

Replaced the back rack with another delta post haste, this time reinforcing the rack's main tube with glue on the inside, and hose clamps on the outside, and lightening the load by about 4 pounds. Hopefully it won't break this time!

If it looks as if it is going too (I had plenty of warning last time as the rack slowly "drooped" from a slight up pitch to a flat pitch), I'll also bolster it from the bottom to the bolt for the rear shock below -- a great suggestion from another user here that'd probably require drilling into the rack however.

I am expecting an order of 30 more of the same batteries. These will be mounted in a box below the front of the seat for a total of 300 (20s15p) on the bike. This will bring my system to voltage parity with other 20s lithium packs, allowing for more accurate performance comparisons, and for me, 10% better hill climbing, acceleration, and range

[xyster]

Just got 29 more 2200mah lithium-cobalt 18650s delivered promptly from all-battery.com. I'm constructing a small 2s15p 30-cell pack to add in series to my bike's pack of the same chemistry.

Originally, I planned instead to make a small 18V 6ah "boost" pack of lithium manganese emoli's -- the cells used in Milwaukee V28 powertools -- but concerns over voltage spikes from the relay damaging the controller led me to take the more conservative route of adding more of what worked before.

Though the specs are the same, the new batteries are a little different than the old one's. The new exterior color is lighter -- as seen in the photo where the green arrow denotes the old style (awaiting this day, I've stored this extra in my fridge for months next to the butter ). The tabs are much thicker, and unlike before, stamped to the end caps uniformly in the same place on each battery. Hopefully resistance through the new tabs will be less.

To construct the pack, I first built the platform on which they'll sit with holes drilled for ports for the XLR charging jacks. Now, I'm lining up the batteries in a row atop cardboard, securing them in place using dabs of silicon glue so that later if I have to, I can peel the batteries apart and replace a bad one, reconfigure the pack, etc.
I folded the tabs so as to make a cradle for the main, 12 gauge power wire, and a second cradle for the 18 gauge charging wire. Doubling the wires in this manner isn't necessary, but provides insurance in case a solder joint breaks, and a little less electrical resistance.

Next up: soldering the first row.

[xyster]

First row done; second row in place. The green arrow shows a placeholder battery to keep the above, overhanging battery in place while the silicon dries.

[xyster]

Finished soldering. Next up is finishing the box, and securing the new pack with homemade shrink-wrap -- tape and cardboard of course!

[Lessss]

Am I misreading those batteries or do you have them in Parallel and series as one large 31 amp hour 7.4V battery?

[fechter]

Xyster, on the side of the battery pack where the cells are jumpered to put them in series, the wires running parallel, will theoretically carry no current, and are therefore unnecessary, at least from a power standpoint. I can see they help hold the pack together.

I was thinking for a massively parallel pack, it might be a good safety feature if the individual series strings each had their own fuseable link to protect against a single cell shorting. Fuses would be too expensive, but a calclulated length of a specific wire could be used as a fuse. I think they make special wire for that.

[xyster]

Am I misreading those batteries or do you have them in Parallel and series as one large 31 amp hour 7.4V battery?

Yep, it's 2-series, 15-parallel for 7.4V nominal and 33ah (15 cells X 2.2ah). This will be added to the other 18-series 15-parallel cells I've been using for about four months now on the bike.

Xyster, on the side of the battery pack where the cells are jumpered to put them in series, the wires running parallel, will theoretically carry no current, and are therefore unnecessary, at least from a power standpoint.

1) do you mean vertical parallel or horizontal parallel ? I'm not clear on of which wires you speak.

2) can you explain why these wires would not carry current? That's a shocker to me! This configuration works in other parts of the pack. But 35 amps is the max I can make this pack draw, most of the time it's around 33-34 amps. Those wires making the S curves are the wires that jumper the two packs together in series, and also connect to the charger. They are 18 gauge. The wires running straight are 12 gauge. Both ultra-flexibility silver spaghetti wire coated in silicon -- solder sticks much better to this wire I've found and it's a real joy to work with in comparison to copper.

After much research at rcgroups.com I learned I probably damaged some cells during the overdischarge event such that they've retained capacity, put lost some current capability permanently. I figured that was the reason for the ~1C max current I'm seeing. Patrick M has the same cells in a 12s8p config and reports 1.8C max.

it might be a good safety feature if the individual series strings each had their own fuseable link to protect against a single cell shorting.

I'm recall Aerowhatt having hundreds of little fuses built for his hybrid SLA/18650 pack. Problem with both fuses and wires:

1) The pack is basically done and until hell freezes over I'm not going to again desolder and resolder it!

2) Space. Where would you put this calculated length of wire?

3) What's the likelihood of an apparently good cell shorting closed circuit while operating within spec? The only cells I've blown up (so far) were via overdischarge from my own ignorance.

[/quote]

Thanks guys for the feedback and suggestions!

[fechter]

Now that I think about it, the low current wires will help balance the cells, but since the current is very low, you could use much skinnier wire, which might be easier to deal with.

I guess I was thinking some of the jumpers (ones that say "most current") could be replaced with fuse wires. Of couse, too late now for that one.

I just keep remembering that Valence video of the lithium battery that has a fairly spectacular "thermal event" after being hit. Having a few cells go off would be better than the whole pack. See the video here:
http://www.valence.com/SafetyVideo.asp

[xyster]

Now that I think about it, the low current wires will help balance the cells, but since the current is very low, you could use much skinnier wire, which might be easier to deal with.

The wires labeled in your pic as high current are the smaller 18 gauge. But, I was thinking by looping it up and down 14 times to connect the 30 batteries, the effective gauge is more like 14x18gauge, whatever that is.

I guess I was thinking some of the jumpers (ones that say "most current") could be replaced with fuse wires. Of couse, too late now for that one.

Fuse wires...like a gauge small enough that it'll burn up if there's a short more than X amps? Wouldn't that greatly increase resistance?

I just keep remembering that Valence video of the lithium battery that has a fairly spectacular "thermal event" after being hit. Having a few cells go off would be better than the whole pack. See the video here:

I watched those videos and studied this issue in-depth before choosing to construct this pack sans BMS.
I perceive the risks of a catastrophic meltdown or damaging fire much less than the risks of me being run over by a car (seriously). I've worked to minimize both risks, but just like I wear a helmet and keep on ridin', I'm not going to add a BMS or other safety system now, unless, upon new evidence, my perception of said risks should change drastically for the worse.

Below is a closer close-up with labels more clearly showing which wires go where. Do you think the loopy 18gauge is OK as far as resistance for carrying 35 amps?

Please excuse the cat fur...curious creatures they are

[safe]

So let me get this straight.

You really are not running ANY kind of protection with your battery pack?

The only "meltdown" was when you allowed the voltage to drop below the safety zone and it burned out about 25% of your batteries. (as you were riding?) Did the fire occur in such a way that you could smell it or feel the heat as you road?

Do you use any protection in your charging or are you simply dividing things up into small units and then praying each one is okay?

(I was just talking with my home insurance company today... is your home insured for a lithium battery fire?)

[xyster]

And here it is all "shrink wrapped" with vinyl electrical tape, sittin' pretty in its almost finished home.

Purpose of the electrical tape wrapping is to:

1) Press backside of wires against their tabs to decrease resistance, and chance of connection failure.

2) Secure bits of solder that sometimes flake off here and there under long-term vibration, preventing one mechanism of short circuits.

3) Provide more strength to the structure.

4) Insulate the wires.

5) Save $ and time finding, buying, cutting and joining special-sized sheets of shrink wrap

I make certain to tape only over the tabs so that the battery's vents are never occluded, and the cells have plenty of breathing space underneath.

Next up: installing pack into finished box.

[fechter]

The wires labeled in your pic as high current are the smaller 18 gauge. But, I was thinking by looping it up and down 14 times to connect the 30 batteries, the effective gauge is more like 14x18gauge, whatever that is.

That's right. It's the equivalent of welding cable. The 35 amps will be divided among all the wires, so each one only carries a bit over 1 amp.

Fuse wires...like a gauge small enough that it'll burn up if there's a short more than X amps? Wouldn't that greatly increase resistance?

If the length of each fuse wire is as short as possible, the resistance will be negligible. Again, since they're all in parallel, the total resistance will be divided by the number of jumpers.