here is some info on 20v yardworks lithium ion

nutsandvolts said:

This is all very interesting. What value resistor did you put in parallel with the original? I wish I had one box the size of a pack of cigarettes that could charge my six batteries in one hour.

Click to expand...

My DMM says about 0.3 ohms, but I thought it was lower; didn't add whatever the connections and wire added. DMM accuracy is lowish at this scale. About 1.5 cm of single strand of picture hanging wire, in parallel with 0.67 ohm wire wound, at end of a few feet of alligator clipped 5 amp RC battery charger cable.

Well, my bridge rectifier and heat sink are about that size... Just wait'll I get some CV mode protection in. Don't want to see more smoked batteries/BMSs.


I pulled my lower 4 batts today. Two were giving me issues and another just started. If batts aren't puffed I'm hoping I can just replace a resistor or two.

I thought I was covered with Torx and Security torx, but my drivers aren't long enough for the width of the hole. Darnit ! Are these security Torx ? Mine are just drivers; are actual torx "screwdrivers" able to fit. Size ? Thanks...

I'm seeing indications on my 4 now charging "good" batts, that 2 of them seem to have 10 milliohms of resistance more than their bank-mate. Once again, could be resistor heat changing resistor value. I think I need something that works better for determing very low resistance values. I've been thinking more about just bypassing the BMSs; but they DO help protect the battery. Anyway, would like to understand more about the BMSs too, and how they might get damaged or be tweaked.

Well, Franktown Radar and my horizontal hand test indicate I might be able to get some riding in now, without rain. I'm REALLY curious to see what kind of range I can get on this bike with at least 4 good batts, using my previous standard test runs. Been disappointed with range lately, but it's been hard to account for the impact of my bad batts and all the switching I did to compensate. Should be fun to run 15 pounds lighter too.

I pulled my son in the trailer this aft. down a dirt/mud road (Baille ?) to go walking on a local ATV trail at end of Terry Fox. With this "kids bike" with bar ends on bar ends looking like some weird sort of chopper bars. Weight probably 330 pounds. Worked fine, even splashing through some mud puddles at tame part of trail.

Shoot; typing this and one of my batts is at 21.7v ! No wonder my BMSs are fried... At least that batt seems fully charged now; 21.00v but dropping slowly. Hmmm, this is the batt with 10 milliohms higher resistance already. I've noted that when a BMS is compromised it tends to be the one in a string that will go high like that.

.

nutsandvolts said:

mikereidis said:

Well, my bridge rectifier and heat sink are about that size... Just wait'll I get some CV mode protection in. Don't want to see more smoked batteries/BMSs.

Click to expand...

Can you make me one of these? Should I call you you mike-guyver?

mikereidis said:

Are these security Torx ?

Click to expand...

I think that some of the batteries have phillips screws, then at some point they changed to security torx, or vise versa. I was able to open a few with just phillips screwdriver, but others didn't work. I'm assuming they are security torx, I wasn't able to see in there.

Click to expand...

Sure why not? I have a dream of one day quitting my day job and building good, cheap ebike/small electric vehicle equipment. Since I've gone salaried I have fewer "excuses" to write off my home office, car and computer expenses. Rev. Can. can subsidize my ebike addiction. Of course production must be done elsewhere, but design and testing here in Canada. Fun thing is, using off the shelf parts like heaters etc. production IS done in China, and only overall design, final assembly and testing is done here. Gee, I think I could get away with paying my 6 year old a few bucks a week for his assistance. My wife a few more bucks, but son probably more helpful.

Stone knives and bearskins...

Gee you must have got some early batteries. My first battery, that came with trimmer, is the first I want to open and it's Torx. I'll have to take batt to store with me to shop for magic tool. Can we share battery serial numbers ? I wrote 4 down somewhere and noted that they all seemed to be in the first 300 numbers or so, but my memory could be faulty.

Just had an "evil" thought that someone could buy batts, rip out guts and return the batts stuffed with heavy filler. I've heard of at least one case of somebody buying something at Best Buy and finding box filled with a brick once he got home. Apparently, someone "returned the item". How do you convince box store returns people YOU didn't put the brick there ? Always open box before leaving store. Lately, they don't even want you to do that until you've paid.

My range last night was WONDERFUL again. 20.7 KM on 2 batts in series, targetting 15, 18, 20 KMH, average 16.2 KMH. From Klock to Aylmer Marina park to past Ruins a bit and back. Batts cut out about 200 metres up start of nasty hills to get back from river level to my home level. I celebrated by running the last 6.7 KM at full throttle most of the way. 29 KMH up the first and nastiest hill on a fully charged to 21.00v (5 minutes after charging) 2 series pack. Since it took 18 minutes (avg 23 KMH) and batts seem half charged now, I guess it was only about 10 amps average. Cut throttle over 32-35 KMH for safety and nightime pothole patrol.

I think the higher internal resistance of the bad batts, whether due to battery puffage or BMS resistor burnage, was killing my range, especially at higher speeds due to I.Squared.R power losses. So at a certain point, it's not worth putting bad batts in series with good ones; range may decrease. Better to save bad batts for 1s "emergency get me home" use.

Up early enough I think I'll try ebiking to work for first time...

mikereidis said:

nutsandvolts said:

mikereidis said:

Well, my bridge rectifier and heat sink are about that size... Just wait'll I get some CV mode protection in. Don't want to see more smoked batteries/BMSs.

Click to expand...

Can you make me one of these? Should I call you you mike-guyver?

mikereidis said:

Are these security Torx ?

Click to expand...

I think that some of the batteries have phillips screws, then at some point they changed to security torx, or vise versa. I was able to open a few with just phillips screwdriver, but others didn't work. I'm assuming they are security torx, I wasn't able to see in there.

Click to expand...

Sure why not? I have a dream of one day quitting my day job and building good, cheap ebike/small electric vehicle equipment. Since I've gone salaried I have fewer "excuses" to write off my home office, car and computer expenses. Rev. Can. can subsidize my ebike addiction. Of course production must be done elsewhere, but design and testing here in Canada. Fun thing is, using off the shelf parts like heaters etc. production IS done in China, and only overall design, final assembly and testing is done here. Gee, I think I could get away with paying my 6 year old a few bucks a week for his assistance. My wife a few more bucks, but son probably more helpful.

Stone knives and bearskins...

Gee you must have got some early batteries. My first battery, that came with trimmer, is the first I want to open and it's Torx. I'll have to take batt to store with me to shop for magic tool. Can we share battery serial numbers ? I wrote 4 down somewhere and noted that they all seemed to be in the first 300 numbers or so, but my memory could be faulty.

Just had an "evil" thought that someone could buy batts, rip out guts and return the batts stuffed with heavy filler. I've heard of at least one case of somebody buying something at Best Buy and finding box filled with a brick once he got home. Apparently, someone "returned the item". How do you convince box store returns people YOU didn't put the brick there ? Always open box before leaving store. Lately, they don't even want you to do that until you've paid.

My range last night was WONDERFUL again. 20.7 KM on 2 batts in series, targetting 15, 18, 20 KMH, average 16.2 KMH. From Klock to Aylmer Marina park to past Ruins a bit and back. Batts cut out about 200 metres up start of nasty hills to get back from river level to my home level. I celebrated by running the last 6.7 KM at full throttle most of the way. 29 KMH up the first and nastiest hill on a fully charged to 21.00v (5 minutes after charging) 2 series pack. Since it took 18 minutes (avg 23 KMH) and batts seem half charged now, I guess it was only about 10 amps average. Cut throttle over 32-35 KMH for safety and nightime pothole patrol.

I think the higher internal resistance of the bad batts, whether due to battery puffage or BMS resistor burnage, was killing my range, especially at higher speeds due to I.Squared.R power losses. So at a certain point, it's not worth putting bad batts in series with good ones; range may decrease. Better to save bad batts for 1s "emergency get me home" use.

Up early enough I think I'll try ebiking to work for first time...

Click to expand...

\


20.7 KM on 2 batts ...with pedaling?

.

here's a teardown and repack of a yw charger...






















it's much smaller now and gets warm but works 4 me
the case i used is a 24v charger...blown
also have to put my connecter on it
but in now fits in by bag and can be brought with me

peace wasp

wasp said:

20.7 KM on 2 batts ...with pedaling?

Click to expand...

Only to get my 6-7 KMH pedal first going. Those nasty hills at the end of my ride are wonderful downhills at the beginning for 7 KM (not ALL hill though). Wish I could give flat land stats but everything is downhill from my place. Made for exhausting home-comings at the END of a day of biking, and a major reason why I've gone electric.

I'll get flat stats some day but for me, the reality is hills.

I should say though, that on my more LRR and aero recumbent I've gotten as much as 44 KM round trip back to my house on 4 batts. This is doing what I call "low speed tourist runs" which suit me on night biking on dark, twisting bike paths with semi-regular surprises, whether open sign holes right on center line or animals or wet tight curves with leaves. Love the wabbits; for some silly reason they run ahead of me on the bike path instead of scooting into the woods.

wasp said:

here's a teardown and repack of a yw charger...


it's much smaller now and gets warm but works 4 me
the case i used is a 24v charger...blown
also have to put my connecter on it
but in now fits in by bag and can be brought with me

peace wasp

Click to expand...

Cool. I see you have vents for the heat to rise vertically. Might want to consider a fan on hot summer days if it's in a hot garage or something. IE, just poing a normal fan at it. These things ARE designed IMO to work (for at least a few years) with no ventilation even if Joe Cdn Tire throws things on top of it, but a bit of airflow never hurts.

nutsandvolts said:

mikereidis said:

Sure why not? I have a dream of one day quitting my day job and building good, cheap ebike/small electric vehicle equipment.

Click to expand...

Cool! You mentioned something about cutoff voltage termination enhancement. When you get that figured out, I would like to order one.
ChargersByMike: When you have too many hedges to trim, and too little time

mikereidis said:

Can we share battery serial numbers?

Click to expand...

The numbers on the boxes must be date or lot codes, I have duplicates

S074713, S075216 (x3), S080301 (x2)

I can't get to the serial numbers easily, my batteries are covered in tape and polypropylene.

mikereidis said:

20.7 KM on 2 batts in series, targetting 15, 18, 20 KMH, average 16.2 KMH.

Click to expand...

Yeah, well if you go slow, you will get good range. Using 2 batteries I was doing 15km but I don't like riding that slow. I ride around with average speed 25-28kph and top speed 42-44kph, 30km trips on 6 batteries 3S2P. I did go 40km once using 2 serial (x3).

mikereidis said:

I think the higher internal resistance of the bad batts, whether due to battery puffage or BMS resistor burnage, was killing my range, especially at higher speeds due to I.Squared.R power losses. So at a certain point, it's not worth putting bad batts in series with good ones; range may decrease. Better to save bad batts for 1s "emergency get me home" use.

Click to expand...

I've been wondering when my capacity and range might start dropping, approx 100 cycles and 2500km and I still have the 30km range full throttle that I started with. I think these batteries are pretty decent.

Click to expand...

Sure. There are many possibilities, but one thought is just to recycle the little circuit board with the 4 charge LEDs, and trigger on the 4th LED going green. I'm sure that voltage could be tweaked too.

On thing I note is that these YW chargers don't seem to be pure constant current, followed by constant voltage. They are "pseudo CC and CV", although current is pretty constant in early charging. But the current is reduced WAY to soon for lowest recharge time. I'm wondering if the charge curve is actually softer than it should be for economic reasons. IE, the charger is limited by resistors set to values to reflect a maximum designed power of the switching section, and the power was kept low to minimize cost of production. Not too surprising for a mere $30.


Yeah must be something else. I see serial numbers are on the internal batts as well as the cases. My second set of 4 batts are also wrapped currently. I will unwrap them after I deal with the first 4 batts I bought:

First one is battery included with trimmer; also the only one of these 4 that has Torx.

JHJDAE050213
JHJCJE050384
JHJCJE050236
JHJCJD050211

So I'd guess the actual production number of these batts are 213, 384, 236 and 211. But did I really get batts in the first 211-384 of production ?

I'm thinking "JHJD" means included with trimmer ? Who knows; enough numbers and we'll see patterns.

Torx is T8, you need a driver at least 7 cm long and less than 7 mm or 1/4". For $4.99 I got Cdn Tire part number 57-3315-0. It's 3" long and works fine. The last Torx on this batt would not release all the way for whatever reason, so I used some pressure and broke the internal screw hole a bit.

One of the two batts I opened has a bit of bulge at the top, The other a bit more on top and some at bottom. Heat rises and top batts get the heat ? One easily came out of case, the other took a bit of prying. Are those "anti-bulge" straps around the batts ? Other than that nothing really looks damaged. Are the batts perfectly flat with no bulging when new ?

I've found the middle batt terminal IS indeed "more negative than negative". I.E. the middle is more direct connection to battery negative. I saw 6 millivolts at 0.66a current, so I though this was a 10 milliohm current sense resistor. Look on circuit board and it says F1, a fuse. Presumably only need for catastrophic when BMS current limit fails ?

There is a 3 big strand current sense resistor.

I'll keep this short for now but I'm thinking of bypassing the BMS (for discharge only, for now at least.) Also might be nice to repackage batts outside of case. 4 cells would be good for 12v stuff. Gotta go...

What's at the top of google search results for "yardworks batteries" ? I'll be editing out my serial numbers later. Not TOO paranoid about Cdn Tire warranty dept reading this thread yet. Others will be more paranoid.

I think I'm going to try 2 of these batts without BMS for a test. I don't think the BMS protects me from my overcharging (I think designed based on YW chargers wimpy limits) so what the heck. BMS may be balancing the cells, but I can watch all cells when charging. If all else fails, the smoking remnants get stuffed back into the cases and returned.

My quick calculations indicate battery in case with BMS etc takes about 1200 cubic centimeters (given wasted space at irregular top). Batt alone, with some room for connections, takes about 600 or half ! Gee I want that compact space and don't mind losing a bit of weight from 8 cases, stock BMSs etc.

An integrated charger/BMS would be ideal. I haven't read the BMS thread here lately, but perhaps I should come up to speed.

Besides, we can start talking 10s, 15s or 20s like the Lipo crowd, instead of these "wimpy" 2, 3 and 4s's. I say we raise our Ps to match them too.

Also would be nice to use taps or spare cells to run all bike accessories. I'd prefer if my lights and computer were "fresh battery bright" all the time. And I want to be able to run a 120vac inverter, first on 12v, later on higher voltages. Self propelled UPS/generator on 2 wheels, but more mobile than the Prius. With regen, you have a human powered generator.


Saving "Lightning Catcher" and "Jacobs Ladder" accessories for the fantasy version, but a big sparking ladder could be useful for theft prevention and expanding the safety bubble via vehicle intimidation.

.

nutsandvolts said:

mikereidis said:

If all else fails, the smoking remnants get stuffed back into the cases and returned.

Click to expand...

The smoking remnants sounds like a good name for a blues band.

mikereidis said:

I want to be able to run a 120vac inverter, first on 12v, later on higher voltages. Self propelled UPS/generator on 2 wheels

Click to expand...

I have an 800W eliminator inverter from canadian tire, also have an 1100W generator from canadian tire. They don't seem to sell the generator anymore but this one is actually small and light enough to carry on my bike. I really don't want to burn fuel though, I will probably sell this one.

Click to expand...

And "charred remains" more punk/grunge/whatever.

The Xantrex chargers are decent for non-sine inverters. I'm ot so sure about Cdn Tire ones; they could be Xantrax OEM, but the reviews on them don't seem as good. I got each on sale, two cig lighter ones, one 300w, one 1000w. 12v all better matched to four 3.7v cells than 5 cells.

Yeah, series hybrid gas/electric bike. The cheap Chinese ones are loud, and seem designed to sit in the garage unused for 2 years before they break (usually from lack of attention/oil changes). But they're getting cheap enough to be disposable.

Yes, I figure it's time for me to bypass the BMSs. They are a pain, and may not be well designed for fast charging, to say nothing of discharging in series with 2/3/4 batts.

Should be able to use the same circuitry, calibrated to 4.2v or 21v with 5+1 taps, or 20+1 taps, for 20 cells or 4 batts in series. I think; will see.

My pictures will have to wait as my camera USB went bad from a pulled cable...

But I have my new BMS-less "20s1p" pack mounted on my bike for a test run tonight.

It looks tiny compared to original 4s; as I said about half the volume. With meter and charger it weighs about 11.5 pounds. Was 15 pounds, but I removed 3.5 pounds of case, BMS, screws etc.

These "training wheel" BMSs have been giving me grief, robbing my precious electrons and turning them into heat. IMO they did nothing to prevent overcharge and relied on wimpy YW charger limits to prevent OC. I don't even think they balance the cells properly, a few of my cells were higher than most of the others. They are the bulged ones. Rest are pretty consistently matched.

Only two things the BMS really did for me: prevent overdischarge at 31amps (but some broke and prevented over 5-18 amps or so), and prevent low voltage which can permanently damage Lithium (and some of those broke too). Yes, I did all the breaking, probably with accidental overcharges.

Anyway, I'm going to roll my own BMS into the system/charger.

Bike feels more responsive. I get a peak of 19 amps now, rather than the previous 18. Weight is lower, especially with the other 4 batts awaiting BMSandCase-Ectomies.

I picked off the white goop and removed the batt voltage sensor (don't think they balance too) connectors from BMS. I will use the same connectors for my own BMS. Can still charge on YW charger hooked to case top and BMS if I want. I need a 20 input voltage monitor solution soon; I refuse to buy AND watch another 16 DMMs.

With good direct, low resistance connections direct to cells, I will try paralleling without diodes. Probably best then if I remove the bulged cells. I THINK I can remove/replace individual cells. Heck, I guess that would allow making these batt packs almost any height with varying widths and/or lengths.

Bulged cells I can use for bike accessories or other projects. I think they work OK, but have higher internal resistance so they show higher voltages (but bring current capability of pack down, and heat up more, thus continuing their demise).


I was hesitant to go this route at first, but having gained experience, and having BMS issues, and seeing the advantages of removing the cells, I'm very happy and comfortable going this route now. IMO, I can still return bad batts after re-assembling into original case, AND the cases no longer get the wear and tear and duct tape marks and so look less "abused" if they are returned.

Must remember to back off at 72 volts or so and switch off and pedal if she gets to 64v.

Now, off to go test this bad-ass 20s3p equivalent batt pack.

.

mikereidis said:

My pictures will have to wait as my camera USB went bad from a pulled cable...

But I have my new BMS-less "20s1p" pack mounted on my bike for a test run tonight.

It looks tiny compared to original 4s; as I said about half the volume. With meter and charger it weighs about 11.5 pounds. Was 15 pounds, but I removed 3.5 pounds of case, BMS, screws etc.

These "training wheel" BMSs have been giving me grief, robbing my precious electrons and turning them into heat. IMO they did nothing to prevent overcharge and relied on wimpy YW charger limits to prevent OC. I don't even think they balance the cells properly, a few of my cells were higher than most of the others. They are the bulged ones. Rest are pretty consistently matched.

Only two things the BMS really did for me: prevent overdischarge at 31amps (but some broke and prevented over 5-18 amps or so), and prevent low voltage which can permanently damage Lithium (and some of those broke too). Yes, I did all the breaking, probably with accidental overcharges.

Anyway, I'm going to roll my own BMS into the system/charger.

Bike feels more responsive. I get a peak of 19 amps now, rather than the previous 18. Weight is lower, especially with the other 4 batts awaiting BMSandCase-Ectomies.

I picked off the white goop and removed the batt voltage sensor (don't think they balance too) connectors from BMS. I will use the same connectors for my own BMS. Can still charge on YW charger hooked to case top and BMS if I want. I need a 20 input voltage monitor solution soon; I refuse to buy AND watch another 16 DMMs.

With good direct, low resistance connections direct to cells, I will try paralleling without diodes. Probably best then if I remove the bulged cells. I THINK I can remove/replace individual cells. Heck, I guess that would allow making these batt packs almost any height with varying widths and/or lengths.

Bulged cells I can use for bike accessories or other projects. I think they work OK, but have higher internal resistance so they show higher voltages (but bring current capability of pack down, and heat up more, thus continuing their demise).


I was hesitant to go this route at first, but having gained experience, and having BMS issues, and seeing the advantages of removing the cells, I'm very happy and comfortable going this route now. IMO, I can still return bad batts after re-assembling into original case, AND the cases no longer get the wear and tear and duct tape marks and so look less "abused" if they are returned.

Must remember to back off at 72 volts or so and switch off and pedal if she gets to 64v.

Now, off to go test this bad-ass 20s3p equivalent batt pack.

Click to expand...

nice mike ...i was wondering who would tear into these first
can't wait to see those pics

nutsandvolts said:

You live on the edge. And you keep that bms-less diode-less case-less pack between your legs?

Click to expand...

At least it's not the snug 10" / 25 cm wide it was before (2 batts side by side with some space for bottom 4). Now I don't even notice it at 14 cm wide, the length of a cell. 84v can shock, when perspired or wires getting pressed into you.

I'm not worried about the lithium so much, more a collision with metal object that ends up welded to my cell terminals and potentially burns from the welding heat. All my terminals are on left now, so left side T-Bone with metal at 3 feet high is worst case scenario. But it might have to through the semi-insulating material my left leg is made of. Unless I ride with my legs/feet "recumbent" on the handlebars like I tried for a minute last night, before thinking about how much emergency manouvres are hampered by that.


Run tonight went well. Cop left me alone. 24.4 KM, avg speed 17.6 KMH,max 35.1 on " big whee" hill at 6.5 KM mark.

Started at about 84 volts or so after settling down from topping up on my own charger at 84.7v. I've read you can extend life nicely by only charging to 4.1v per cell or 20.5v per YW batt.Wonder how much ? I keep thinking some fabulous new chemistry will come out within 2-3 years so only need as many cycles as to get through 3 years.

Going up first, biggest nasty Aylmer Marina park set of hills at 18 KM with battery starting at 76v open circuit. Went 10-15 KMH and ended that set of hills with open circuit 72v. Worst part of hill voltage went down to 63v. Hmmm, maybe some bulged cells have high internal resistance ? Will check; that could cause worse than expected voltage drop and drag down whole pack. Anyway, glad I didn't have some wimpy BMS kicking out on me. Last nasty hill the voltage dropped to 57v and my "manual BMS" compensated by dropping throttle.

I've read that dropping Lithium Mg to under 3v per call when under load induced voltage drop is not so harmful like dropping under 3v open circuit. So maybe "manual BMS" is better. If you're tired and bleeding and just want to get home, you may not care about running them to 2.9v.

BTW, I think zig-zagging nasty hills can raise RPM which at full throttle anyway, improves efficiency. Get some interesting motor noises when transitioning from zig to or from zag.

Arriving at home, open circuit voltage was 71v. Now with bike in garage at maybe 15 celcius, it has risen to 77v 1 hour later; it rose to 75v in first half hour. Some of that is normal recovery; some may be warmth rise; it was relatively chilly tonoght; maybe 9 celcius. These batts are supposed to be worse in cold weather.

Charging heaters moving into house now. $30+ ones are useless as loads; must be some solid state stuff. $25 ceramic is noisy. $20 cheapie has no thermostat but is nice and quiet and fan takes little power. I think this fan is the particularly inductive one that gives me spikes though. It now has 2 cords: one for heater/load, the other for fan which during charging is always running at full 120vac speed.

Price of oil dropping but the heaters will be primary this winter, unless heating oil gets a lot cheaper.

Starting to think of "e-sledding" or "e-windboarding"on frozen river this winter. Batts will warm themselves with internal heat. Just need to find some 120vac outlets though. Probably have some on Rideau Canal. Hmmm, maybe just some studded tires on the bike; is that against NCC rules ?

Pics.

"Experimental prototype" tape securing method:
You don't see the cells too well in this pic (see pic after), but you can see the yellow of their sides under DMM and switchbox/charger. Measuring tape extended to 30 cm. 3 original batt cases are shown. On BMS under 20 cm mark you can see just above 18 cm mark the left end of 3 strands of whatever used for the current sensing.


These are the business end of the cells, with terminals. Red tape covers the voltage sensing connectors to help prevent nasty sparks while still keeping package compact. I used transparent shipping tape to wrap the 4 cell packs together, so I could keep an eye on the packs and their bulges without having to rip off yards of duct tape.


A pic to show size comparison of removed 20s cell pack on left with equivalent 4s batt pack on right. Bet that makes you want to ditch those YW cases.


Mounted on bike. A lot more leg room now. Was "snug" before; now I don't notice it and no pedal interference issues.


Gratuitous pic supposed to be showing my 84.5 volts on right reference DMM before I go ride, but pic got cut off ? Must be my ebikes controller warranty fairy godmum or something.

.

nutsandvolts said:

Hmm yes indeed.
https://www.ktrakcycle.com/index.html
http://www.youtube.com/results?search_query=ktrak&search_type=

Click to expand...

Oh yeah I've thought about that quite often for the long local winters where I live. Apparently they are crap. Fun, entertaining, but completely impractical for commuting. About 2/3rd the way down this thread is the review... entertaining review at that. :wink:

http://endless-sphere.com/forums/viewtopic.php?f=3&t=2853

Not to mention there would be no easy way to get a motor on that thing... forget about front wheel drive... spin, spin, spin. Cool concept though.

.

nutsandvolts said:

Taking the idea custom though, with 5 series motor on treads, would probably be worth a few EV grins.
People around here would go wild if I rode one of those downtown, its all downhill from here.

Click to expand...

Haha.. yeah.. I could see the grins from here! Seriously though if you could wire up a 5305 into that and maybe double the width of the tread somehow I bet it would be a LOT more viable. It's going to be like 28 here tonight with a chance of snow... on Sept. 10th... *sigh*... brought in the tomatoes....

.

pwbset said:

nutsandvolts said:

Taking the idea custom though, with 5 series motor on treads, would probably be worth a few EV grins.
People around here would go wild if I rode one of those downtown, its all downhill from here.

Click to expand...

Haha.. yeah.. I could see the grins from here! Seriously though if you could wire up a 5305 into that and maybe double the width of the tread somehow I bet it would be a LOT more viable. It's going to be like 28 here tonight with a chance of snow... on Sept. 10th... *sigh*... brought in the tomatoes....

Click to expand...

Yeah, that's pretty much an electric snowmobile, no ?

Back to batts/cells:

In the 4 batts with 20 cells, I have 4 bulged badish ones. At rest, they show lower voltages. When charging they show higher voltages. I'm charging now and it's easier with access to all cells, because I simply pick the worst cell, with the highest voltage, and monitor it to ensure it doesn't go above 4.2v. Slows down the charge for the rest, and I'm sure higher internal resistance lowers my pack performance, but it works better IMO, without BMSs than it did when fresh, new and unbulged.

I'm getting the impression it's the physical bulging which actually damages cells. I think that's why they use those super-tight bulge bands around the cells. Interesting to note all bulged cells are either top or bottom cells. My worst is a bottom. Heat has vertical effect...

FWIW here is my voltage readings open circuit, some 20 hours after I finished my run last night:

10:30 PM Wed. Sep 10.

Total: 76.9v

Batts:
19.24+19.33+19.30+19.28 = 77.15
19.33-19.24 = 0.09v variation/range
0.09/19.285 = 0.0046668 variation fraction

Cells: (no decimal points; too tiring)

3836 3841 3845 3842 3839 Top and bottom bulged; bottom has highest voltage charging
3.845-3.836 = 0.009v range Strange that open circuit range is pretty small if this is worst battery

3853 3856 3862 3863 3859
3.863-3.853 = 0.010 range Seems fine

3853 3853 3855 3855 3853
3.855-3.853 = 0.002 range Nicely balanced

3822 3865 3869 3862 3822 Top and bottom bulged
3.869 - 3.822 = 0.047 range Open circuit range pretty big


Actually, I DO have a basic BMS now Overcurrent control in the form of a 30a breaker (Self resetting) and a 30a fuse in series. CB is 12v though; fuse may be same; but I think they're OK(ish). I will see and better than nothing.

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nutsandvolts said:

Are you measuring watt hours used in any way? It would be good to know if those bulged cells have less capacity. It would be better to know why they are bulging. I think someone else on this thread said they had bulged cells too, and not from overcharging. Cycle Analyst is great for watt hour usage, thats the main reason I got one. I know my rough range, but wind can really change power consumption. As far as I can tell, my capacity hasn't dropped yet, or if it has not by very much. And I'm hesitant to open these batteries, I opened two just to look at them, they are working so well that I don't want to mess with them. Of most interest is how well they hold up over time and number of cycles.

Click to expand...

Only measuring watt hours by rough estimation so far. Open circuit voltage is the best indicator (other than maybe an amp-hour meter) of charge remaining on lithium batteries. That 4 LED indicator on batts is voltage driven, and does not (I think) put a load on batts like normal battery testers need to. It just goes on voltage. I've tried to get a mapping between voltage and charge, but my estimates are still too rough. I'll try some more accurate load tests at some point to find a decent mapping.

Watts Up meter would be cool, but haven't gotten around to ordering one yet. With a few A->D converters and some code, I'm hoping to eventually create my own Super Cycle Analyst anyway (with blackjack, and hookers. ). I actually ordered a CA but they weren't ready and I said just ship the rest ASAP please.

Just as something to consider, one could keep the batteries in cases with BMS intact, and still bypass the BMS for charge only, or discharge only, by running thick wires in through top of case. Could also avoid any connector issues. Also possible to run wires to all cells for voltage monitoring, even though BMS is still connected and operational.

But yeah, I was VERY hesitant to do this at first, so I understand completely if others don't want to take the jump I have. Me; I'm not going back now. Too many pros and not enough cons.

EDIT: BTW, I find it funny that there is a "warranty void if sticker removed" sticker INSIDE the battery case on the top. What is that supposed to protect ?? Someone removing the connector thing in the top ?

I DO suspect that returned batteries will be opened, inspected, analyzed and possibly recycled by the manufacturer here in Canada, and that's why they are easy-ish to open. Maybe 100% of first 100 returned batts, and say 10-20% after that; but if they will recycle could be 100%. So I think they WILL notice if people start returning batts that have clearly been modified or replaced with stones or whatever. Probably more than 10 Joe Cdn Tire returns for every ebiker return at least though.

Maybe in a year when batt warranties run out I could place a sign near new batts asking people to sell me bad ones for $10 each or something. Bet they'd have at least 3 good cells left. I think Cdn Tire is banking on selling many "replacement batteries" when warranties run out. That thinking, IMO is why they call them "replacement" and not "accessory" and why Bells Corners store is not stocking them yet. Bet Mgr figures he'll stock them next year; or maybe he's just clueless that equipment won't sell without batts and chargers. Or maybe they want you to buy trimmer first and use that batt on all other equipment.