here is some info on 20v yardworks lithium ion

Stats from my full charge and short run last night:

11:40 - all 8 batts showing 20.97-20.98v after a few minutes of settling after low current top-up charge.

12:40 - Bank A: 20.96/20.91/20.85/20.92
- Bank B: 20.94/20.96/20.95/20.96

1:10 - Bank A: 20.94/20.88/20.80/20.89
Bank B: 20.93/20.95/20.95/20.96

1:12 - 1:47 - a 15-25 KMH local run for 10.75 KM. Bike was reasonably warm in charging garage, but it was a bit cool outside. I used Bank B so I could keep a better eye on battery 3 in Bank A which appears to be leaky and may be returned under warranty.

1:47:30 - Bank B: 20.11/20.11/20.08/20.12

10:00 - Bank A: 20.90/20.83/20.71/20.83 (Keeping watch on batt 3!)
Bank B: 20.21/20.22/20.21/20.22


BTW, another way to look at voltage differences at LVC is that small voltage changes in the 18-21v range are equivalent to much larger AH or WH changes. IE, 0.1v difference at 20v is a MUCH bigger change than 0.1v at 17v.

My battery numbering/lettering/designation scheme has changed so this is a "blind test". Will compare with my earlier discharge stats to see if some batts are truly much better or worse than others.

Keeping the voltages matched makes my manually switched current charging job easier in series. At one point in my charging however I must have tripped the over-charge protection on 3 batts, because one batt showed 21.24v open circuit (!!!) while the others were a good deal lower. Voltage soon dipped to 20.99v range and didn't stay so high.

Would be easier to have four matched, accurate DMMs for manual charging, but I have in mind a micro-controller solution with multiple D to A converters for charging, and charge and discharge analysis. Sort of a cross between an intelligent charger and an ebikes CA. And more, of course. Want a regen controller hooked in there too.

Bought my son a $15 Salvation Army Triumph Rave bicycle yesterday. Good shape, but some rust on chain and sprockets. See one advertised locally for $70. :) 6 speed Shimano, wonderful brakes and tires. Still a bit big for him. 20" wheels. Hmmm. :) It was fun to ride with seat all the way up. Maybe I try my 20" motor/wheel on this thing. :) :) Son can have the $15 "Barbie" bike with 16" wheels I got for daughter until he grows into this 20" bike. Daughter can have his old 12" wheel chopper bike. Everyone is happy. Many wheels now at Reid residence.
 
Mike! I really like your kid-friendly approach to E-bikes. I plan to do similar with my grandkids (14,13 and 10) They get stuff that works OK but I dont use. Nothing wasted! And they learn about E-bikes!
otherDoc
 
strbmx said:
The Batteries went down to $109.99 and the Chargers dropped $10.00 too :)
Click to expand...

Sorry, old news. :)

Latest news is you might be able to get them for $99.99 now. (If cash rings 129.99 by mistake. Read back a few posts of mine.)

Don't really need my YW chargers now. My cheap charger does 4 at once at 12+ amps. Maybe I'll use one if I ever decide to trim the grass again, and buy a batt for that purpose, and as a spare.
 
docnjoj said:
Mike! I really like your kid-friendly approach to E-bikes. I plan to do similar with my grandkids (14,13 and 10) They get stuff that works OK but I dont use. Nothing wasted! And they learn about E-bikes!
otherDoc
Click to expand...

Yeah, the kids can be useful, like for safety testing (Ouch, daddy that light bulb/heater is hot!) and stress testing of components too. :) Just tonight my 6 yr old son detected the smell of burning ceramic heater long before my allergy ravaged nose would have. Seems the standard nichrome heater is just annoying when the fan is too slow to cool the heater and the safety temo switch kicks off. But the ceramic seems happy to start burning it's internal plastics. :(

Tonight I decided to fix my recumbent properly before riding it again. In the meantime, the bike intended for my son, which is too big for him still, was so tempting I couldn't help myself. At 11:30 PM work began, and 1 hour 50 minutes, some wrenching and lots of duct tape later, the job was done.

To keep on topic, here is a picture of my "duct tape integrated battery, control, monitoring, charger, and controller unit":bikedcacrave 012.jpg

Further info and pictures on tonight's creation in my thread: http://endless-sphere.com/forums/viewtopic.php?f=3&t=5749&p=91626#p91626


I want to ride my bicycle, I want to ride my bike ! :)
 
nutsandvolts said:
which uses A123 batteries, which plug into AC and charge in 5-6 hours. The kit also can toggle into original Prius hybrid operation, using the NiMH batteries. I believe she said you can't purchase these conversions in canada yet, but they are testing them.
Click to expand...

I considered A123/Dewalt batts for my bike, and rejected them pricewise in Canada, in favor of these YW batts given the wonderful info in this thread and your reports. (OK, I bought one and thrashed it first too, but you convinced me to make the $200 investment in a trimmer I wouldn't have bought otherwise.)

I've been following the prices for Prius PHEV kits and don't think they are economical yet, in terms of money saved on gas. Part of the reason is that some company is selling these and must make a profit and give warranty etc. So I will likely "make my own kit" given the experience I now have with these batts and that I will gather.

It may sound laughable but I'm going to run the numbers with the prices we're getting on the YardWorks batts. I half suspect I could get close to break-even at current gas prices. And I could start small to test. 10-12 of these batts for $1-1.2k in series would be the right voltage for me, and provide 6ah or so for 1200-1400 WH or so. That's just 2-4 batts more than I already have.

I think I will look for a metal box of some sort (with ventilation/fan hole(s)) to mount these batts in. That would help make them portable between bike and car, or inverter for power failure etc. (BTW, Prius can also be a big UPS/backup gen, with 1KW at 12v and up to 5KW or so at 200+v)
 
I ran a pretty fully matched 2s discharge and charge cycle last night. My theory has been, if batts are good, then batts in series should discharge and charge in unison, and stay matched, as long as the BMS is not tripped on one battery for any length of time (more than a few seconds). Probably more important on charge, as charging still seems to happen on one battery when BMS trips on the other, while discharge BMS trip stops the series config from being useful for locomotion. (And because I quickly drop throttle and switch to other bank.)

My battery 1 and 2 in Bank A both started at 20.97v. I did a higher speed run 25KMH measured average to Trans Canada trail and back. Required going up rather steep (up to 10%) incline on Notch Road where Gatineau Hills start. Speed dropped to 8-9 KMH range on incline, so I added some pedal power (By sitting back on this kids bike) to help. I got 14 KM, or about 14-15 WH per KM.

I don't have the paper with end voltages, but about 5 minutes (?) after trip Voltages were: 16.71 and 17.47. Seems mismatched right ? I think these voltages are just small statistical diffs between the batts and these are the "natural" voltages they settle at, after the BMS tripped on one, at the small current I was pulling at the time (on a slight incline) to get the most KM from them, even though I dropped my throttle setting/speed to get the last few maH from them.

I suspect that if I did this trip again tonight, I would see very similar voltages on both batteries. "Matched" and balanced batts can still show 1 volt or so of difference when run to LVC, IMO.

I charged the 2 batteries in series in exactly one hour and the voltages stayed matched once they had been charged for maybe 10 minutes or so. At end of charge both were showing 20.84v (Matched ! :) ) 5 minutes later they were 20.77v each, and 7 hours later they were 20.68v and 20.67v respectively. Funny, the lower battery at discharge turned out just SLIGHTLY better charged. Maybe because it's lower voltage gave it a bit more charging current, but with only one 100th of a volt difference, it's hard to draw any firm conclusion. Close enough to be same.

I limited initial charge current to 10amps indicated.

I say indicated because I 've seen 5 amps (DC) indicated when my AC power meter indicated 6 amps (AC RMS) being drawn from ac 120v line. Since it's all in series, current must be the same. I think the full-wave rectified DC, with no BIG (and not useful economically since it would need to be very expensive at these volts/amps) capacitor to smooth the DC will not read correctly on a DC meter. I'd say it's 6 amps RMS but that could be misleading too as the batt is not a purely resistive load; it has voltage and when the AC cycle is under that voltage, no current flows.

BTW, I came to the conclusion earlier that half or full wave rectified DC should be OK on these batts, as it's nothing more stressful (except for my higher currents) than inserting and removing the batt from YW charger 60-120 times a second, which I figured the batts could handle. So far, they have. I should note that some of my batt wires are now looking a bit burnt. I think perhaps a few too many charging episodes where the BMS on 3 of 4 batteries tripped.

As usual, I modified the charging current lower as the batt voltages kept rising to 21.00v. 9.5 to 10 amps indicated (perhaps 11.4 to 12 amps realish batt RMS) was good for 10 minutes. So although this is a 12 amp, 2c charger, you can only charge at that rate for 10 out of 60 minutes. I declined charging current to about 1 amp at end, for last 14 minutes (Would have been faster than 60 minutes if I had a load which could do between 2.37a and 0.96a at 46 minute mark.)

I could have dropped charging current even more to top the batts up to 21.00v, but at that point, time spent monitoring and fiddling with switches gets minimal gain in voltage/charge. By charging to 20.84 open circuit level, I pretty much matched the YW chargers which go green at about 20.80-20.81v.

So, when I eyeball/rough calculate these currents and times, I calculate about 4.9ah indicated, or about 5.9ah "real" (after adding 20% for DC/AC RMS issue) going into these batts. Seems about right. Average real "DC RMS" current was about 6 amps for 1 hour, or average 1c rate.


So my conclusions: - Batts that are matched and charged/discharged together in series will tend to stay matched, even though voltages could differ by a volt or so at full discharge.

- It's not neccesary to match batt voltages, but it does make series charging easier and allows all batts to come to full charge in unison. By easier, I mean I don't have to use my battery select switches to charge lower battery to high battery voltage to match other. If you don't have such switches and use them, you can only partially charge your battery set. (1 will be at full charge while others are less charged.)

- Matching batt voltages at full charge also increases your range of course.

- In the end, matching voltages are not necessary, but are useful for extending your range and making series charging easier (or more battery filling). Sort of like two gas tanks with a single filler nozzle that splits exactly half the flow. If one tank start with more gas, you must stop when that tank is full. Since I'm the only one here at present charging with anything but a YW charger, for the rest of you, matching just helps increase your discharge range to the maximum.

Cool. :) I'm pleasantly, slightly surprised that the full charge voltages stayed matched through a complete discharge and charge cycle. Now to look for returnable batts that don't match this well...
 
mikereidis said:
I ran a pretty fully matched 2s discharge and charge cycle last night. My theory has been, if batts are good, then batts in series should discharge and charge in unison, and stay matched, as long as the BMS is not tripped on one battery for any length of time (more than a few seconds). Probably more important on charge, as charging still seems to happen on one battery when BMS trips on the other, while discharge BMS trip stops the series config from being useful for locomotion. (And because I quickly drop throttle and switch to other bank.)

My battery 1 and 2 in Bank A both started at 20.97v. I did a higher speed run 25KMH measured average to Trans Canada trail and back. Required going up rather steep (up to 10%) incline on Notch Road where Gatineau Hills start. Speed dropped to 8-9 KMH range on incline, so I added some pedal power (By sitting back on this kids bike) to help. I got 14 KM, or about 14-15 WH per KM.

I don't have the paper with end voltages, but about 5 minutes (?) after trip Voltages were: 16.71 and 17.47. Seems mismatched right ? I think these voltages are just small statistical diffs between the batts and these are the "natural" voltages they settle at, after the BMS tripped on one, at the small current I was pulling at the time (on a slight incline) to get the most KM from them, even though I dropped my throttle setting/speed to get the last few maH from them.

I suspect that if I did this trip again tonight, I would see very similar voltages on both batteries. "Matched" and balanced batts can still show 1 volt or so of difference when run to LVC, IMO.

I charged the 2 batteries in series in exactly one hour and the voltages stayed matched once they had been charged for maybe 10 minutes or so. At end of charge both were showing 20.84v (Matched ! :) ) 5 minutes later they were 20.77v each, and 7 hours later they were 20.68v and 20.67v respectively. Funny, the lower battery at discharge turned out just SLIGHTLY better charged. Maybe because it's lower voltage gave it a bit more charging current, but with only one 100th of a volt difference, it's hard to draw any firm conclusion. Close enough to be same.

I limited initial charge current to 10amps indicated.

I say indicated because I 've seen 5 amps (DC) indicated when my AC power meter indicated 6 amps (AC RMS) being drawn from ac 120v line. Since it's all in series, current must be the same. I think the full-wave rectified DC, with no BIG (and not useful economically since it would need to be very expensive at these volts/amps) capacitor to smooth the DC will not read correctly on a DC meter. I'd say it's 6 amps RMS but that could be misleading too as the batt is not a purely resistive load; it has voltage and when the AC cycle is under that voltage, no current flows.

BTW, I came to the conclusion earlier that half or full wave rectified DC should be OK on these batts, as it's nothing more stressful (except for my higher currents) than inserting and removing the batt from YW charger 60-120 times a second, which I figured the batts could handle. So far, they have. I should note that some of my batt wires are now looking a bit burnt. I think perhaps a few too many charging episodes where the BMS on 3 of 4 batteries tripped.

As usual, I modified the charging current lower as the batt voltages kept rising to 21.00v. 9.5 to 10 amps indicated (perhaps 11.4 to 12 amps realish batt RMS) was good for 10 minutes. So although this is a 12 amp, 2c charger, you can only charge at that rate for 10 out of 60 minutes. I declined charging current to about 1 amp at end, for last 14 minutes (Would have been faster than 60 minutes if I had a load which could do between 2.37a and 0.96a at 46 minute mark.)

I could have dropped charging current even more to top the batts up to 21.00v, but at that point, time spent monitoring and fiddling with switches gets minimal gain in voltage/charge. By charging to 20.84 open circuit level, I pretty much matched the YW chargers which go green at about 20.80-20.81v.

So, when I eyeball/rough calculate these currents and times, I calculate about 4.9ah indicated, or about 5.9ah "real" (after adding 20% for DC/AC RMS issue) going into these batts. Seems about right. Average real "DC RMS" current was about 6 amps for 1 hour, or average 1c rate.


So my conclusions: - Batts that are matched and charged/discharged together in series will tend to stay matched, even though voltages could differ by a volt or so at full discharge.

- It's not neccesary to match batt voltages, but it does make series charging easier and allows all batts to come to full charge in unison. By easier, I mean I don't have to use my battery select switches to charge lower battery to high battery voltage to match other. If you don't have such switches and use them, you can only partially charge your battery set. (1 will be at full charge while others are less charged.)

- Matching batt voltages at full charge also increases your range of course.

- In the end, matching voltages are not necessary, but are useful for extending your range and making series charging easier (or more battery filling). Sort of like two gas tanks with a single filler nozzle that splits exactly half the flow. If one tank start with more gas, you must stop when that tank is full. Since I'm the only one here at present charging with anything but a YW charger, for the rest of you, matching just helps increase your discharge range to the maximum.

Cool. :) I'm pleasantly, slightly surprised that the full charge voltages stayed matched through a complete discharge and charge cycle. Now to look for returnable batts that don't match this well...
Click to expand...

thx for the info
and i agree they seem to balance back out on charge
i have also only noticed the difference in bats on the bottom half charge
i still never rewired for c-...been to busy modding kids powerwheels...great use for my old sla's

peace wasp
 
anyone using the yardworks lithium ion, may wana open the case and look at the cells from time to time. my bms and cells where warm after a short ride but not hot. but i did see the cells are starting to swell,
could be a fire down the road.

cheers

http://www.youtube.com/watch?v=Xd76G89ciyY
 
karma said:
i did some more tests the bms failed and shorted the cells, all cells read 1v, so i would say there safe from exploding if it where the old lithium ion i would have 3 degree burns on my ars :lol:
Click to expand...

oh well warrenty time lol
any details on your testing?

peace wasp
 
Think I'm suffering from BMS failure too, though I suspect it's from over-charging, and probably not a concern on YW chargers.
The YW chargers generally shouldn't overcharge, and I think if the BMS has to sink too much current it might fail/melt etc.

One of my batts can't handle the startup current requirement of XLyte 72v, 20a controller. Not the big cap inrush, but the smaller one when motor starts with PF. It handled 11a in a quick load test I just did, before I welded my load switch with the inrush to cold light bulbs. :)

Another batt seems OKish but sustained usage at 18a seems to trip it sometimes. Perhaps the current limit changed because some resistor burnt and/or changed value under heat stress.

I guess it's time for a few battery-ectomies and exploratory surgery. Right after I get another 50+ KM of fun riding in. :)

My 20" youth mountain type bike is getting lower range, like 26 KM for 4 YW batts, instead of the 40 I get on my recumbent. Partly aerodynamics I guess, and partly speed. This bike with 2" wide knobby tires and front shocks gives me the confidence to go fast on paths, dirt roads etc. Took a muddy, stony one today I wouldn't touch with recumbent. Maybe 12% ! incline on semi-mud at one point and went like a champ. :)

I think I'll look for an adult mountain type bike for my next project. Mountain bike trails/TransCanada trail a few kms away here in Gatineau... Too much fun... :)
 
nutsandvolts said:
mikereidis said:
Another batt seems OKish but sustained usage at 18a seems to trip it sometimes.
Click to expand...

Parallel configuration makes a huge difference. From a standstill, if I twist the throttle all the way, cycle analyst shows 1500 watts, on very steep hills I have seen it go to around 1900 watts (this is my "250 watt" motor :lol:). 30A is not a problem at all. With 3S2P the BMS never trips, except for LVC if I discharge too low.
Click to expand...


I think I solved my issue, and it's not permanent BMS damage. Turns out when these batts are charged to say, 21.30 volts or so, they will trip BMS when in series with 1 or more batts and I start the motor.

However, they work fine as a single battery at 21.3v. EDIT: Sometimes; but once voltage drops enough they seem OK.
 
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