here is some info on 20v yardworks lithium ion

I got all excited when I saw the "Yardworks 20V (6Ah) / 22" Lithium-ion Hedge Trimmer" was only $69.99, but then I saw:

Yardworks 20V (6Ah) Lithium-ion Battery (60-2181) and Yardworks 20V (6Ah) Lithium-ion Diagnostic Battery Charger (60-2182) sold separately.

Oh well. How do these prices ($130 for battery) compare to other Lithium Ion batteries available in Canada ?

BTW, I'm in Aylmer North and looking forward to an electric ride to work in Bells Corners a few times this year, once I get my Vision R40 recumbent electrified. I've been looking to buy motor/controller/throttle from ebike.ca, but I think I might go local through Juergen, even if it's a few more bucks or takes a few more days. I imagine local support etc. can be a good thing.

Anyone know if it's legal to e-bike ride on the Quebec side on the multi-use paths on the Ottawa River ? Any run-ins with cops in Ottawa area ?
 
OK, so the Yardworks trimmer is $200. That's $130 for battery, $40 for charger, and the trimmer itself is thrown in for $30 more.

I can buy one trimmer and put the $200 under the "household budget" instead of my "bike budget". :) I'm not sure my wife would let me buy a 2nd one for "spare parts" under household budget though...

So for $400 I get two trimmers, 2 chargers and a 37v, 6ah pack good for say 15 km of range.

Apparently the trimmer can run for one hour. So perhaps it's a 100 watt motor ? Wonder what I could do with the motor... Perhaps electrify my 6 year old son's bike ? :)

I don't suppose there will be any 50% off sales on the trimmer this coming fall. That would be a steal ! Just 15% off to $170 and the trimmer comes for free. I don't think the bare battery will go on sale but the trimmer might, or perhaps the upcoming small chain-saw ?

The Ping batteries seem to be selling for just under $1.00 US per Watt-Hour and they are LiFePO4. These Yardworks batteries seem to be about $1.20 Canadian per Watt-Hour and are Lithium Ion. So they are a bit more expensive and older battery tech for the privilege of buying down the street at local C-Tire.

OTOH, the warranty at C-Tire might be better, especially if Credit-Card doubles your warranty, or does C-Tire offer "protection plans" ?
 
I bought the last trimmer/edger on the shelf in Bells Corners. I saw no batteries or chargers, but there were 4 hedge trimmers there. I don't expect the batteries or charger to go on sale, but I'm hoping the trimmer goes down to $170 at least to make the trimmer "free" for motor experiments.

I noted that the hedge trimmer is also rated for 1 hour operation and does 3200 RPM, whereas the grass trimmer/edger does 8000 RPM.

I see on CTire website there is also now a "Yardworks 20V (6Ah) Lithium-ion Leaf Blower $49.99" for these batteries. I don't suppose "2-speeds: 125 MPH air velocity with 110 CFM air volume; 85 MPH air velocity with 75 CFM air volume" will help me go much faster with the blower pointed to the back of my bike... :)

I will try some load/capacity/voltage sag testing tonight using the trimmer; on real grass/weeds if weather good. If the motor runs for 1 hour, perhaps it consumes 6 amps and 110-120 watts ? Perhaps about 1/10th of a horsepower ?

Any guesses about internal resistance of these packs ? I'm guessing 25 milli-ohms per 5 cell pack, given that they can put out 5C or 31 amps...


Forgive a newbie question, but if I connect 2-4 of these in series, do I need any diodes or other mods to BMS ? I understand parallel needs that, but I think I'm OK with series for now. Will start with 37v when I get my motor/controller, but 18.5v might be worth a quick test. 74v also sounds very exciting.
 
I tripped the BMS once in deep, wet, very heavy grass using the trimmer. I imagine this is why CTire needed a battery with 31 amps of output. Trimmer seems decent for an electric, but if I had intended to buy a trimmer I would go with gas for my 3 acre property.

For some reason I got a big spark when probing the positive side of battery with my DMM probe. Is there a negative/ground near the positive terminal ? Only happened once.

I ran a load test last night using an old fashioned 1500w, 120vac heater. Resistance with cord was about 8.0 ohms. Results indicate about 5.75 amp-hours at average of 19 volts for about 110 watt-hours. Looks good.

Here are the results. Time in minutes is on left, voltage on right. My 2.2 digit DMM could only tell me 21 volts open load after full charge and 20 volts on load start at 0 minutes. No better precision. I got busy when the "Knee" occurred about 130 minutes in. LVC kicked in at 14.78 volts:

-1 21+
0 20+

7 19.74
8 19.71
9 19.69
10 19.67

25 19.49
30 19.44
35 19.40
40 19.36

50 19.28
60 19.18
70 19.05

80 18.9

84 18.84
85 18.82

90 18.75
100 18.62
110 18.49
120 18.32

knee

135 17.78
137 17.59
138 17.48
140 17.24
141 17.10
142 16.94
143 16.75
144 16.55
145 16.30
146 16.01
147 15.63
148 15.11

148.5 14.78
148.6 0

lvc

about 5.75 ah
 
Hi Mikereidis,
i am from aylmer too in deschenes exactly, near the river,

i am curious to know a little more about the load test you did with an old fashion 1500 watts 110 volts ac heater

1 did you plug it in directly or you used an inverter please tell me more about that ...cause i was thinking for winter maybe i will use a electric heater to heat the car faster...

and is the test results discharging with the trimmer or with that ac heater ( at very low setting i would assume )
 
slayer said:
Hi Mikereidis,
i am from aylmer too in deschenes exactly, near the river,

i am curious to know a little more about the load test you did with an old fashion 1500 watts 110 volts ac heater

1 did you plug it in directly or you used an inverter please tell me more about that ...cause i was thinking for winter maybe i will use a electric heater to heat the car faster...

and is the test results discharging with the trimmer or with that ac heater ( at very low setting i would assume )
Click to expand...

Hi, wonderful, one of us should start an Ottawa area thread. Perhaps I'll do it this weekend if nobody else does.

I'm in Aylmer North, on Klock, near Pink. Every direction is down from my house, until I get to Gatineau Hills... :)

No inverter. Heater was connected directly to battery with speaker wire and spade type connectors. 7.7 ohms on the heater plus 0.3 ohms in wire gave about 8 ohms total. This drew a peak of 2.5 amps and an average of 2.3, to just under 2 amps at low voltage cutoff.

I DO have 300 watt and 1000 watt inverters from Xantrex (bought on sale at CTire) and considered using those for a load test, but a simple, mostly purely resistive load is better for consistent testing. Also, I'm not sure the inverters would run, or not break, at 20 volts instead of 12-15. I may try an inverter just to see how it runs.

If you have 120vac available from outlets, don't even think about wasting these wonderful batteries to generate heat, except for occasional testing perhaps. My heater got noticably warm, with an average of 45 watts running through it. It has a small AC motor for fan also, but I don't think it was turning.

My test results were with the heater as a more or less constant load. I'm turned the "old-fashioned" thermostat control all the way up so it would be always on for testing. This testing probably wouldn't work with most modern electronic heaters.

My earlier "trimmer load" testing indicated the battery is good for 20 minute of moderate trimming, 20 minutes of heavy trimming,plus at least 2 hours of no load running.


I'm also looking to heat my car and garage a bit this winter. I got a Prius recently and milage is wonderful (best is 3.7L/100km on 27km commute at 60-70 kmh), but cold weather will crank up the fuel consumption.
 
mikereidis,

Nice testing - this gives us an idea of the discharge curve of these batteries under constant load (as opposed to constant current). A question for you:
- How did you calculate total Watts-hours from your voltage-time graph? Was it by calculating amps at each V point you took; then using both the Volts and amps graph over time to add up used Watt-hours in total?


I would really like it if someone could do some load tests to determine voltage sag under different current draws on these batts. This would give us a good idea of the internal DC resistance of these packs so we can compare their quality to other batteries. See my suggestions to do so here:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=4908&start=60#p81636
 
ZapPat said:
I would really like it if someone could do some load tests to determine voltage sag under different current draws on these batts. This would give us a good idea of the internal DC resistance of these packs so we can compare their quality to other batteries. See my suggestions to do so here:
Click to expand...

Yes most definitely...

Eric
 
ZapPat said:
mikereidis,

- How did you calculate total Watts-hours from your voltage-time graph? Was it by calculating amps at each V point you took; then using both the Volts and amps graph over time to add up used Watt-hours in total?

I would really like it if someone could do some load tests to determine voltage sag under different current draws on these batts. This would give us a good idea of the internal DC resistance of these packs so we can compare their quality to other batteries. See my suggestions to do so here:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=4908&start=60#p81636
Click to expand...


I multiplied 5.75 amp-hours by an average of 19 volts to get about 110 watt-hours.
I got 5.75 AH by multiplying 148 minutes or 2.467 hours by 2.33 amps.
I got 2.33 amps by dividing 19 volts by 8 ohms.

I determined the rough average of 19 volts by noting that 19 volts was reached at about the 73 minute mark, almost exactly half the run time. But the fast sag at the end may have made my 19 volt estimate a bit optimistic. That said, I don't know what voltage it started at, except between 20 and 21 volts. That said, it was under 20v at about 5 minutes.

Yes, it would be more accurate to calculate the precise area, or have equipment to do so. Anyway, I also calculated a "usable" capacity, which is that before the "knee" at 120 - 135 minutes. If the knee is at 135 minutes, then:

-> 135 = avg 19v * 2.375 a = 45.125 watts * 2.25 hours = 101.53 watt-hours usable

I have a hobbyist and professional background in electronics, so I understand about resistors and load tests etc. I have relatively little personal equipment these days though. So how much are 100 - 1000 watt power resistors these days anyway ?

Perhaps I should just rip up this old heater and use the element as a variable resistor. Without that, I was figuring on running 20v, 40v, 60v, and 80v, which will give me data on peak currents of about 2.5, 5, 7.5 and 10 amps. Cut the element in half and I can go 15, and 20 amps too. On up to 30 I guess. But of course that would mean I'd be testing packs of 1-4 batts, as opposed to single batts.


Anyway, lots of fun. I need some 20-30 amp fuses now to help avoid the excitement of big sparks again ! :) I'll go dig in my old parts boxes. Some parts are from 1973 when I was 10... Ya never know when you'll need a 20A low voltage fuse 35 years later...
 
ZapPat said:
mikereidis,

- How did you calculate total Watts-hours from your voltage-time graph? Was it by calculating amps at each V point you took; then using both the Volts and amps graph over time to add up used Watt-hours in total?

I would really like it if someone could do some load tests to determine voltage sag under different current draws on these batts. This would give us a good idea of the internal DC resistance of these packs so we can compare their quality to other batteries. See my suggestions to do so here:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=4908&start=60#p81636
Click to expand...


I multiplied 5.75 amp-hours by an average of 19 volts to get about 110 watt-hours.
I got 5.75 AH by multiplying 148 minutes or 2.467 hours by 2.33 amps.
I got 2.33 amps by dividing 19 volts by 8 ohms.

I determined the rough average of 19 volts by noting that 19 volts was reached at about the 73 minute mark, almost exactly half the run time. But the fast sag at the end may have made my 19 volt estimate a bit optimistic. That said, I don't know what voltage it started at, except between 20 and 21 volts. That said, it was under 20v at about 5 minutes.

Yes, it would be more accurate to calculate the precise area, or have equipment to do so. Anyway, I also calculated a "usable" capacity, which is that before the "knee" at 120 - 135 minutes. If the knee is at 135 minutes, then:

-> 135 = avg 19v * 2.375 a = 45.125 watts * 2.25 hours = 101.53 watt-hours usable

The battery still puts out decent current from 135 - 148.5 minutes, so it will still power a bike at reduced power, but when voltage sags from 17.78v to 14.78v in 13.5 minutes, that's "running on fumes" I guess.

I have a hobbyist and professional background in electronics, so I understand about resistors and load tests etc. I have relatively little personal equipment these days though. So how much are 100 - 1000 watt power resistors these days anyway ?

Perhaps I should just rip up this old heater and use the element as a variable resistor. Without that, I was figuring on running 20v, 40v, 60v, and 80v, which will give me data on peak currents of about 2.5, 5, 7.5 and 10 amps. Cut the element in half and I can go 15, and 20 amps too. On up to 30 I guess. But of course that would mean I'd be testing packs of 1-4 batts, as opposed to single batts.


Anyway, lots of fun. I need some 20-30 amp fuses now to help avoid the excitement of big sparks again ! :) I'll go dig in my old parts boxes. Some parts are from 1973 when I was 10... Ya never know when you'll need a 20A low voltage fuse 35 years later...
 
Corrected results for 10 amps. Much better when I put the voltmeter right on the battery terminals:
5.63 AH * 18.5v = 104.1 WH

18 minute voltage was 18.54v and this seems to be right in the middle between 6 minutes (19.03v) and 30 minutes (18.01v) which are each 6 minutes from beginning or end. Conclusion: 18.5v "nominal" voltage seems fair. 5 cells = 3.7v per cell.

I tried to estimate internal battery resistance and came up with estimates from 47 - 66 milli-ohms. I did this by taking the load off for 5 seconds every 8 or 12 minutes and seeing how high the voltage jumped. Some of that jump is "Recovery" though, so hard to tell. Perhaps 60-70 milli-ohms is fair ?

Ambient 68F

fully discharged at 10a, 5.75ah
fully charged and left in charger 20 hours

open circuit: 20.76v

10A thru tapped heater element designed for 115vac at 15a. Fast fan was directed at element. This test ran 12 seconds (0.5%) less time than previous test. Could be slight aging or cooler heater element having lower resistance.

20v/10a = 2 ohms

-1 20.76

minutes, voltage
0 20.10 (20.76v-20.10v)/I = 0.66v/10.05 a = 66 milli-ohms
1 19.45
2 19.28
3 19.19
4 19.13
5 19.07
6 19.03
7 18.98
8 18.94
9 18.90
10 18.86
11 18.81
12 18.78 (19.28v-18.78v)/I = 0.50v/9.39a = 53 milli-ohms
13 18.74
14 18.69
15 18.65
16 18.62
17 18.58
18 18.54
19 18.51
20 18.47
21 18.43
22 18.39
23 18.36
24 18.32 (18.79v-18.32v)/I = 0.47v/9.16a = 51 milli-ohms
25 18.29
26 18.24
27 18.20
28 18.14
29 18.09
30 18.01
31 17.93
32 17.81 (18.22v-17.80v)/I = 0.42v/8.9a= 47 milli-ohms
33 17.64
34 17.35
35 16.92
36 16.17

36.5 15.00

9.25 A * 0.608 H * 18.5v = 5.63 AH * 18.5v = 104.1 WH
 
ZapPat said:
If you do this, make sure the voltage readings are done right at the pack's output (as I'm quite sure you know, Ns&Vs - this is mostly for others that might want to do this too to add to our knowledge base).
Thanks for all your posts, man! I just wish these packs were on special sometimes, but somehow I don't think this will happen. :roll:
Pat
Click to expand...

Woops! :oops:

Never thought of this till I re-read your post. My voltage measurements were taken after maybe 0.3 ohms of speaker wire, so this could have increased the apparent sag on the 10 amp test by maybe 15% or so. (0.3/2.1 ?)

Anyway, I'll try to set up something better this weekend. Need a new, decent DMM too. Was eyeing an ExTech 600 AMP AC & DC clamp meter that also does tons of normal DMM stuff. On Home Depot website but not in stores... :roll: :(
 
A Watt's Up meter is a fairly handy tool...~ 60 bucks,a tad cheaper if you hunt around.60 volt max though.A doc wattson will measure a higher voltage.

http://www.powerwerx.com/product.asp?ProdID=3809

Thanks for testing these batts...

Eric
 
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