Using EagleTree's MicroPower eLogger as a bike computer...

[mace1934]

Gary,

Sorry for the delay; I've been away.

I've had that solar array for about 18 years. For many years it powered a well pump, but had been sitting unused for a while until I started using it for my bike. Six 60 watt panels; for the bike app. I have horizontal pairs wired in series. Each pair can charge a 10S A123 pack, or, as I usually do lately, 2 packs (either unmodified DeWalt packs or 10S bricks from DeWalt packs) in parallel.

I'll attach a little bigger pic of the panel charging the Rockhopper, and a micrologger graph of a pair of DeWalt packs being charged in parallel. They had been run down to a little over 1/2 capacity and had voltages of 33.07 and 30.75. After charge, their resting voltages respectively were 36.78 and 36.82.

Note that as the pack voltage rises to about 37, the current drops off to nil. Very convenient. No electronics needed.

There's more info on my experiences with solar charging A123 cells here (needs updating):

http://ruthnlarry.net/evs/bikes/26650/solchg.htm

There's also data on cell balancing on the site.

I wrote about some of these early results (as "mace") on the Tidal Force forum; I've since dropped out of that forum and I don't know if there are any of my posts left.

Most of my rides are into town, around town doing errands, then return - a distance of 15 - 20 miles. The reason my "mileage" is "good" is because I'm a slow poke, mainly because I have to get back with power to spare; the final 2.5 miles uphill is a real drain. I usually pedal some for a little exercise, but when I went to town and purposely did absoluely no pedalling, I still used only about 21 Wh/mile for the ride. The hub motor was at 148 degrees F on my return; it has been as hot as 160 degrees when I pushed it too far.

It's wonderful that you are working with EagleTree to help them come up with a unit more suited to our ebike needs. THANKS!

Best,

Larry



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[GGoodrum]

Great stuff, Larry. That is VERY cool that two of these panels in series will do a 10-cell pack, pretty much automatically. Where can you find these 60W panels?

I should get the "final" production v3 Micrologger tomorrow. I want to do another video with it on my bigger bike, which is a 26" Electra "Townie", a sort of high-end "beach cruiser"-type that is popular here in California. It now has the second 4840 controller that Bob Mcree modified for me, with the higher power 4110 FETS and the boost for the current limiter, up to about 85-90A. Anyway, it is much better suited to handle the increased power.. I must say, however, that I get immense pleasure from blowing past these spandex-clad 20-somethings, huffing and puffing up the hills around here, on a 20" folding bike. That's really the only time I pedal, just to really confuse them. 8) At my age, it's better than sex.

-- Gary

 

[mace1934]

Gary, here's one source (among several - even HomeDepot I hear):

http://www.gaiam.com/retail/3/SL_SolarElectric_PV

My panels are made up of 36 cells; each cell nominally develops (open circuit - OC) 0.5 V in full sun. Two of my panels in series, normal to the sun, will develop about 38 V +/- about 2 V OC depending on time of day and year, temperature, atmospheric clarity, etc.; they will deliver about 2 amps to 10 partially discharged A123 cells in series (see the graph in my previous post) when the voltage is around 30 - 33.

Usually it takes my array of 6 60W panels about 90 minutes to recharge the 6 DeWalts after a ride to town and back; each two panels in series charges two DeWalts in parallel.

DISCLAIMER: I'm sharing my results (still a work in progress) as one tinkerer to other tinkerers. I do not want to suggest that these things are as simple and safe as they may seem from my brief comments. A bit more info on my website: http://ruthnlarry.net/evs/bikes/

I also have a Townie, but with a Bionx 350 on it. Fine for around town, but rather weak on hills. Yours must be a blast to ride up hills. I think I'd worry about the dropouts, though (I'm a worrier). Just checked - my Townie has a steel front fork (a magnet sticks to it), but the dropouts seem small. Anyway, be careful. Looking forward to the movie!

Larry

 

[GGoodrum]

Thanks for the info on the solar panels. I'll check it out.

My Townie has steel dropouts and front shocks. Pretty beefy. I also have a hefty torque arm on it.

 

[deecanio]

Hi Guys,

Gary, can't wait to see the townie in action - are you swapping the kit straight over from your folder? that would be an awesome setup!!!!


cheers


D

 

[GGoodrum]

Hi Guys,

Gary, can't wait to see the townie in action - are you swapping the kit straight over from your folder? that would be an awesome setup!!!!


cheers


D

No, it is a separate setup. The folder has a 5303 "Racer", and the Townie's is a 5304 "Cruiser". Each now has a 4840 controller that Bob Mcree modified by replacing the stock FETs with 100V 4110s, and for both, he "adjusted" the current limiter upwards, so that both will allow over 85A. The folder has two 10s4p a123 packs in series, each with embedded LVC boards conncted to the controller's brake inhibit lines. The Townie has bag on the rack in back with four big sub-packs, two that are 6s6p and two setup as 4s6p. Each 6s6p and 4s6p pair are connected in series, and have a 10-cell LVC board connected. Each of these 6s6p/4s6p combos are then connected in series so the total setup is 20s6p, or 66V/13.8Ah.

Yesterday I went on a ride that totaled about 15 miles. For the first 10 miles, or so, I was taking it pretty easy, as my 24-yearold niece was riding with me (on my "other" folder, the one in my current avatar...). I used 5.34 Ah in 10.12 miles, which is 528 mAh/mile. It used 336 Wh, which is a respectable (well, for me anyway... ) 33.2 Wh/mile. Later, I did a speed run home. I don't know how many Ah/Wh I used on that yet, but I hit 48 MPH, and I was blasting up and down every hill. I didn't get the new MicroLogger on Saturday, so I didn't video this ride. If it comes today, I will do another video.

I think the limit on the second controller is a bit less than it is on the 20" folding bike. Instead of 5500W peaks, I was seeing around 4800-5000W, which is still gobs more than I'll need. The Townie, having better tires and more weight, didn't "burn rubber", like the folder, but I think the acceleration is actually a bit better.

-- Gary

 

[mace1934]

Gary,

Are there any new micro logger developments?

Larry

 

[GGoodrum]

Gary,

Are there any new micro logger developments?

Larry

Yes, actually...

After blowing up several units, connecting them to my 20s6p a123 setup, due to the arc/surge blowing the regulator chip that powers the unit, we decided to step back, and take another look. They couldn't really go to a bigger regulator, without a board re-design, and there was no room to add any big caps.

What we are looking at now is to use the same case and display that is used for the Seagull downlink system, and put a new board in there. There will be a small remote sensor that can go back with the pack/controller that connects to the main unit with a small serial cable. there will also be a a small 4-wire cable that will go down to the motor that has a plug adapter that will go in between the DIN plugs for the hall sensors. This will provide an input to the unit for figuring out motor rpm/bike speed, and will also be used to supply power for the unit (it doesn't need much...).

The Seagull box is not much bigger than a WattsUp unit, and it will come with a way to mount it to the handlebars.

I should get the prototype in a few weeks, just after the first of the year. In the meantime, I'm going to continue my testing with aV3 unit, but only connected to half the pack. You can scale the voltage input in the software, as a setup function. Anyway, I should have a new replacement tomorrow, or Tuesday. I just recently upgraded my setup to run a 24s6p a123 configuration, so I'm hoping to do a new video this week, with the overlays. Also, they have fixed the car user inteface on the PC application, so the replays will have an analog speddometer instead of just a digital readout.

-- Gary

 

[mace1934]

Thanks. Looks like a real winner in the making!

I've been noticing a problem lately: different (intact) DeWalt packs discharging at significantly different rates - up to 2 fold. I use 2S3P PACKS, with 2 eloggers on 2 of them and a Whattmeter (WM) on a third (it would be nice to have 6 eloggers).

Here are data from two recent charges, using an elogger or WM on each (numbers are Ah to charge, same pack order):

1.33, 1.53, 0.79, 0.88, 1.29, 1.60
1.32, 1.14, 1.12, 0.72, 1.23, 1.36

A graph follows, showing packs 7 and 9 (third and fifth in the above line-up) being charged in succession by 2 series-connected 60 W photovoltaic panels.

Thinking that the DeWalt BMS' might be part of the problem, I'm going to remove the cell clusters and make up packs without BMS, but, following your procedure, I'll keep the cell taps assemblies. I plan to make just one cell tap harness, to use on each pack during cell voltage measurements and balancing.

Thanks again for sharing.

Larry

 

[GGoodrum]

Thanks. Looks like a real winner in the making!

I've been noticing a problem lately: different (intact) DeWalt packs discharging at significantly different rates - up to 2 fold. I use 2S3P PACKS, with 2 eloggers on 2 of them and a Whattmeter (WM) on a third (it would be nice to have 6 eloggers).

Here are data from two recent charges, using an elogger or WM on each (numbers are Ah to charge, same pack order):

1.33, 1.53, 0.79, 0.88, 1.29, 1.60
1.32, 1.14, 1.12, 0.72, 1.23, 1.36

A graph follows, showing packs 7 and 9 (third and fifth in the above line-up) being charged in succession by 2 series-connected 60 W photovoltaic panels.

Thinking that the DeWalt BMS' might be part of the problem, I'm going to remove the cell clusters and make up packs without BMS, but, following your procedure, I'll keep the cell taps assemblies. I plan to make just one cell tap harness, to use on each pack during cell voltage measurements and balancing.

Thanks again for sharing.

Larry

I think either you have a couple of flaky BMS units, or maybe a loose connection in the wiring harness? How are they connected, three packs connected in parallel first, and then in series, or do you simply have three two pack series strings with their outputs then paralleled together?

-- Gary

 

[mace1934]

I can't locate any bad connections, but the recognition of this problem has spurred me to take the time to do it right, and get the cells out from under the limitations of the DeWalt BMSs, whether they are at fault or not.

Larry

 

[mace1934]

During rides, the packs are series-connected in pairs, the pairs connected in parallel. L.

 

[jumpjack]

Would it be safe to use EagleTree V4 on an ebike with 60V/1500W brushless motor?
http://www.eagletreesystems.com/micropower/micro.htm