I agree on starting with a "needs new battery" type cordless mower. I picked up a 36V WORX WG788 which also is supposed to have "IntelliCut" which appears to be a hall sensor and magnet on the back of the motor's axle, so the controller can regulate the power to the motor for constant mowing speed, no matter the load. Unfortunately this controller let the smoke out and I have considered getting a cheap 36V eBike controller as well as just using the PM motor directly on a new pack, but found that the inrush current is quite significant so a controller or current limit of sorts is going to be needed to avoid blowing things up. However, my yard is so small that for the time being, I can easily mow it with a real (reel-type) push mower, so the e-mower remains one of the many projects waiting for time or another loving home. I checked and the PM motor is fine, in case anybody is interested, it is located in the south of the SF bay area, aka Silicon Valley.
Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Michael Ross Sent: Monday, April 28, 2014 12:46 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Recommendations for push mower motor? I have another battery from these people that seems just fine (after taking it apart to see inside) http://www.aliexpress.com/store/product/24V-40AH-LiFePO4-Battery-Pack-El ectric-Bicycle-electric-Scooter-bicycle-E-Bike-Lithium-Ion-Long-life/328 001_771068114.html This one is 24V 40Ah LFP and weighs 9kg. $500 including shipping BMS and charger. 3 to 7 day delivery and the met that. These that 18650 cells with welded straps for conducting the juice. I think I will try to get a used 24V B&D instead of reworking my old bottom of the line MTD. I think my wife would love to have an electric mower. She hates asking me to start them for her. It would be nice not having all the oil checking and filling, And as the current mower works - the rod knocking and smoking. We have an acre of mostly flat yard - 40Ah would go a long ways and the charge time is about 2 hours. On Mon, Apr 28, 2014 at 3:25 PM, Peter Eckhoff <[email protected]> wrote: > Hello Mike, > > I'll second what Cal is saying below. To get the nut off, you have to > place a wrench on the nut and "impact" it until the nut loosens. I would > **not** use a compressed air impactor tool. I use my fist. Be careful > because everything is free wheeling. If you leave your knuckles in the > path of the blade, your knuckles are going to get whacked. There is no > other place to place another wrench unless you weld a nut to the top of the > motor shaft. > > Like Cal, I keep a set of several "small plastic blade insulators" on hand > which is how they are described in the User's Manual. The word "insulator" > may seem like a misnomer but it is to "insulate" the shock of hitting a > rock from damaging the armature. > > I converted a corded B&D to cordless. It uses 9 - 5 amphr 12 volt LA AGMs > to power the mower. It is enough to do a 7K square foot lawn. What used > to take me 1.5 hours to do when corded, now takes about 45 minutes. > > I use a 1.3 amphr AGM for the tripping a small contactor. This battery > goes down faster than the pack. I would use about a 2 amphr battery for > each hour the contactors are tripped. That should give you plenty of > cushion. > > I wrote a two part article for the Electric Auto Association's Current > Events magazine. I have the submittals in PDF format. The B&D motors are > DC universal motors that operate at 120 volts. The corded version has a > full rectifier bridge on a little heat sink. It was mainly a rewiring job > to bypass the rectifier. > > I think the AGMs are the wrong type of battery for this project. Normally, > when not cutting the lawn, the motor consumes about 4 amps. When cutting > thick grass, the motor consumes about 8 amps. It can spike to 10 amps in > real thick grass or when the mower clogs up in thick grass. > > I have been contemplating upgrading this mower to Lithium. A set of 40 - > 3.2 volt 10 amphr would be about right for an hour's worth of cutting and > still have some reserve. I saw an ad for Shorai 12Volt 12 Amphr batteries > for $117 each and they weigh about 1.7 pounds. My 5.0 amphr batteries > weigh 3.5 pounds each for an added weight (starter + pack support + > contactor) of 35 pounds onto a mower that weighs 47 pounds for a total of > around 82 pounds. This is about the weight of an ICE push mower. Twelve > Shorai batteries would be around 20 pounds. The mower would be lighter and > so would your wallet of $1400 plus shipping. > > I have thought about purchasing 4 - 100 amphr CALB batteries and then use > a converter to step up the voltage to 120 volts. At an efficiency of 85%, > the amphrs to the motor would be about 8.5. I am not sure if a converter > could handle that much amperage. I was going to do some more homework > before asking the experts here. Four CALB batteries would be about 600 > dollars and a converter would run in the lower several hundreds. The > savings would be substantial but I am not sure if the electronics would > handle the load. > > The other thought would be to run the 4 CALBs into an inverter and leave > the rectifier bridge intact. The inefficiency of the inverter plus the > inefficiency of the rectifier bridge would likely sap the pack of a lot of > useful energy. I think this would be a nonstarter. > > I know of someone using a self contained electric mower. You might want > to shoot him an email at theadm *A*T* AOL. If you are in the RTP area, we > are both "local". > > Everyone else I see running an electric mower are running with a cord. If > you want me to, I will ask my neighbors their brand and opinions. > > > On 4/28/2014 1:27 PM, Cal Frye wrote: > >> I'm on my second Black and Decker push mower, corded type. I have a >> small lawn, so avoiding running over the cord is not a major problem. I >> won't advise on motor or batteries, but I can say B&D has a plastic shim >> in the stack of washers holding the blade to the motor shaft. Said shim >> has raised edges which grip either side of the blade, and an opposing >> pair of edges which grip in turn a keyed, square washer above the blade. >> This square washer is driven by the motor, and the blade is driven by >> the plastic shim. Hit too hard an obstacle, and the plastic edges shear >> off and the blade rotates freely. >> >> This is effective, but is also a wear point, and I've learned to buy the >> shims by the half-dozen. My eyes don't always find the rocks in the yard >> before the blade does :-( >> >> Best regards, >> -- Cal Frye, www.calfrye.com >> /Be an Internet Sceptic/ Stop. Think. Connect. >> www.stopthinkconnect.org - Be at least as safe on the >> Internet as you are crossing the street! >> >> "I sincerely believe that banking establishments are more dangerous than >> standing armies." -- Thomas Jefferson, letter to John Taylor. >> >> >> >> Michael Ross <mailto:[email protected]> >>> April 28, 2014 12:58 PM >>> I have an old simple ICE push mower, that might be worth converting. >>> >>> ... >>> What about the shock of the blade hitting something nearly immobile? That >>> is a lot of shock that small engines are able to handle - special >>> consideration in the regard with electric motors? >>> >>> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/ >> attachments/20140428/339eb705/attachment.htm> >> -------------- next part -------------- >> A non-text attachment was scrubbed... >> Name: compose-unknown-contact.jpg >> Type: image/jpeg >> Size: 770 bytes >> Desc: not available >> URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/ >> attachments/20140428/339eb705/attachment.jpg> >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ >> group/NEDRA) >> >> >> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ > group/NEDRA) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... 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