Hi thank you all for the advice, and so fast. I took the advice to work with a cordless mower rather than re-purpose an ICE mower. Craigslist brought me a B&D CMM1200 which seems to be quite a hoss at 1200W. 24V. Bagger/mulcher, 1.5A charger. The only thing I could see amiss was a missing knob on the push structure replaced with a hex nut, and a worn out blade. The batteries look like two gel Pb cells shrink wrapper together - not very big by the scale of the diagram. The wheel leveling seemed very easy - hope it holds up. I like the thick plastic hull - I think that makes a lot of sense - polyethylene can take a lot of abuse and will bend not break. The owner did not have a very big yard so he couldn't say much about mowing time. $145 seemed like a very fair price.
I will be curious to see where it cuts off and to what voltage it charges. I guess I will have to find some other thing to convert. On Mon, Apr 28, 2014 at 6:05 PM, Peter Eckhoff <[email protected]> wrote: > Thanks Mike for the recommendation. > > My blade on my B&D MM675 measures 17.5" even though the specs say 18" > cutting path. Most of the lower voltage electrics have a 14" blade. The > smaller mower means more passes. Something to think about. > > > On 4/28/2014 3:45 PM, Michael Ross wrote: > >> 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-Electric-Bicycle-electric-Scooter- >> bicycle-E-Bike-Lithium-Ion-Long-life/328001_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) >>> >>> >>> >> > _______________________________________________ > 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... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140428/b7065432/attachment.htm> _______________________________________________ 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)
