Mark Widmer
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Welcome to you too, from one joined-in-May-2011 member to another :biggrin:
Cordless electric enthusiast, new to forum.
- Thread starter Mark Widmer
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Paul Schruben
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replacement batteries for the B&D CMM1200
I find that the OEM battery by B.B. Battery, model BP17-12, has the longest run time as it ages, and twice the service life as the other brands I've tried - UB12180 and Gruber Power.
For my next battery I considered a Shorai lithium motorcycle battery. The 18 Ah equivalent LFX18A1-BS12 weighs 2.12 lbs, versus 13.56 lbs for each of the CMM1200 lead batteries. Too bad they cost three times as much at $190 each. I asked Shorai which model they recommended for the B&D mowers. They said they cannot supply a battery for that application. I'm guessing the motorcycle batteries might have problems with the discharge rate, or the deep cycling, or the charger.
Black and Decker makes Li-battery powered trimmers, chain saws, leaf blowers, etc, but so far no mowers. I think lithium battery costs are still too high for the mowers to reach mass-market sales numbers. For instance, the Bosch Rotak 43 LI mower is available in the States this year for $500 from fruugo.us, but with a feeble 36 V, 2.6 Ah battery. That works out to 94 Wh, compared to the CMM1200 battery packs at 408 Wh. Spare 2.6 Ah Bosch batteries cost a whopping $300! The Bosch 36 V 4.5 Ah mower batteries are not available yet AFAIK.
Paul~
I find that the OEM battery by B.B. Battery, model BP17-12, has the longest run time as it ages, and twice the service life as the other brands I've tried - UB12180 and Gruber Power.
For my next battery I considered a Shorai lithium motorcycle battery. The 18 Ah equivalent LFX18A1-BS12 weighs 2.12 lbs, versus 13.56 lbs for each of the CMM1200 lead batteries. Too bad they cost three times as much at $190 each. I asked Shorai which model they recommended for the B&D mowers. They said they cannot supply a battery for that application. I'm guessing the motorcycle batteries might have problems with the discharge rate, or the deep cycling, or the charger.
Black and Decker makes Li-battery powered trimmers, chain saws, leaf blowers, etc, but so far no mowers. I think lithium battery costs are still too high for the mowers to reach mass-market sales numbers. For instance, the Bosch Rotak 43 LI mower is available in the States this year for $500 from fruugo.us, but with a feeble 36 V, 2.6 Ah battery. That works out to 94 Wh, compared to the CMM1200 battery packs at 408 Wh. Spare 2.6 Ah Bosch batteries cost a whopping $300! The Bosch 36 V 4.5 Ah mower batteries are not available yet AFAIK.
Paul~
floating ground
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I've got a B&D CMM1000/1200 mule (a CMM1000 recalled and given a new upper deck).
Paul, have you looked at LiFeMnPO4 batteries from GBS? They're for sale at electricmotorsport.com. I too am thinking of replacing my 3rd set of dying lead acid batteries with Lithium ones. These GBS batteries are designed for traction, while the Shorai seem to be designed for starting gas engines. And the GBS batteries are cheaper. I'm this close ->.<- to buying a pair, but when you include cell balancers and shipping, its a $350 investment . . . and no one I can find has done this before. Is the charge circuitry built into the mower going to play well with the GBS cells? I don't know.
There IS a fellow over on the mynissanleaf.com forums who has put a different brand of lithium batteries (Thundersky?) in his electric mower, but he's got custom battery management circuitry, software, etc. More than I want to get into.
Phil
Houston, TX
PS: Much thanks to Mark Widmer for his electric mower blog. I was googling for info and his site came up, and on his site he talked up this forum. So I joined LMF!:smile:
Paul, have you looked at LiFeMnPO4 batteries from GBS? They're for sale at electricmotorsport.com. I too am thinking of replacing my 3rd set of dying lead acid batteries with Lithium ones. These GBS batteries are designed for traction, while the Shorai seem to be designed for starting gas engines. And the GBS batteries are cheaper. I'm this close ->.<- to buying a pair, but when you include cell balancers and shipping, its a $350 investment . . . and no one I can find has done this before. Is the charge circuitry built into the mower going to play well with the GBS cells? I don't know.
There IS a fellow over on the mynissanleaf.com forums who has put a different brand of lithium batteries (Thundersky?) in his electric mower, but he's got custom battery management circuitry, software, etc. More than I want to get into.
Phil
Houston, TX
PS: Much thanks to Mark Widmer for his electric mower blog. I was googling for info and his site came up, and on his site he talked up this forum. So I joined LMF!:smile:
Mark Widmer
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Hi Phil, and hello again Paul! This thread appears to be the de-facto Black & Decker forum here, so I am replying to the above post here. I have been pretty incommunicado over the winter, but Phil's project in getting lithium ion batteries for the CMM1200 have resparked my interest.
One question I have is, what does one do for a charger for the LI-ion batteries? Did a charger come with them? I would be leary of using the mower charger designed for sealed lead acid on Li-ion.
Mark
p.s. one reason I'm less active lately, other than it being off-season, is that I started a new job back in December.
floating ground
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Hi Mark,
Welcome back! 'Round these parts, mowing season is about 11 months long :smile:
All I bought were batteries and cell balancers. I emailed the battery seller about the charging issue, and he seemed to think the built-in charger on the mower would work okay. The batteries arrived well (probably fully) charged. After installing them, I did a quick 3 minute test mow then plugged the brick power supply into the mower, and the brick's green LED, indicating full charge, came on immediately. My first impression is the stock brick and charging circuit may never recharge the LiFePO4 batteries to 100%, but that will actually be better for long term life of the batteries. Time will tell!
Hope your new job's a good one.
Phil
Mark Widmer
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I'd be interested to hear back after a couple mowings and recharge cycles on how it's working out. Are these the 20 Amp-hr ones I saw at electricmotorsport.com?
Hey, you wrote you're a lithium enthusiast. So I'll just mention that I have a lithium-ion powered string trimmer from Worx that I really like -- this will be my third season using it.
Hey, you wrote you're a lithium enthusiast. So I'll just mention that I have a lithium-ion powered string trimmer from Worx that I really like -- this will be my third season using it.
Hello everyone. First post. Long time e-power user here - just not for lawn mowers - yet!
I just ran across this thread searching for information on modifying the batteries on cordless electric lawn mowers. There isn't much information out there - at least not specific to modding a newer cordless mower.
I dabble with e-power as a hobby (electric model aircraft and ebikes) and don't like noisy mowers. So a cordless mower seems like a logical choice. The lead-acid powered mowers are heavy and duration is poor. Gotta fix that...
I just ordered and received a B&D RB-3610 replacement battery assembly to see how easy it would be to replace the batteries in it. This fits the B&D CM/SPCM-1936 models. It is roomy inside so it looks like it will be pretty easy. So I'll proceed and get an actual mower.
In approximate terms, the initial evaluation shows that with LiPos, the battery capacity can be doubled while halving the battery weight. By the time all miscellaneous components, taxes and shipping are paid, this will cost around $400. That's not cheap, but then you've got a cordless mower that can be charged in an hour that should be able to mow a large yard (or perhaps an average yard a couple of times). And the OEM battery that comes with the mower is also available for use.
The nominal voltage will also be a bit higher but more importantly, the voltage under load will be considerably higher given the extremely low internal resistance of the LiPos. This should translate into less bogging in thicker grass.
I would consider some sort of "watt-meter" mandatory on something like this. I'll throw on an old Astro Wattmeter on it. This will report voltage, amps, power and capacity (Ah). I would attach it to the top of the battery enclosure so it can be viewed in use.
Anywho, I'll start ordering the materials this weekend. It could be a month before I have this done as I'll have to wait for the batteries to ship on a slow boat from China.
More details to follow...
Rob
I just ran across this thread searching for information on modifying the batteries on cordless electric lawn mowers. There isn't much information out there - at least not specific to modding a newer cordless mower.
I dabble with e-power as a hobby (electric model aircraft and ebikes) and don't like noisy mowers. So a cordless mower seems like a logical choice. The lead-acid powered mowers are heavy and duration is poor. Gotta fix that...
I just ordered and received a B&D RB-3610 replacement battery assembly to see how easy it would be to replace the batteries in it. This fits the B&D CM/SPCM-1936 models. It is roomy inside so it looks like it will be pretty easy. So I'll proceed and get an actual mower.
In approximate terms, the initial evaluation shows that with LiPos, the battery capacity can be doubled while halving the battery weight. By the time all miscellaneous components, taxes and shipping are paid, this will cost around $400. That's not cheap, but then you've got a cordless mower that can be charged in an hour that should be able to mow a large yard (or perhaps an average yard a couple of times). And the OEM battery that comes with the mower is also available for use.
The nominal voltage will also be a bit higher but more importantly, the voltage under load will be considerably higher given the extremely low internal resistance of the LiPos. This should translate into less bogging in thicker grass.
I would consider some sort of "watt-meter" mandatory on something like this. I'll throw on an old Astro Wattmeter on it. This will report voltage, amps, power and capacity (Ah). I would attach it to the top of the battery enclosure so it can be viewed in use.
Anywho, I'll start ordering the materials this weekend. It could be a month before I have this done as I'll have to wait for the batteries to ship on a slow boat from China.
More details to follow...
Rob
The batteries are VRLA (valve-regulated lead acid) BB BP10-12 which are nominally 12V and 10Ah capacity for a gentle and unrealistic-in-this-application 20hr discharge. As these batteries are discharged in an hour or less in this application, the 1hr rated capacity of 6Ah is more realistic. This loss of capacity with discharge rate is known as the peukert effect. And since the discharge rate can be even higher than this and lead acid doesn't retain capacity well when deep cycled, this could be further derated to 4Ah or less.
The only reason to use lead acid batteries in this application is to reduce the initial cost. Users pay for this later by living with heavy and inefficient batteries that have a short cycle life.
The only reason to use lead acid batteries in this application is to reduce the initial cost. Users pay for this later by living with heavy and inefficient batteries that have a short cycle life.
Attachments
The main power connector is an Anderson Powerpole SBS50. Main wires are 14AWG and charge wires are 18AWG. Charge connectors are PP15 Powerpoles. All wire/connector connections are crimped.
Battery connections are 1/4" fastons. These are poor connections for high currents. These produce relatively high resistance connections that can become much higher resistance after a period of time.
Battery connections are 1/4" fastons. These are poor connections for high currents. These produce relatively high resistance connections that can become much higher resistance after a period of time.
