LiPo Snowblower

[MN Driver]

I have an 18" wide electric plug-in snowblower that I got for about $100 (normally $200) last year during a sale that went on about this time last year. Worked great but plugging it in and dragging the cord behind me is annoying and it is a bit of a pain trying to keep the electric cord out of the wet slush at the end of the driveway to avoid getting zapped. This summer I completed converting my plug-in 120v black and decker mower to battery power using 9 spare Honda hybrid NiMh sticks(54 cells series) and it does the job although higher voltage would be ideal.

Now that the same ad was in the newspaper just last week, I went to the garage and stared at it a bit thinking about the colder weather and snow coming soon enough and put two and two together that this electric snowblower might also be a good candidate to convert to battery power. Figuring that both were possibly universal brushed motors I tested it out by tossing my hobby charger into NiMh mode at 5 amps and it sprung to life under constant current, of course 150 watts isn't getting it to max speed but it worked. I grabbed my 54 NiMh cells, low on charge but a moment of overdischarge doesn't hurt NiMh cells much if any are completely empty, it fired up and I was satisfied but it isn't quite up to full speed and to throw snow I need full power.

What would the average voltage be going through a bridge rectifier into the motor of something like this? In the mower threads most people were powering theirs by 80v packs and I remember most people who did it say that it is slightly underpowered from the original power source but plenty good to do the job. With a single-stage snowblower, the performance is directly related to how fast the paddle is spinning and I want to have this as close to peak power as I can get so I'm aiming for the voltage that the motor ends up seeing as an average after bridge rectification but I'm not sure what that would be. I'm looking to go with the Turnigy 5Ah 4S 20c hardpacks that are going for $23 right now from the HobbyKing USA warehouse and put enough in series to get a decent voltage. I was thinking that either 6 or 7 of those for 24(88.8v nom-100.8v charged) or 28 cells(103.6v nom - 117.6v hot). If I put more voltage through the motor than usual the brushes will arc over and if I'm buying more voltage than I need than I'm spending more money than I need. I'll also plan to use this same pack for the electric mower and possibly share it with an ebike for the summer months. If the pack was only for the snowblower I'd probably skip the idea entirely based on the cost of the cells but if I share these cells with other purposes it makes more sense.

I know not to charge HobbyKing LiPo cells in freezing temperatures so I'll either need to use a heated box or charge them away from flammables in the basement using as many precautions as I can, but what I'm more interested in is that I never hear about their discharge performance when they are cold, can I pull 15 amps from these cells if they are -10f?

 

[MattyCiii]

Is there anything LiPo can't do?

 

[hillzofvalp]

By pass existing electronics, beef up the motor wires, and run a voltage u will inexpensively and practically be able to charge...like 12s-18s. With lipo u need to keep cells and balance so a higher voltage will need more $ to support.

What is the rating on it when it is plugged in? 110V 5-10A? Find out what the motor is actually seeing

Oh wait I guess this would have 2 additional motors for the wheels...


Alternatively u could buy the lipo and blow the snow up... Lithium is a salt so i would assume it has some water dispersive quAlities

 

[ohzee]

Is there anything LiPo can't do?

I use lipo packs on my fleshlight.. one of the best uses I could find.

j/k wish I had one.

 

[MN Driver]

By pass existing electronics, beef up the motor wires, and run a voltage u will inexpensively and practically be able to charge...like 12s-18s. With lipo u need to keep cells and balance so a higher voltage will need more $ to support.

What is the rating on it when it is plugged in? 110V 5-10A? Find out what the motor is actually seeing

Oh wait I guess this would have 2 additional motors for the wheels...


Alternatively u could buy the lipo and blow the snow up... Lithium is a salt so i would assume it has some water dispersive quAlities

No, I wouldn't need additional motors for the wheels as the propulsion power comes from the paddles being in contact with the ground once it gets through the snow, they are reinforced rubber so they grip like tires, actually better because they can still pull the unit forward while scraping against ice.

It looks like this but the Toro uses a plastic paddle that probably doesn't grip the ground as well and will likely get a bit torn up.
http://media.toro.com/PublishingImages/ProductCatalog440X510/1800-Power-Curve-38381co2367_sn_38381_r.jpg

The problem is that I never thought I'd do this project and didn't break out the Kill-a-watt when plowing snow to get a good idea of what sort of energy that I'd use. The rating on the unit is 13 amps, I just did some runs messing with it scraping it against my driveway really hard as a load, probably looking like an idiot to my neighbors but it's all in the name of science. :wink: Seemed to pull 1300 watts, 11 amps. Most snowfalls I could finish the driveway with this in about 20-25 mins. I'm thinking without the bridge rectification that I should expect a small amount of additional efficiency? Either way, I'll fire up the gasser or just plug this one back into the wall if I need the extra 'range' but I'm planning on using the little voltage checkers for 4s packs to know when to stop.

"By pass existing electronics, beef up the motor wires, and run a voltage u will inexpensively and practically be able to charge...like 12s-18s. With lipo u need to keep cells and balance so a higher voltage will need more $ to support."

12s will definitely not provide enough motor/paddle speed, that isn't even half the 120v voltage it sees from the wall. If I was going to be fine with the voltage of 18s, I'd just hook my 54s NiMh pack to it and avoid the safety issues associated with charging LiPo inside, waiting for them to warm up before charging them, and dealing with the multiple small packs using a charger only designed for 8 LiPo cells max. Problem is I don't have more NiMh cells to add to what I have now, if I did, I'd be all over that idea instead because the capacity I've got so far is good and the voltage doesn't sag too bad at only 15 amps. It is easy for me to bulk charge 5 sticks at a time with my charger as it will pump in 48 volts and accurately stop when things are charged, so I'd charge each half and then I'm set. The capacity isn't big enough to where the pack would have any weight or size issue as NiMh cells and I'd have 6.5Ah cells that still all get 6Ah or better so it may be more ideal. I don't like dealing with self-discharge though in the winter. In the summer I'd mow every week or every other week so it wasn't much of a problem, just charge first and then mow. In the winter I need to clear snow with less notice and its nice to have something immediately ready so I can go to work.

 

[hillzofvalp]

It might be an AC motor, the kind that can run straight off 110, in which case DC might not work very well at all with it. Maybe run some tests first with whatever DC you have..

Honestly I would pursue a more robust A123 pack if I were you, if you haven't already bought anything. worry free.. longer lasting...

How about just use extension cord for closer areas and then have a battery pack to connect when you get around the puddles and end of driveway? How about 3 dewalt 36v (30s A123) that you can use for other cordless tools? That's 227Wh, 99V, and on toolking around christmas they're like $80.. (the 8s 28V version was ~$60 on toolking last holiday season.) Maybe you can find a good deal on a 36V power tool that you actually need.. which includes one or two batteries.. Then buy an extra!

The Bms in the packs limits to around 20A.

Just a thought. I think 227Wh hours could give you 10-20 minutes, depending on what's going on with your drive system / motor choice

 

[MN Driver]

It might be an AC motor, the kind that can run straight off 110, in which case DC might not work very well at all with it. Maybe run some tests first with whatever DC you have..

Honestly I would pursue a more robust A123 pack if I were you, if you haven't already bought anything. worry free.. longer lasting...

How about just use extension cord for closer areas and then have a battery pack to connect when you get around the puddles and end of driveway? How about 3 dewalt 36v (30s A123) that you can use for other cordless tools? That's 227Wh, 99V, and on toolking around christmas they're like $80.. (the 8s 28V version was ~$60 on toolking last holiday season.) Maybe you can find a good deal on a 36V power tool that you actually need.. which includes one or two batteries.. Then buy an extra!

The Bms in the packs limits to around 20A.

Just a thought. I think 227Wh hours could give you 10-20 minutes, depending on what's going on with your drive system / motor choice

The motor is a universal motor, it has a small bridge rectifier set built into the part where you plug in the extension cord. I know it is because I connected it to my hobby charger, pushed 5 amps through it and it spun up quite nicely, then I connected my NiMh pack that has 54 cells to it directly to the extension cord plug and it spun up aggressively but the lower voltage of this pack had it spinning at a slower speed than I think it needs to be spinning. I know this will work using a DC supply, the motor is pretty much the same as the ones used with the electric lawn mowers.

A123 cells aren't bad cells but they are far too expensive for almost every application that they are used unless that application really needs a smaller and lighter cell, otherwise for the same price you could land more capacity using a cheaper LiFePO4 and just raising the voltage a bit. In e-bike applications they make some sense because they are compact and the needs for a good C rate far outweigh their need of higher capacity but LiPo is a much better and far cheaper option. I'm planning to use Lipo because I don't want to solder up a bunch of little cells, with the Hobby King packs, life is much easier. Slightly less robust or shorter life by a little, sure, but its not like I'm going with lead-acid here. I also think it is going to take more than 227Wh. If I go with LiPo and use 6 of the 4s packs at 5Ah, I'd have 444Wh and the price wouldn't be too bad. With the Dewalt packs, I wouldn't be able to use those as-is for an e-bike project as 20amps is too limiting and I have no reason to buy high-priced overhyped Dewalt power tools either and I'm not interested in soldering a bunch of tiny cells 2.xAh cells after breaking apart those packs. Doing the math, I don't think those cells would get 227Wh 30s is 96v nominal and I don't think those cells are 2.36Ah, are they? Either way I'm not looking to have a pile of cells that tiny. If I want to double the Ah with the HK packs, its quite a bit easier than with little A123 cells. ...and I'm not dealing with Headway cells.

I guess what I still really need to know is what average voltage comes off their cheap and dirty full-bridge rectifier they are using?

 

[Ypedal]

Single stage blowers dont cut it out here, 2 stage or forget it.. :lol:

If the thing was not blowing 15 amp breakers under slushy loads you can pretty much use that as a guideline for max amps consumed.. 15 amps for 30 minutes = 8ah of usable energy, so a 10ah pack should do fine at equal voltage.

You want to set the voltage so that when cells reach the end of the job you still have good snow throwing voltage available !!.. so 100v / 3.6 = 27.7 ..... i'd make it at least a 24 cell setup 4x 6S or 5x 5S

 

[MN Driver]

Single stage blowers dont cut it out here, 2 stage or forget it.. :lol:

If the thing was not blowing 15 amp breakers under slushy loads you can pretty much use that as a guideline for max amps consumed.. 15 amps for 30 minutes = 8ah of usable energy, so a 10ah pack should do fine at equal voltage.

You want to set the voltage so that when cells reach the end of the job you still have good snow throwing voltage available !!.. so 100v / 3.6 = 27.7 ..... i'd make it at least a 24 cell setup 4x 6S or 5x 5S

Single stage works here most of the time as a majority of our snow is dry unless its there too long during a warmer day and it gets compacted and melted together into a heavy melty slush that even a 2-stage gets clogged up with. I've got my gas snowblower too but I always find the most convenient time to snowblow is at 11PM or some very early morning time where everyone is sleeping, it would be nice to have something that won't wake up the neighborhood.

I was thinking of something between 24 and 28 cells, 28 seems a little high in voltage to me at 114.8v hot off a 4.1v charge or 117.6v briefly if I charge to 4.2v, I'm going to use 4.1v to terminate the charge though. Sounds like 24 cells will do great. I'll probably work together an adapter so I can charge the cells as an 8s pack or possibly solder on new balance taps instead of an adapter. Not sure which way would be the easiest way to go about this. I'll also need to get some little low voltage buzzers too. I'm not sure I need 30 minutes of run time or not at this point and the rating plate says 13 amps max, probably pulls more than that under heavy load and a bit less with a reduced load but usually I can get the driveway done pretty quick. I'll use the gasser or just plug this in if I need extra capacity, my goal is to have this work out 90% of the time with the lighter snowfalls. We usually don't get more than 6 inches(15cm) of snow more than about 3 or 4 days out of the year.

 

[Harold in CR]

Hope this is not too OT, but, I have never figured out why everyone figures 110 volts is the standard residential house voltage. It is 120v, not 110.

Watching all you guys argue about tenths or hundredths of a volt in battery charging-discharging, then using 110 v as house voltage, really makes me wonder.

It's not 110-220. Actually, 115 is right at the low voltage scale for residential voltage. I worked a s a power company lineman for 11 years. If we hung a transformer, it had to be between 116 and 126v or we took it back down and turned it in for testing at the supplier level.

Also, in my illustrious US Govt provided vacation to the People's Rupublic of Viet Nam, I became the generator Shop Honcho. I had a 60KW Detroit powered generator hooked up to Battalion area, that I did one line at a time. It was governed at exactly 60 cycles at 123 volts.

SO, when figuring those battery volts, go for 115v MINIMUM.

 

[gogo]

FWIW, I'm a veteran corded electric lawn mower and that helps me with cord management so that part seems easy for me when using my corded electric snowblower.

I used my 48V 20AH Ping battery with a 2500W 48V inverter and a short cord a few times and that was very useful. It was nice to be able to throw the electric snow blower into my sedan without having the gas smell. The lightness of the corded electric comes in handy sometimes and when combined with the battery/inverter on a cord, even more handy.

 

[MN Driver]

Hope this is not too OT, but, I have never figured out why everyone figures 110 volts is the standard residential house voltage. It is 120v, not 110.

Watching all you guys argue about tenths or hundredths of a volt in battery charging-discharging, then using 110 v as house voltage, really makes me wonder.

It's not 110-220. Actually, 115 is right at the low voltage scale for residential voltage. I worked a s a power company lineman for 11 years. If we hung a transformer, it had to be between 116 and 126v or we took it back down and turned it in for testing at the supplier level.

Also, in my illustrious US Govt provided vacation to the People's Rupublic of Viet Nam, I became the generator Shop Honcho. I had a 60KW Detroit powered generator hooked up to Battalion area, that I did one line at a time. It was governed at exactly 60 cycles at 123 volts.

SO, when figuring those battery volts, go for 115v MINIMUM.

My thoughts were that the bridge rectifier would pull the average voltage down a bit below the RMS household voltage to where it might even be below 100 volts but I wasn't sure. I'm still not sure what the definitive number is and whenever I try to use a DC volts setting on a multimeter to the wires going into the motor, I never get an answer there because of how jumpy and dirty the voltage is. I'm not arguing about the RMS household voltage at all, in fact mine reads 122v right now. The voltage that matters is the voltage that the motor normally sees through the bridge rectifier circuit. More importantly, I don't want to go over because with the A/C supply, the voltage likely dips enough to allow any arcs to die before the comm flashes over. If I go with a voltage higher than what it normally sees than I stand to risk flashing the comm over and also wasting more energy spinning the drum faster than it normally spins. The problem is I don't have any DC supply to try and make an 'eyeball' estimate of RPM to try and match the speed. Also it depends on the voltage drop through the whole system too, since its a series motor if I let it run unloaded the blower drum spins at ludicrous but loaded it will spin more along the lines at the speed it should. If I connect a battery that doesn't have the wavy characteristics of a bridge rectified source I might need lower voltage just to keep things under control.

 

[MN Driver]

FWIW, I'm a veteran corded electric lawn mower and that helps me with cord management so that part seems easy for me when using my corded electric snowblower.

I used my 48V 20AH Ping battery with a 2500W 48V inverter and a short cord a few times and that was very useful. It was nice to be able to throw the electric snow blower into my sedan without having the gas smell. The lightness of the corded electric comes in handy sometimes and when combined with the battery/inverter on a cord, even more handy.

I don't have an inverter that could handle a load like this or a battery with the capacity at the right voltage to connect an interver to it. It's a great way to do it but adding the inefficiency of an inverter and buying a batter that doesn't suite any of my other needs(like an e-bike, my electric lawnmower) would be less useful than getting a pack that might do the job for all three uses.

 

[Ypedal]

i'd bypass the rectifer and run a big fat switch in series with the motor directly to the battery.. volt it as high as you need to throw the snow as far as you need it to go !

 

[Harold in CR]

i'd bypass the rectifer and run a big fat switch in series with the motor directly to the battery.

This is what I was trying to reference my post to. I never seem to get all the info into my posts. :lol:

 

[MN Driver]

I suppose since its still under warranty if I'm careful enough about how I connect things up, I might be able to swing a motor replacement if something decides to fry. I'm looking to be as reversible as possible until I'm confident that I'm not going to blow it up the first time I try to push a driveway full of 8" snow. I'll slip a thermistor next to the motor to monitor temperature but I'm more worried about burning the commutator up at peak loads when I mash it through the pile of snow at the end of the driveway and what gets rammed into where the mailbox is at. It has survived so far using power from the plug through a heavy gauge(12 or 14AWG, I'd have to check) 100 foot extension cord which I bought for the mower, far longer than really needed for a snowblower. I've got a 15 amp cartridge fuse left over that is rated for 250v ac 125v dc to put in, although its slow blow that I think is designed mostly for a 18k A/C condenser and might blow too late to save the motor but it might save me if there is a serious jam or a catastrophic short.

 

[hillzofvalp]

THat was my initial reaction as welll...

 

[MN Driver]

I'll post an update. I haven't been too active on this project due to the lack of snow. We finally got a snowfall of about 5" here this morning to get some real data, before this it was a paltry 2" or so.

This stuff was wet and nasty, I had a baseball bat in hand to knock the snow out of the chute. Got the driveway done in 25 minutes but the whole extension cord and wet snow makes this all take longer than it needs to. I used .47kwh in the 25 minutes although there was probably two minutes worth of smacking a wet slug of snow out of the chute, it wasn't as bad as I thought it would be though and as soon as I have this thing running on LiPo and am not trying to avoid running over the cord this will be quicker and easier.

I took a side cover off of the electric snowblower and found a little device with the following details. It has two connections on the bottom for line and load.

Suppl. Prot. General Industrial
TC-2 50/60Hz 1.0KA, U1 125Vac
OL0 250vac 1.0KA, U1 50Vdc
OL0 50vdc 0.2KA, U1 250vac

The front says L2 15A

A supplementary protector is basically a circuit breaker except instead of trying to protect supply wiring, it is designed to protect the load. There is one of these on your garbage disposal for example, the little reset switch. This one seems to be automatic since there is no switch, so I took a look to see what the details are using this resource I found.
http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/1492-wp001_-en-p.pdf

TC-2 means Trip Current is more than 135% of current rating.
The front says L2 15A. Not sure what the L2 is but it seems its 15 amps and trips at 135% of this or above, possibly 20 amps. I don't think it's ever tripped and I've jammed it a few times for a second or two.

Either way, this little self-reset overcurrent device isn't rated for the DC that I'll put it through. Should I remove it and replace it with the 15 amp DC cartridge fuse or should I leave it there and put the fuse in series just in case it works outside of its ratings and might save the motor if it gets hung up?

It looks like Steveo is also doing a similar conversion, no recent updates to his thread. Steveo's Toro Powercurve 1800 appears to be nearly exactly the same outside of the design of the paddle, handle, and controls. The chute, belt covers, and plastic case appear to be pretty much the same. Now that I'm looking at LiPo again it seems I'm back to the search for the best deal.

I'm looking at either 8 of the ZIPPY 5Ah 20C 4s at $26.99 each to make a 32s pack (118.4v nom) $215.92
...or 5 of the Turnigy 5Ah 20C 6s at $42.66 each to make a 30s pack (111v nom) $213.30

I really like the idea of a simpler pack to assemble of 5 units but am thinking that if I go with 8 smaller packs that if I get a bad cell in one that I'm not out as much if I run with just 2 fewer cells than I otherwise would have with a 30s pack. What do you guys think?

 

[kfong]

I recall seeing an earlier post about such a product. Not something I would boast about :wink:

Is there anything LiPo can't do?

I use lipo packs on my fleshlight.. one of the best uses I could find.

j/k wish I had one.