Battery powered log splitter
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Dan Freeman
Minister of Fire
Hmmm. Good question. I would imagine not too far in the future with all the battery powered tools now, even some that need a lot of power, and more companies jumping on the battery-powered band wagon.
Isaac Carlson
Minister of Fire
I don't think battery powered splitters will be along anytime soon as they'd need a big battery. Maybe if they could utilize a large push mower or ride on mower battery.
I'd buy an electric splitter, a kinetic splitter to be precise, but that's what I'd be buying in gas powered too.
I'd buy an electric splitter, a kinetic splitter to be precise, but that's what I'd be buying in gas powered too.
Isaac Carlson
Minister of Fire
Warning back of the envelope calculations
I can run my hydraulic log splitter solo for 4 hours on a tank of gas I do not know what my 20 ton splitter fuel tank hold but lets assume 1 gallon (I doubt it, but lets keep the numbers easy). Gas is around 125,000 btu /gallon but the gas engine is probably 37% efficient. Therefore, the gas splitter is using 46,250 btus for that 4 hour stretch to actually move the hydraulic pump with the rest waste heat and noise. It would get a lot more complex to go further as I would need to split the energy between actual splitting and idling while I grab wood from the stack, line it up and then throw it in the loader. For a SWAG lets use 50% fuel use between idle and split, so that 23,000 Btus. Do a direct conversion and that is 7000 watts (I am rounding off) in 4 hours. Motors are pretty efficient but there is conversion loss between a battery and the motor so lets use a 90% conversion factor from the battery to the hydraulic pump shaft so bump the power up to 7800 watts. I have to be careful now to keep the units straight. 7,800 watts in 4 hours is about 2 KWH, multiply but 4 hours and that is 8 KWH or less than the capacity of a Tesla Powerwall (12.2 KWh usuable).
My plug in EV get has a 16 KWh battery and gets 3.1 miles per KWH so that is 25 miles of driving. I think the Chevy Bolt is in the 5 miles per KWH so that is 40 miles of driving. Depending on the time of year and sun my 2.2 KW solar trailer array can charge up my EV in about a day to day and a half.
Now lets imagine an electric splitter optimized for energy use. A kinetic splitter uses a flywheel to store up energy to make the split but I will stick with an electrically driven hydraulic splitter with a few modifications. An electric motor has nearly instantaneous torque from start so no need to idle it but there is a 3 times current inrush to start and stop it so odds are we need a variable speed drive in the mix so that the electric motor is always running but at a very low speed (and power draw). Put in a clutch between shaft and pump and the motor running at idle speed with no load draws very little. Now mount a switch on the lever so that when the wood is set down and ready to split, the switch engages when the lever is moved forward and goes into a preprogramed motor ramp up in speed. Most people leave a gap between the log and the splitter blade so the motor does have some time to speed up. Electric motors have lots of torque available almost instantly so the pressure will build up quickly. Once the log is split and the switch on the lever is disengaged, the variable speed drive would slow the motor down and pull the blade back until a limit switch detects the travel has stopped and then the clutch opens up. Note there may need to be some idling circulation to keep the hydraulic oil cool for some period of time so maybe the clutch is not needed.
The big issue with this concept is how much power and torque can the motor develop? If its a plug in unit, the maximum amperage is limited to 12 amps or 1440 watts. That is really not going to develop enough torque so there will be need to put in two speed pump which most splitters have. Ideally go with a 240 volt power cord like used on EV which can draw 40 amps, that will supply 9,600 watts will be plenty of power as long as the motor can handle it. Note battery's have two ratings, storage capacity and power output. A powerwall is rated for 5000 watts continuous power out, 7000 watts peak so the a splitter run off a battery may have less torque potential.
My guess is a electric kinetic splitter is probably the better choice as its storing power during the idle time so the power draw is lower on a continuous basis. Hydraulic systems are not very efficient as there is lot of heat produced so overall power input is probably lower with a kinetic splitter.
Note a Powerwall weighs 269 pounds so its not particularly portable. Cycling portable batteries hard is not great for battery life so odd are the splitter will need to be near a large battery. If someone has an EV with the capability to output power out the battery like a Lightning then it could be corded to the truck.
So based on my back of the envelope calculations a true battery splitter is a while down the road. Battery power density is improving but the yearly improvement rate is starting to slow down. Solid State batteries my give a 20% boost but my guess is not many folks will want to move a 30 or 40 pound battery around the yard.
I can run my hydraulic log splitter solo for 4 hours on a tank of gas I do not know what my 20 ton splitter fuel tank hold but lets assume 1 gallon (I doubt it, but lets keep the numbers easy). Gas is around 125,000 btu /gallon but the gas engine is probably 37% efficient. Therefore, the gas splitter is using 46,250 btus for that 4 hour stretch to actually move the hydraulic pump with the rest waste heat and noise. It would get a lot more complex to go further as I would need to split the energy between actual splitting and idling while I grab wood from the stack, line it up and then throw it in the loader. For a SWAG lets use 50% fuel use between idle and split, so that 23,000 Btus. Do a direct conversion and that is 7000 watts (I am rounding off) in 4 hours. Motors are pretty efficient but there is conversion loss between a battery and the motor so lets use a 90% conversion factor from the battery to the hydraulic pump shaft so bump the power up to 7800 watts. I have to be careful now to keep the units straight. 7,800 watts in 4 hours is about 2 KWH, multiply but 4 hours and that is 8 KWH or less than the capacity of a Tesla Powerwall (12.2 KWh usuable).
My plug in EV get has a 16 KWh battery and gets 3.1 miles per KWH so that is 25 miles of driving. I think the Chevy Bolt is in the 5 miles per KWH so that is 40 miles of driving. Depending on the time of year and sun my 2.2 KW solar trailer array can charge up my EV in about a day to day and a half.
Now lets imagine an electric splitter optimized for energy use. A kinetic splitter uses a flywheel to store up energy to make the split but I will stick with an electrically driven hydraulic splitter with a few modifications. An electric motor has nearly instantaneous torque from start so no need to idle it but there is a 3 times current inrush to start and stop it so odds are we need a variable speed drive in the mix so that the electric motor is always running but at a very low speed (and power draw). Put in a clutch between shaft and pump and the motor running at idle speed with no load draws very little. Now mount a switch on the lever so that when the wood is set down and ready to split, the switch engages when the lever is moved forward and goes into a preprogramed motor ramp up in speed. Most people leave a gap between the log and the splitter blade so the motor does have some time to speed up. Electric motors have lots of torque available almost instantly so the pressure will build up quickly. Once the log is split and the switch on the lever is disengaged, the variable speed drive would slow the motor down and pull the blade back until a limit switch detects the travel has stopped and then the clutch opens up. Note there may need to be some idling circulation to keep the hydraulic oil cool for some period of time so maybe the clutch is not needed.
The big issue with this concept is how much power and torque can the motor develop? If its a plug in unit, the maximum amperage is limited to 12 amps or 1440 watts. That is really not going to develop enough torque so there will be need to put in two speed pump which most splitters have. Ideally go with a 240 volt power cord like used on EV which can draw 40 amps, that will supply 9,600 watts will be plenty of power as long as the motor can handle it. Note battery's have two ratings, storage capacity and power output. A powerwall is rated for 5000 watts continuous power out, 7000 watts peak so the a splitter run off a battery may have less torque potential.
My guess is a electric kinetic splitter is probably the better choice as its storing power during the idle time so the power draw is lower on a continuous basis. Hydraulic systems are not very efficient as there is lot of heat produced so overall power input is probably lower with a kinetic splitter.
Note a Powerwall weighs 269 pounds so its not particularly portable. Cycling portable batteries hard is not great for battery life so odd are the splitter will need to be near a large battery. If someone has an EV with the capability to output power out the battery like a Lightning then it could be corded to the truck.
So based on my back of the envelope calculations a true battery splitter is a while down the road. Battery power density is improving but the yearly improvement rate is starting to slow down. Solid State batteries my give a 20% boost but my guess is not many folks will want to move a 30 or 40 pound battery around the yard.
Interesting question. Does seem at least possible that a splitter could be run on batteries. Would really be interesting if it had somewhat of a solar 'dog house' to protect all the vital equipment from weather, but then the solar could charge the batteries in the 'off' season use. Of course that would also be the big downside for me - a battery splitter would need a modest (in both size and cost) battery pack, but if that pack is 'only' dedicated to the splitter, seems it would spend a lot of time sitting... at least at my place. When I get a load of wood, I process it. but in an average year, that could be 3, 4 or 5 times which could be a weekend of use for the splitter 5x per year... sitting the other 47 weeks.
As far as battery/electric power, it might be convenient to consider splitting the wood and work up from there vs working down from a gas engine. If you know the average force applied, the length of the log and the time you want to spend, that is literally the 'power' equation. You just have to come up with good approximations of each!
Example:
Force: Well, I have a '30 ton' splitter, but I doubt it goes that high very often. Seems like a lot of people split a lot of wood with small splitters in the single digit ton range. So maybe 8 tons on average, 16,000 pounds?
Distance: I cut wood about 20" long. Most logs seem to 'split' when the upper half is penetrated, so force applied for 10 inches on average
Time: 'Cycle' times of 10 seconds are pretty good, so maybe 6 seconds on the split and 4 on the return
Punch that into an online calculator because it is early and I am lazy... it's about 3,000 watts.
Most likely that is still too high because I would expect force to generally drop off as the split progresses. The return stroke would be almost trivial in power and with a good design, if you aren't splittin' you aren't drawing power.
But either way, a 3KW burst for 6 seconds is certainly in the realm of possibility. Seems like kids with hot rod skate boards and e bikes can pretty easily pull 50 amps from a 72V battery for way longer than 6 seconds!
So overall, seems doable, though I'd probably want a companion e-bike, e-scooter or e-skateboard to use the battery in the 47 week off period!
As far as battery/electric power, it might be convenient to consider splitting the wood and work up from there vs working down from a gas engine. If you know the average force applied, the length of the log and the time you want to spend, that is literally the 'power' equation. You just have to come up with good approximations of each!
Example:
Force: Well, I have a '30 ton' splitter, but I doubt it goes that high very often. Seems like a lot of people split a lot of wood with small splitters in the single digit ton range. So maybe 8 tons on average, 16,000 pounds?
Distance: I cut wood about 20" long. Most logs seem to 'split' when the upper half is penetrated, so force applied for 10 inches on average
Time: 'Cycle' times of 10 seconds are pretty good, so maybe 6 seconds on the split and 4 on the return
Punch that into an online calculator because it is early and I am lazy... it's about 3,000 watts.
Most likely that is still too high because I would expect force to generally drop off as the split progresses. The return stroke would be almost trivial in power and with a good design, if you aren't splittin' you aren't drawing power.
But either way, a 3KW burst for 6 seconds is certainly in the realm of possibility. Seems like kids with hot rod skate boards and e bikes can pretty easily pull 50 amps from a 72V battery for way longer than 6 seconds!
So overall, seems doable, though I'd probably want a companion e-bike, e-scooter or e-skateboard to use the battery in the 47 week off period!
EbS-P
Minister of Fire
Think smaller off the shelf conversion. 10 ton max. 15 amp
Yeah it’s not ideal but you have to have trade offs.
1.5kw at let’s say 65% duty cycle. Call it 1 kWh.
So 4 of these and a 2000w 12 v inverter
Amazon product ASIN B07KQSRNQ7
I’m guessing for around 3500$ you could get 2-3 bourse of spitting.
Edit… 48v system might better.
Boss Industrial 10-Ton 15 Amp Electric Dual Direction Log Splitter ED10T20 - The Home Depot
Unleash the power of the Boss Industrial 10 Ton Professional Compact Electric Log Splitter for efficient wood splitting, both indoors and outdoors. With a dual-action design, this electric wood splitter
www.homedepot.com
Yeah it’s not ideal but you have to have trade offs.
1.5kw at let’s say 65% duty cycle. Call it 1 kWh.
So 4 of these and a 2000w 12 v inverter
Amazon product ASIN B07KQSRNQ7
I’m guessing for around 3500$ you could get 2-3 bourse of spitting.
Edit… 48v system might better.
Isaac Carlson
Minister of Fire
I converted my gas splitter to electric for about $100. I got a used 240v 3hp motor and put new bearings in it and bought a 100 ft cord. It works great and hardly uses any power. I can do a lot of splitting and not see it on the power bill. At $5 a gallon, it saved me more than it cost just in the first year, and I don't need oil, gas, spark plug, pull start, etc... Just plug it in and split all day if needed. It's just as fast as a gas splitter and quieter and it doesnt burn my nose with exhaust. I have a 4 way on it and it will easily split over a cord an hour.
Electric is great if you do it right. A battery doesnt seem like a good idea because it needs to stay charged and it will need to be replaced at some point, which is $$$.
Electric is great if you do it right. A battery doesnt seem like a good idea because it needs to stay charged and it will need to be replaced at some point, which is $$$.
I can definitely see the advantages of a 240v splitter, especially for non- commercial use doing about 5 cords a year. I would like to see more electric splitters offered with this option.
Isaac Carlson
Minister of Fire
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