Corded Mower Conversion to Lipo

[fechter]

Nice job! You got me thinking about a 120v leaf blower I have. I hate dragging the cord around.

Depending on the stock switch design, it might handle the DC OK. I'd be on the lookout for spares though.

A cheap brushed controller that can handle the voltage would be nice, and you could rig a hall effect sensor to a lever and have a throttle. Even a bike throttle might work if you could figure out a way to get it on the handle. I haven't seen any cheap brushed controllers for that voltage, but it wouldn't be too out of the question to get a 48v one and modify it.

There might be a good DC rated switch made for solar systems.

 

[Ykick]

Using RC Lipo I suppose somewhere between 24S-32S might be worth a try? Probably depend on the situation but I think my mower would probably still do fine with 10-20% lower RPM. Sharp blade...

Yeah, modding 48V brush motor controller might be the ticket for more advanced speed functions?

Give the decent old RC Lipo a 2nd life!

 

[edcastrovalley]

Well done !!..

I love my Lipo Leaf Blower

http://ypedal.com/Leaf/blower.html

The switches keep failing.. currently running directly to andersons and no more problems.

Think of installing a relay switch?

I really should put one in but I'm looking into brushed controllers which may not need one.

 

[edcastrovalley]

Nice job! You got me thinking about a 120v leaf blower I have. I hate dragging the cord around.

Depending on the stock switch design, it might handle the DC OK. I'd be on the lookout for spares though.

A cheap brushed controller that can handle the voltage would be nice, and you could rig a hall effect sensor to a lever and have a throttle. Even a bike throttle might work if you could figure out a way to get it on the handle. I haven't seen any cheap brushed controllers for that voltage, but it wouldn't be too out of the question to get a 48v one and modify it.

There might be a good DC rated switch made for solar systems.

I was looking at your thread with the brushed controller upgrade and I take it that you upgrade the components (mosfets, caps, etc.) with new ones that can handle the higher voltage and then and add a resistor to "fool" the controller into thinking it's making 48 vdc but makes 120 instead?

 

[dnmun]

i use a switch in the circuit current of the BMS to turn the battery on and off so you could use a microswitch on the handle.

 

[fechter]

I was looking at your thread with the brushed controller upgrade and I take it that you upgrade the components (mosfets, caps, etc.) with new ones that can handle the higher voltage and then and add a resistor to "fool" the controller into thinking it's making 48 vdc but makes 120 instead?

It's probably not worth the work unless you have all the stuff lying around already.
New FETs (but the mower probably maxes out at 15A, so this should be easy)
new main capacitors
new freewheel diode
modify voltage regulator for high voltage input (use a wall wart).

The only real trick with the mechanical switch or contactor is to get enough separation between the contacts when they open so you can't draw an arc. Normally you'd be opening the switch under light load, so this helps a lot. Leaf blowers are always under load.
Real EV contactors may also use small magnets next to the contacts to 'blow out' the arc. The magnetic field causes the arc to bend.

Another possible cheapo way would be to use a FET that has the gate switched by the stock switch. You could use a 9v battery as a gate supply. Simple on/off but no arcing. A 9v battery used like this would last for several years.

 

[ohzee]

http://www.amazon.com/Ryobi-Cordless-Propelled-Mower-RY14110/dp/B00BIM6E4K/ref=pd_sxp_f_pt/175-2712320-3539603

found me the 48v mower above used for 50 bux without any batter whatsoever.

had it cutting grass on 12s lipo before the sun went down. Not as quite as id like , but a big improvement over the gas mower I have.

Going to sharpen the blade tomorrow and see how she does in the back yard.

 

[dnmun]

"Another possible cheapo way would be to use a FET that has the gate switched by the stock switch. You could use a 9v battery as a gate supply. Simple on/off but no arcing. A 9v battery used like this would last for several years."

if you have an old BMS with the output mosfets still intact you could use it as the switch like richard says here. then have a microswitch on the handle so it could be controlled right at your fingers. instead of the circuit current for the mosfets coming from the battery cells, it would come from the 9V battery. the BMS has the pull down resistors on the gates already and the gate resistor to control the inrush of current.

 

[edcastrovalley]

It's probably not worth the work unless you have all the stuff lying around already.
New FETs (but the mower probably maxes out at 15A, so this should be easy)
new main capacitors
new freewheel diode
modify voltage regulator for high voltage input (use a wall wart).

The only real trick with the mechanical switch or contactor is to get enough separation between the contacts when they open so you can't draw an arc. Normally you'd be opening the switch under light load, so this helps a lot. Leaf blowers are always under load.
Real EV contactors may also use small magnets next to the contacts to 'blow out' the arc. The magnetic field causes the arc to bend.

Another possible cheapo way would be to use a FET that has the gate switched by the stock switch. You could use a 9v battery as a gate supply. Simple on/off but no arcing. A 9v battery used like this would last for several years.

Very interesting information here. Thanks. I like the simple FET switch idea!

if you have an old BMS with the output mosfets still intact you could use it as the switch like richard says here. then have a microswitch on the handle so it could be controlled right at your fingers. instead of the circuit current for the mosfets coming from the battery cells, it would come from the 9V battery. the BMS has the pull down resistors on the gates already and the gate resistor to control the inrush of current.

No old BMS laying around but I have one thats sort of in use still. Hmmm, maybe I can "borrow" it for a while. 8)

http://www.amazon.com/Ryobi-Cordless-Pr ... 20-3539603

found me the 48v mower above used for 50 bux without any batter whatsoever.

had it cutting grass on 12s lipo before the sun went down. Not as quite as id like , but a big improvement over the gas mower I have.

Going to sharpen the blade tomorrow and see how she does in the back yard.

Nice looking mower! You got a good deal on that one. Easy to modify too.

 

[dnmun]

i have a buncha dead ones. lemme know.

 

[fechter]

Here's a schematic of the crude FET switch. One downside is you need a double throw switch to make it work well. There are some ways to make it work with a SPST switch but it will take more circuitry.
It may be necessary to put a reverse biased diode across the motor to catch the voltage spike when you turn off the switch. The diode doesn't need to carry much current but needs to be rated for the full pack voltage plus some headroom. I'm not sure what current rating it would need but something like 3A might handle it.

Also not shown: a fuse. A real good idea somewhere in series with the pack.

 

[edcastrovalley]

i have a buncha dead ones. lemme know.

Let me know what you want for them. I might need an extra for the corded weed eater too. You can pm me if you want. Thanks

 

[edcastrovalley]

Here's a schematic of the crude FET switch. One downside is you need a double throw switch to make it work well. There are some ways to make it work with a SPST switch but it will take more circuitry.
It may be necessary to put a reverse biased diode across the motor to catch the voltage spike when you turn off the switch. The diode doesn't need to carry much current but needs to be rated for the full pack voltage plus some headroom. I'm not sure what current rating it would need but something like 3A might handle it.

Also not shown: a fuse. A real good idea somewhere in series with the pack.

Nice circuit! It looks like something I could handle. I assume the 3 fets are to allow enough current to flow to the motor. I'll have to open up the handle switch to see what kind it is. It would be nice if it's a double throw.

 

[fechter]

Most standard microswitches like the kind used for the door interlock on a microwave oven are double throw. It may be possible to fit one of those switches to the existing one. The switch driving the FET gates can be very low current.

I showed 3 FETs in parallel just as an example that you can parallel as many as needed to get the required current rating. If you have a single big one that can handle the current, that would be fine.

 

[edcastrovalley]

Free mower in the Santa Rosa, CA area. It looks like a 24vdc version with (2) 12v sla batteries. The guy says it needs batteries. It's a little far away for me or I would be on my way.



http://sfbay.craigslist.org/nby/zip/4525144499.html

 

[silviasol]

Well done !!..

I love my Lipo Leaf Blower

http://ypedal.com/Leaf/blower.html

The switches keep failing.. currently running directly to andersons and no more problems.

Think of installing a relay switch?

I really should put one in but I'm looking into brushed controllers which may not need one.

It would be over amp draw, the switch is sending power thru it right? I have a neon light sign that flickered and the switch got extremely hot, this was due to the switch not handling the current. Replaced with a better quality switch and bright as ever. Of course a relay that handles high current would fix that.

 

[silviasol]

I have been looking for a mower after reading this thread to upgrade to lipo. Seems every day I am seeing a new one. Look at this beutie for only $50! Hoping it can be delivered tomorrow.

http://minneapolis.craigslist.org/hnp/grd/4516826047.html

 

[edcastrovalley]

It would be over amp draw, the switch is sending power thru it right? I have a neon light sign that flickered and the switch got extremely hot, this was due to the switch not handling the current. Replaced with a better quality switch and bright as ever. Of course a relay that handles high current would fix that.

Either that or the original switch was worn out. Putting in a better/larger switch usually helps. I'll be upgrading the switch to a mosfet style switch or maybe a switch out of a battery mower before long.

I should mention I'm right in the middle of moving so I'm slower than usual on working on my projects. The original mower switch will have to do for another month or so. I sure miss be riding around on the ebike or watching world cup, etc. 8)

I have been looking for a mower after reading this thread to upgrade to lipo. Seems every day I am seeing a new one. Look at this beutie for only $50! Hoping it can be delivered tomorrow.

[/quote][/quote]
Any luck in getting the mower? That's a good one for the price!

 

[silviasol]

It would be over amp draw, the switch is sending power thru it right? I have a neon light sign that flickered and the switch got extremely hot, this was due to the switch not handling the current. Replaced with a better quality switch and bright as ever. Of course a relay that handles high current would fix that.

Either that or the original switch was worn out. Putting in a better/larger switch usually helps. I'll be upgrading the switch to a mosfet style switch or maybe a switch out of a battery mower before long.

I should mention I'm right in the middle of moving so I'm slower than usual on working on my projects. The original mower switch will have to do for another month or so. I sure miss be riding around on the ebike or watching world cup, etc. 8)

I have been looking for a mower after reading this thread to upgrade to lipo. Seems every day I am seeing a new one. Look at this beutie for only $50! Hoping it can be delivered tomorrow.

[/quote]
Any luck in getting the mower? That's a good one for the price![/quote]

No reply. Now looking at this one who says he can deliver it to me.

http://minneapolis.craigslist.org/ram/tls/4515947007.html

 

[edcastrovalley]

No reply. Now looking at this one who says he can deliver it to me.
http://minneapolis.craigslist.org/ram/tls/4515947007.html

A 20" mower! We will all be jealous..

 

[silviasol]

I think I will like it. I didn't get a message back today though... Hopefully

 

[Samd]

It's tiem for ES to have a cordless tool section IMHO.
Gnarliest mower, 24s fan cooled LIPO battery drills, 63 volts Dyson cordless vacuums, that sort of thing 8)

 

[silviasol]

Well I got the mower but it has wiring issues, the battery is good. May have to add my own controller/wiring.

Edit: the battery cells are dead/puffed/corroded. Didn't think lead acid batteries would do that. Going to start a build thread next week.

 

[Tommy L]

Awesome to see others do different types of conversions!

I'm in my Second season with my Electric Lawn Tractor Running on a 1.88KW Pack of LiFePO4.
It is totally Awesome! I'm so happy I did this! I can't wait to do a Car Conversion
Tommy L sends.......


[youtube]ygu8bV423wU[/youtube]

 

[edcastrovalley]

Well I got the mower but it has wiring issues, the battery is good. May have to add my own controller/wiring.

Edit: the battery cells are dead/puffed/corroded. Didn't think lead acid batteries would do that. Going to start a build thread next week.

I wonder what type of batteries it has. Maybe some really old SLA types? I'm looking forward to your thread. 8)

Awesome to see others do different types of conversions!

I'm in my Second season with my Electric Lawn Tractor Running on a 1.88KW Pack of LiFePO4.
It is totally Awesome! I'm so happy I did this! I can't wait to do a Car Conversion
Tommy L sends.......

Awesome mower! Very stealthy too. There must be some belt you engage for the cutting blades. At least you can hear some kind of belt starting up. Nice work! 8)

It's tiem for ES to have a cordless tool section IMHO.
Gnarliest mower, 24s fan cooled LIPO battery drills, 63 volts Dyson cordless vacuums, that sort of thing 8)

Not a bad idea. Last night I plugged my Ryobi corded weed eater into my battery pack. Another tool here. I worked great. I just packed the battery pack into a backpack and carried it around. It definitely saved a lot of time not dealing with cords. Maybe I can start another thread? Post a few pictures. What the heck...