Has anyone ever converted a battery mower to AC?

Thread Starter

ThirtyWest

Joined Jul 15, 2017
140
Battery failure after failure. Order one online with 2x the aH and it lasts less than the original ok the first few tries.

my yard isn’t that big and I have miles of cord.

how involved would it be to make a box that sits in the “battery trunk” of my Ryobi that rectifies 110 to 40VDC?

the batteries normally are 2 to 4 aH.

It’s an awesome mower; quiet enough to talk on the phone while working. I just am tired of batteries.
 

Thread Starter

ThirtyWest

Joined Jul 15, 2017
140
I’m trying to find that Max.
I think I’m gonna have to go inside and read the placard on the motor.

the cord is, if I recall, 20a. It runs half of my Christmas lights.
 

Alec_t

Joined Sep 17, 2013
11,538
As Max says. Note that DC motor start-up current (stall current) is several times the rated running current, so the converter would have to be rated to handle start-up.
 

Thread Starter

ThirtyWest

Joined Jul 15, 2017
140
What is the cord rating? Looks like many mains-powered mowers need a motor of around 1300W (nearly 2HP). That's a current of ~ 12A @ 110V.

Cheaper and less hassle to buy a power converter rather than make one.
Exactly.

I just need to find the motor specs for the

RYOBI 40109
 

MaxHeadRoom

Joined Jul 18, 2013
21,267
Looks like a BLDC motor with variable speed controller.
You might have a slight problem building a supply that small.
But if you always start at zero rpm and slowly increase, you may get away with a smaller supply, just a transformer and a bridge.
Max.
 

Ylli

Joined Nov 13, 2015
976
I'm a little confused here. Battery is 40 volts, 5 AH = 200 w-hrs. Even a small 1 HP motor is going to draw 800 watts. So the unit has a run time of 15 minutes?
 

MaxHeadRoom

Joined Jul 18, 2013
21,267
Of course the current or power dissipated will depend on the typical and/or average loading.
Much of the time, I suspect it is lightly loaded.
Especially with RPM control.
Max.
 

Audioguru again

Joined Oct 21, 2019
1,776
The problem is the poor quality of the replacement batteries. They were bought "online" which usually means cheap poor quality No-Name-Brand from ebay. You usually get what you pay for, minus the boat trip from China.
 

upand_at_them

Joined May 15, 2010
475
Funny...I have an AC-powered mower that I'm thinking about converting to battery. But using a small car or lawn tractor battery. I've measured power consumption with a Kill-a-watt and the 45 minutes it takes me to mow doesn't consume much power at all.
 
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MaxHeadRoom

Joined Jul 18, 2013
21,267
Funny...I have an A/C-powered mower that I'm thinking about converting to battery. But using a small car or lawn tractor battery. I've measured power consumption with a Kill-a-watt and the 45 minutes it takes me to mow doesn't consume much power at all.
Do you know the nature of the motors?
Max.
 

Bernard

Joined Aug 7, 2008
5,620
About 5 years ago, @ US $ 75 for a single 12V, 7.5 AH SLAB, ?, my lady friend cried for help so rewinding a microwave transformer to 24 V, 35 A FWBR was back mowing weeds & grass. Grass now replaced with gravel. Wire might be # 10THHN. @ 3,?, turns/V.
 
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