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24 volt motor run time Answered

Hi all,

We just finished a remote control lawn mower project that utilizes 2 24V wheel chair motors and two wheel chair batteries for drive power. The balde is powered by a gas engine. The unit weighs in at around 260 lbs and is used for some serious slope mowing. The issue I have run into is that I can only get about 1 hour run time before having to recharge. Does anyone have any suggestions as to how to increase the run time without decreasing power?

Thanks

23 Replies

user
Athra (author)2015-01-27

i need motor driver circuit to run wheel chair using voice commands

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user
sspence (author)2013-05-10
user
sspence (author)real57vetteguy2013-05-10

Then you are out of luck.

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sspence (author)sspence2013-05-10

You could try lighter batteries, like NiMH or Lithium Ion.

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user
real57vetteguy (author)2013-05-09

I Had intended On Keeping The Batteries, I Just Wondered If The 150 Amp Altetnator WasaEnough To Keep Them Charged?

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user

You're running a mean current of only 35A right now, why on earth use a 150A alternator ? A 50A alternator would probably be all you need. If you're charging SLA type batteries, you should NEVER charge them at a 1hour rate ANYway, or they'll die in 100 charge cycles, so if we said 5 hours rate, then you'd only need 7 or 8 A to charge them.

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mpilchfamily (author)2013-05-08

Add more batteries in parallel or use larger capacity batteries.

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user

if two 12V are wired in series to produce 24V how would I wire them parallel?

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user

You don't wire the current batteries in parallel. You buy 2 more batteries and wire them together in series. Then take that and wire it to the current batteries in parallel. Thus doubling your run time but also doubling your charge time and may require a second charger.

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user

Let me ask you this! I am running 2 12AH 12V batteries in series right now, If I change to 3 50AH 12V batteries in series, resulting in 36V and a total of 150AH vs my current 24AH, how do you think this will affect the run time? I know it will produce more speed which is nice but how much more run time?

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user

I was incorrect, I am running 2 35AH batteries right now, What scares me is if I add 2 more 50AH batteries I am going to be weighing 360 lbs instead of 260. That will make it that much more difficult to unload and get unstuck if that happens, I am thinking the alternator might be the best bet!

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user

Alternator will work fine if you can get one that can handle 24V and give the amperage needed to run the motors. Typically and alternator is good enough to supply a car with the power it needs to run the engine and electronics and trickle charge the battery. Those motors require much more than that.

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user

I agree, my thought process is to run a GM 1 wire alternator converted to 24V, possibly a 150 amp alternator. Even if I had to plug in the charger from time to time it should increase the run time a great deal!

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user

Keep the batteries, let them take the surges when the motor starts, not the alternator. 150A is a 3.6kW into the motors....

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user

The result would be burnt out motors. Maybe not after the first few runs but it will damage the motors. Either burning out the coils or wearing out the bearings and seizing the motors.

Changing to 2 50Ah batteries in series will improve your run time considerably over the current batteries. Should get close to 4 hours on those.

4 of them in the above mentioned series parallel configuration would improve it even more.

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user

So the easiest thing to do would be to pick up 2 50AH batteries and wire them in series/parallel with the existing 12AH should help considerably?

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caitlinsdad (author)2013-05-08

You need to lighten the unit so it doesn't put as much load on the motors while moving. Gear up or down the motor to have it run more efficiently. I guess the batteries are in series, maybe add an additional set in parallel. Does the mower have a bagger that drags as it fills up?

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user

There is no way to lighten the mower, its a gas engine, two electric motors, two batteries, a frame and mowing deck, there is nothing to lighten. As far as gearing it is geared as low as possible, any lower and it would be crawling at a snails pace. I like the additional set in parallel, and I have also considered an alternator, I have an idea I will mention above!

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user
steveastrouk (author)2013-05-08

If you have a gas engine, run an alternator off it and run the thing off the gas engine, not batteries.

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caitlinsdad (author)steveastrouk2013-05-08

If you have an intern, have him push the thing around. Save your money in tooling costs to rig up the engine.

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user
qquuiinn (author)2013-05-08

Try a different motor controller or some batteries from hobbyking. The li-ion ones can run for a looong time

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real57vetteguy (author)qquuiinn2013-05-08

How would a different motor controller increase run time?

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