run time question

[wheels]

Hey guys,

I am building another campground cruiser, but this time i'm seriously considering going electric. I've built my own bicycle lighting system, so i'm comfortable with this project.

I am trying to figure out if it will be worth it... going electric or not. I would like to have a run time of atleast 8-10hrs... might be wishful thinking though. I would settle for 5-8hrs i guess.

anyways... my project will have 15 inch tires and need gearing to get me to 15-20mph max. i'm thinking about going with a 24V 900 Watt motor... and over volting to 36V. For size reference, please refer to pics in this Introduction Thread

so, going by this formula...

Amp hr = Watts / Volts

if i had 900W / 36V, i would need 50ah batteries to give me a solid run time of 5hrs... correct? leaving some juice in the batter for overkill.


how does weight play into this?
what else am i missing?
where do i factor in 'amps' for this project, or do i really need to?


thanks for any input.

 

[Bluethunder3320]

im a fan of gas because you can get a 6.5hp engine that weights 40 pounds, for $100-$140, and run it for as long as you need to. easy to mount and hook up. pretty quiet too.

http://www.harborfreight.com/predat...d-for-all-states-except-california-68120.html

im not so sure how to figure out run times, ill leave that for the electric experts.

run a gas engine forever as long as it has oil and gas and doesnt break.

 

[wheels]

thanks for the link... i actually used a blue harbor freight motor for the first campground cruiser. Thought i would be a little different this time.

 

[racerc2000]

overvolting to 36 volts is bad for the motor. in short bursts its not a big deal but running it for long periods of time will get the motor pretty hot.

how big of a toy do you want? you will need a beefy frame and quite a few batteries

I remember back in the day I took a razor mx350 dropped in a 750 watt 36 volt motor and ran it with 4X 12volt batteries 12ah each.

it was pretty fast at 48 volts but would hardly get an hour run time.

just something to think about. my brother used to get commercial battery backup batteries all the time from work (upgrades etc old units get tossed batts still good or good enough)
and they were a good size like 10X4

you would prop need like 6X 12volt gell cells

im sure its possible but long run time + performance dont mix unless you have a team of engineers.


find someones old lawn tractor. slam it to the ground and add a clutch. itd give you a good run time and 20mph+

 

[wheels]

i've read several threads on here saying it was safe(over-volting)... so, that's the only reason i was planning on doing it.

to be honest, i'll probably just go with another gas engine. seems to be alot cheaper.

this was the first campground cruiser... (from my introduction thread):

 

[wingnut]

I like electric. I converted an old gokart to electric for my kids when there were stepping up from a plastic Power Wheels toy. It was perfect for them. Also, you can't beat electric for quiet operation. If you're cruising around a campground, your neighbors will really appreciate it.

That said, you will always pay more for for electric to get similar performance. For the record, to compute run time:

amp hours / watt * volts = time

So with your configuration:

50 / 900 * 36 = 2.57 hours

It's not really that bad because, presumably, you would design the cart so that you spend very little time at full throttle.

I think that size will be a limiting factor for you. The problem is that batteries with the capacity your talking about take lots of space (particularly lead acid). If you were building something the size of a golf cart then you'd have the space. If you're looking to build something like the one in your last picture, then that doesn't leave much room for batteries. You'd have to go with Lithium Polymer to come close and they can be spendy at that size.

 

[wheels]

Thanks for the info Wingnut... i appreciate it. I really like the idea of it being quiet... but, i would like a lot more run time than just a couple of hours.

 

[wkearney99]

The upside to electric is you're not burning fuel to run it and it's a lot quieter. The downsides are battery weight/cost and recharging time. If you're recharging from the engine or generator running in an RV then you're not saving any fuel. But being able to run it more quitely might make it nicer to use later at night or during the early hours.

 

[racerc2000]

i've read several threads on here saying it was safe(over-volting)... so, that's the only reason i was planning on doing it.

to be honest, i'll probably just go with another gas engine. seems to be alot cheaper.

this was the first campground cruiser... (from my introduction thread):

I wouldnt say its not safe persay but. depending on the specific motor you use it can destroy itself with a 10% overvolt some can withstand a 200% overvolt

the stock motor I had was a 12 volt 350 watt. in stages I had overvolted it to 24 volts it started to self implode wires inside de soldered from heat it was messy.

I replaced it with a 750 watt 36 volt motor I settled on 48 volts but for a while it was run at 60 volts. but I deemed having a 5th battery mounted to the rear fender was overkill (4 was max that fit in the frame)

I dont know the exact specs your looking for in voltages. but I would suggest a higher volt motor then 12. a 24 or 36 will take an overvolt much better then a 12. but. the 12 will give you the highest top speed then it will die.
aluminum heat sinks could help or getting heavy duty high temp motors



gas does endup being cheaper. and if you needed you could quiet down the gas motor. could even rebuild the same type of vehicle with a scooter motor

 

[wheels]

thanks for input fellas... i ended up ordering a 6.5 hp engine with electric start.... and a torque converter.

thanks again.

 

[oscaryu1]

I wouldnt say its not safe persay but. depending on the specific motor you use it can destroy itself with a 10% overvolt some can withstand a 200% overvolt

I had mine at 200% for a year. Killed two sets of batteries and a controller, then the frame. Still have the motor. Looks great inside.

the stock motor I had was a 12 volt 350 watt. in stages I had overvolted it to 24 volts it started to self implode wires inside de soldered from heat it was messy.

That's not solder.

I replaced it with a 750 watt 36 volt motor I settled on 48 volts but for a while it was run at 60 volts. but I deemed having a 5th battery mounted to the rear fender was overkill (4 was max that fit in the frame)