running 24v@36v?

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rpmarco
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running 24v@36v?

howdy,

first post here, so don't haze the frosh too hard :)

just a general question on stepping up voltage--was curious as to people's experience/advice with running a spec'd 24v or 36v motor @ 36v or 48v, respectively. from what i've been reading about discharge rates for sla batts, it seems a lower A discharge is desirable, and it seems like increasing voltage is an easy way to do that. just wondering about the effect on the motor, controller, and overall efficiency. i'd appreciate any thoughts. thanks!

Gman
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Re: running 24v@36v?

`rpmarco,
Glad to see you here, Welcome to our V is for Voltage Community. I think we exchanged post on Instructables, your in the right place to get some very good answers, and we don't haze we help.
It would probably help to let us know again, I believe you stated you had a 36 Volt controller and a 24 Volt motor both from a old Scooters. What are you trying to build, another Scooter?

Peace Out,
Gman

Now that we have clarified our beliefs, your invited to join us as we begin building on them to define our Community Mission Statement

Peace Out, <img src="http://tinyurl.com/ysafbn">
Gman

andrew
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Re: running 24v@36v?

rpmarco,
If your goal is to increase range than it is best to keep the voltage the same and either get larger batteries, or add batteries in parallel.

If your goal is to increase top speed, than you may want to increase the system voltage.

High discharge rates are not really a big deal for SLA batteries, and don't derastically affect life. As long as they deliver the range you need, than I wouldn't worry about it.

---
Avatar taken from http://www.electricmotorbike.org/
Anyone got one they want to sell?
My KZ750 Project: here

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

rpmarco
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Re: running 24v@36v?

hi guys thanks for the responses. have a couple different projects going on at the moment--a 36v 900w bicycle push trailer (and a 250w 24v version for my dad); a single-wheel 400w 24v pusher; and an e/hpv in the works. most of the stuff was bought, though i did pilfer the motor and guts from a 250w scooter scored at a garage sale.

my question was mostly aimed at the effect on the motor and controller when running higher voltage. for example, you can run (according to the manufacturer) an e-tek motor at anywhere from 48-72v. if i'm assuming correctly, higher end controllers like altrex controllers can be programmed to run at different voltages as well.

so why if you're buying a chinese knock-off motor or controller do they specifically state either "24v" or "36v", etc. as if you could not run either at a different voltage? if you have a 36v controller, i'm assuming you couldn't run the system with a 48v pack (@ 48v). but does the efficiency of a motor drop when stepped up beyond it's mfd. stated voltage?

thanks again for any insights.
rob

Gman
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Re: running 24v@36v?

` ;)
FWIW, I have a 48 Volt China system, and was told by the Mfg recently, both my Hub Motor and Controller would handle close to 60 volts, I don't have the exact figures handy right now.
We'd love to see some pictures of your projects, and maybe even a Blog.
We also have several EV Collaborative Hand Books about building various EV's and could your project in them. Keep us updated.

Peace Out,
Gman

Now that we have clarified our beliefs, your invited to join us as we begin building on them to define our Community Mission Statement

Peace Out, <img src="http://tinyurl.com/ysafbn">
Gman

andrew
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Re: running 24v@36v?

you can run (according to the manufacturer) an e-tek motor at anywhere from 48-72v

Interesting! Did you contact the B&S directly, or where did you get that information?

if i'm assuming correctly, higher end controllers like altrex controllers can be programmed to run at different voltages as well.

Most controllers have an operating voltage range. You don't need to reprogram the controller to run at different voltages, but if you run too low a voltage some will switch off the power to try and protect the batteries from over discharge. If you run a higher nominal voltage than that specified you might destroy the controller. Some controllers can handle slightly higher voltages okay and offer a reasonable life, but it will probably be shorter.

so why if you're buying a chinese knock-off motor or controller do they specifically state either "24v" or "36v", etc. as if you could not run either at a different voltage? if you have a 36v controller, i'm assuming you couldn't run the system with a 48v pack (@ 48v). but does the efficiency of a motor drop when stepped up beyond it's mfd. stated voltage?

For controllers, it is usually an upper limit spec, but check the spec sheet to be sure. For motors the listed voltage is the rated voltage. Most motors can be run higher without problems, but beware that it will be easier to draw a lot more current at higher voltages and overheat the motor. Motors heat up about the same per amp no matter the voltage, and heat is your primary concern unless you want to run a motor way over the rated voltage.

To clarify, it is okay to over voltage a motor but not a controller in most cases.

---
Avatar taken from http://www.electricmotorbike.org/
Anyone got one they want to sell?
My KZ750 Project: here

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

Frying Pigeon
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Re: running 24v@36v?

I ran a 300 watt 24v scooter motor on 36v and it did fine. It was much more fun than at 24v. It almost went fast enough to make my eyes water. It did smoke a little going up a hill once, but I think that was a drive-train problem, because after I made some adjustments, it took the hill without smoking.

I also used a 24 volt controller which cost about $24 on ebay, and was rated for 30 amps. I had to add some wire to the heavy solder traces on the pcb, but having done that, it handled 36v fine.

I eventually switched to a 36v 600 watt hub motor, but the scooter motor went at least as fast as this hub motor on 36 volts. I am still using the 24v pwm controller from ebay on the hub motor.

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