Step Up Transformer 24 to 48 volt to run motor

[rollingreenhills]

I have googled the living whatsit out of this. . .

Can you use a step up transformer in the following circumstance.

2 x 12v 22ah Panasonic SLA linked in serial to run this transformer:

http://www.ebay.co.uk/itm/281755037627?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Specs say "24V * 20A = 480W", so I am expecting the motor to be underpowered, but by how much do you think?

The motor is a 500w 48v bafang BPM. It is a 230 rpm model in 20" wheel. I am upgrading from a unite 1020z chain drive, which had nearly zero torque.

When these SLA batteries die I will get some lithium battery, but I would like to use them, rather than get shot of them, perhaps that is unrealistic.

Best Regards W . .

Oh! I recived the following info from handy chap on Google Plus called Jim Conner:


Hi +kermit green - I didn't know that a 1200W version was out there... I might have to order one of those for myself.. for a little project I've been playung around with for which I have not yet made a video. The specs on the 1200W unit (if you're buying the same one I'm looking at) seem a little confused though... They say that it's limited to 20A input current (which would mean that on 24V the max you could get out of it would be 480W), and then they say that it has a 30A fuse on there (which would let you pull 720W max from 24V)... This might give you some problems running a 500W motor, as the 500W rating will be the continous-power rating for the hub motor, rather than the maximum peak power it can pull (which is probably over a kilowatt)... On my own 250W motored bike, I've seen the motor pulling around 850W peak power. I wouldn't worry too much about damaging the converter... as long as you don't connect the input power the wrong way around, or directly short-curciut the output, it should be pretty much bullet-proof.

Anyway... onto the current limit... The biggest problem with the current limit is working out which way to turn the screw to get it to maximum power. When I have set up my own units in the past, I've used a string of low-voltage light bulbs (either 12V car lights, or a string of fairy lights) so that I can twiddle the amp control and work out of the lights are getting brighter or dimmer. Once you work out which way gets brighter, wind it all the way up to maximum - You don't really want to limit the current you're supplying to the motor.

Hope that helps - ping me again if you need more help or a better explanation. Cheers!!

 

[rollingreenhills]

This did not work.

The bike was Ok on the flat, but as soon as a load was applied i.e. a small hill, the controller would cut out.

I think the step from 24v to 48v was too big considering the required current.

Write up here:

http://dorkythorpy.blogspot.co.uk/2016/05/using-step-up-transformer-to-run-ebike.html

 

[wesnewell]

You're just wasting your time and money. If you want to use lead batteries, get 4 7ah 12v batteries. That's 336wh compared to 288wh for your current battery,

 

[parabellum]

This did not work.

The bike was Ok on the flat, but as soon as a load was applied i.e. a small hill, the controller would cut out.

I think the step from 24v to 48v was too big considering the required current.

You are just adding more useless weight and lowering your efficiency with additional conversion, by common sense you should be mowing in opposite direction. :lol:
Then, current control of those cheap controllers is not to rely on, I will not wonder if you see over 1KW in high load, low speed condition. As well there can be block time, where current control is off for a sec. to let you start mowing.
Right way to go is- getting god 48V lithium based battery and have fun for many years to come. There are absolutely no advantages in LA batteries.

 

[999zip999]

What ? What ? What happened to my two posts ? Holy dictatorship.

 

[amberwolf]

I looked thru the moderator logs, and none of your posts (or anyone else's in this thread) have been altered or removed.

Maybe you replied to him in one of his various other threads?
https://endless-sphere.com/forums/search.php?author_id=45259&sr=posts

Here's a list of all of your posts, most recent first, that anyone can access from your profile.
https://endless-sphere.com/forums/search.php?author_id=14986&sr=posts

 

[rollingreenhills]

Dear parabellum,

Thank you for your reply, there are 2 irrefutable advantages to lead acid:

-The low initial cost.
-Low skill level in use.

They may be heavy, bulky and generally rubbish, but for those a a steep learning curve and tight budget they are a blessing.

I do now have a functioning lifepo4 pack. I am not a complete idiot but it took me 4 weeks (on and off) to get it finished, and it cost £240.

With my 24v SLA system I was up and running in 1 hour, and it cost me £105.

I don't doubt lithium is the holy grail of batteries, but for someone with very little electronic experience lead acid offers a way into the EV field, without too much hair loss.

Kind regards,

rollingreenhills

 

[parabellum]

Dear rollingreenhills I started with your thinking initially. Now, after 6 or so years, looking back I understand how much of irrecoverable time and strength was lost swimming against stream of progress, and how pleasant and relaxing it is not to resist the pace of technology.
If you where in possession of ready 48v LA system, I would say wear it and go Lithium after, but spending 1 dime in LA system is counterproductive and you seem to know it.
As to your arguments, they are valid, but I try to not observe isolated spot advantages but system efficiency as whole. And as end result they are loss, loss unfortunately.
Time is priceless, jump over few steps whenever possible.