Soyachips' Electric Vespa

Post up a thread for your EV. Progress pics, description and assorted alliteration
soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Thu, 16 Sep 2010, 18:20

Hi 7circle,

Thanks for the great feedback!

The 5Ah battery is very similar to the Jaycar one in your link. I think the brand is Fullriver or something. The GP batteries are 30Ah and are being used for the traction circuit not the accessories battery.

When I measured 12.7V the charger was disconnected so I guess this means that the battery is a bit sick?

I could use a bigger 12V battery but my main problem is lack of space. Depending on whether or not I can find a smallish DC-DC converter I may end up going with a bigger battery. I just don't want to end up limiting my night time riding by how long the 12V battery lasts!

The reason for a separate 12V battery is that I want my lights to stay on if I'm riding at night and the traction circuit dies. They don't have to last too long as I'll get straight off the road. Also I was trying to satisfy NCOP-14 and for me it was simpler to have a small 12V battery than work out how to give priority to the lights.

The non-isolated converters I've seen have the input and output sharing the same negative which is problem for me as I'm using the frame as the 12V ground. 150W sounds about right in terms of size.

What do you mean by a parallel diode and resistor circuit for charging? It sounds like I should have this!

Thanks for the recommendations on power supplies. I'll check them out. The Amtex ones look ideal but might be pricey.

Not sure if I've completely sorted out the min voltage on the Cycle Analyst. The latest min voltages aren't too low (43V) but I need to do more riding to tell for sure.

Re: fuses on the 12V circuit, I have a 15A fuse close to the + terminal of the 12V battery but where else should I have them?

Thanks!
Andrew

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Thu, 16 Sep 2010, 18:25

Hi acmotor,

Thanks for your input. I'm convinced I need an isolated DC-DC converter so now just have to find one the right size and price!

Cheers,
Andrew

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Wed, 05 Jan 2011, 04:28

I've been doing a little bit of riding on the scooter to test how everything is working and so far it's been pretty good. In terms of range I've been consistently getting 30km per charge but I haven't really pushed it yet as there are still some issues with the battery management system. Once that's sorted out I'll be able to charge the battery pack to a higher voltage and run them lower without risk of damage.

I've also made some changes to the gearing as my top speed was around 65km/h. The shop where I bought the motor said that I could safely run it at 1 mph per volt which at 51.2V equates to 82km/h, so I changed the small sprocket inside the crank case from 12 teeth to 14 teeth.

Image

Image

Image

The taller gearing means that it doesn't accelerate as well as it did before but it now goes above 75km/h without any problems.

However, at these higher speeds, the scooter develops a noticeable wobble like the tyres are stuck in grooves in the road or something and the scooter moves a little from side to side. I'm not sure if it's coming from the front or the back wheel but it's pretty scary when it happens! It was pretty windy at the time which might have played a part but after doing a bit of searching online it seems like small wheels, tyre pressure, anything loose, bearings, frame or forks out of alignment, something to do with suspension? might be responsible. Is anyone an expert in these things that can shed some light and is there a way to improve or fix the problem?

As a start I'll check the bearings are ok and everything is done up like it should be. I was also thinking of getting some new inner tubes and tyres as I'm not sure how old these ones are.

7circle
Senior Member
Posts: 540
Joined: Thu, 04 Feb 2010, 02:18
Real Name: Ken
Location: Melbourne

Soyachips' Electric Vespa

Post by 7circle » Sat, 08 Jan 2011, 08:09

Just a thought did the old motor use a pinion gear to make the crank spin in the opposite direction?

I've been thinking about the sum of torque moments lately and worry that having all rotating parts spinning in the same direction can cause issues when trying to change direction like the gyroscopic effects.

But your spot on to check steering column bearings and alignment of rear wheel with front wheel. Tyre balance is important too.

great conversion.

7C

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Sun, 13 Mar 2011, 04:22

OK so not much riding going on but I'm adding a DC-DC converter. It's a Vicor VI-231-CV which can output 200W, plenty for what I need.

My 12V 5ah accessories battery was running out of juice too quickly when using the headlight. I think this was because the current being drawn was too much for the battery and must have been damaging it. In the end the battery would only last a few minutes before the voltage got too low to use. Also from memory it only got up to 12.3V after charging.

The headlight is 30W so with other bits and pieces I'm guessing the system was drawing around 3A which is double the battery's max current rating. With the converter I should be able to draw up to 15A without any problems other than trying to keep it cool!

Image

Image

I've also replaced the wheels, tyres and tubes with new ones. The wheels were a little out of shape and I wasn't sure how old the tyres and tubes were so that's one less thing to worry about!

Image

Image

The tyres are quite different to the old ones so it'll be interesting to see what they feel like.

Image

Image

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

Soyachips' Electric Vespa

Post by EV2Go » Sun, 13 Mar 2011, 14:40

You should get a smoother ride on the new tyres... Any diffference in diameter that effects gearing?

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Sun, 13 Mar 2011, 21:27

No the diameter is the same but at some stage I'm probably going to adjust gearing again. I changed from 12 to 14 tooth on one of the small sprockets but I think 13 tooth would be ideal. I don't have any adjustment or tensioner on that chain and 13 tooth would give me the right tension without having to use a half link. I think it will also give me the right balance between initial acceleration and top speed. I guess that's the nature with these kinds of projects!

User avatar
Thalass
Senior Member
Posts: 741
Joined: Sun, 12 Aug 2007, 07:29
Real Name: Ben Rypstra
Location: Perth, WA, AU

Soyachips' Electric Vespa

Post by Thalass » Mon, 14 Mar 2011, 00:27

Nice scooter! Any video of it in action? I prefer motorcycles myself, but for in the city scooters are great.

Also, where did you get the dc-dc converter from? And how much was it?
Last edited by Thalass on Sun, 13 Mar 2011, 13:28, edited 1 time in total.
I'll drive an electric vehicle one day.

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Mon, 14 Mar 2011, 03:56

Sorry no videos yet but will post the links here when I do.

I bought the converter new old stock on eBay from a surplus place in the US for $50 including shipping. Otherwise they're about $300 new here!

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Sat, 30 Jul 2011, 07:54

Well I finally got around to installing the DC-DC converter and it looks like it's all working properly. I'm now able to ride at night without my 12V circuit dying on me!

Image

Image

I've also installed new wheels, tubes and tyres in an attempt to fix the wobbles I was getting at higher speeds and so far it seems to be helping. Will do some more testing over the coming weeks to see if the problem has really gone away. Fingers crossed.

The last change is I've connected a buzzer to the BMS to tell me when any of the cells reach 2.5V so I know when to recharge. However I've noticed that when I accelerate quite hard, the buzzer comes on. I know as a general rule that I shouldn't discharge the cells too low but is it also a problem for the voltage to sag like this for brief periods?

7circle
Senior Member
Posts: 540
Joined: Thu, 04 Feb 2010, 02:18
Real Name: Ken
Location: Melbourne

Soyachips' Electric Vespa

Post by 7circle » Mon, 08 Aug 2011, 23:08

I would investigate the voltage sag further. If one cell is going below 2.5V I wonder how far it really is falling.

You may need to swap out that cell.

As you said it's under "quiet hard" (like the ev pun) accell that it alarms.

Depending on your wiring it could just be a bad connection between the batteries.

Would be fun to ride.

Thanksfor the update.
Ken 7C

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Tue, 10 Jul 2012, 04:01

Ok so I'm finally back on the road after a long break. Unfortunately the last time I was putting everything back together I accidentally fried my BMS so I've added a distributed MiniBMS system in its place. Seems to all be working fine and will hopefully keep the cells better balanced.

Here are some pics of charging up the cells one-by-one to try and balance the pack and the MiniBMS modules on each cell. Looking forward to clocking up some more KMs now that it's running again.

Image
Charging up individual cells to balance the pack.

Image

Image
New MiniBMS cell modules on battery under seat.

Image
New MiniBMS cell modules on batteries under left cowling.

Image
Old petrol tank lid covering all the bits under the seat.

soyachips
Groupie
Posts: 173
Joined: Mon, 04 Aug 2008, 05:44
Real Name: Andrew Lo
Location: Sydney

Soyachips' Electric Vespa

Post by soyachips » Tue, 10 Jul 2012, 04:10

I also just got my indicators working after struggling for a while. The problem was that I bought LED indicators and needed to either use inline resistors to get a normal flasher relay to work or use an LED flasher.

I first bought an LED flasher and wired everything up but it didn't work. Then complained to the place I bought it and they sent me another one but that also didn't work! Bought another LED flasher from a different place and that didn't work. I then tried inline resistors with a normal relay and that didn't work either.

In the end I needed to use inline resistors AND the LED flasher to get it to work! Crazy and frustrating but at least now I have indicators :-)

Post Reply