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Post up a thread for your EV. Progress pics, description and assorted alliteration
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Nevilleh
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Post by Nevilleh » Fri, 18 May 2012, 13:18

Let me clarify that and say "commercially successful". By that I mean no-one will ever build a car powered by PbA batteries that can come anywhere near competing with even the most rudimentary petrol driven one for ease of use, convenience and range, not to mention the time taken to "fill the tank".
It is just now possible to build an electric car powered by Li batteries that can achieve the performance of a petrol driven one in many areas, except it still takes all night to recharge the thing.
What is successful for one person is not necessarily so for another. Electric powered milk carts have been around in the UK for years, so you would say they are successful, but I wouldn't use one for everyday transport - would you?
Look at Mitsubishi's iMev: Costs twice as much as the equivalent ice model (Lancer?), doesn't accelerate as well, doesn't go as far or as fast and takes all night to recharge. You better not run out of volts far from a friendly motel!!
I admire anyone who has built an EV no matter what it is powered by - its a lot of work. But the easy part is sticking a motor and controller and some batteries into an existing vehicle. The hard part is making it suitable for everyday use and NOT having another car (ice) for use when the going gets serious.
I use a Falcon ute to deliver electric scooters. Why? Because I can't make an EV that will do the job. Wish I could.

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Post by Richo » Fri, 18 May 2012, 20:34

Nevilleh wrote: Look at Mitsubishi's iMev: Costs twice as much as the equivalent ice model (Lancer?)


You mean a Colt.
If the iMiev looked like an EVO more people would but it.
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Post by Richo » Fri, 18 May 2012, 20:40

Nevilleh wrote: I use a Falcon ute to deliver electric scooters. Why? Because I can't make an EV that will do the job. Wish I could.


eV Ute
This one has since been changed to LiFePO4 and one motor removed so has more range and less wheel spinning.

I'm sure a falcon ute could do it - even if it is a Ford.
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Post by Nevilleh » Fri, 18 May 2012, 21:48

Richo wrote:
Nevilleh wrote: I use a Falcon ute to deliver electric scooters. Why? Because I can't make an EV that will do the job. Wish I could.


eV Ute
This one has since been changed to LiFePO4 and one motor removed so has more range and less wheel spinning.

I'm sure a falcon ute could do it - even if it is a Ford.


Oh yeah, heaps of grunt, might be nearly as fast as the Falcon! But he says "range 37 miles" maybe 60 kms and certainly not at that speed. A typical scooter delivery is from here to Auckland, a 500 kms round trip and usually is done in a day. Can't do that in ANY EV currently available. Even with Li cells, if I had enough on board to do that, I couldn't carry a payload!
My BMW is perfect for daily use, off to town and back, down to the coffee shop and so on. Usual day is about 65 kms or so and all in 50 and 70 zones, but my point is that I still need two vehicles.

Mitsubishi only call it a "Colt" in Australia - they know not to use big words over there Image

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Post by 4Springs » Fri, 01 Jun 2012, 00:01

I dropped off the Brumby to the Engineer yesterday, and picked it up again today. His workshop is 30 km away, so this is my longest trip so far.
He seemed happy enough with it, except he would like to see a bit more restraint added to the batteries in the rear battery box. This makes sense, there is a lot of weight there. Here is a photo of the batteries:
Image

He is concerned that there is not enough to restrain the batteries in the event of a rear collision, with the force on the batteries towards the rear of the vehicle. Currently they are only really held by the board across the bottom (can't really see it in the photo), and the door that closes behind them. He recommended that I put in a single piece of angle iron the entire length of the box behind the batteries (so across the face of them in the picture), anchored at each end. He'd also like to see something in the gap to stop any sideways movement. He made the comment that while this might not be technically enough to restrain the 280 kg of batteries against a rear impact, it would be enough to satisfy him in this case. This is considering that if the batteries escaped in that direction they have a ute tray to run into, and not something more fragile, like the back of someone's head. Image

I took it to a weighbridge, and it came in at 1460 kg (front only 800, rear only 700). Add 163.2 kg for theoretical passengers & luggage = 1623.2 kg. GVM is 1620 kg, so I should have removed the tarp before I weighed it! As someone else has stated, fortunately my engineer is human, and he decided to allow it.

I only just made it back home, almost ran out of juice. It was charged up overnight, but with the trip to the weighbridge, and the bit of driving that the engineer did, the battery was flatter than I had anticipated. Doesn't help that home is 200 m higher than the engineer's workshop. Gave me a good value to set my Zeva Fuel Gauge Driver zero point to.

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Post by weber » Fri, 01 Jun 2012, 06:16

Well done, 4Springs.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

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Post by Thalass » Fri, 01 Jun 2012, 06:57

Congratulations!
I'll drive an electric vehicle one day.

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Post by Richo » Fri, 01 Jun 2012, 21:09

Nevilleh wrote:Mitsubishi only call it a "Colt" in Australia - they know not to use big words over there Image


http://www.mmnz.co.nz/
I don't know the Mitsubishi website in NZ would suggest otherwise...
The iMiev is right next to the Colt which look pretty similar and nothing like the Lancer.

Sorry 4Springs for being off topic.
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Post by Johny » Fri, 01 Jun 2012, 21:23

I have seen/followed petrol Mievs here in Austrlaia - they were/are called "i" or i-kei. The iMiev is a lot smaller than the Colt or Lancer and is based on the i-kei.
http://en.wikipedia.org/wiki/Mitsubishi_i

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Post by 4Springs » Mon, 27 Aug 2012, 00:02

Well, I'm finally legal!
I took the Brumby in to the Engineer again the other day to have my modification plate fitted. Wasn't until then that I found out I had to take it to an Approved Inspection Station as well.
So the process in Tasmania is:
1. Apply to the Transport Department to get approval for the modification.
2. Once approval is granted, talk to an Engineer and start the work.
3. Once the work is done, the Engineer forwards his report on to the Department.
4. The Department sends a modification plate to the Engineer, who affixes it to the vehicle.
5. Take the vehicle to an Approved Inspection Station to get it inspected. They complete an "AA" form.
6. Take the AA form into Service Tasmania (where we go to pay our rego etc.), who will update the database with the new engine number etc.

The Engineer charged $706.50 including the modification plate. The Approved Inspection Station charged $110. Service Tasmania did not charge anything. This brings my total cost up to $12,500.

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Post by 4Springs » Mon, 27 Aug 2012, 02:04

And an update on the range and economy:

Last time I drove I flattened the battery, and set the Zeva fuel gauge driver zero point. So this time I drove into our local city (200m lower than home), and at the end of the 30km trip the gauge was sitting exactly on half.   I topped it up to just under full, and arrived home with just a little left in reserve. So I suppose my usable range is about 40km, or a bit further downhill.

The next day I took it for a drive out to a nearby town, a round trip of 36km. This trip is much flatter, and the fuel gauge was showing a bit lower than half by the time I returned. This time I could measure the amount of power used to recharge. The figures come out at 24 kWh/100 km, a bit better than previously estimated. This figure is without the battery heaters. The battery heaters run when plugged into the wall socket, and use about 100 W, depending on the ambient temperature.

With our current power and fuel prices, this works out as $5 per 100km, which is less than half what it was as a petrol car, and a bit better than our brand new diesel Hyundai i30 hatch.
Our city council provides free parking a little way out of the city centre. I found some power outlets along a wall, and so the council may be helping me out with my power costs! At about $1.50 a trip, I don't think they'd be too worried.
In a similar vein, my workplace has offered to put in an electric vehicle bay in the carpark. They will install a power outlet for me (and anyone else) to use to charge up during the day. They are quite enthusiastic about it, and it may encourage others to go electric.

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Post by 4Springs » Fri, 21 Sep 2012, 03:06

Decided to check how balanced my batteries were:
Image

My balancing zeners only work a little each time I charge, and I've only been charging since I've been driving - since about the 20th of August.
The numbers across the bottom are the battery numbers 1-12. Batteries 2 & 10 are harder to get to, so I don't always measure them. I have checked the voltages on 5 occasions, but only the last 3 are dated. So the graph shows that the batteries are now more balanced than they used to be. Battery 12 in particular has come down closer to the average.
With the batteries fully charged, all globes glow for a few seconds when I turn the charger on. I did this initially as a check that all regulators were still operational, and found that one was not. One of the zeners on battery 11 had a dry solder joint, and had gone open-circuit. If you look at it on the graph, you can see that battery 11 is now the highest voltage.

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Post by StudentEV » Wed, 03 Apr 2013, 03:30

Hi 4Springs

Congrats on getting your EV on the road! I hope I can find an engineer that cheap for ours when the time comes!

I also hope I didn't need to get permission from Vicroads or the state dept. of transport to start modifying the vehicle! I had better look into that...

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Post by 4Springs » Wed, 14 Aug 2013, 02:52

Brumby in its natural environment - helping with the pruning!
Image
You can't see him, but the dog has been relegated to the front seat to make way for the branches. Branches are on the way to the cows to be recycled.


Driving home today was much wetter than in that photo. Pouring with rain and 45km/h winds. There was water over the road in several places, I didn't see it in the dark and ploughed straight through. This is one time that the extra weight is a good thing - I reckon the unmodified Brumby probably would have floated. Electric Brumby was undaunted though, with water spraying high in the air both sides.
I had a good look under the bonnet when I got home and found a bit of splash. I had put in some splash panels though (made of corflute!), so everything important stayed dry. Circuit breaker didn't trip when I plugged it in. This is the wettest I've every had it, and so far so good!

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Post by Rattrap » Wed, 14 Aug 2013, 15:38

i'll have to keep an eye out for you on the road!   :)

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Post by offgridQLD » Sun, 25 Aug 2013, 00:24

Nice Build, Utes make great a great EV base. That's one hell of a big pumpkin! Image

Nevilleh wrote:
Look at Mitsubishi's iMev: Costs twice as much as the equivalent ice model (Lancer?), doesn't accelerate as well, doesn't go as far or as fast and takes all night to recharge. You better not run out of volts far from a friendly motel!!
I would say the 1.2lt 4cly 2013 Mitsubishi Mirage is a more equivalent ICE model car to the Imiev. The Mirage is 36% slower than the Imiev in the 0 - 100kmh dash . Even the 2lt lancer that isn't a good comparison is the same spec 0- 100kmh as the Imiev. Remember the Imiev is a single speed auto so you need to compare it to a Automatic transmission ICE car.

Though I do agree all cars have there compromises its just a matter of finding the one that fits your needs, price, style.

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Post by 4Springs » Fri, 11 Oct 2013, 15:59

About to start purchasing my new lithium pack. Always a good idea to run my plans past the good folk at AEVA before making purchasing decisions!

My plan is:
48 cells, LFP130AH from EV Power. This should make a 20kW traction battery.
Elcon TCCH-156-11 charger from evassemble.
Nevilleh's BMS. I've been building this for some time now, and I'm about at the stage where I need to put some modules on some cells to make sure they work.

I selected that charger because I'd like to be able to charge from a 10A outlet. My interpretation of the specs (here) is that this model will use a maximum of 208V x 11A = 2.3kW. This should utilise the available power source well, without tripping any circuit breakers.
By the look of this information (link) I can specify either a simple charge enable/disable control, or a 0-5V current control for the charger. Would there be any particular advantage of the 0-5V control? Given that I am making the BMS myself, I could implement this if it was going to be of benefit.

I am moving from 144V to 154V (nominal). I think that everything should cope:
IOTA-DLS-55 DC/DC converter
Kelly KDH14800D controller
Kostov 17R motor

Can anyone see any problems with this plan? Any more suitable charger, or a better place to buy it from?


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Post by Johny » Fri, 11 Oct 2013, 18:52

I agree with being to charge off a 10A GPO - makes life easy.

The 0-5V current control, coupled with a control system and the BMSs will make a much better charge-and-forget system where you just never have to think about cell balance. If you can select a charge rate at or just under the BMSs cell balance current then enter that mode when any cell hits the bypass voltage it makes a nice EV.

Just my opinion. The charging/pack management side of an EV is a huge part of it's success or otherwise.

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Post by Renard » Fri, 11 Oct 2013, 19:07

Johny wrote:
The 0-5V current control, coupled with a control system and the BMSs will make a much better charge-and-forget system where you just never have to think about cell balance. If you can select a charge rate at or just under the BMSs cell balance current then enter that mode when any cell hits the bypass voltage it makes a nice EV.


I second that.
If you are top balancing, when Neville's BMS reports a cell reaching 3.6V and then bypassing (assuming that's the set parameter), you want the charger to drop to less than 0.5A. This can be achieved using the 0-5V control. As I have seen, the charger current is linearly dependent from zero to full between the settings of 2V and 5V.
Iout = Imax x 1/3 (V-2)
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Post by BigMouse » Fri, 11 Oct 2013, 22:35

I agree that current control of the charger is handy for the same reasons mentioned by Johny and Renard. The "CAN" version is better for that though, in my opinion. The Elcon's "CAN" is really just UART. You can make an optoisolated dongle for it pretty easily. There's info on doing it out there somewhere. It's a lot easier to tell the charger digitally that you want 400mA than it is you generate a precise 0-5v analog signal from a microcontroller. This is what I've done with my own BMS and it works nicely.

Elcon provides all the specs for the "CAN" commands, it's not hard to implement.

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Post by antiscab » Sat, 12 Oct 2013, 00:50

4Springs wrote:
Elcon TCCH-156-11 charger from evassemble.


I should point out that that charger is actually cheaper bought directly from TC Charger (US$500 + ~US$130 shipping when buying a single unit) for a 2kw unit (which is what the 156v 11A charger is).
Although depends what your bank charges to send money to China

power is actually limited to 2000W, 11A or 208v, whichever is less (also you can specify a specific end voltage)

actual current drawn from the mains is 2150W/mains voltage with an upper limit of 15A.

CAN bus option is ~US$45 extra IIRC

re balancing at low current - be aware that floating (holding a voltage above 3.45v at low current) lithium batteries is fairly bad for them (overcharging).

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Post by 4Springs » Sat, 12 Oct 2013, 03:01

Thanks for all the replies so far!
Johny wrote: The 0-5V current control, coupled with a control system and the BMSs will make a much better charge-and-forget system where you just never have to think about cell balance. If you can select a charge rate at or just under the BMSs cell balance current then enter that mode when any cell hits the bypass voltage it makes a nice EV.

So I really just need two states - "flat out" and "throttled back". I could use a digital output and a couple of resistors. Digital output on = 5V, digital output off = lower Voltage. Work out the Voltages with the handy formula that Renard gave.
BigMouse wrote:The "CAN" version is better for that though, in my opinion. The Elcon's "CAN" is really just UART. You can make an optoisolated dongle for it pretty easily. There's info on doing it out there somewhere. It's a lot easier to tell the charger digitally that you want 400mA than it is you generate a precise 0-5v analog signal from a microcontroller.
I do have a spare RS-232 UART on the board. Sounds like it would not be difficult to make this talk. But, is there any advantage? Do I ever want any other states than the two mentioned above? As Matt mentions, the CAN option is an extra $45, and extra mucking around.
Matt wrote:I should point out that that charger is actually cheaper bought directly from TC Charger (US$500 + ~US$130 shipping when buying a single unit) for a 2kw unit (which is what the 156v 11A charger is).
Although depends what your bank charges to send money to China

power is actually limited to 2000W, 11A or 208v, whichever is less (also you can specify a specific end voltage)

actual current drawn from the mains is 2150W/mains voltage with an upper limit of 15A.

CAN bus option is ~US$45 extra IIRC

re balancing at low current - be aware that floating (holding a voltage above 3.45v at low current) lithium batteries is fairly bad for them (overcharging).
Thanks for that Matt, this is good information.
I'm not quite sure what you mean with the last line though. This is how I understand it:

I'll be implementing top balancing.
State 1: Charger on full bore, all cells charging at maximum current.
State 2: When any cell gets to a certain voltage, the BMS will switch in a resistive load, which will shunt about 0.5A. As suggested by Johny and Renard, I could also tell the charger to reduce current down to about 0.5A.
State 3: Once all shunts are on, or once a certain total voltage is reached, the charger will shut off altogether. This is all controlled by the BMS, but it looks like I could also get the charger programmed to shut off at a certain voltage as well.

So what voltage is best for State 2?
And is throttling back the current the way to go? If so, how much - to 0.5A? I can see that if the cells were very unbalanced, this would give a better outcome, because the cell with high Voltage would then get almost no current. That cell Voltage would stay the same, while the others caught up. Is that neccessary though? Without throttling back the current, the Voltage would keep on increasing, but would increase slower than the other cells, letting them catch up. Is this what you mean Matt with your warning about floating at low current?

Also, while I'm asking questions, what is the best shut-off Voltage (State 3) for these cells?

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Post by BigMouse » Sat, 12 Oct 2013, 04:29

[quote="antiscabre balancing at low current - be aware that floating (holding a voltage above 3.45v at low current) lithium batteries is fairly bad for them (overcharging).[/QUOTE"]

I don't mean to hijack the thread, but I've heard this statement before but I haven't found any definitive source. Is this a myth propagated by word of mouth (or forum posts)? It's an important topic and if you have a source you can share that mentions it, I'd be very interested to read it. It's part of the top-balancing process, which is the most common form of balancing in use on EVs. If it's bad, then a lot of people are damaging their battery packs.

(EDIT: This seems to support that statement. There's probably others out there. http://jes.ecsdl.org/content/158/3/A322.abstract)

(EDIT 2: More evidence: http://www.diodes.com/_files/products_a ... x/an40.pdf Would be good to find something referring specifically to LFP batteries though, but it's probably common to lithium chemistries. Good to know.)
Last edited by BigMouse on Fri, 11 Oct 2013, 17:47, edited 1 time in total.

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Post by BigMouse » Sat, 12 Oct 2013, 04:38

4Springs wrote: I do have a spare RS-232 UART on the board. Sounds like it would not be difficult to make this talk. But, is there any advantage? Do I ever want any other states than the two mentioned above? As Matt mentions, the CAN option is an extra $45, and extra mucking around.


IIRC, the extra $45 is what they charge for the CAN converter box. Others have had luck getting them to sell the CAN charger without it, but then the issue is finding a compatible connector. The part number is available somewhere, but I remember it not being readily available from the normal suppliers (Digikey/Mouser/Farnell). They provide the same connector for the other charger control options as a flying lead. I'm not sure if all the pins are there or not, but if they are, you can easily open the connector and reconnect the wires where you need them. Somebody who's purchased a non-CAN charger would be able to tell you and I'd be interested to know myself. There is a ton of information out there about the inner workings of these things.

I also recall talk about all Elcon chargers having CAN capability in the socket already, but I don't remember for sure. It's worth looking in to. Like I said above, I think the extra cost associated with CAN is the converter box, which isn't necessary if you are using UART over optocouplers to talk to the thing.

The advantage would be the ability to set the current with a reasonable level of precision without worrying about trimming voltage dividers for a very specific analog voltage. The setup effort involved in getting that control voltage juuust right is not insignificant, and if a trim-pot is used, the value will tend to drift with changes in temperature and humidity (not to mention vibration). Digital control is much more elegant, precise, and reliable.

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Post by antiscab » Sat, 12 Oct 2013, 05:27

BigMouse wrote:
antiscab wrote:re balancing at low current - be aware that floating (holding a voltage above 3.45v at low current) lithium batteries is fairly bad for them (overcharging).
I don't mean to hijack the thread, but I've heard this statement before but I haven't found any definitive source. Is this a myth propagated by word of mouth (or forum posts)? It's an important topic and if you have a source you can share that mentions it, I'd be very interested to read it. It's part of the top-balancing process, which is the most common form of balancing in use on EVs. If it's bad, then a lot of people are damaging their battery packs.


Top balancing isn't bad - most top balancing arrangements don't throttle back the charger when one cell reaches the voltage cut off - they *stop* the charger

some latch and leave the charger off, others let the charger start again once the voltage comes down a bit. The later repeats until the battery is balanced.

as far as data goes - on my emax I had 15 x 40Ah cells charged by a 48v lead acid charger - 3 stage, CC 8A, CV 57.6V, CV 54.4V

it used to float at 54.4V for hours at a time.
battery capacity halved in 2 years (and 22'000km, ~500 cycles equivalent)

i was using an EV Power BMS at the time (4.2v high voltage cut off, balancing at 3.65v)

at the same time I was converting an MR2 with 90AH cells.
I was charging up the cells individually with a lab power supply, floating at 3.6v overnight.
Every cell I did that to bulged and lost capacity.

I haven't floated a lithium battery after that.

On my Vectrix I use a TC Charger, 42 cells 60Ah, CC 10A, CV 153.3v till current falls to 1.5A.
its 3 years and 70'000km (800 cycles equivalent) later and capacity loss isn't measurable
still using EV Power BMS modules (3.6v shunt, 4v charger cut off)
BigMouse wrote: They provide the same connector for the other charger control options as a flying lead. I'm not sure if all the pins are there or not, but if they are, you can easily open the connector and reconnect the wires where you need them.


All the chargers I have had shipped with the enable option have had all pins in the plug, just only 3 of them are only connected to the wires as that's all the enable option needs
Last edited by antiscab on Fri, 11 Oct 2013, 18:29, edited 1 time in total.
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