4Springs' Brumby

Post up a thread for your EV. Progress pics, description and assorted alliteration
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Thalass
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Post by Thalass » Fri, 19 Feb 2016, 18:41

Man, that is one fine working mans EV you have there.
I'll drive an electric vehicle one day.

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4Springs
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Post by 4Springs » Sun, 06 Mar 2016, 14:17

Ok, it is time to document my second charger...

When I first built the car it had a lead-acid battery, and so I had a lead-acid charger. When I upgraded to a lithium battery I bought a lithium charger. The old charger didn't sell so it sat in the shed. Once I had made my BMS and gained some experience in these matters I realised that my lead-acid charger could also be used to charge the lithium pack.
After some discussion with Paul9 and others over here, I did the following:
1. Moved the lithium charger (TC Charger) from under the bonnet to under the tray behind the back wheels.
2. Installed the lead-acid charger next to the lithium one.

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This photo is from the rear of the vehicle. You can see the galvanised iron brackets (held on in part by two dodgy-looking tek screws!). These hold a plywood sheet (the brown bit) up against the bottom of the tray. The plywood forms a "base" for me to screw into so that I didn't have to pierce the tray in multiple places.
The lithium charger is black and is on the left. The lead-acid charger is yellow.
When I look at this photo I cringe a bit when I see the tow bar bolts above where the camera is. I have hit my head and other body parts on this towbar many times and now have an instinctive fear of it - apparently even from photos!

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This photo is from the right-hand side of the vehicle.
The grey box contains some connections and some electronics, explained later.

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These photos show how you use the two chargers. The first charger uses a retractable cord that comes from behind the fuel filler door on the outside of the vehicle. We normally just use this cord. Plug it into any 10A 240V socket and it will draw about 10A.
The second charger is powered via the black socket inside the tray. One photo shows it with its grey foam cover, and another shows it with a yellow extension cord plugged in. So if you want to charge faster, and have a second 10A 240V socket available, you can plug an extension cord in here to power the second charger. The second charger will only work when the first charger is plugged in, and draws about 5A.

Now if you are following along so far, and haven't peeked at the next photo, you may have realised that with both chargers connected I will draw about 15A. And you might wonder if I wouldn't have been better to wire into a single 15A plug? Well here is my cunning plan:
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This photo shows the 15A "powerboard" that I bought from Bunnings. It has a 15A plug (note the wide earth pin) and four 15A sockets. So I can plug this into a 15A socket and plug my two chargers into it as shown. There is a 15A circuit breaker in the device, so it will trip if someone comes along and plugs something else in at the same time.

The electronics I spoke about earlier is to do with turning the second charger off. I have a relay which is controlled by the BMS. When the battery is down and needs charging the BMS switches the relay on to provide 240VAC to the second charger. Once the battery voltage indicates that the battery is nearly full the BMS switches the second charger off, and puts the main charger into dribble mode.
I didn't have any outputs left over on the BMS, so I had to run this relay off the "enable" line provided for the TC Charger. Got it to work after some fiddling...

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Post by 4Springs » Sun, 06 Mar 2016, 14:33

I have left a space under there for a second TC Charger the same size as the first one. Currently I am using 10A + 5A = 15A * 240V = 3.5kW or so. This charges at about 15km (of range) per hour. If I installed a second 10A charger, and therefore had three chargers altogether, then I could charge at about 25km per hour. So in that case I could charge from 3 x 10A sockets, or 1 x 10A and 1 x 15A, or make up a converter to charge from a J1772.

I did have a problem with the second charger. Occasionally it would stop charging and flash an error light. The user manual was not very helpful, it said to reset it, or if it persists to contact the manufacturer. This only happened after a few hours of charging, and would be fine with a reset as suggested. I wondered whether it might be overheating (despite there being a different error light for overheating), and installed a fan. But the error still occurred.
So I settled on a software fix. I reprogrammed the BMS to have a short rest from charging every 2 hours. 240VAC power is now removed from the second charger every two hours, hopefully resetting any errors that may have occurred.

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Post by coulomb » Sun, 06 Mar 2016, 16:41

4Springs wrote: 240VAC power is now removed from the second charger every two hours, hopefully resetting any errors that may have occurred.

I'm a bit nervous about interrupting power to Elcon/TC chargers when drawing significant power. They draw a fearsome arc, and I have suspicions that the bridge rectifier may get blown up more often when doing this.

It would be great if the BMS could disconnect the enable line, so the charger draws very low power, then turn off the AC supply. Enable and mains can come on together for simplicity. Of course, this is more complexity, but it sounds like your BMS is very programmable.
Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

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Post by 4Springs » Sun, 06 Mar 2016, 19:20

coulomb wrote:I'm a bit nervous about interrupting power to Elcon/TC chargers when drawing significant power. They draw a fearsome arc, and I have suspicions that the bridge rectifier may get blown up more often when doing this.

It would be great if the BMS could disconnect the enable line, so the charger draws very low power, then turn off the AC supply. Enable and mains can come on together for simplicity. Of course, this is more complexity, but it sounds like your BMS is very programmable.

Thanks coulomb,
The main charger (the 10A TC) is controlled by the BMS and throttles back nicely. This second charger is the one that is unceremoniously cut off, and this is nominally a Chennic. I describe it a bit in this thread here.
I agree that a less drastic way to switch it off would be ideal, but there doesn't seem to be any. It would turn itself down/off if the voltage climbed high enough, but that won't happen with this lithium pack. There are no control lines at all unfortunately.
I was thinking that this was the way that I used to control this charger when connected to my lead-acid pack, but reading back through that thread it looks like I turned it off with a relay only when it had reduced its output current. With the current set-up it will be cut off in full (5A) flight.

Before I came up with the software solution I had toyed with the idea of a circuit that would cycle the power whenever the Chennic's error LED came on. This would be a nicer solution, but quite a bit more work...



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4Springs
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Post by 4Springs » Mon, 06 Jun 2016, 00:17

Latest project:
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This box takes 240 VAC in from the left, and delivers it (or does not) to the socket at the top. The circuit board is a Jaycar remote control receiver. So the idea is that when I press button 1 on the remote control the box turns on the 240 V, and when I press button 2 it turns off. The remote control is sitting next to the box.

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This is it installed behind the seats. The rocker switch can turn off the 240 V - it is shown in the on position. The red momentary switch turns on the 240 V to the socket, the same as pressing button 1 on the remote.

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And here is a picture showing the true purpose of the installation - a heater! For some reason the picture is sideways, but anyway I can turn on this little heater from the house when I get up in the morning, and hopefully the car will be warm by the time I get out there.
I've made the heater easy to remove for the warmer months. For car shows I can plug something else into the socket. A strobe light perhaps? Or a loudspeaker that yells at people? A smoke machine!

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Post by Paul9 » Mon, 06 Jun 2016, 19:03

Good idea 4Springs!

Tasmania is not a tropical state is it? No banana trees and sugar cane?

Cheers
Paul

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Post by Paul9 » Tue, 07 Jun 2016, 03:45

Hi 4Springs

At car shows could you plug your charger into the socket and recharge your batteries if the car show didn't have any spare sockets? Maybe save you some money?

Just me trying to think of other ideas apart from loudspeakers and strobe lights.

Cheers
Paul

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Post by 4Springs » Wed, 08 Jun 2016, 00:25

Paul9 wrote: At car shows could you plug your charger into the socket and recharge your batteries if the car show didn't have any spare sockets? Maybe save you some money?
HAHAHAHAHAHAHA
I'll put you with the people who say I should put a wind turbine on it. Or an alternator.

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Post by Paul9 » Wed, 08 Jun 2016, 01:36

Well I originally thought (after a few red wines) that maybe you could plug in a charger and then plug in a dc-dc converter to the charger to get your 12v then plug in an inverter to get back up to 240v ac and then plug another charger into the inverter!

The above, combined with the wind turbine you suggested, could keep your car going almost ad infinitum!

I have not had my original idea above patented or anything yet, so if you want to adopt that arrangement, that would be fine. I am a huge supporter of open source anything.

Cheers
Paul

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Post by carnut1100 » Mon, 22 Aug 2016, 05:16

I was lucky enough o have a short drive in this machine a few days ago.
It was the first DC car I've driven. Also the first with a transmission.
It's an awesome little rig!
You've done a top job mate, full marks!

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