Prelude conversion project - some questions

Technical discussion on converting internal combustion to electric
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Re: Prelude conversion project - some questions

Post by francisco.shi » Tue, 27 Aug 2019, 14:43

You are right about the increase in resolution. It is a very long time since I did uni.
The idea of keeping the old measurements was to make a low pass filter. I just not very good at explaining it.

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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 29 Aug 2019, 10:46

Hindsight is a wonderful thing - If I'd thought about it, I might have realised that the AC input cables were going to be quite difficult to terminate with so little clearance between the wall and the PCB. Still, they're installed and the radius isn't too tight.

One more connector to install and we can start testing the control system.
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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 01 Sep 2019, 21:43

Well some good progress made this weekend - it's finally spun the wheels. @reecho kindly offered the services of his open EVSE which allows you to charge a Type-2 car from a 15 A GPO, at least for testing. However a couple of issues have popped up making it a no-goer for the time being.

First of all, the inverter is wired up and it spins the motor freely in either direction. Since we'll be using the gearbox for reverse, we'll set the direction as forward and leave it there. The reason we're not driving it anywhere is because the accelerator pedal still isn't installed, and until that's in we can only test it with a potentiometer, which is really not safe to drive with :) I will make a couple of brackets to mount the pedal this week and hook it up.

The precharge process works well, and it takes about 4-5 seconds for the caps to charge. The brake pump and power steering fire up on the switched circuits no trouble and the DC/DC converter supplies enough current to keep things running smoothly. I only learned that it has an Enable requirement, so I'm supplying it with 12 V from the switched supply fuse box. Another thing that TC never tells you when you order their chargers...

The battery charger is another show-stopper. The ZEVA BMS detects a charger, and allows you to set the voltage and current. Upon exiting the setup menu we plugged in and the AVC2 diligently starts the coolant pumps and charging is allowed. However it wasn't charging. It gave a red-red..green green error, which is of course not documented anywhere in the instruction manual. It had AC power, and it had DC bus, so despite being told to charge to 300 V and only at 10 A, it wouldn't charge.

So we added pins to the Enable lines - D and F according to the manual.
Enable.JPG
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Once these were connected, the charger fired up and proceeded to throw 20 amps DC (24 amps from the AC side) until the RCBO rightfully tripped. SO it seems the CAN bus settings are not sticking, and only the Enable line works. Which says to me they have sent a charger which is set to a fixed voltage and current, and therefore would over-charge the battery by a full 100 volts! :o So, no, we're not charging this just yet. I really hope there is a way of making it work using the settings available, otherwise we're up for another several week wait for a new charger...

Finally, the other show-stopper is the speedometer. Some week back I noticed strange behaviour where I would turn the car off and the radiator fan would fire up. It wouldn't stop until I disconnected the 12 volt battery negative. It would happen again the next time I turned the car on. However I found by pulling Fuse 12, the back-feed went away.

Unfortunately, Fuse 12 supplies most of the dash instruments, including the speedometer. So I really need to find the source of the back feed now. When the car is turned off, the radiator fan relay is energised. And remains so, until the battery is disconnected fully. Will take some more detailed work, undoubtedly in the footwell again :(
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Re: Prelude conversion project - some questions

Post by weber » Mon, 02 Sep 2019, 07:11

Congratulations Chris. Well done.

I was wondering why such a long precharge time. We do it in half a second in the MX-5. But I see you have no choice. It's built into the Greatland inverter.
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Re: Prelude conversion project - some questions

Post by coulomb » Mon, 02 Sep 2019, 08:33

jonescg wrote:
Sun, 01 Sep 2019, 21:43
It gave a red-red..green green error, which is of course not documented anywhere in the instruction manual.
Typical. I found a lot of undocumented or poorly documented error codes with the older chargers.
So we added pins to the Enable lines - D and F according to the manual.
...
Once these were connected, the charger fired up and proceeded to throw 20 amps DC (24 amps from the AC side) until the RCBO rightfully tripped.
Yikes. I don't suppose you can tell if the CAN bus is working, e.g. seeing packets coming back? Perhaps the Zeva BMS would tell you if there were no CAN bus responses. They have used some odd CAN bus frequencies over the years.
I really hope there is a way of making it work using the settings available, otherwise we're up for another several week wait for a new charger...
On the really old models, the enable line was actually an analogue input, intended for a battery temperature gauge. You could control the charger output (charge current, I think, but it might be power) by varying the voltage at the enable pin (with respect to the negative end of the 12 V supply, pin E on yours) between 2.0 V (zero output) and 5.0 V (maximum output). It's linear between these two, so 3.0 V for 33% output etc. They haven't documented this for years, so the changes that this has survived to the latest models seems slim, but it might be worth a try. If by some miracle it works, it might even be possible to get the Zeva to control it like that (some BMS have this feature), but if not, it might enable supervised (!) charging at reasonable power using a potentiometer (warning: on the old models, this part of the circuit was at battery pack negative potential, not isolated).

It's a pity that I don't have firmware for these. I have a thing called UniCan™ that converts any of the older models to a CAN model. You need some special (but inexpensve) hardware to allow the processor to be flash programmed. I don't even know if these newer models have that programming interface enabled. My understanding is that they use an ARM based processor now (the older ones had a now obsolete and unobtainable 8-bit NXP processor).
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 02 Sep 2019, 08:52

We tried putting resistors in series with the enable line, and it was an on or off situation, so I don't think I can adjust the charging current that way.
Anyway, the set voltage is way too high, assuming we've not successfully changed it via the ZEVA. I can get a charge in from a 32 A socket but I'll have to watch it like a hawk.
Mainly so I can test it on the road etc, as the battery is pretty much empty at the moment.
I have a feeling we'll be ordering a replacement charger...
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 02 Sep 2019, 08:56

weber wrote:
Mon, 02 Sep 2019, 07:11
Congratulations Chris. Well done.

I was wondering why such a long precharge time. We do it in half a second in the MX-5. But I see you have no choice. It's built into the Greatland inverter.
I could actually solder an additional resistor in parallel to speed it up, but I think we can afford the 4 seconds.
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Re: Prelude conversion project - some questions

Post by T1 Terry » Mon, 02 Sep 2019, 09:41

The red/green flash means the battery is not connected. My Prius plug-in does it frequently so I've learned to actually check that every time I plug in the 240vac from the motorhome.
Because the motorhome PIP inverter has an eco mode that shuts off the 240vac side until it sees a load, simply plugging the Prius in doesn't work because the TC charger has to go through the whole start up thing before it connects the charging part to put a load on the 240vac supply line. No load, no 240vac supply, so I have to turn the 240vac water heater on in the motorhome to get the inverter going, then check the TC charger hasn't chucked a wobbly, then turn the hot water off before it overloads the inverter and the whole lot shuts down.
I still can't determine which battery the TC charger can't see a connection to, the EV battery or the 12v aux battery. The TC charger 240-vac connection also has a 240vac to 12v DC wall wart connected, I'm wondering if this wall wart is on the way out so the TC doesn't see the 12vdc it's looking for and puts up the red/green fault light flash and it isn't the EV battery it isn't seeing at all ..... that would make a lot more sense really

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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 02 Sep 2019, 09:48

The HVDC box almost done (minus the Aircon HV supply)
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With the bonnet on:
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The rear does sit about 25 mm lower than the front, so I think we'll need some stiffer springs to correct this.
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 02 Sep 2019, 14:11

Ah - might have a solution to the charger issue. I hadn't grounded the Charge Sense pin of the EVMS3 before attempting to change the charger settings. So that might explain that problem (hopefully). But the backfeed through fuse 12 remains a problem...
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 02 Sep 2019, 22:13

On this day, 2nd of September, 2019, Francess' 1988 Honda Prelude drove out of the workshop a new vehicle.





My lovely wife Kat offering commentary, and is no doubt as relieved as me to see the light at the end of the tunnel.

Charger still won't play nice, so I suspect I've been sent the wrong kind. Will need to get a new one on the way ASAP.

Overall pretty relieved. Will have to do a more detailed report later in the week.
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Re: Prelude conversion project - some questions

Post by weber » Mon, 02 Sep 2019, 22:37

Woohoo! :clap: :beer: :champagne:
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Re: Prelude conversion project - some questions

Post by brunohill » Mon, 02 Sep 2019, 23:54

Great job but you don't want it to fail an inspection over the front left parking light.

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Re: Prelude conversion project - some questions

Post by brendon_m » Tue, 03 Sep 2019, 05:41

Well done, it's certainly coming together. Now you just need to quickly finish it off and start a crx :)

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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 03 Sep 2019, 08:42

Yeah I think I'll try and get the battery charged up at a nearby 32 A socket and sort out these backfeed gremlins. In the meantime I'll be ordering a CAN-only charger from TC.

And I'll need to line up a date with the engineers...
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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 03 Sep 2019, 09:53

So it seems my request for a charger with CAN-bus and enable control was lost in translation. They sent me an Enable only charger. So I am up for a new charger, and will be trying to find a use for this one... $1500 later.
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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 03 Sep 2019, 10:13

And now it turns out the CAN-bus controlled charger won't go as low as 301 V max. 320 V is the lowest it will go. Grrr!
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Re: Prelude conversion project - some questions

Post by coulomb » Tue, 03 Sep 2019, 10:55

jonescg wrote:
Tue, 03 Sep 2019, 10:13
And now it turns out the CAN-bus controlled charger won't go as low as 301 V max. 320 V is the lowest it will go. Grrr!
Huh? Surely you can just ask for a lower voltage in the CAN packets. I've tested EV chargers on my 50 V solar energy system, but certainly there is a lower limit. In the 6.6 kW range, the "312 V 20 A" model has an output voltage range of 110-440 VDC.
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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 03 Sep 2019, 10:58

She seems to suggest it won't be stable at less than 320 V DC. I've ordered a new one anyway. I'd rather see that it works (or not) first before attempting to fit the last two battery modules in the boot somewhere, where they won't have easy access to cooling circuits etc.
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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 05 Sep 2019, 08:59

While I wait for the new charger to arrive, I thought I would try and isolate this fan-coming-on-after-switch-off problem.

I put fuse 12 back in, turned the car on, then turned it off, and sure enough the radiator fan came on.

As it was running I went through the dash fuse box pulling out fuses until it stopped... I pulled out every single fuse and it kept on going!

Since fuse 12 had something to do with it, I went back to the new relay I'd added in place of the A/C control unit on the passenger's side. All the while the fan was running. And then suddenly, before I'd even got to the relay, it stopped. :?

And then I remembered.

As an ICE car, the Prelude has a feature where the cooling fan runs for about 10 minutes after parking to cool the engine day down. In fact there is a warning sign on the front of the car saying as much:
fan warning sign.jpg
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This must be powered from the ECU, which is still installed in the car. Sure enough pulling the ECU fuse from the under-hood fuse box stopped the fan, but it started again upon plugging it in. When I left it out, everything in the car works just fine, but the clock and stereo are unpowered. So I think I can put up with the fans running for ten minutes after switch-off. The fan seems overpowered and inefficient for what it does, but it's designed to fit in that space so I'm hard-pressed to find an alternative.

So it's a problem that doesn't need fixing :)

In the interim I will look at ways of getting the last two battery modules in the boot or spare tyre well. It will be a pest to plumb up, but I have a feeling the car will perform much better with the higher voltage pack.
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Re: Prelude conversion project - some questions

Post by jonescg » Sat, 07 Sep 2019, 13:37

I have been getting the charger to behave as best it can today - spend last night balancing down the highest cells. I think we shed about 0.06 volts overnight... Its working, albeit slowly.

The charger put in about 10 kWh on the AC side, but the highest cells were hitting 4.2 V so I had to leave the 'charge sense' grounded and supplement the car with a power supply overnight to ensure the 12 V battery doesn't drain down. No point running pumps etc when all I'm doing is bleeding a 70 Ah module at 0.1 amps...
balancing start.jpg
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balancing 12 hours later.jpg
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I also hooked up the regen feature with the Greatland inverter. It operates from the brake - as soon as it receives a 12 V input (from the brake light source) it applies some regen force. Yet to take it for a drive and see how it feels.

I also built a clamp for the 12 V auxiliary battery and secured it, changed the blown turn signal bulb, reversing bulb and the park light bulb, and wired up the reversing lights to the main harness.

We're almost ready to paint the underside with tar and get it inspected!
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Re: Prelude conversion project - some questions

Post by jonescg » Sat, 07 Sep 2019, 16:40

A quick test of the charger and it seems the ancillary systems are working as they should.
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The coolant is pumped through the battery at any temperature above ~18'C while the A/C relay switches on at 25'C. It oscillates a bit, so I need to incorporate more averaging and hysteresis into the code I think.
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Quick drive to Lesmurdie falls and back (6.6 km) to try it in 2nd and it accelerates acceptably. SO I thin this car will be driven a lot like a manual ICE until the rest of the battery is fitted.
Subsequent charge put about 1 kWh back in, or roughly 150 Wh/km which is pretty ordinary given the speeds, but I'm only guessing here. Not till the battery is properly balanced will I be able to say for sure what the range is.
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Re: Prelude conversion project - some questions

Post by jonescg » Sat, 07 Sep 2019, 16:58

Oh the brake regen is good, but not particularly strong. It puts about -20 amps back in as you dab the brake, or about 5 kW. Better than nothing.
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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 08 Sep 2019, 19:34

Well we had hoped to take the Prelude for a bit of a maiden voyage to Mundaring, but only made it as far as the bottom of the weir before it stopped.
Upon turning off and on again, it was clear the drive contactor wasn't happy, suffering pretty significant voltage drop, dropping out, followed by re-connecting.

RAC towtruck to the rescue...

Back at the workshop I pulled the offending Kilovac contactor out. Now, I had removed the economiser circuit under instruction that it can prevent the Greatland from precharging properly. But when it's normal current was close to 8 amps, something wasn't quite right. I replaced the contactor with a new one, this time retaining the economiser.

Worked first go, no grief, and the contactor circuit was drawing a measly fraction of an amp.

I love a quick solution :)
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 09 Sep 2019, 11:39

Drove the Prelude to work today - I'll have to grab some video. It goes well, but it does feel underpowered. I expected it to be underpowered given the lower pack voltage, but it does seem a bit ordinary. You must take off in 2nd if you want any respectable acceleration, particularly up hills. The regen braking is good, but it's almost worth adding a switch which doesn't activate the brake lights. 5 or 6 kW isn't much braking power. It certainly feels like an auto in that will 'run on' once you are up to speed. So it will take some care and slight change in driving style.

I rolled down Welshpool Road in 5th and briefly hit 100 km/h and it felt fine and stable. I'm yet to hit the ton on flat ground, but something suggests it might be at the end of it's legs by then. The battery still isn't fully balanced yet, so I'm still missing out on a fair bit of capacity. Also, I'm doing supervised charging at all times until the new charger with CAN control arrives.

I will take it to Freo at lunch for a charge and see how it goes. The trip back up the hill might be a slow one. Perhaps 3rd all the way up?
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