Prelude conversion project - some questions

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

Post by jonescg »

I have abandoned the automatic A/C on for the battery cooling. It means the A/C compressor is running too much, especially when charging. The heat exchanger seems to do a very good job of keeping the cells close to 30'C on a hot day, and if you were really concerned you could just leave the vehicle on for 15 mins before charging.
It was close, but not quite elegant enough.

New wiring diagram as follows - I abandoned the diode and grounding relay, so now it's 100% controlled form the cabin A/C switch.
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Re: Prelude conversion project - some questions

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On a very hot day, the battery stays cool. After parking up and letting the coolant pump run for a bit, it settled down to about 31'C. It doesn't run when charging any more, cause it makes a hell of a racket and draws way too much power. That said, the sound deadening stuff is helping a bit, I think.
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No luck on tuning the speed of the compressor down though. However, Hondas are notoriously hard to keep cool, this one in particular. So turning the power down would make a barely effective A/C system even less effective.
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brendon_m
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Re: Prelude conversion project - some questions

Post by brendon_m »

Not worth setting the temp threshold to something like 35°C?
Just for those rare days it gets hot in Perth...
Or maybe throw in an extra parameter like only if over 60% charge and over 35°C in the cells that way you can still mitigate the worst times of degradation and not have to worry about the charger rate not keeping up

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Re: Prelude conversion project - some questions

Post by francisco.shi »

What is the red light on the dash?

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Re: Prelude conversion project - some questions

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Brake (!) lamp. It comes on and off when you start the car. Probably hangover from it's ICE days.
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Re: Prelude conversion project - some questions

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Francess dropped in this afternoon to get the last few minor quibbles sorted before it goes over the pits next week. The main job was swapping out the drive contactor to a GV240 with auxiliary contacts so I can put a green LED in the cabin to indicate that the car is ready to drive. In the process of isolating the HVDC I noticed that the rear contactor was stuck, and even after removing all the loads and powering it on and off I couldn't unstick it. So at least the drive contactor doesn't stick, but the isolation back there is clearly not working like it should. Almost like you need some kind of state machine to control what gets turned on and when. Or just don't use it at all :/

Anyway, at least now there's a green LED next to the key switch which lights up whenever the drive contactor is closed, and it also stays lit up should the drive contactor ever stick.

I also installed a PWM generator which reduced the speed of the A/C compressor. It is quieter and draws half as much power, but I'd say the cooling capability is certainly reduced. I think that's just a Honda thing though - they were always pretty feeble A/C systems.

Hopefully it sails over the pits like we expect it to!
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Re: Prelude conversion project - some questions

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Public service announcement from Francess - she is so happy with her Prelude she is inviting folks to help celebrate it's rebirth as an EV on the 15th of February:

"You're invited to join us at a celebration, champers moment, for the official completion of the Prelude Conversion on 15 Feb 5pm BYO dish to share & drinks.... I'l have homemade dip with carrots, nuts, sultanas.... cuppas 🙂 RSVP 0417 997 016 for exact address to be texted 🙂 Verbena Ave, Darlington is the location."

Champagne will be popped, perhaps not struck across the stern. It should be fully licensed by then :)
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Re: Prelude conversion project - some questions

Post by bladecar »

Mmm, Any chance of a bus to get a lift home after the party? :)

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Re: Prelude conversion project - some questions

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It's all downhill at least!
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Re: Prelude conversion project - some questions

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Hmmm, that champagne should be struck across the bow anyway, not the stern!

:-D
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Re: Prelude conversion project - some questions

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OK so a bit of a nuisance problem with the drive contactor. Sticking is bad enough, but it seems to be causing grief now. Francess said she took off up a slight hill and felt the drive drop out. She turned it all off, and the auxiliary circuit supplying the green LED was open. Well that's one way to unstick it...* She turned the car on again, held start for 5 seconds, it engaged the drive contactor and the light came on. She drove off normally and it's been fine all day. We'll keep an eye on it, but if it keeps playing up I'm going to have to devise a more reliable solution for precharge and isolation. Definitely a big manual isolation switch in the boot.

*My suspicion is that despite the green LED indicating it was closed (on) the contact was poor. Once a big load was put on the contactor the voltage drooped enough that the controller cut out, opening the contactor and this time it actually dropped out.
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Re: Prelude conversion project - some questions

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The sticking contactor issue persists, so I am planning in installing a service disconnect in the back just ahead of the fuse.
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This ought to do the trick.
This makes unsticking it a little easier and safer, but I would like to know why it's still doing it. There should be no other capacitors in the system outside of the inverter.

Edit - the reason I don't currently have an isolation point is because the contactor inside the battery pack was supposed to be managing precharge, but hasn't, and is also currently stuck. I've decided to abandon the idea, so next time I have the car for a while I will pull the battery pack out (again) and pull the offending contactor out. I will replace it with a busbar. There will be nothing back here in need of switched 12 V then.
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Re: Prelude conversion project - some questions

Post by francisco.shi »

Any chance the charger or DC-DC converter for 12v may be causing the problem?

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Re: Prelude conversion project - some questions

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francisco.shi wrote:
Sat, 15 Feb 2020, 16:32
Any chance the charger or DC-DC converter for 12v may be causing the problem?
It's a possibility, but more likely I think it's a timing thing within the inverter. Besides, these are already powered constantly by the traction pack since the master contactor is stuck on. The main +12 V supply to the inverter and drive contactor is interrupted by the BMS should a cell go out of spec. But this series might experience a brief signal to close the main contactor at power-up (key to ON) when it's not supposed to. I also don't know for certain if the contactor is closed and conducting, or if it's sort of closed enough to activate the auxiliary circuit, but not conduct. I'd need to probe around a bit first to ascertain that. Either way, I tell Francess to go through the precharge process (turn key and hold on START for 5 seconds) all the same.
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Re: Prelude conversion project - some questions

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I have no idea how far I'd have to dig back to find out which contactor you are using, so I'll just ask :lol: Is it a GX14CAB Gigavac or one of the smaller contactors? I'm not sure if I posted this before, but we gave up on using anything smaller than the GX14 series because of contactor sticking and then no main circuit through the terminals even though the T1 and T2 contacts were making a circuit. A very heavy load combined with engaging the contactor would get it to clean the contacts and make a circuit, but then it would be welded shut. We rarely have this problem with the GX14 series, although we did have one weld shut because the connection to the X1 positive cable was loose causing the contactor to not close rapidly and the arc welded it closed. After fixing the poor connection, a solid hit on the top with a hammer jarred the contacts free and it has worked fine since.
I have those little grey round contactors (GV200) in the PHEV Prius and they stick on a regular basis so there are two of them in parallel so I get an error warning if one welds closed. The next time I pull the lot out I'll be replacing them with the GX14 units and that should end the welding contacts saga

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Re: Prelude conversion project - some questions

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The welded contactor inside the battery is indeed a GX14 contactor. The drive contactor up the front used to be a Kilovac 200, but since replaced it with a GV240 contactor with auxiliary contacts for alerting me to a stuck conductor. And it's stuck again. So my solution is to abandon the master contactor inside the battery pack, and replace it with a busbar. The manual isolation switch will make working on the car safe. I might put a couple of female banana pins there so you can do a manual precharge when re-energising the car (main capacitive load is the aircon compressor, but the DC/DC and charger might play a role too).

Unfortunately replacing the master contactor means pack out... again. A big days work, but should make it far more reliable.
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Re: Prelude conversion project - some questions

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Added the isolator and the warning stickers.
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The drive contactor is unstuck now, but it made a funny high pitched 'boing' noise while toggling it on and off.

Later in the year when I have the time, space and inclination I will drop the pack out and remove the offending master contactor.
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Re: Prelude conversion project - some questions

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OH! Forgot to mention, I got the weights too.
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Pretty sweet balance!
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Re: Prelude conversion project - some questions

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That's a nice bit of weight measuring kit, is it yours or borrowed?
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Re: Prelude conversion project - some questions

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It cost me $110 inc. to drop in to Racing Dynamics in Malaga to have it done.
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