[DRIVING] 1979 MG Midget with GS450h and custom battery pack

Tell us about the project you do with the open inverter
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[DRIVING] 1979 MG Midget with GS450h and custom battery pack

Post by ggeter »

Folks,

The time has come to introduce my project. I sold my Lexus GS350 to fund it (we didn't need two cars in the Age of Pandemic anyway). So, I've got a rolling chassis with no engine or transmission that needs light restoration, so I've budgeted ~$4000 for that. The car has a 3.9:1 solid rear end. I want to use the existing drive shaft and differential. Also, will not need A/C, power brakes, power steering, or heater. Just a motor, inverter, batteries, charging and monitoring...

I'm an IT consultant by trade, a hobby programmer (I have some experience with Arduino building a lighting control system for my house), and an engineer by education. I'm no idiot, but I'm none of you guys, either.

So, I've got $12K in the EV conversion budget at the moment plus or minus...

I've read up and down these forums. I've watched Damien's videos. I've done gearing calculations. I've done enough battery math for a hundred scenarios.

My head hurts -- there are too many options -- and I need a swift kick in the pants. Some guidance, if you will. What would *you* do with a decent MG Midget rolling chassis and $12K? I'd like to get between 50 and 80 mile range. It'll be an in-town car, so if it can't got over 60 mph, that'll be fine. It would be the stuff of nightmares to roll this little buggy much faster than that anyway.

What I've considered:
  • GS450h transaxle (yes, I believe it will fit) with matching inverter, Damien's goodies, a DIY 24KWh battery pack, DIY BMS from this site, DC/DC from a Chevy Volt, and commercial charger
  • Nissan Leafs are going for <$6000 around here in running condition with less than 60k miles. Transplant everything in-tact into the MG?
  • Leaf drive motor, Leaf Inverter, boards from the OpenInverter project, DIY pack, BMS, and commercial charger
  • Leaf drive motor with a Prius inverter configured for DC/DC and charging (one day) plus DIY battery pack and BMS
  • Lower voltage motor from EVWest, prius inverter, to keep battery costs down?
Help my troubled mind and help me narrow this down.

Thanks, guys!
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Re: 1979 MG Midget in Texas

Post by LRBen »

Personally with a RWD setup I would go with the GS450h in the gearbox housing, then inverter and as many batteries as you can fit in the front. You might be able to giggle things around and put some stuff in the fuel tank area as well. A toyota hybrid inverter should be able to act as a charger as well.

If you wanted to use the leaf motor you would need to reduce the output down or go through the original gearbox, which might be tricky on yours.

I wouldn't bother with lower voltage motors from EVWest. I think it's been shown on here quite often that the hybrid inverters are more than capable of using lower voltage batteries to power whatever you need.
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Re: 1979 MG Midget in Texas

Post by SciroccoEV »

LRBen wrote: Sat Dec 05, 2020 5:19 pm Personally with a RWD setup I would go with the GS450h in the gearbox housing,
Have you ever seen the size of an A series gearbox? I doubt there's enough room for the 450h unit and it's pretty heavy too.

If it were my project, I'd think about doing what I'm planning to do with the Lotus Excel. Use the first reduction stage of a transverse EV transaxle. I'm going to use Leaf components, but the Outlander rear motor/gearbox would probably be a good match for a Spridget.

The idea is similar to the reduction gearbox now available to put on the back of the Warp9.
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Re: 1979 MG Midget in Texas

Post by ggeter »

LRBen wrote: Sat Dec 05, 2020 5:19 pm I wouldn't bother with lower voltage motors from EVWest. I think it's been shown on here quite often that the hybrid inverters are more than capable of using lower voltage batteries to power whatever you need.
How low a voltage would be practical on a small in-town only car? I know 288v is what the 450h system is originally, but can one get an efficient 50 mph out of, say, 120v?
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Re: 1979 MG Midget in Texas

Post by ggeter »

SciroccoEV wrote: Sat Dec 05, 2020 10:30 pm
LRBen wrote: Sat Dec 05, 2020 5:19 pm Personally with a RWD setup I would go with the GS450h in the gearbox housing,
Have you ever seen the size of an A series gearbox? I doubt there's enough room for the 450h unit and it's pretty heavy too.
The gearbox is 280 lbs, per Damien, and the original 1500 motor and gearbox tipped the scale at 350 lb. Add back in the inverter and a dcdc converter, and comes out even?

Measuring the engine bay, I *think* the bell housing will fit up near the original engine mounts and the tail of the unit would be just shy of the original transmission cross member. It'll be hysterical looking, but do-able.
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Re: 1979 MG Midget in Texas

Post by nickcox »

If you were more budget constrained, I would suggest the leaf motor and diy battery. But with how much funds you have available, I definitely think you should go big! GS450H 👍 You only specified the minimum requirements you have, but I think you should give it the big power option 😜 It will be such an awesome car to drive with incredible performance, and be more of a brand ambassador to show off the viability of electric conversions, rather than a barely capable "golf cart" or "city car" ev.
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Re: 1979 MG Midget in Texas

Post by ggeter »

Spend... I'll update this post as I buy all the things. All prices include shipping or freight cost.
  • GS450h VCU board purchased from Damien. Exchange rates are fun... US$443
  • GS450h transmission purchased - eBay ~$750 **Seller tried to ship without power cables. Caught that in time and cancelled.
  • GS450h inverter purchased - eBay ~$530
  • GS450h oil pump controller - eBay ~$90
  • 1200 LiFePo 6aH 32650 cells - BatteryHookup - ~$5000 shipped with spacers. Target is 308v, 20KWh
  • TSM2500 3.3KW charger with car kit - Thunderstruck EV - ~$1300
  • Dilithium Design BMS with 2 satellites to support 96S and touch screen interface - Thunderstruck EV - ~$1800
  • 2018 Chevy Volt DC/DC converter - eBay - ~$130
  • GS450h transmission from Benzeen in California - $450 delivered.... wowza. UPDATE.. too good to be true. Oil pump missing. Now I've got to find one. UPDATE: Benzeen refunded me $100 for the missing pump. Good on them, but won't pay for a replacement. Total for transmission, delivered to Texas from Ca.: $350.
  • Oil pump + flywheel from same seller on eBay. ~$400 for both, shipped. Ouch. The total for transmission, oil pump, oil pump controller, flywheel (for spline), and handful of connectors to make up a harness comes to around $935ish.
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Re: 1979 MG Midget in Texas

Post by ggeter »

Battery build info...

Using 12p96s configuration of 32650 cells from BatteryHookup for 307v nominal. This is about 360 pounds of batteries and will take up a bit more space than I was hoping, but the real limiting factor will be the rear springs :)
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Re: 1979 MG Midget in Texas

Post by PatrcioEV-ATX »

www.coilsprings.com

Make sure you weigh everything you put in and tell them you want stock plus "X". I did that with a conversion a few years ago and it looked and rode great when the springs were replaced.
1998 Ford ZX2 - DC EV conversion(sold) http://evalbum.com/2093
2012 Nissan Leaf (sold)
2016 Mercedes B250e (sold)
2023 Volvo C40

Current: 1964 Rambler Classic 660 w/ GS450h set up. 36kwh Tesla batteries from B250e.
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Re: 1979 MG Midget in Texas

Post by ggeter »

PatrcioEV-ATX wrote: Mon Dec 21, 2020 4:21 pm www.coilsprings.com

Make sure you weigh everything you put in and tell them you want stock plus "X". I did that with a conversion a few years ago and it looked and rode great when the springs were replaced.
Awesome -- thanks for the link!
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Re: 1979 MG Midget in Texas

Post by ggeter »

Test Fit Pictures.

Almost where I want it, can move back 4-8 inches maybe. Need to remove some bits from the engine bay, but even if this is all I could get, it will work. But I know where mounts need to be, and can probably use the existing transmission mount:
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Re: 1979 MG Midget in Texas

Post by Bratitude »

Awesome, bring in mr sledgehammer and I bet could move it back even further 😅

this thing is going to be scary fast! hope some structural bracing is in its future!
https://bratindustries.net/ leaf motor couplers, adapter plates, custom drive train components
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Re: 1979 MG Midget in Texas

Post by Tremelune »

Very cool. I've been banging my head against how to convert my MGB without keeping the transmission or buying a pricey TorqueBox.

I'm very curious to see how you mate that Lexus package up to the chassis and driveshaft. Don't forget to match the angles!
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Re: 1979 MG Midget in Texas

Post by ggeter »

Tremelune wrote: Thu Dec 24, 2020 8:30 pm Very cool. I've been banging my head against how to convert my MGB without keeping the transmission or buying a pricey TorqueBox.

I'm very curious to see how you mate that Lexus package up to the chassis and driveshaft. Don't forget to match the angles!
Indeed. Angles.....

My plan is to make the front mount pivotable and the rear mount shimmable. That way, when I bring it to the driveshaft shop, they can add or remove shims as needed to fine tune the angle. I figure if I level the oil pan with the bottom of the frame rails, I'll be pretty close to start.

I also was struggling with whether or not to keep a stock transmission. My donor car came without a motor or transmission, so made the decision a little easier. I really wanted to do a rear drive unit from a Toyota/Lexus hybrid with electric 4 wheel drive, but that would have meant a completely new rear end. That would have been the ideal solution, but was way out of the budget. I would have needed professional help with that rear end, and that gets pricey.

Nice thing about using the 450h is it has two gears built in and is capable of highway speed out of the box. This will mostly be an in-town errand runner, and I see being in 1st gear most of the time, but having a taller gear will be convenient.
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Re: 1979 MG Midget in Texas

Post by ggeter »

Update: back from extended vacation -- more parts have arrived. USPS confirms that Damien's VCU is on its way.

Now that all the large bits are here, I am able to execute a set of steps. Here is the order I believe is appropriate:
  • Local shop to rebuild the brakes
  • Transmission final fitment and mounting strategy -- once this thing is mounted, I'll know where I stand from a final packaging standpoint, which will lead directly to...
  • Battery pack build -- Striving to put 1/2 the weight up front, and 1/2 over the rear axle + fitment of BMS
  • Test wire-up for getting the motor spinning / charging / BMS functionality worked out
  • Fitment of drive shaft
  • Final placement of control boxes, wiring, etc.
  • Dash integration
Concurrent to all this, I am testing and charging/balancing the battery cells as much as possible before building the pack.
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Re: 1979 MG Midget in Texas

Post by slanceley »

ggeter wrote: Tue Jan 05, 2021 8:15 pm Now that all the large bits are here, I am able to execute a set of steps.
Sounds like a good plan. V Interested to see how you get on, I think you're a few steps ahead of me on a similar journey. I'll try to help if i can!
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Re: 1979 MG Midget in Texas

Post by ggeter »

Things slower than expected, but here's where I am with some pics:

* Suspension completely removed from car for ease of repairing brakes, brake lines, axle bearings, seals, etc. Also give me so extra room to work on placing components.
* Battery units at good stage: 8 total units. One of them with BMS leads. Will likely use 10g bare copper wire in a bundle to get power off the 12p strings. Individual cells are Battery Hookup model 6ah 32650 LiFePo4. 1152 of them (!)
* Engine bay cleaned up, ready for degrease and paint

It's coming along, but right now it's more of a battery project :)
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Re: 1979 MG Midget in Texas

Post by ggeter »

Updates as of 10/2021

* Got brakes rebuilt, rear end re-fitted
* Front suspension removed and mostly re-fitted with new shocks all around
* GS450H unit mounted for fitment. Will add more steel and bolts as my comfort level rises
* Battery packs about 50% complete. If I had know hand-building these would have taken this long, I'd have gone another route
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Re: 1979 MG Midget in Texas

Post by ggeter »

Video of first spin! Because I've never done this before, I got some things wrong in the video:

1. Resolvers are made with Cat 8, not 6. I do use Cat 5 for a few things. No cat 6 was harmed to make this Frankenharness.
2. That's the oil pump controller mounted on the inner fender well, not the motor itself.
3. I claim to hear relays in the transmission when turning on VCU -- I think it may be the solenoids.
4. Drawing 7 amps max at 31v with max torque set at 200 right now.
5. VCU was loaded with the "v3 User" version from Damien's GIT with no mods.

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Re: 1979 MG Midget with GS450h and custom battery pack

Post by ggeter »

UPDATE 2022-02

Both battery racks welded up and packs racked. New driveshaft in place. Next is all the wiring and we're off!
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Re: 1979 MG Midget with GS450h and custom battery pack

Post by Tremelune »

Very cool. Keep going!
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1979 MG Midget with GS450h (unlocked input shaft) and custom battery pack

Post by ggeter »

UPDATE: SHE ROLLS!

After a year and six months, we're moving and learning. I'll push some videos later to YouTube.

Lessons:
1. If you set max torque below 500, the tires will hitch and screech toward the top of the throttle travel. Problem solved when max torque set above 1000 (using Damien's VCU code - User Interface version)
2. This little car screams when set to 1500 max torque. So much fun. But amp draw is not getting above 10 amps. Got some debugging to do on where my sensor is sitting
3. I am not locking the front spline in this build (!!). A few reasons for this: a. the pump I got is noisy and I didn't change the bearings; b. the thought of having to run a fragile $300 pump all the time gives me the willies; c. this 1800 pound car does not need both motors. It's running at 40% power on MG2 and it's too much.
4. I *do* use the pump to get rolling, but since the front spline is allowed to freewheel, the internal oil pump is, too. So once underway, I can turn off the pump and tool on down the road without sounding like I have an air compressor under the hood.
5. Future mod to code is to get MG1 to spin up fast enough at stop signs to build oil pressure, completely keeping the pump out of the mix.

Can't wait to share more findings. Thanks for the support!
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Re: 1979 MG Midget with GS450h and custom battery pack

Post by Tremelune »

Very cool. I wish there was a lighter, smaller version of this gearbox with less power, but hey...It's always nice to have a little extra!

Show us some photos of everything installed!
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Re: 1979 MG Midget with GS450h and custom battery pack

Post by ggeter »

Some pictures of full install. Hard to see the transmission unit as it's buried under the inverter and behind the battery pack.

The Pizza Hut box is my temporary transmission tunnel -- it's covering the U-joint at the output of the transmission.

Battery Hookup 6ah LiFePo4 cells, 12p 96s for ~22Kwh capacity. A little over 400 pounds of batteries. Dilithium Design BMS and Thunderstruck charger. Chevy Volt DC/DC.

Simple 12v Bosch water pump and little aluminum ATV radiator with no fan (yet). System gets warm, but not hot. Haven't run it for more than 10 minutes at a time under power yet, so we'll see where that settles out. Small coolant reservoir at highest point in engine bay. Circuit runs from reservoir thru inverter, then trans, then radiator, then DC/DC, then back to reservoir.

Lots of zip ties and electrical tape. Front to back HV wiring is scavenged 600v #4x3. I used copper tubing to make the cable ends. Just stripped wire, stuffed it into the tubing, and beat the snot out of it to make it flat. I did add solder before flattening and melted that in with a butane torch.

Total investment *not* including the donor car: less than $16K
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Re: 1979 MG Midget with GS450h and custom battery pack

Post by TheSilverBuick »

Inspirational!

I feel like these projects are simpler to take on for IT/electrically mined folks than us mechanically minded folks, but seeing two concurrent projects going forward with the GS450H is very motivational to figure it out!
Need to learn. Starting from the basics.
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