# 1972 Electric Opel GT conversion



## dladd (Jun 1, 2011)

vmrod said:


> Well, I'm back from a very long european vacation and ready to continue with my Opel GT conversion.
> 
> 33 out of 112 batteries were shot ...snip... Doesn't matter, it was a test pack.
> 
> ...


Sounds like a great build, I love your attitude.


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## Hollie Maea (Dec 9, 2009)

Looking forward to watching your progress! You are a bit ahead of me and my GT, but I'm glad that someone else is working on one at the same time. I also like that you are "future proofing" your car. I plan to do that with my controller as well.


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## dougingraham (Jul 26, 2011)

vmrod said:


> *What needs to be purchased?*
> 
> HV cable. Will likely use 4/0. Might be a tad overkill, but will reduce voltage drop. Never know how many amps gets pushed through in the future.
> 
> ...


Sounds like a nice build. Just a couple of comments.

4/0 cable is way overkill. Assume 20 feet at 1000 amps. Voltage drop will be 0.98 volts with 4/0 cable. The 60 cell pack is going to sag a ton more than that. Probably close to 30 volts. 1000 amp drop with 2/0 and 20 ft would be 1.56 volts and with 1/0 would be 1.97 volts. This is not significant. I used 2/0 everywhere and in retrospect I should have used 1/0 on the battery side and maybe 2/0 in the motor loop. 2/0 is annoying enough I don't want to think about working with 4/0. And that is at peak current. Your average current is probably going to be 200 amps and that makes those drops 1/5 of the 1000 amps mentioned above or 0.2, 0.3, and 0.4 volts for the three sizes. Your actual drop will probably be less than this because the 20ft is just a conservative guess. You might want 4/0 if you were drag racing. But would that be in this car?

I gave up on the jack and spare tire. The spare in my car was 28 years old and had never even been mounted in 146k miles. Save the space and 30 lbs of weight for batteries. Put the tow truck service on your insurance for the few dollars it costs per year (or get triple A) and keep a cell phone on you to call them if you ever need to.

Best Wishes!


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## vmrod (Jul 2, 2010)

Thanks for the tips Doug.

The Opel would not make for a good drag car (in it's current state). However, with a new rear end and tranny....who knows?

I get skittish looking at the ampacity tables for welding cable. Always thinking that I should go with a bigger cable than I need to.

I would buy the super-flexible cable, so it is not so hard to work with. So, running a larger cable than what you can get by is not really going to hurt anything, except for the extra weight. I already have 4/0 cable routed from the controller to the motor.

My Saturn Sky does not have a spare tire. Just a fix-it kit. I MIGHT go that route in the Opel, but if I can mount the batts and have the stock place for the spare, I like it. This also means that one day, I can remove the spare and install more batts, if I choose to.

It will be challenging (for me) to install the batts where I want (in the car), but once done, it will be worth it to me.


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## vmrod (Jul 2, 2010)

I cut out a couple small brackets in the front area of the car, where the 12V battery used to sit. (just forward of where the radiator used to be) The mock-up box of 16 Calb-100ah batts fits nicely in that space. 

Next, I started cutting out the floorpan directly under the fuel tank (which is no longer in the car). I got about 3/4 of the task done. There is a structural member that is integral to the rear suspension. I hadn't noticed it from inside the car. Looks like I can still stick to my plan and cut that metal away too. I'll just need to beef up that suspension bracket with some additional metal and welding afterwards. I was going to put 26 cells here, but it looks like I can get 30 or 31 in this place.

If 31 cells can fit in place of the fuel tank, then I'll try to see if I can cut another section of the floor out, just forward of the fuel tank area (immediately forward of the structural member that the rear shocks mount to). 13 cells would go here. (hopefully). That would have 44 cells in the rear and 16 in the front. (60 total).


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## vmrod (Jul 2, 2010)

Did a little more floor-pan cutting. I was dissapointed in that I was expecting to easily place 10 cells behind each seat (under the rear deck). (I even ordered 2 additional cells.) As usual, 'stuff' was in the way, so I can only put 8 there. After some crafty thoughts, I figured out how to get 10 in the area.

So, I am getting closer to my solid battery placements.

16 batts in the front. No brainer, mock pack fits.

26 batts in the fuel tank area. Still have more metal to cut-out, but getting closer.

10+10 batts under the rear deck behind the seats.

62 batts!

I still have room for more, but this will be enough for now. 

Need to get some more time now! Kinda tough with a 12 week old baby!


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## vmrod (Jul 2, 2010)

Received my batteries (62) this past Friday!!! Thanks Don.   

3 of them are already being charged. (I have 3 single cell chargers handy at the moment.)










I also finished cutting out the rear floor pan area. Still have minor trimming here and there, but the tough part is done!

Next step is gonna be building battery trays/boxes.


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## Hollie Maea (Dec 9, 2009)

Nice! Any pictures of the car you can post?


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## vmrod (Jul 2, 2010)

I don't have recent pics handy. If my son gives me a bit of time this evening, I'll take some pics of the floor pan cut-outs. I could take some of the engine compartment too. (I took a few of that area some time ago.)

Bear in mind that it will look messy.


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## vmrod (Jul 2, 2010)

Here is the rear pack. It holds 2 rows of 13 calb-100ah cells (26 total). It should be virtually invisible once installed. 
View attachment 16093


It will sit underneath the rear-most deck where the spare tire sits. 
View attachment 16094


The cutout right behind the driver's seat will hold 10 cells. I'll duplicate this behind the passenger seat too. The rear deck will cover these. 
View attachment 16095


The space upfront will hold 2 rows of 8. (16 cells total). I have a dummy row of 8 and a dummy single cell for placement check. 
View attachment 16096


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## Hollie Maea (Dec 9, 2009)

Images not showing up. Maybe try uploading them at tinypic.com ?


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## vmrod (Jul 2, 2010)

I'll try reposting the pics tonight. They don't appear to have uploaded.


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## vmrod (Jul 2, 2010)

Here is pic #1.


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## vmrod (Jul 2, 2010)

Here is pic #2 and 3.


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## vmrod (Jul 2, 2010)

....and finally pic #4.


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## Hollie Maea (Dec 9, 2009)

Looks great! I'll probably end up stealing some design cues from you


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## vmrod (Jul 2, 2010)

I was able to re-use the stock motor mounts. Worked well.

I'm re-using the clutch too. Won't need it so much, but it's there.


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## kerrymann (Feb 17, 2011)

vmrod said:


> Before I left for vacation, I actually drove it around with a test battery pack. The pack was pretty sickly and after checking things out the other day, about 33 out of 112 batteries were shot. Most of those were close to 0 volts, some around 1.5volts. The good batts were at 3.28volts or thereabouts. Doesn't matter, it was a test pack.


Cool project. What batteries were you testing with that over a third of the pack died?


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## vmrod (Jul 2, 2010)

Short answer:
I was using 'Lifetech' batteries, and a BMI 'smart' charger.
(now skip to the end)

Long answer:

My first set of Lifetech batteries had a rough start (56 cells). I ran them through the paces, until the overall voltage was low (about 2.8v average per cell). Apparently, some cells were lower than others, and the pack became unbalanced. They would not charge properly afterwards. I was sent replacement cells, which I installed into the battery packs. All cells were individually charged to 3.65V.

My second set of batteries (56 cells) were only used a few times. (less than 5 times, and only once taken down to 80%DOD for proof of range). They were used in parallel with the first set of batts.

The batteries are cells grouped together as a 4-cell unit. Each 'unit' has a circuit board connected for balancing during charging. They are all daisy chained together for common LCV or HCV alarms.

The cell balancers worked OK on some groups (and not so good on other groups), however they didn't seem to communicate with each other. (If they did, they did not do a good job.) So, some units had higher voltages than other units. (Unknown to me at the time.)

I was told that the charger would shutoff automatically once the proper charge was reached. It would never overcharge. Well, that was true. However, I was a newbee, and didn't know about over-volting a single cell (or 2 or 3....) due to imbalancing. I was confused about getting a HCV alarm, but was reassured that with my properly selected charger, I could not overcharge or damage my pack(s). So, charging continued.

I had started tearing the packs apart and individually charging each cell with a LiFePO4 charger. It took a long time to charge 56 cells. (I left the newest packs intact and charged them as a unit on the big 'smart' charger. I would simply unplug the charger when a HCV alarm sounded).

When I performed my final test, the 'bad' pack was fully charged (individually charged cells) and the 'good' pack was fully charged up to the HCV alarm. (Which was pretty close to the charge voltage).

After the test, I hooked up the 'smart' charger to both packs (in parallel), and charged as you would expect. Funny, I started to get both high and low cell voltage alarms on the same pack(s). I unplugged the charger, and let the project sit for a year while I vacationed in Europe.

After returning, I tore down the packs completely. I measured and recorded the voltage for all the cells. I think I had 33 out of 112 cells which were under 2 volts. (Some under 0.5V) About 50 cells were around 3.2V. The rest of the cells were close to 2.75V (or something like that).

The remaining 'good' cells will be used to make aux. 12V packs for my EV's, and serve as future test batteries for other smaller projects. 

----------------------------------------------------

My big lessons.

1. Ensure any HCV ALWAYS cuts off the charger.

2. Ensure a LCV cuts the load, warns the driver, and/or disconnects the load. (Best is not to ever even get this alarm.)

3. Ensure the cells stay balanced. Monitor often enough to gain trust in the cells ability to stay close to each other and the equipment in balancing them.

4. Never use a Lifetech battery in an EV application. I will not rule out the use of the cells, however use a well trusted BMS.


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## vmrod (Jul 2, 2010)

The Calbs are in and charging!

First they come here, where they are charged on a digital charger. Up to 5 can be charged at once.










Then I put them back into the box. Once a row is completed, it gets wired up in parallel with the others.











Once the entire box is done, I again top off the charge (digital charger), so that all of the cells are again full.

Once the last crate of cells are completed (next couple days), then all 3 crates will be connected together, and once more connected to the digital charger. (probably take a couple hours to confirm that they are all full).

They will rest together until the battery boxes are installed in the car.

Speaking of which....the metal for the boxes has been delivered. The front battery box is nearly designed, and about 25% of the box is completed. Fits the cells perfectly so far.


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## tomofreno (Mar 3, 2009)

vmrod said:


> My big lessons.
> 
> 1. Ensure any HCV ALWAYS cuts off the charger.
> 
> ...


 Good guidelines. If a newbie follows these s/he will not get into trouble.


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## nucleus (May 18, 2012)

I like how you have kept the battery weight low in the car.


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## vmrod (Jul 2, 2010)

with the exception of the top and cell hold-down apparatus, the front battery box is complete and installed. The cells fit snugly in place, no room to spare.

It would have been nice to weld it all up, then install it, but it could not be put into place once fully welded. (too big to get into the area) I ended up welding only a couple pieces together. The rest was installed with steel rivets. It feels very sturdy and secure. 

The battery box in the rear (old gas tank location) will be the next one to tackle. Should be much easier than the first one for sure. It will also be a tight fit for the cells, but most of it can be fabricated and welded before installation into the vehicle. Can't wait to start on that one!


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## vmrod (Jul 2, 2010)

The rear battery box is almost complete. Mainly needs to get welded into the car. 

The battery boxes behind the seats (under deck) are now in construction. 

These cell holders fit the cells snugly. A few more are still needed. They will then get assembled into 2 boxes.


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## vmrod (Jul 2, 2010)

Car is up for sale in the classified section.
Awesome vehicle.


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