# Project B-ohM-W



## FarFromStock (Mar 16, 2009)

I'm a bit slow in getting this build thread started seeing as how it's been in-process for more than 5 months now. But like they say, better late than never! 

So here are some of the basics on the build. 

- It's a 1975 BMW 2002. The ICE was pretty tired with more than 250k miles on it. 

- I decided to have RebirthAuto do the actual conversion because if it was left to me, it would take 2+ years to get road worthy.

- We are keeping the 4-speed manual transmission and Rebirth has made an adapter from a single block of aluminum to mate the transmission and the Warp9 motor through the stock clutch/pressure plate. 

- Power will come from 11 Deka Deep Cycle GEL 12VDC 97.6AH Batteries. 8 will be mounted in the trunk and 3 in the engine compartment along with a service battery.

- Controller is a Soliton1 with liquid cooling running through a heat exchanger to keep everything cool.

- Air conditioning is supplied through a GM compressor mounted to the front of the Warp9 with a custom mount made by Rebirth.

- Monitoring/instrumentation will be via PakTrakr.

- DC/DC converter was originally planned to be Kelly Controls but I believe that has since changed. (I'll update once I know the specs)

- Battery charger was also originally planned to be a Kelly but that has also changed. (I'll update once I know the specs)


I'll post progress pictures as it moves along.


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## FarFromStock (Mar 16, 2009)

Some pictures of the ICE removal:

*In its native environment*










*Exiting*










*Just hanging around*










*Elvis has left the building!*


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## FarFromStock (Mar 16, 2009)

*Let the conversion begin:*


*The blank canvas*










*Custom adapter plate and clamshell mount with rubber isolators, courtesy of RebirthAuto*
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*About to make a 'love connection'*
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*


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## Sutitan (Feb 23, 2009)

Awesome, I cant wait this car done. Prepare to be bugged about test results with the Soliton1 (atleast i know i'll bug ya)

Just a question, how come you decided on 11 12v batteries instead of 12 12v (132 vs 144 nominal voltage). I guess im just so used to seeing people running 48, 72, 120, 144, 156 volts thats its a bit strange to see a 132.

Another question, what color is the 2002? it looks like that malaga color BMW had. cant really see that well in the pics


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## FarFromStock (Mar 16, 2009)

*Motor being prepared for its new home*



















*Is this thing going to fit?*










*Like a glove!*


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## FarFromStock (Mar 16, 2009)

Sutitan said:


> Awesome, I cant wait this car done. Prepare to be bugged about test results with the Soliton1 (atleast i know i'll bug ya)


Thanks! I can't wait to start driving it and providing routine updates on performance of the Soliton1.




Sutitan said:


> Just a question, how come you decided on 11 12v batteries instead of 12 12v (132 vs 144 nominal voltage). I guess im just so used to seeing people running 48, 72, 120, 144, 156 volts thats its a bit strange to see a 132.


It was a decision based primarily on real estate. I will post some pictures of the trunk and engine bay and how we had to lay out the battery trays to accomodate the 11 batteries and still have some room in the trunk for groceries. 



Sutitan said:


> Another question, what color is the 2002? it looks like that malaga color BMW had. cant really see that well in the pics


The color is the original Siennabraun but my wife and I are trying to decide what the final color will be. My best friend is in the paint & body industry so we can go just about any direction with it.


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## dtbaker (Jan 5, 2008)

you're not going to cut a hole under rear seat/trunk to hang the batteries lower? you'd have lots more room in the trunk!


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## FarFromStock (Mar 16, 2009)

*A/C compressor with custom machined mount and pulleys*


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## FarFromStock (Mar 16, 2009)

dtbaker said:


> you're not going to cut a hole under rear seat/trunk to hang the batteries lower? you'd have lots more room in the trunk!


That wasn't really a practical solution at the time. We removed the fuel tank and were able to fit 4 batteries there. Another 4 were fit between the wheel wells/shock towers directly behind the back seat. We were trying to keep all of the batteries outside of the passenger compartment. If the 11 batteries don't provide the performance or range that I need, we'll relook the remaining space and go from there. The spare tire well is a prime candidate.


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## FarFromStock (Mar 16, 2009)

*Trunk battery trays being mocked-up*


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## Woodsmith (Jun 5, 2008)

I love the 2002, it's a great car, one of the first normal cars I worked on after playing with Land Rovers during my school days.

What is the AC compressor for? Are you going for AC or are you using the compressor for the brakes? That is the sort of mounting I want to put on my conversion to use the AC compressor for my brake vacuum. I don't have a motor yet though never mind a tail shaft to work from.


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## FarFromStock (Mar 16, 2009)

After all the battery trays were mocked-up, I had Rebirth pull everything back out so that we could repaint the trunk and engine bay. We decided to go with a satin black which should make all of the machined aluminum 'pop'.

*Here she is back at my house with my buddy Steve prepping it for paint.*











*Steve getting busy*
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*The finished product*


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## FarFromStock (Mar 16, 2009)

Woodsmith said:


> What is the AC compressor for? Are you going for AC or are you using the compressor for the brakes? That is the sort of mounting I want to put on my conversion to use the AC compressor for my brake vacuum. I don't have a motor yet though never mind a tail shaft to work from.


It's for air conditioning which was a 'must have' before the wife would agree to the conversion. 

We are using a MES-DEA Vacuum Pump for the brake booster.


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## FarFromStock (Mar 16, 2009)

Once the engine bay and trunk were painted, I brought it back to Rebirth for final fabrication. So here are, what I consider, the good pictures!

*Back at Rebirth (in the lower right is the heat exchanger for the controller)*











*Motor back in*











*Battery trays going back in*



















*House and front batteries going in*









*Here you can see the heat exchanger and coolant recovery/expansion tank mounted where the original radiator was*


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## FarFromStock (Mar 16, 2009)

*Vacuum pump mounted underneath between the battery well (original fuel tank) and spare tire well*










*Trunk batteries and charger with some of the battery hold-downs*




























*And this is where the controller will mount. This one is being use for placement, mine will be natural aluminum color.*


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## FarFromStock (Mar 16, 2009)

*It's ALIVE!!!*

Here are a couple videos that the good folks at RebirthAuto took of the B-ohM-W being road tested. 

This one is of some stop-and-go traffic:

http://www.youtube.com/user/rebirthauto#play/all/uploads-all/0/V5sf3JbPyCE


This one is of the highway run. They were able to run it up to 90mph! At 80mph it was drawing ~350 amps.

http://www.youtube.com/user/rebirthauto#play/all/uploads-all/1/W8PBEGcHBok


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## Sutitan (Feb 23, 2009)

Less then 48 hours and its done  fastest build EVER!

do you have any performance/range figures?


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## vpoppv (Jul 27, 2009)

Cruising at 80. Nice. I seriously don't think my ICE could do that....


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## RKM (Jun 9, 2008)

FarFrom Stock,

Beautiful.

The Al adapter plate and clam shell motor mount are particularly impressive! Very pretty design and execution (this not be cheap!). The AC mount is also a work of art. Laser or waterjet? Very, very nice.

Rob


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## Guest (Sep 25, 2009)

Very nice and kudos to Rebirth for an excellent job on the adaptor. Clean and fast. 

Pete


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## FarFromStock (Mar 16, 2009)

RKM said:


> FarFrom Stock,
> 
> Beautiful.
> 
> ...





gottdi said:


> Very nice and kudos to Rebirth for an excellent job on the adaptor. Clean and fast.
> 
> Pete


I've been very impressed with all of the work Rebirth has done on my conversion. They have been very methodical on planning the project and not much has been left to chance.


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## Thaniel (May 25, 2008)

Excellent looking machine work on the adapter plates. Also love the aluminum battery trays. I've seen a lot of people going with steel and the Aluminum isn't that much more and will weigh much less.

Mounting the one battery rack to the motor brace seemed an interesting choice. Over all though excellent work.


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## rebirthauto (Nov 3, 2008)

Thaniel said:


> Excellent looking machine work on the adapter plates. Also love the aluminum battery trays. I've seen a lot of people going with steel and the Aluminum isn't that much more and will weigh much less.
> 
> Mounting the one battery rack to the motor brace seemed an interesting choice. Over all though excellent work.


Thank you all for the kind words.

We try not to build anything half-way, and we are convinced that FarFromStock is the kind of guy who would build quality as well, if he just had the time to do it himself.

FYI there are no batteries mounted to the motor brace, there is just a bunch of TIG welded braketing that our inside guy Ron went to great lenghts to layout. The engine compartment was particularily challenging because we couldn't really mount any two batteries on the same plane, and as you can see, space was at a premium.

We can't wait to wrap it up and hand it back so that we can finally see this very cool car get some new shiny paint.

Sebastien


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## FarFromStock (Mar 16, 2009)

Well, after 22 months, the paint is finally done!




























Just need to reinstall a few remaining trim pieces and then start working on the interior. We will eventually pull all of the remaining polished aluminum pieces (mirrors, door handles, bumpers) and black them out too.


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## drivin98 (May 9, 2008)

A lot of earlier pics seemed to have disappeared from this thread so don't be shy about showing us how it looks under the hood and trunk lid now.

Looking very nice.


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## FarFromStock (Mar 16, 2009)

It's been a long, long time since I've updated this thread. All of the pictures from the original build disappeared when Rebirth took their site down, so I'll try to post some pictures from the original build.

We had been driving the car regularly to work, but after we relocated, the distance was too far to go on a charge. As such, the car has sat in the garage with only an occasional weekend excursion. Now that the lithium battery market and technology has matured, I'm looking at changing from the existing LA gel batteries to a lithium chemistry. I'd appreciate any recommendations on the best way to attack the conversion from LA to lithium.


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## dtbaker (Jan 5, 2008)

FarFromStock said:


> I'm looking at changing from the existing LA gel batteries to a lithium chemistry. I'd appreciate any recommendations on the best way to attack the conversion from LA to lithium.


first step is to decide on battery type, format... nominal pack voltage and ah of cells to get the range you want. I would stay clear of junked or refurbished packs from OEM evs, and stick with NEW LiFePO4 large format cells for simplicity sake. I haven't checked recently, but I think CALB cells are still available, although I'm not sure if the 130ah, 160ah, or 200ah capacity cells are the most available these days.

you will need to change out your charger... and decide if you are going to let the charger do its 'top-balanced' charge cycle with or without BMS monitoring, active shunting, or go commando with occasional manual top balancing, or bottom balance and use a BMS to stop charge cycles.

and then total re-design of your racking.... you'll want to consider that you MAY need access to all terminals for checking/balancing; unless you run monitor wires of suitable gauge... and you'll need to think about how you want to strap/rack/contain the cells. I would highly recommend 'tight-fit' design/fab using 1/4" polyprop plastic. It's easy to work with, non-conductive, pretty tough, and you can fabricate custom brackets pretty easily. I have a couple shots in my build gallery that might give you some ideas: http://www.envirokarma.org/ev2_mx5e/gallery/121209_bbox02.htm and out of the car http://www.envirokarma.org/ev2_mx5e/gallery/121109_frack_v1.htm


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## Duncan (Dec 8, 2008)

I will differ completely from the advice for your batteries

OEM cells are not only a LOT cheaper but they are much much higher quality than the likes of CALB

I love my Volt battery - cheap AND excellent


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## dtbaker (Jan 5, 2008)

Duncan said:


> I will differ completely from the advice for your batteries
> 
> OEM cells are not only a LOT cheaper but they are much much higher quality than the likes of CALB
> 
> I love my Volt battery - cheap AND excellent


not saying you might not get lucky, and get a well matched not too old pack out of a wrecked Volt or Tesla.... but you might also get an unmatched low capacity nightmare... for cheap.


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## Duncan (Dec 8, 2008)

dtbaker said:


> not saying you might not get lucky, and get a well matched not too old pack out of a wrecked Volt or Tesla.... but you might also get an unmatched low capacity nightmare... for cheap.


I have not heard of anybody getting that from a Volt or a Tesla 

The Leaf cells don't seem to be as robust

BUT - EVERYBODY who has bought "New" cells from China has had several fail on them

Read people's threads - everybody with "New" cells has had to replace some

And that includes the Headways I bought


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## Duncan (Dec 8, 2008)

dtbaker said:


> not saying you might not get lucky, and get a well matched not too old pack out of a wrecked Volt or Tesla.... but you might also get an unmatched low capacity nightmare... for cheap.


I have not heard of anybody getting that from a Volt or a Tesla 

The Leaf cells don't seem to be as robust

BUT - EVERYBODY who has bought "New" cells from China has had several fail on them

Read people's threads - everybody with "New" cells has had to replace some

And that includes the Headways I bought


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## dtbaker (Jan 5, 2008)

Duncan said:


> I have not heard of anybody getting that from a Volt or a Tesla
> 
> The Leaf cells don't seem to be as robust
> 
> ...


Headways are a COMPLETELY different format than the CALB.... The smaller format requires multiple parallel/series connections that seem to be problematic for DIY BMS management. The large format in straight series for DC motors is perhaps not the 'best', but it may be the simplest. My concern with used battery packs, especially if sold in 'chunks' from scrapped vehicles, is that batteries of different age, with different capacity and internal resistance are problematic to balance during charge/use cycles.... 

CALB was the 'best' a couple years ago (versus thundersky or others with looser production tolerance on internal resistance in batches), and the only ones I am aware of failing were user error with over charge or over discharge under load.

I posted my recommendation purely on personal experience, and having a total of 30k miles or so on two EVs. I think it is important to mention actual results over the long haul in answering the OP question in the best path to migrate from lead to Lithium with an old school DC setup.

I have had a couple cells fail.... completely my fault for running an old school Curtis controller with no LV alarm too far and toasting a cell. Second one was when I loaned the car to a non-builder, who ran it until it stopped despite warnings. neither case was the fault of the batteries; just not idiot-proof. My basic point is that as soon as you mix age and capacity, and complicate with series/parallel, you will likely have more problems than straight series of new cells regardless of brand.


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## Duncan (Dec 8, 2008)

Hi dtbaker
That is it EVERYBODY who has bought CALB or whatever "has had a few cells fail" 

But Tesla or Volt modules? - I haven't heard of any failures and I am being seriously BAD to my Volt cells - no BMS and my controller set to 1200 amps 

As far as "buying in chunks is concerned" I agree - if you are building a lawn tractor then you may "buy a module" - but for a car you should be looking at a "Battery" or even two!

If I compare Volt modules to CALB cells - I have eight modules in my car which gives me 14 kWh and 300v to 340v operating voltage
The battery comes complete with a nifty mounting clamp thing - you do have to drill out about a hundred spot welds to take it off the bottom plate
All of the busbars lots of connectors - a neat water cooling/heating system
And if you are smart enough a built in BMS system

I would need about 100 CALBS to get the same voltage - with all of the connections - no nice cooling/heating system and no neat mounting/clamping system

Eight modules verses about 100 for the CALB's


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## dtbaker (Jan 5, 2008)

Duncan said:


> Hi dtbaker
> That is it EVERYBODY who has bought CALB or whatever "has had a few cells fail"
> 
> But Tesla or Volt modules? - I haven't heard of any failures and I am being seriously BAD to my Volt cells - no BMS and my controller set to 1200 amps
> ...


Duncan, I really don't want to get into a pissing contest regarding large format versus recycled OEM modules. I was attempting to outline the simplest path forward on a Lead->lithium upgrade for the OP... and since he has a DC motor, is presumably built everything for a battery pack with a nominal voltage between 120v-160v.

Given that nominal voltage, easily accomplished with 38-48 large format cells in series, that would be my recommendation.

Your situation, with 300+volts presumably running an AC motor, is completely different.... and furthermore, how do you KNOW you don't have any dead cells? especially if you don't have a BMS? I think its great that you are happy with putting together used Volt packs; lets talk about it again after you have 10k-15k miles on the pack to see how they hold up.


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## MattsAwesomeStuff (Aug 10, 2017)

I'm with Duncan on this.

From all available evidence, OEM packs are massively superior to home-assembled rigs... and I say that from someone still choosing to home-assemble their own pack because I'm cheap.

As Duncan said, the evidence is almost comically stacked, with basically zero issues from anyone using OEM packs, and almost universally everyone who built their own has experienced partial failure. It really couldn't be more lopsided.

Economies of scale alone mean that the OEM companies are ordering amounts that can ensure quality, where even the largest companies selling to home users are basically buying unwanted leftovers. The quality is going to be where the scale is, and OEM vehicle companies have 100-10,000x the scale of the small sellers.

Then there's the cost-effectiveness. Used OEM modules are somewhat scrap and a burden to own as they come from crashed vehicles, so they get sold for pennies on the dollar. What was a $40,000 car often gets sold to scrappers for $250-500, who then spend labor to get what value they can out of the vehicle. You're paying something on the scale of 5-20% of what the batteries are worth.

This versus, when you order new cells yourself, you're paying new price for them, no discount, they had to be made for you.

So, OEM is higher quality, less expensive, and then sold to you at a fraction of their value from the scrap yard.

Really just superior in every way.


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## Duncan (Dec 8, 2008)

dtbaker said:


> Duncan, I really don't want to get into a pissing contest regarding large format versus recycled OEM modules. I was attempting to outline the simplest path forward on a Lead->lithium upgrade for the OP... and since he has a DC motor, is presumably built everything for a battery pack with a nominal voltage between 120v-160v.
> 
> Given that nominal voltage, easily accomplished with 38-48 large format cells in series, that would be my recommendation.
> 
> Your situation, with 300+volts presumably running an AC motor, is completely different.... and furthermore, how do you KNOW you don't have any dead cells? especially if you don't have a BMS? I think its great that you are happy with putting together used Volt packs; lets talk about it again after you have 10k-15k miles on the pack to see how they hold up.


Nope
I'm using a Hitachi 11 inch forklift motor and a Paul & Sabrina Controller set to 1200 amps - so actually quite similar to the BMW with a Warp and a Soliton

If he wanted to keep the voltage down - so he could re-use his DC-DC and charger then simply using the Volt pack as two strings would do that

As far as my cells are concerned I do a regular check with a Cellog8 - which checks each set of three cells in parallel 
A check at the bottom 295v - and a check at the top 340v 
All sets the same within 0.01v at both ends

I've been driving this as my daily driver for about two years on this pack and doing a wee bit of motorsport
I did melt my first motor at the drags in march - and I had to get a replacement ($150) -


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## brian_ (Feb 7, 2017)

dtbaker said:


> ... and since he has a DC motor, is presumably built everything for a battery pack with a nominal voltage between 120v-160v.
> 
> Given that nominal voltage, easily accomplished with 38-48 large format cells in series, that would be my recommendation.
> 
> Your situation, with 300+volts presumably running an AC motor, is completely different...


While a stock Leaf battery runs 360 volts (nominal), the Leaf modules can be configured for lower voltages, either by using a partial pack or by paralleling modules or strings of modules. Much of the Nissan cabling can still be used in some reconfigurations. A single Leaf module contains a series combination of two parallel cells, so it is equivalent to a pair of 66 Ah prismatic cells in series; 38 to 48 large-format cells in series are equivalent to 19 to 24 Leaf modules in series. If none of the Nissan wiring is used, Leaf modules simply cut the number of required interconnections in half compared to building up a battery from individual (large enough to not need parallelling) cells.

I don't see the relevance of AC versus DC (brush commutated) motors to the cell characteristics - both are available for a wide range of voltages, although "forklift" motors are normally run at half the voltage of modern EV motors (which are all AC).


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