# Planning a 1985 VW "Doka" Conversion!



## Hollie Maea (Dec 9, 2009)

Looking forward to working on this project. It's going to be fun!


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## Roy Von Rogers (Mar 21, 2009)

I would recommend the CALB CA series cells for your project, so far they have been shown to be the best bang for the buck, and are reliable.

It seems that you estimation of KWh needed would put you in to the 100 cell count, since it is within the range of the Reinehart voltage limit. 

You didnt state which Remy motor you have, standard or water cooled, I'm not sure what the amperage limit is on your motor, but if it is the standard, then 100ah cells would do, but if you have the water cooled, you may go up to a higher amp CA cell, depending on room.

As to distance, figure 10 percent of the total weight of the vehicle to be the watt hour used per mile, its a good estimation of what to expect.

There is more, but I hope I gave you at least a start in this conversion project.

Roy


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## Hollie Maea (Dec 9, 2009)

Roy Von Rogers said:


> You didnt state which Remy motor you have, standard or water cooled, I'm not sure what the amperage limit is on your motor, but if it is the standard, then 100ah cells would do, but if you have the water cooled, you may go up to a higher amp CA cell, depending on room.


I'm not sure what the motor cooling system has to do with the cell size, but at any rate the controller is the limiting factor with a current limit of 300A. With the pack sizes we are considering, battery C rate won't be an issue.

If we do go with a 35 kWh pack, LiFePO4 might be pushing it...that would be a 800+ lb pack!


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## frodus (Apr 12, 2008)

Hollie Maea said:


> I'm not sure what the motor cooling system has to do with the cell size, but at any rate the controller is the limiting factor with a current limit of 300A. With the pack sizes we are considering, battery C rate won't be an issue.
> 
> If we do go with a 35 kW pack, LiFePO4 might be pushing it...that would be a 800+ lb pack!


You mean 35kWh.... 35kW is golf cart territory!


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## Hollie Maea (Dec 9, 2009)

frodus said:


> You mean 35kWh.... 35kW is golf cart territory!


Haha, fixed it. That one is all on Autocorrect though...


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## Roy Von Rogers (Mar 21, 2009)

Hollie Maea said:


> I'm not sure what the motor cooling system has to do with the cell size, but at any rate the controller is the limiting factor with a current limit of 300A. With the pack sizes we are considering, battery C rate won't be an issue.
> 
> If we do go with a 35 kWh pack, LiFePO4 might be pushing it...that would be a 800+ lb pack!


Because I'm hoping they have the liquid cooled one which can take higher amps. As is, if the worst case claim is 1600lb load, including the weight of vehicle, it will be underpowered, I know he says worst case, but never the less if you transport stuff, it wouldnt be a bad idea to build towards the higher weight.

Besides I just wanted to know which he had. And yes I know the controller limits it.

Roy


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## Yabert (Feb 7, 2010)

ElementalEnergy said:


> we estimated we'd need somewhere in the ballpark of a 35 kWh battery pack. This might be cost prohibitive for us...


Well... considering your motor controller package you can probably afford to used two chevy volt battery pack (around 2K$ each, car-part.com as example).
For your 360v limit, you can use two time 84 cells in series, who consisted of 14 packs of 12 cells from the volt battery*, for a total of 28 kwh (315v nominal, 90Ah).

*A Chevy volt battery can roughly be considered as 8 pack of 12 cells for 96 cells in series (360v 45Ah)


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## Hollie Maea (Dec 9, 2009)

Roy Von Rogers said:


> Because I'm hoping they have the liquid cooled one which can take higher amps. As is, if the worst case claim is 1600lb load, including the weight of vehicle, it will be underpowered, I know he says worst case, but never the less if you transport stuff, it wouldnt be a bad idea to build towards the higher weight.
> 
> Besides I just wanted to know which he had. And yes I know the controller limits it.
> 
> Roy


Remy motors are always liquid cooled. The "standard version" has oil cooling of both the rotor and stator. There is also a version with water cooling of only the stator. Not sure which version we'll be working with, but again either way we will be limited by the controller.


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## Hollie Maea (Dec 9, 2009)

Yabert said:


> Well... considering your motor controller package you can probably afford to used two chevy volt battery pack (around 2K$ each, car-part.com as example).
> For your 360v limit, you can use two time 84 cells in series, who consisted of 14 packs of 12 cells from the volt battery*, for a total of 28 kwh (315v nominal, 90Ah).
> 
> *A Chevy volt battery can roughly be considered as 8 pack of 12 cells for 96 cells in series (360v 45Ah)


Not a terrible idea...we would use the whole two packs though--the Rinehart can actually handle 96s.


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## Moltenmetal (Mar 20, 2014)

Yabert beat me to it- two Volt packs sounds like a near perfect fit for what you want.

I want to see what these Remy motors look like in a build. Interested to see how the oil cooling is set up.


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## ElementalEnergy (Feb 6, 2015)

The volt packs sounds like a promising idea. We also have access to a 24 kWh Enerdel pack at a really good price, but we'd be limiting ourselves below our ideal performance. It would be nice to have 32 kWh for around the same price! Looking into it now... thanks!


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## 67BGTEV (Nov 1, 2013)

Nice project and a good motor. Good luck


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## Hollie Maea (Dec 9, 2009)

It's Christmas! The beast has arrived...


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## 67BGTEV (Nov 1, 2013)

If you remove the Gearbox and if it has adapter plate, could you please share details or make a template of the adapter plate?


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## ElementalEnergy (Feb 6, 2015)

Update: engine is out!


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## YogaSlackerSam (Jul 20, 2015)

How is the build going?


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## Otmar (Dec 4, 2008)

ElementalEnergy said:


> Our next big design decision will be battery selection. Our ideal scenario was to get around 80-100 mi range unloaded, and maybe 50-60 miles loaded up with job equipment (1,600 lbs of solar panels, worst case). For that, we estimated we'd need somewhere in the ballpark of a 35 kWh battery pack.


Wonderful Project! 
I love the DOKA and bought one to convert but then sold mine to focus on the VW camper. 

I'm a bit concerned that your range numbers are optimistic. Was this just a guess or have you calculated things? Your target range for the pack size may be ok driving gently around town on a warm summer day, but on the freeway I would expect that you are looking at over 500 wh/mile, especially if you leave the rack on it. Then our wonderful northwest rain will add more drag as well. 

Looking forward to watching the progress!


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## ElementalEnergy (Feb 6, 2015)

Update: resurrecting this project after a busy solar season. 

Transmission is out! Ready to get an adapter plate made. We are leaning towards having one fabricated for us. We're trying to work on an accelerated timeline so I think it's going to be worth it for our first go around. 

Also I've changed the plan for the drive train and batteries. Should be coming into some Thundersky 90 Ah batteries (about a ~30 kWh pack), and an Azure Dynamics AC55 motor soon. Since we are working on another conversion project on a little Austin Healey Sprite (build thread coming soon!) I'm thinking the AC55 is better suited to the Doka, and we'll use the Remy/Reinhart for the Sprite. 

In response to Otmar's question, it was an estimate - in part based on an existing conversion (http://www.evalbum.com/4831) as well as best guesses. With a 30 kWh pack we should be in pretty good shape I think!


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## RIPPERTON (Jan 26, 2010)

Big mistake with the Chundersky's.
keep with OEM's like Volt or Leaf, better quality and you need less of them.


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## Roy Von Rogers (Mar 21, 2009)

I wouldn't, those OEM's are firebombs waiting to happen, unless you spend a lot safeguarding them

Stick with lithium ion phosphate, its a proven technology if bottom balanced and charged properly.

Remember if its got an "O" in the chemical description, and it burns, you aint gonna stop it from burning down to the ground. 

By the time the fire dept gets there, its all over with.

Roy


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## palmer_md (Jul 22, 2011)

Roy Von Rogers said:


> I wouldn't, those OEM's are firebombs waiting to happen, unless you spend a lot safeguarding them
> 
> Stick with lithium ion phosphate, its a proven technology if bottom balanced and charged properly.
> 
> ...


While I agree with you that the iron phosphate cells seem to be more stable on paper, they still have "O" in their chemical composition. (LiFePO
4​) If handled properly and monitored the Leaf and Volt cells have been pretty reliable. The energy density improvement is hard to pass up and the cost savings when buying from the salvage yard is also hard to pass up.


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## Roy Von Rogers (Mar 21, 2009)

LiFePO4 is an intrinsically safer cathode material than LiCoO2 and manganese spinel. The Fe-P-O bond is stronger than the Co-O bond, so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration.


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## RIPPERTON (Jan 26, 2010)

My god what a crock Roy. Outside of YouTube, Ive seen more LiFePO4 fires than LiPo or 4.2v fires. Ive seen LiFe cells like A123 pouches spontaneously ignite and burn to the ground for no reason.
The only LiPo fire Ive seen (mine at QLD raceway) was due to me abusing them by both overamping and undervolting.
I wouldnt be surprised if LiFe cells disappear from the market.
Thundersky cells will all bloat no matter how well you treat them and have a high fail rate.
Nissan and Chev didnt chose to run their cells because they were crap.


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## Hollie Maea (Dec 9, 2009)

I put a screw through an NCA cell the other day. It dead shorted, and got hot enough to burn my fingers, but didn't go thermal.

LiFePO4's safety advantage is overstated.


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## Moltenmetal (Mar 20, 2014)

Any of these chemistries can be dangerous if abused, especially if you choose to run and charge without either a BMS or the great care that must be taken without one. It's easy to get lazy.

LiFePO4 has poorer energy density but more temperature tolerance than some of the others. It's a good DIY chemistry, but definitely not intrinsically safe.


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## Otmar (Dec 4, 2008)

I wouldn't put all that much value in these reports of one "safe" event. I've failed a few cells in testing, sometimes they seem tame, others not so much. It helps to know how to make them fail with high state of charge, heat and internal shorting. Here's a paper with some reasoning behind different chemistries. 

http://www.mpoweruk.com/lithium_failures.htm

The first 40 seconds of this video is a nice show of what LiCo can do when properly heated and shorted, the fireworks piles are cell modules. The rest of the video can be skipped. There is a reason that Tesla does such a great job isolating and containing cell modules, unless of course you cut the pack in half by hitting a pole sideways at 80+ MPH. 

https://www.youtube.com/watch?v=kE_u731EmYA


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