[kerrymann]

Originally Posted by marc02228

Does this thing have a name?
I just had a look under my car and it is missing.

The holes for it are still there right? I believe it is just called: "brace, front subframe; Simple cross bar. Ties end of front subframe together"

http://www.flyinmiata.com/salvage/chassis.php

It's only $10 for a used one here in the US but I can't imagine it would be much more expensive in DE.

[kerrymann]

Now I have power!



Well I finally got a few hours to assemble my 250 A123 cells into modules. Once I got the system down it went pretty quickly. I have the cells assembled into 4 modules. 3 identical ones made of 3p18s that will go behind the seats where the gas tank used to go. The other cells get mounted in a single module of 3p29s that goes up front where the radiator used to be. I went back and forth on how I was assembling the modules but the final design just uses bolts nuts and washers do make it very DIY friendly. If people are interested I can post specific details on the tab connections.

Once I had all the tab connections I needed a way to mount them. I made up some quick end plates with some L brackets so I can connect cables to clamp them together.

For cables I actually had a bunch of left over flight control cables. I simply cut them down and spliced them together. I originally going to use some eye bolts but happened to have these cables.

I also cut up some .008 aluminum into 8" squares to act as cooling fins. I slid them in between every other cell.

This greatly increases the heat transfer from the cells. Individually the cells will be just fine but when you stack them together you decrease the cooling surface area by several orders of magnitude. To solve this aluminum uses the large surface area from the sides and conducts the heat away to the fins. The fins stick out 1" from either end of the cell for convection to wick the heat away. Keeping the cells cool is critical to maintain cell life. This is a fair weather car so I won't be driving it in the cold but this also could be used for heating if you needed.

This pack still needs some adjustment but I wanted to get it made before I left town for a few weeks.

[marc02228]

Maybe you could place a spring between the nut and the L bracket. That's the way I am planning to assemble my pack.

Great idea with the cooling. But maybe the cells could get damaged when they are rubbing to the aluminum while driving? If I remember right the cells have a thin isolated coat around them.

Did you mount your motor directly to the frame of the car?
Someone, who was looking at my miata told me, to use the original dumper to mount the electric motor due to vibrations from the gearbox, wheels, etc. But I am not sure, what's the best way to do it.

[kerrymann]

Originally Posted by marc02228

Maybe you could place a spring between the nut and the L bracket. That's the way I am planning to assemble my pack.

Great idea with the cooling. But maybe the cells could get damaged when they are rubbing to the aluminum while driving? If I remember right the cells have a thin isolated coat around them.

Did you mount your motor directly to the frame of the car?
Someone, who was looking at my miata told me, to use the original dumper to mount the electric motor due to vibrations from the gearbox, wheels, etc. But I am not sure, what's the best way to do it.

I thought about a spring but decided it's really not needed. The cables were proof tested to 1100lbf so I don't have to worry about the 2-300lbf tension I am putting on them. Even if your cables were to stretch just re-torquing them once should be fine. If you are really worried about it I would actually recommend a couple Belleville washers.

The cooling fins aren't my idea, just a copy of what A123 does for their modules. The cells are restrained completely by the tension on the cables. You want to make sure that the cells do not move at all so they don't rub against the fins or whatever kind of battery box you are putting it in, not to mention the cell tabs flexing. I recommend 9g forward, 6g down and 4.5g sidewards for sizing.

I mounted my motor directly to the subframe.

[kerrymann]

DIY A123 modules ready to go



Now that I am back stateside I took the afternoon to build the final version of my modules.

I made up some quick templates to crank out new cooling fins that look a lot more professional then Rev 0.

...I also made up new end plates and end bars...

...and replaced the end cables with .25" all thread...

So in short I remade everything but the cells from before. The result is a module design that I am finally happy with and can easily made with pretty basic hand tools cheap and quickly. I'd say once the cells were ready (tested, destickered and 2 hole punched) I took me about 4-8 hours to assemble 250 cells into modules.

I dry fit the modules in the back of the Miata so I can start on the mounting brackets.

3 modules get installed here where the fuel tank used to be and a 4th one get's installed up front where the radiator used to hang.

Next up is the mounting brackets for the modules and installing the BMS. Assuming I don't have to suddenly leave the continent for work again those items shouldn't take too long.

[kerrymann]

Charge!



Since I have battery packs now I need a way to charge them. So I got the charger mounted tonight:



I chose this location because I wanted the weight up front to help with weight distribution. It is also next to the battery terminals at the charger making the cable run short. I also wanted to place it on the passenger side to offset some of my weight as I will be driving it to work sans passenger most of the times.



I went with the Manzanita Micro PFC20. I could have gone with the cheaper Chinese made Elcon but I wanted a made in the USA quality unit and the capability of adjusting the current draw on the fly. We have seen great improvements in controllers (i.e. Evnetics) but this charger really seems right out of the 90's. For my relatively small pack 20amp max is plenty though if I got that PFC60 I could recharge from my morning commute in less then 30 minutes. I have something special in mind for the charge port but more on that later....

[kerrymann]

BMS install



I got all the BMS mid boards installed today. The Lithiumate Lite is about as simple a system to install as possible (short of not having a BMS .

Some of the things I like about it so far is the board to board connection is realatively easy and the diagnostic light on the PCB that blinks 6 times to let you know you installed it correctly and that it is working. The boards are pretty small and fit well with 3 cells in parallel. Part of the way through I realized if I installed half of the boards upside down this gave you a bit of extra clearance.

Notice I said upside down NOT BACKWARDS! This brings me to one of the things I don't like on the system. If you install a cell backwards (i.e. wrong polarity) it is dead. Even for a millisecond. Elithion is very clear about this in their literature but it just seems like a diode to protect the boards would have been a easy fix. So with that in mind, I made sure I had a little installation procedure and followed it. Elithion manual seems very good along with some videos (with no audio for some reason) but for my application I set the pack on it's side and did half where the PCB would hang down to gravity. I was anal and checked every connection with the DMM first then verfied the LED blinked before tightening the nuts down.

I did one full side then flipped the module and did the mid boards in the other direction.

Cut then stripped all of the wires to the right length.

I then made the connections, again one side at a time.

This just helped to get in a pattern and ensure no mistakes.

Just to reiterate what I said about the BMS earlier. If I had cells that I was 100% confident in then I would not have bothered. But being this is an experimental pack design I am far from it (not even close to 3 sigma . So I decided I needed to montior each cell. I looked into Battery Monitoring Systems and wasn't impressed. I found the Elithion system gave this functionality along with a management system for a very reasonable price and had a lot more features. I must say for someone that is skeptical of BMS I am preety impressed with the system so far. But I am not done yet either...

I am also looking if I can use the lithiumlite system just for monitoring and keep my pack bottom balanced.

BTW, Before I purchased I also found all the fabrication was done here in Colorado (Broomfield, CO). I am a big fan of buying locally so this was icing on the cake for what I already thought was the best system and best value.


I also bought a set of KYB struts with springs for only $150. I will hold off installing them till later:

[marc02228]

Originally Posted by kerrymann

[B]

I bought my Soliton1 from them (Jim Husted + Eric Pedersen) and had no problems. Again the Rebirth adapter is great but I had been planning around a plate style adapter so life got a little more complicated. I did hear back from Steve and he said their drawing called out the right thread pitch on the hub but the machinist made a mistake. He offered to send it back and they would fix it but I already have it in the car with the bolts I had found.

Yesterday I got the adapter, too. Nothing changed. Still blind holes and no fine threaded hub.
Even the dowel pins are missing^^

I ordered M12x20 grade 10.9 for the hub. I think 25mm length would be to long for me.

Are the 2-4 small ones and the motor connecting screws 3/8?
What thread are the other screws?

Hard to find imperal screws here, in Germeny

[kerrymann]

Originally Posted by marc02228

Yesterday I got the adapter, too. Nothing changed. Still blind holes and no fine threaded hub.
Even the dowel pins are missing^^

I ordered M12x20 grade 10.9 for the hub. I think 25mm length would be to long for me.

Are the 2-4 small ones and the motor connecting screws 3/8?
What thread are the other screws?

Hard to find imperal screws here, in Germeny

I think normally people reuse the pins from the motor. I had forgotten to remove mine before I sold it so I asked Steve for the dowel pins. They were back ordered from Mazda so they made me up a set. In fact I am not sure they ever charged me for them. The blind holes are the way the adapter was supposed to be. Nothing wrong with it, but for me it caused issues as I originally designed my controller mount around thru holes in the other adapter.

I am surprised about the threads. Maybe it shipped before I found the issue?

The 4 bolts to the motor are 3/8". Not sure what you mean about the smaller ones. I'll be working in Spain in a month and I think my connection goes through Frankfurt. I drop off some of those ye olde train bolts.

[marc02228]

Originally Posted by kerrymann

I think normally people reuse the pins from the motor. I had forgotten to remove mine before I sold it so I asked Steve for the dowel pins. They were back ordered from Mazda so they made me up a set. In fact I am not sure they ever charged me for them. The blind holes are the way the adapter was supposed to be. Nothing wrong with it, but for me it caused issues as I originally designed my controller mount around thru holes in the other adapter.

I am surprised about the threads. Maybe it shipped before I found the issue?

The 4 bolts to the motor are 3/8". Not sure what you mean about the smaller ones. I'll be working in Spain in a month and I think my connection goes through Frankfurt. I drop off some of those ye olde train bolts.

I don't know, I ordered the adapter at the end of June.
Ok, it's annoying, but not that bad. I just thought they would have changed the thread in the meantime.

There are the bolts for the hub: M12 x 20
the bolts for the motor: 3/8" x ? (I don't have my measurements here, right now)
then there are two kind of threads for the connection from the adapter plate to the gearbox.
3-4 smaller threaded holes and the other are larger threaded. What kind of threads are these?

What do you mean with your last sentence? I don't understand that one