Warp Factor II Battery Modules

[EVDragRacer]

[EVDragRacer]

[EVDragRacer]

[EVDragRacer]

[EVDragRacer]

[EVDragRacer]

Silver coated copper bus bars from Storm Copper.

[EVDragRacer]

[EVDragRacer]

[EVDragRacer]

[EVDragRacer]

First test for my 4000amp 425volt battery pack, along with two Evnetics Shiva 3000amp 425volt controllers.

[fechter]

Yeah baby, keep going
Those look like they should be able to put out some amps.

[mvly]

The batteries look like chocolate candy stack. mmmmm.

[EVDragRacer]

I am not here often, so I will add a few bits of info before I go.

Each 10P 28volt module weighs about 40lbs. A bit heavier that wanted, but worth it's weight in gold when you do not have to worry about bus bar resistance and heat. Our connection method with reduce heat and resistance, while making it fairly easy to remove a 10P pack at anytime in the car without removing the pack.

The whole pack weighs around 600lbs, we have replaced the older Camaro body with a 2012 Camaro body made from fiberglass, so, the added pack weight will not make much of a difference. We estimate the car will weigh 2300lbs compared to 2650lbs last year. We will have 3000amps to launch with if we want, we will start at 2000amps and work up slowly monitoring motor temps. We have geared the car for a top speed of 170mph in the 1/4 mile, 3.25 in the rear and two GearVendors overdrives to utilize the enormous amounts of torque we have available.

[EVDragRacer]

One last thing, the red stuff is high temp silicone. I used the silicone for two reasons, one two add flexable support to the upper cell and tab structure, the other is to seal the folded aluminum wrap down away from the tabs. After doing QC on over 1000 cells I noticed some tabs were very close of not touching the cut pouch end, this conducts juice and fill short out a cell if touches the tab. I folded the tab upper edges when needed to prevent this from happening, seems on some cells the glue sealant was too low and on others the tab was sitting a little crooked. Most of the cells were just fine.

[miro13car]

Where your A123 cells came from?

[Hillhater]

doesnt your "bus bar" clamping system result in you having over 1000 clamped connections in series to achieve 425v ?

[EVDragRacer]

doesnt your "bus bar" clamping system result in you having over 1000 clamped connections in series to achieve 425v ?

The specs:

106 series connection bus bars.
848 parallel connection bus bars.

The parallel bus bars are bolted together on the first level, the series connections extend above the first top layer of lexan. Did you not see the pictures?
This is the most secure way to deliver 4000BA without overheating the tabs.

A123 has a 50 million dollar recall because their welding machine did not properly connect the cells, all their modules shorted out! I will not have that problem.

[999zip999]

Thanks for the pics. Looks good. Clean.

[Hillhater]

Yes Ron, i saw the pictures,..thats when i realised what you had done with your "parallel" modules.
Its just that your "Bus Bars" in each parallel pack are not actually continuous bars, but a sandwich of ten tabs and ten / eleven spacers. Each side of every tab is a "working" contact face, so each pack has 40 contact faces ( 10 +ve and 10-ve tabs) each of which will be carrying your full 2000+ Amp load. It just seems you have a lot of extra joints carrying full load current.
( 40 per pack x 106 packs = 4240 EXTRA connections ! )
...Ron, what happens if ONE of those contact faces "drys" out and goes OC. ?

[EVDragRacer]

Yes Ron, i saw the pictures,..thats when i realised what you had done with your "parallel" modules.
Its just that your "Bus Bars" in each parallel pack are not actually continuous bars, but a sandwich of ten tabs and ten / eleven spacers. Each side of every tab is a "working" contact face, so each pack has 40 contact faces ( 10 +ve and 10-ve tabs) each of which will be carrying your full 2000+ Amp load. It just seems you have a lot of extra joints carrying full load current.
( 40 per pack x 106 packs = 4240 EXTRA connections ! )
...Ron, what happens if ONE of those contact faces "drys" out and goes OC. ?

If we are to have a contact "drys" the BMS will pick-up the problem and we will replace the 10P pack. I do not think my connection method is overkill, I matter a fact I know it is a must to carry 4000+ amps safely.

Do you think crunching tabs together is a better solution? Less meat = more heat!

Ask A123 about there 55Million dollar mistake welding tabs together.

[fechter]

I've always found bolted connections to be quite reliable if properly done. The ability to repair them later is also an excellent feature. Some anti-oxidant grease might help them last longer (but in a drag racer, that probably doesn't matter much). Solid copper seems like overkill, but less resistance is better. Aluminum would be much lighter. One of the real engineer types could do the math on it to see how much more loss there would be with aluminum. Aluminum does tend to corrode and make crappy connections over time.

[Hillhater]

Ron, are you really going to install a BMS that monitors every one of your 1000+ cells individually ?
.... when they are paralleled in packs of 10 ??
I suspect the first indication of a dry joint will be a blown module from 2000+A all going through one or two cells in a pack.

We all need and use bolted connectors , ( much better than bullets etc) ....but every joint is a possible failure ( especially at 2000+ A ) and can be managed since usually those bolts are simply clamping 2 contact faces together.
But this design has resulted in an extra 4000+ bolted contact joints, with 20 contact faces per bolt, most of which are carrying the full load 2000A current !
A single , unitary ( solid) bus bar for each pack of 10 tabs would avoid that situation.

[Arlo1]

I am not here often, so I will add a few bits of info before I go.

Each 10P 28volt module weighs about 40lbs. A bit heavier that wanted, but worth it's weight in gold when you do not have to worry about bus bar resistance and heat. Our connection method with reduce heat and resistance, while making it fairly easy to remove a 10P pack at anytime in the car without removing the pack.

The whole pack weighs around 600lbs, we have replaced the older Camaro body with a 2012 Camaro body made from fiberglass, so, the added pack weight will not make much of a difference. We estimate the car will weigh 2300lbs compared to 2650lbs last year. We will have 3000amps to launch with if we want, we will start at 2000amps and work up slowly monitoring motor temps. We have geared the car for a top speed of 170mph in the 1/4 mile, 3.25 in the rear and two GearVendors overdrives to utilize the enormous amounts of torque we have available.

So whens the first run im holding my breath! Very exciting!

[EVDragRacer]

Ron, are you really going to install a BMS that monitors every one of your 1000+ cells individually ?
.... when they are paralleled in packs of 10 ??
I suspect the first indication of a dry joint will be a blown module from 2000+A all going through one or two cells in a pack.

We all need and use bolted connectors , ( much better than bullets etc) ....but every joint is a possible failure ( especially at 2000+ A ) and can be managed since usually those bolts are simply clamping 2 contact faces together.
But this design has resulted in an extra 4000+ bolted contact joints, with 20 contact faces per bolt, most of which are carrying the full load 2000A current !
A single , unitary ( solid) bus bar for each pack of 10 tabs would avoid that situation.

Each 10P cell pack will require a BMS board. Not worried about my connections, very confident in design. Better than welding, ask A123.

[EVDragRacer]

I've always found bolted connections to be quite reliable if properly done. The ability to repair them later is also an excellent feature. Some anti-oxidant grease might help them last longer (but in a drag racer, that probably doesn't matter much). Solid copper seems like overkill, but less resistance is better. Aluminum would be much lighter. One of the real engineer types could do the math on it to see how much more loss there would be with aluminum. Aluminum does tend to corrode and make crappy connections over time.

I did many weeks of research on the best aluminum for the bus bars, had Luke give me some great info. The lowest resistance aluminum can not be bought in bus bars, could not even find it in USA, after running the resistance numbers with heat build-up, copper was my choice. Silver coating was also a must. All the work was done at Storm Copper in Tenn.