# Headway 40160 Opinions



## MN Driver (Sep 29, 2009)

You should add more details about your conversion. What vehicle, weight(stock, current, or whatever you have), which Optima batteries you have now, etc? This will save others from trying to piece it together from your previous posts, either that or link an EValbum or garage page with those details might be easier.

Putting 32kwh into pretty much any car should give very respectable range, around 100 miles(with a little padding) for a car that does 250wh/mile. I'm not sure what you car does now with the lead-acid or will do with lithium though. Unless you need extreme amperage, heavy hill climbing, extremely high ambients(location?), or highway use with an aerodynamically challenged car I have a feeling the Headways won't need any other ventilation other than free air exposure. Then again I'm not too familiar with the Headway cells so I'm shooting at the hip here but please add more details about your conversion, driving style, location, and especially vehicle and motor/controller specifics.

Any way you cut it, if you are replacing the rough volume of a lead-acid Optima with Headway cells, once you've finished the Headway build which I expect to be a bit tedious with that many cells, you should end up with a far better performing car with much more range and far better performance(of course limited to motor/controller too).


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## frodus (Apr 12, 2008)

Headways shouldn't be "free air", these batteries (along with other cylindricals) are not designed to be in the elements....


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## MN Driver (Sep 29, 2009)

yeah, I didn't mean it that way. Not free air as in under the car or anything but in the car but not enclosed in an air sealed box. On second thought even prismatics are placed in boxes with little ventilation but it really depends on the power requirements versus pack size though for cooling requirements. A rally car of some type that runs fast enough to need a beefy motor is going to need more attention than a lightweight aero commuter.


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## Yabert (Feb 7, 2010)

Brute Force said:


> I'm looking at upgrading from my Optima Yellow Tops to Lithium power. A little research and some napkin drawings have brought me the Headway 40160


I just build an Headway battery pack for my Smart Fortwo and I have few questions for you:

-Why pay 25% more for same capacity?
-Why pay more for same peak power? (and maybe less power capability).
-Why pay more for only 5-10% less weight (without counting the extra bus bars need)?
-Are you ready to manage 2000-3000 parts? Really..
-Why choose to manage 6-10 times more connections/faults chance?

The only variable I don't know is the space/form factor and without this information, I suggest at 100% to you to go with Calb cells.


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## Brute Force (Aug 28, 2010)

My EV is more of a build than a conversion. And rally car is an accurate description. The aerodynamics will be pretty good once I get the bodywork attached (Lamborghini Diablo replica).

I'll be replacing the 21 Optima D34 Yellow tops with a roughly equivalent volume of lithium cells. The battery pack is three modules that are easily swapped out from under the car. The new modules will be closed to the elements, but have duct work for clean dry forced ventilation.

I'm keenly interested in feedback from anyone who has used Headways. I've read the posts discussing corrosion problems and DOA cells. My understanding is these were production start up issues that appear to have been addressed. Are they shipping a mature, robust product these days?


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## Brute Force (Aug 28, 2010)

Hi Yabert,

What lead you to the Headways for your application?

The three battery modules are 7" wide by 8" tall by 71.5" long (each). Width I can fudge out to around 7.375", but length and height are set in stone.

The 4C discharge continuous discharge specification on the CALB cells is a non-starter. I need something that can hang in the fight for more than a burst.

Yeah, it's a LOT of parts to mess with. 630 cells. 42 buss bars. 1260 screws, with washers. But wait, there's more...


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## Yabert (Feb 7, 2010)

Hi

The energy density lead my choose. I can't put 48 Calb cells where I have put 48 (8p) headway 10Ah. But with another car, the thing was probably be different.



> The 4C discharge continuous discharge specification on the CALB cells is a non-starter. I need something that can hang in the fight for more than a burst.


Seriously??? You will need more than 170 hp from the cells continously? I think you miss something! You will probably don't hit over 4C for more than few second before you will reach an insane speed.... 

And especially with single speed ratio, the motor won't be able to eat a lot of Amps at high speed.
I saw the same phenomena with my motorcycle. During hard acceleration I hit 15-20C (30Ah pack) from the cells for 2-3 sec. but right after that, the current start to drop and I don't hit over 5C for more than 4-5 sec because after that I have reach over 50 mph.

Currently, I think the main problem with headway is the barely strong negative terminal (see my build thread).


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## jackbauer (Jan 12, 2008)

Well , I run a 48s4p pack of 40160 16ah headway cells. So far very happy with the performance. No bms so far. Did a bottom balance a few weeks back. Some of the earlier cells had serious safety issues with the positive end rupture disc. See some tests I performed here:
http://www.evbmw.com/headway.htm

Newer models seem very stable. There are some issues with off center drills etc. I only had one cell with a weak negative terminal out of 200 pieces.


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## Yabert (Feb 7, 2010)

Hi Jack

Do you have real information about those cells IR?

I ask because the <8mΩ who can find on this site sounded catastrophic to me.
And the ≤5mΩ I saw on the Headway cells specification sheet don't sound really good too compare to Calb cells impedance.


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## Brute Force (Aug 28, 2010)

A picture is worth a thousand words:

http://www.facebook.com/media/set/?...4006180078.735347.283142505077&type=1&theater

Yabert raises a good point. Do I really need more than 130kw continuous power? If this was a commuter vehicle, I'd have to admit the answer is no. In August I ran in the 80 MPH class in an Open Road Race. I plan to kick back up to the 100 MPH class if I can get things to hang together. That means I need to be able to charge hard out of the corners and hit 140 occasionally on the straights. That's takes a lot of average watts and some huge bursts heaped on top. It would be nice to have some margin instead to running the ragged edge.

It's not set in stone yet, and I appreciate the input.


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## alexcrouse (Mar 16, 2009)

Can i have your Optimas?


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## Duncan (Dec 8, 2008)

Hi Brute,

This is a competition car -right?

You don't need 100miles range - you need enough range to do the job and a battery that can deliver as much power as you can use
This is where the 10C and 15C outweigh the CALB 3C

You will need a 300Kg pack of CALB or a 100Kg pack of Headways - 
What will 200Kg less weight do for your performance?


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## drgrieve (Apr 14, 2011)

Sinopoly (ThunderSky) are 3C according to spec sheets. (Seems strange that all cells have the same rating though)

From the manufacturer spec sheets Calb 60 gives 600, 100 gives 800, and 130 and 180 give 1000 amps.

What would be the interesting fact to know, and I've tried asking several ev owners with not much success, is the expected real world voltage sag between different cells in a pack configuration in an actual running car. 

So far I've found that Calb 180 cells @ 1000 amp will drop from 3.3 to 2.6 volts and that headway 8ah cells in 12P @ 1000 amps will drop from 3.3 to 2.8 volts.

So that's 2 out of 20 different cells worked out.


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## Brute Force (Aug 28, 2010)

Silverstate is 90 miles one way, probably out of the question. Big Bend is 118 miles, half south, half north, might be possible if I swap in a fresh set of batteries at turn around. Sandhills is 55 miles, split in two legs, may be doable on one set of batteries depending on the speed class. Pikes Peak is only 12.5 miles, but has a 7% average grade and 156 turns.

Sandhills sapped the Optimas in just 10 miles. I need capacity.

More thoughts on kw. The 130kw at 4c is only valid when the batteries are still at the nominal 3.2 volts. By the time the cells reach the 2 volt cutoff, that power level will have dropped to 80kw. That's the part that catches my attention. If I can't maintain speed across the finish line, I don't get to the podium.


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## Yabert (Feb 7, 2010)

Duncan said:


> You will need a 300Kg pack of CALB or a 100Kg pack of Headways


 
Hummmm! A 100 kg of headway 40160?? It's not enough.

50S 4P = 160v 64Ah will give you only 87hp (manzanitamicro spec 0.008 ohm) and 130hp (headway spec 0.005 ohm) at 1000A discharge (15-16C)......
And 100S 2P will be worst.

100 Kg of 38120P 8Ah can be better (around 170 hp) but it's not that much!


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## Bowser330 (Jun 15, 2008)

you should also look into going over the 48cell limit since you are running soliton-1's....they can take up to 340V and can limit your motor voltage to whatever you want....

So if you let the sagged voltage determine the pack voltage, 160V/2.6V = 61cells...

Sagged: 160V [email protected]
Nominal:195V [email protected]
Charged:220V [email protected]

This way, even when the pack is sagged you can output 160kw (160V*1000A)

320kw total from both setups, 430hp!**

**if the pack can output 2000A and sag to 2.6V/cell


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## EVfun (Mar 14, 2010)

drgrieve said:


> What would be the interesting fact to know, and I've tried asking several ev owners with not much success, is the expected real world voltage sag between different cells in a pack configuration in an actual running car.
> 
> So far I've found that Calb 180 cells @ 1000 amp will drop from 3.3 to 2.6 volts and that headway 8ah cells in 12P @ 1000 amps will drop from 3.3 to 2.8 volts.


I have 60 amp hour Thunder Sky cells made in early 2010. They sag to 2.8 volts at 360 amps (6C discharge rate.)


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## DavidDymaxion (Dec 1, 2008)

EVfun: Great data point, thanks for posting.

For how long can they hold sagging to 2.8 V at 6 C? I had heard before the big cells typically can only do it for a small number of seconds, but the Headways can do it for most of the capacity (minutes at 6 C). How about for your cells? Thanks.


EVfun said:


> I have 60 amp hour Thunder Sky cells made in early 2010. They sag to 2.8 volts at 360 amps (6C discharge rate.)


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## rwaudio (May 22, 2008)

I would also like to know more about the sag and heat build up from prismatics.

Headway 38120S's (10ah) sag to 2.7x at ~12C (once they are warmed up) They get too hot to touch if you keep them at that discharge for more than a minute. A 10C discharge builds up a huge amount of heat and in open air I wouldn't consider this a safe continuous discharge let alone in pack with 100's of these little heaters in a confined space.

A123 20ah pouches sag to 2.95 at ~12C and only really builds up heat in one terminal that eventually spreads to the whole cell. (the headway may be like this too, and the hot terminal is the outside can) The cell never gets too hot to touch though and cools off 10x faster than a headway cell.

Does anyone know if the 40160 is better/worse than the 38120 as far as getting rid of heat?

Would prismatics be better if they weren't housed in a big plastic insulator?


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## Brute Force (Aug 28, 2010)

The current battery pack configuration under consideration is 78s8p. That way the pack voltage won't drop below 156 volts, even at full discharge cutoff voltage. More cells in series means more BMS modules to pay for and wire.


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## EVfun (Mar 14, 2010)

DavidDymaxion said:


> EVfun: Great data point, thanks for posting.
> 
> For how long can they hold sagging to 2.8 V at 6 C? I had heard before the big cells typically can only do it for a small number of seconds, but the Headways can do it for most of the capacity (minutes at 6 C). How about for your cells? Thanks.


Once you leave the test bench and hit the streets it becomes one of those things you cannot really test. I have full power from about 1800 to 3200 rpm (battery amps 360, motor amps declining from 720 to 360.) It doesn't stay in that window very long. I know that most of the drop is instant and then the pack voltage continues to drop, perhaps 0.1 volt per second (0.003 vpc per second.) I set my Zilla low battery voltage indicator to 89 volts (2.78 vpc) so if I hold my foot to the floor long enough on a freeway grade the light will come on.


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