# Winston LYP Batteries?



## Erobison (Sep 14, 2012)

Does anyone have any experience with the Winston LYP batteries found on the Kostov website here:

http://kostov-motors.com/tractionmo...c-dc)/lithiumbatteriesbmsandchargers/lyp60ah/

I'm after about a 12-20 kWh pack depending on the voltage requirements of my project (still in the very beginning prelim. design stages) and these look like the solution. These batteries list a maximum discharge rate of <20C; compared that to the HiPower 60Ah cells at 480A (8C) and the CALB 70 Ah at 700A (10C).

Are these cells really any different from other Li batteries, or are they just a more ballsy with their spec sheets? I'd like to have something that can dish out 900 or 1000A into a Soliton 1 and these seem like the ticket. 

I'd be interested in everyone's thoughts.


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## rwaudio (May 22, 2008)

Erobison said:


> Does anyone have any experience with the Winston LYP batteries found on the Kostov website here:
> 
> http://kostov-motors.com/tractionmo...c-dc)/lithiumbatteriesbmsandchargers/lyp60ah/
> 
> ...


Based on some recent testing that people have done it appears that the CALB CA (grey) cells are the best cell in terms of low sag for high C rates like that. They are however new cells so there is no long term data on them. I have a pair of CA 60's that are going to go in series with my A123's for testing. Hopefully they perform well!


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## EVfun (Mar 14, 2010)

I have the parent to them, from before Thunder Sky split into Sinopoly and Winston. I have February 2010 Thunder Sky cells labeled LFP but came with a spec sheet as LiFeYPO4 cells (notice the Yttrium.)

They can manage 6C discharge rate in the summer and a 5C rate in the winter with the cells staying over 2.7 volts until quite low on charge. I'm using 60 amp hour cells so I'm looking at 360 amps summer and 300 amps winter. For short impulse current I don't doubt 10C, but you have to consider the rest of the system. I set my controller to cut back at 2.5 vpc (95 volts for a 38 cell pack) so finding out what I can do for a few seconds doesn't help much, I can't really leave it that way without giving up the low voltage protection the controller can give the pack. 

I bet the new CALB CA cells would do even better but don't really know. I saw Jack do a test, but the cell tested was just over 100 degrees Fahrenheit fresh off a fast charge when he did it. Also, it was a 40 amp hour cell and it has been common to find that smaller capacity cells can sustain a higher C-rate discharge for a given amount of voltage sag.

If the Winston LYP cells are like the late Thunder Sky LYP cells I would be inclined to use them, especially if they are available for a buck and amp hour. I'd like a pack of 45, 100 amp hour cells, but my pack of 38, 60 amp hour cells have a lot of life in them. I don't see any degradation in performance yet.


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## Erobison (Sep 14, 2012)

rwaudio:

Is the sag a function of the batteries internal resistance, or of the rate at which the chemical reaction inside the batteries can take place, or a little of both?

EVfun:

The car I'm planning would be a performance oriented commuter, as much as that sounds like an oxymoron. During my daily commute It would probably only see pulse discharge rates a couple or 3 times each having a duration of probably <5 seconds. I'm not going to be taking it to the race track or anything but I would like to be able to put a hurting on some unsuspecting mustang/camaro/etc. drivers when the opportunity presented itself...

That being said is it reasonable for me to hope for 15C discharge rates with Li batteries, even if only for a few seconds, or is that too ambitious?


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## rwaudio (May 22, 2008)

Erobison said:


> rwaudio:
> 
> Is the sag a function of the batteries internal resistance, or of the rate at which the chemical reaction inside the batteries can take place, or a little of both?
> 
> ...


The cells don't have an "internal resistance" the way we traditionally think of it, there is an apparent or equivalent series resistance that relates to the chemical properties of the cell. However the lower that "internal resistance" the less heat that is created and the higher the output voltage and more usable power from the battery system.


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## Erobison (Sep 14, 2012)

Sure, I'd buy that. So can the sag still be calculated using v=i*r using the internal resistance listed in the battery spec sheets?


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## Siwastaja (Aug 1, 2012)

Internal resistance is just a _model_, not a real physical feature. Of course part of it is simple electrical resistance in conductors, contact etc., but the rest is chemistry. It also varies: higher temperature -> lower Ri; higher SoC -> lower Ri; cell ages with cycling -> Ri rises.

No, you cannot use the spec sheet Ri to define the voltage sag. They typically report a high-frequency resistance, which is a completely useless number for any purpose (it's just easier to measure and gives better numbers). But look at the discharge curves, they tell you what you need directly. Of course given that they are the real results from real tests. This is always the problem with any Chinese products; they may be or may not.


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## EVfun (Mar 14, 2010)

Erobison said:


> EVfun:
> 
> The car I'm planning would be a performance oriented commuter, as much as that sounds like an oxymoron. During my daily commute It would probably only see pulse discharge rates a couple or 3 times each having a duration of probably <5 seconds. I'm not going to be taking it to the race track or anything but I would like to be able to put a hurting on some unsuspecting mustang/camaro/etc. drivers when the opportunity presented itself...
> 
> That being said is it reasonable for me to hope for 15C discharge rates with Li batteries, even if only for a few seconds, or is that too ambitious?


I don't think Winston cells will do well with 15C discharge rates, even for a few seconds. I don't think it would cause any noticeable damage, but would expect the voltage would drop under 2 volts when the load hit. That kind of sag would limit motor rpm unless you have a high voltage pack. Perhaps the CALB CA cells would be better, but I've only seen limited independent testing so far (just now getting into the first few EV conversions.)

It seems really unlikely you would need more than 1000 battery amps on the street. Even with a Shiva or Zilla Z2k you wouldn't need the battery amps turned up higher to blow the doors off someone at a traffic light (unless you have a low voltage conversion.)


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## Erobison (Sep 14, 2012)

Whether I _need_ 1000A is something I'm not sure of yet; still working on performance estimates so we'll see. 

I see what you mean about the voltage sag though, and thanks for your and everyone else input..


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## Ampster (Oct 6, 2012)

Also see this discussion.

http://www.diyelectriccar.com/forum...-winston-thundersky-batteries-1-ah-75023.html


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## Erobison (Sep 14, 2012)

Yea I've been looking at that one as well. Good info.


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