"known to work" controllers with Rshunt values for the CA

[tron]

Just like Fechter's motor/controller post I decided to create a new post for submissions of Rshunt values for different controllers and Cycle Analyst either Direct Plug in or stand alone. I'm still sorting my new build out so I don't have a submission myself but thought it would be a good idea to organize this info in a post. Hopefully this will turn into a list that can be used by anyone.
So, send 'em in guys!!!

 

[Ypedal]

Depends on how accurate you want to be but i've found that there are very small differences from individual controllers of the same brand.. i adjust mine by using an inline CA along with the Integrated one, run around the block , record AH used and adjust the integrated until i get both meters to match ! :wink:

 

[Anonymous]

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[tron]

Arrg,
Well, live and learn. I was hoping this would be easy. Thanks for setting me straight guys! I'm learning lots, and its the fun that counts. I guess we can close this topic now.

 

[Anonymous]

.

 

[kriskros]

i have a 36v 20amp infineon set to 4.5 CA [ d irect plug in] says .98 amp no load.... dont know if this is any help

 

[Anonymous]

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[boostjuice]

The Cyclone 48V 1000W external controller has an onboard 15milliohm total parallel set of shunt resistors (1% tolerance). Out of range of the cycleanalyst (9.99milliohm max) and overly high (wasteful of power). God knows why they designed it with such a high shunt value. I had to use the supplied 45A shunt. Oh well, another 1.5milliohms on top of the controller shunt is only 10% extra power loss

 

[tron]

nutsandvolts wrote: Thinking on this further I guess it wouldn't be a bad idea to post rshunt values because it could at least get people into a same range if their calibration is way off.

So my post may still have life! This would be a great starting point for people that haven't gotten past the CA instructions. This seems to have been a sticking point for many forum members.I guess it's not a total solution for calibration but an easier way may come out of all this. My Rshunt values were way off and for others this may be the case. A list of values for given controllers would be a good starting point. I realize Justin can't have every CA calibrated for every controller leaving the shop especially for controllers he doesn't sell or service (that wouldn't be feasible) but an average Rshunt value for a given setup would be alright. This is were the forum members can step in.

 

[patrickza]

I had a thought last night. Does it really matter what your rshunt value is? If you have a 10ah battery pack, and your cycle analyst says you've used up 20ah when your bms cuts the power then you just correct it for next round. That way your CA will be "calibrated" to show 10ah when you're empty. Whether this is really 10ah or only 9.2 or 10.4 doesn't really matter, as long as it's consistent. What I'm keen to know is when will I have no more juice left, and how do my rides compare with each other.

Sure your wh/km reading will be off, but how much does that matter if you're only using the CA as a fuel guage.

I haven't tried this yet as my headway pack is still new so I don't want to run it to cutout, but I'm thinking I will when I've done a 20 odd cycles.

Thoughts?

 

[tron]

Aren't all the new Shenzhen controllers calibrated at 3.8 Mohms? Wouldn't this work, at least, for a starting point?

 

[Anonymous]

.

 

[patrickza]

I had a thought last night. Does it really matter what your rshunt value is? If you have a 10ah battery pack, and your cycle analyst says you've used up 20ah when your bms cuts the power then you just correct it for next round.

This assumes you're actually getting 20AH, which you're probably not. What you're saying would be good enough to know the difference between usable "full" and "empty" and be useful as a guide to how much power you have left, but definitely not a good way to calibrate for actual amp hours.

That way your CA will be "calibrated" to show 10ah when you're empty. Whether this is really 10ah or only 9.2 or 10.4 doesn't really matter, as long as it's consistent. What I'm keen to know is when will I have no more juice left, and how do my rides compare with each other. Sure your wh/km reading will be off, but how much does that matter if you're only using the CA as a fuel guage.

If you don't care if it's actual amp hours, but are more interested in just gauging how much capacity remaining relative to a fully charged pack, it's useful, but the accurate way is to have the amp measurement correct, or at least reasonably correct.

Yep all I really need is the full or empty but I had a chat with my uncle a few days ago. He has a clamp meter that will read up to about 40 amps, and a cycle trainer I can put the bike on to give it some resistance. Should work perfectly, and I'll be able to tell exactly how many AHs I'm getting out of my 10AH headway pack. Now all I need is a bike rack that will carry a 40kg bike!

 

[tron]

The new Infineon controllers shunt are now all a consistent at 3.8 mOHM . Does that mean I can program my CA's Rshunt value at 3.8 mOHM and voila? Will that put me in the ballpark?
I'm still looking for some insight with this post I made: http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=12181 Any help would be greatly appreciated. This stuff is driving me nuts. :x

 

[icecube57]

My 72v ecrazyman controller has a CA shunt value of 3.690m compared to my watts up meter its only off 0.05A per 5AH. It read high. I actually prefer it that way. I still use my watts up across my one of my 36v sub packs to have tandem readings.

 

[oatnet]

1.399 is the default value for the CA-SA with its own potted shunt. Just moved the shunt to a direct connect cycleanalyst and had to look it up.

-JD

 

[aaannndddyyy]

Just put my CA direct with a crystallite 35a 36-72v controller and a 5304 hub on the road, the way I calibrated the shunt value without meters ect.
I know my ping battery is 12 amps , so set the shunt value two 1000 mOhms then went out with a freshly charged battery ran down to cutoff CA reads 16amps used, quick math’s works out two 25% over, soo reset shunt two 1250 mOhms (25%) recharged battery went out ran two cutoff CA reads 12amps used, sorted I think unless any of the tec guys here can shoot this method down.

 

[tron]

I believe that you're not using all the amps/h in your Ping battery when you draw it down to the preset cut off. You'd have to use all of your battery's capacity to use all 12amps I believe. Hey I'm not a tech either, but I think that it's a little more complicated to calibrate the shunt value than that. As with Andy, can anyone correct me?

 

[oatnet]

You are correct tron. The bms hopefully will cutoff at least at 80% DOD. In addition, the discharge rate, pack balance, ambient temperature, battery quality, etc etc can all affect what you get out of the pack. You would do best to use published rshunt values for your controller. It won't be lab accurate, but given that the unpotted shunt in xlyte controllers changes resistance when the controller heats up, it is not a lab-accurate sensor you are reading anyhow.

-JD

 

[aaannndddyyy]

I am not a 100% shore but dod and rated capacity must be different,
I am talking about the batteries rated capacity, my 12A battery gives 12A not 80% or 10A
If a 20A battery only gave 16A (80%) before cutoff there would be a lot of unhappy epeople about.

 

[oatnet]

I am not a 100% shore but dod and rated capacity must be different, I am talking about the batteries rated capacity, my 12A battery gives 12A not 80% or 10A

You don't know you are getting 12ah since your rshunt value is not set correctly.

On the other hand, I am 100% sure (having bought/built dozens and dozens of packs over the past few years) that LiFe cells rated at 12ah will store 12ah to 100% DOD. Take a look a Doc's discharge curves for varieties of cells:
http://endless-sphere.com/forums/viewtopic.php?f=16&t=8926&p=138796&hilit=doc+headway+discharge+curve#p138758

I am also 100% sure that if you pull 12ah from 12ah cells every time you will vastly shorten their cycle life (a123's aside), which is why BMS's typically cutoff at 80% DOD (I shoot for 70% myself)

If a 20A battery only gave 16A (80%) before cutoff there would be a lot of unhappy epeople about.

Yes, newbies are frequently disappointed when they find that they can only pull 80% of their LiFe pack, just like they are frequently suprised that their 16 cell "48v" Life pack actually charges up to 58.4v. They are even more disappointed if they use Lead Acid, becuase that has a 50% DOD. But that is nothing, when I was a newbie in early 2007, I was disappointed when NIMH rated at 3.6ah only delivered 1.4 ah to 100% DOD. In those days, everyone expected the ah ratings to be ridiculously inflated, now we are overjoyed that they are reasonably close.

-JD

PS - since voltage varies with the rate of discharge, and decreases the more a battery is discharged, you will find that watt-hours (wh) is a more accurate measure than AH.