Programming the KT controller - Configuring P5 parameter

-

P5 is the customizing parameter for the battery gauge.  It is described as a limiter to reduce excessive fluctuations in the meter during throttle use but it is also used to determine when the display should show the relative depletion of the battery. I personally want 1 bar (value of U in formula below) to tell me that the battery is close to dead because some semblance of actual battery voltage would be nice to know when I'm 15 miles from home. The KT LCDs are supposed to detect battery voltage and determine the base voltage of the pack but at certain voltages, it's possible that it can get confused and think it's seeing a fully charged 36v pack when it's really a nearly depleted 48V or 52V pack. Leaving P5 at 0 just leaves the meter reading at the mercy of the display logic and will probably be OK over time if it can figure out and remember the pack's voltage.

There is a formula that can be used to configure P5 and it incorporates the low voltage configuration in parameter C12


U = (Voltage value from C12) + (P5 / 3.77)


C12 determines the minimum voltage for the battery pack and is customizable (from 2V less to 1.5V more) but is dependent on the smart display's ability to determine the base pack voltage.  It has the following possible values

0= Default value-2V
1= Default value-1.5V
2= Default value-1V
3= Default value-0.5V
4= Default value 30V for 36 V battery, Default value 40V for 48V battery (and 45V for 52V battery ?).
5=Default value+0.5V
6=Default value+1V
7=Default value+1.5V

there is no documentation around the default value for 52V batteries but it should be ~42V.  Since there is nothing that specifies 52V support we'll need to assume that the smart display will default to 40V for the default voltage so C12 needs to be set for 7 (minimum pack voltage of 40+1.5 = 41.5V or 45V if the display can successfully detect 52V).

7 Seems like a nice conservative value to set as minimum voltage to avoid stressing the battery pack with excessively low voltage drawdown.

<pure speculation>
I suspect removing the battery or powering down the battery will cause the smart display to have trouble determining the base battery pack voltage.  

For example, if I plug in a 58V battery pack, it can figure out that it's a 52v pack, but if I run the pack down to 54V and then unplug it and replug it (without charging first) will result in the display thinking it's looking at a fully charged 48V pack.
<\pure speculation>


For consistent results, it's probably best to only plug a fully charged pack to avoid any confusion for the smart display. 

Comments

Post a Comment

Popular posts from this blog

My experience converting an e-Bike

-
Image
I purchased a decent inexpensive "Nashbar Flat Bar Road Bike" ~$230 from Bike Nashbar back in April 2017 and rode it twice over the next 2 or 3 years. Life got in the way, I became even more sedentary.  With just a few months to go before I retire, I decided it was time to get back on the bike and spend my days being active walking and biking. Thinking that an eBike could help me up the hills, I figured I could probably get some more seat time for more exercise.  I found this reasonably priced kit on Walmart.com to convert my regular hybrid bike to an ebike for as little money as possible.  A new project with new stuff to learn will be a good time.   After looking at tons of options on Amazon and Walmart and trying to figure out if I should purchase a 48v or 36v motor, I decided to go small for my first project because lower voltage would mean fewer batteries, lighter weight and lower overall cost. I didn't want a front wheel drive bike though it might be slightly ea...
Read more

So you're about to start a new Job? (navigating the benefits enrollment process)

-
Image
My daughter recently graduated and started her first job out of school and I thought some of the things we helped her figure out during her first week of work would be helpful for other young professionals who are venturing out into their first step into adulting. Most kids coming out of college have grown used to living on the bare minimum and should leverage that minimalist life style to great advantage.  My daughter once mused to herself that if she could live on less than $500 per month while going to school, what was she going to do with $2,500 a month? Save! was my simple answer.  Your future self will thank your younger self, even if you don't see or understand why today. Life Rule #1: The earlier you start saving and investing, the more money you'll have when you are ready to retire. If you started saving your summer job money and didn't use any of it for college, it's a great head start, but you're not done yet! It's important to get enrol...
Read more