Graphing ideas

G3CWI

Veteran
Location
Macclesfield
I have been recording the charge times for my Orbea Gain. I now have a short list something along the lines of:

23%-76% 63 mins
35%-82% 72 mins
15%-95% 142 mins

(not real figures above).

I want to put these into some simple format so that I can measure the current charge % and predict how long it will take to reach some higher amount (maybe 80%). However, I cannot think of a good way of doing this. Any clever ideas that dont involve 3d graphs?
 

MartinQ

Veteran
I have been recording the charge times for my Orbea Gain. I now have a short list something along the lines of:

23%-76% 63 mins
35%-82% 72 mins
15%-95% 142 mins

(not real figures above).

I want to put these into some simple format so that I can measure the current charge % and predict how long it will take to reach some higher amount (maybe 80%). However, I cannot think of a good way of doing this. Any clever ideas that dont involve 3d graphs?
Argh ... edited to remove my lack of understanding ...

The time charge relationship is a curve (exponential?), rather than a straight line, so you want to use the difference data (difference in charge and time) to construct a time charge graph from which you can read off the differenced data. The problem is that to "plot" the curve from the differenced data, you'd need an estimate of the starting charge time 0->?. The only way of doing this that comes to mind is if you assume some from of exponential model (or similar) and so this could be estimated at the same time as doing the fit of the differenced data. Not a trivial problem, but could be done with a bit of excel hacking
https://web.nmsu.edu/~snsm/classes/chem435/Assignment/fitting.html
 
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A rudimentary approach would be just to log charge state from 0% to 100% in 5-10 minute intervals (more often if you can bear it) and plot charge % by time on a XY scatter graph, time would have to be linear to be any use. Then you just subtract present charge % from the desired charge %, and you can eyeball your approx charge time.

Or if you can assess time between each percentage increase, 1 through 100, you could create vlooup in excel that would give you your time by entering your desired figures in a table. The hard part is getting the charge times which may well be unique to your battery and charger combo.

Downside of both these approaches is, you're going to be sat with your battery for a few hours, so better have a few beers and a good book handy... or set up some timelapse photography? :okay:
 
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YukonBoy

The Monch
Location
Inside my skull
Assuming battery is lithium ion there will be a constant current charge state which will be between 0.5 and 0.8 of the discharge rate of the battery. Then a second stage when the cells approach 4.2V which is called the saturation charge. Note these will change as the battery ages and eventually dies, then time to get remove current battery and get new battery for you bike.

To prolong battery life do not fully charge unless you need every last drop of energy for your ride. The higher voltages of a full charge stress the battery cells much more.
 
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