algorithm for charge termination?
09-11-2005 | 07:15 PM
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algorithm for charge termination?
Is it possible to get the exact formula for various chargers that detect a voltage drop for termination of nimh and nicad?
I am curious as to the exact formula written out in text or numbers with the time and all the different numbers. Some I am curious about are triton,969,ice,elite
I am curious as to the exact formula written out in text or numbers with the time and all the different numbers. Some I am curious about are triton,969,ice,elite
02-20-2006 | 07:47 PM
#3
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RE: algorithm for charge termination?
You know it as the threshold voltage. Basically when the charge begins to drop 4 mv on NiMh or 10 mV on NiCd. so if a cell is fully charged at 1.35 volts per cell and then begins to drop beyound the threshold voltage is done! Which is why the Triton pauses every now and then.
John
EDIT -> I believe that the charging voltage is 1.42. 1.35 is fully charged at rest. It's also dependent upon temperature, but that's as far as I care to stick my neck out.
John
EDIT -> I believe that the charging voltage is 1.42. 1.35 is fully charged at rest. It's also dependent upon temperature, but that's as far as I care to stick my neck out.
02-20-2006 | 08:06 PM
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RE: algorithm for charge termination?
Yep, I kinda knew that much. It must be a bit more complex than that. There has to be a time figured in somehow. I am after the specific formula for a specific charger compared to some others. Maybe it is not as simple as I think,,,?
02-20-2006 | 08:14 PM
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RE: algorithm for charge termination?
No time. You're making it too complicated. There could be a temperature component but basically it's what you already know. When the voltage drops the pack is finished, and or if the temp of the pack is above 110 - 113 F it's done.
02-20-2006 | 08:19 PM
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RE: algorithm for charge termination?
I'd like to leave out the temp component and just figure out the peak detection . Some chargers (if it occurs slowly enough) will drop well over the setting for delta. I believe it has to be over a specified length of time. This is why I wanted to know the formula.
One example I can think of is the ice charger can see a drop of 1/2 volt very quickly yet still not terminate,,,,
Two different extremes , I suppose.
One example I can think of is the ice charger can see a drop of 1/2 volt very quickly yet still not terminate,,,,
Two different extremes , I suppose.
02-20-2006 | 08:27 PM
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RE: algorithm for charge termination?
Okay now for the heavy guns. http://www.maxim-ic.com/quick_view2...._pk/1666/ln/en
Read how Maxium uses their MAX713 IC to monitor NiCd charge. You really are making this a lot harder that it is. If you really need to see what's happening you need a scope. Your meter is too slow.
John
Read how Maxium uses their MAX713 IC to monitor NiCd charge. You really are making this a lot harder that it is. If you really need to see what's happening you need a scope. Your meter is too slow.
John
02-20-2006 | 08:42 PM
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RE: algorithm for charge termination?
I think that is it, I guess it is called "program structure" or maybe it is just called software. If I can understand it I would like the specifics on each charger. I do notice that the triton and digital piranha is very very similar. The mrc chargers are very similar to each other also and have a bunch of safeties built in. They will stop for a number of reasons: I , of course , want to know the exact formulas,,,
02-20-2006 | 08:49 PM
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RE: algorithm for charge termination?
I don't understand it all, but those maxim controllers sure remind me of the pulse chargers by duratrax. I think they may be as simple as you say in that any drop of the mv set-point will terminate charge. This is consistant with some of the intellipulse series.
02-20-2006 | 08:58 PM
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RE: algorithm for charge termination?
You could probably write your own software for the chargers. It sounds like fun. 
I am doing some reading on the maxim controllers and it seems to take a 5 ms sample of voltage then a timed interval between 21 and 168 seconds. It does the calculation to see if the voltage has dropped and then decide to keep chargeing or to stop. It does this repeatedly until the voltage drops. This is kinda what I am after for the different chargers. Something written out in text form or numeric form.
More research, thanks so far for help.
I am doing some reading on the maxim controllers and it seems to take a 5 ms sample of voltage then a timed interval between 21 and 168 seconds. It does the calculation to see if the voltage has dropped and then decide to keep chargeing or to stop. It does this repeatedly until the voltage drops. This is kinda what I am after for the different chargers. Something written out in text form or numeric form.More research, thanks so far for help.
02-20-2006 | 09:02 PM
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RE: algorithm for charge termination?
ORIGINAL: U-dUd
I don't understand it all, but those maxim controllers sure remind me of the pulse chargers by duratrax. I think they may be as simple as you say in that any drop of the mv set-point will terminate charge. This is consistant with some of the intellipulse series.
I don't understand it all, but those maxim controllers sure remind me of the pulse chargers by duratrax. I think they may be as simple as you say in that any drop of the mv set-point will terminate charge. This is consistant with some of the intellipulse series.
Lot's of different ways to achieve the same result. Hope you play with the PIC processors. You don't have to be a electrical wizard to program them. They are a lot of fun and you can put your ideas on charging algorithms to practice and then change it all be programming, after you have a series pass FET or transistor to regulate the current.John
EDIT -> It's my bedtime so I'll see you in the morning if you have more questions.
02-21-2006 | 12:12 PM
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RE: algorithm for charge termination?
ORIGINAL: U-dUd
You could probably write your own software for the chargers. It sounds like fun.I am doing some reading on the maxim controllers and it seems to take a 5 ms sample of voltage then a timed interval between 21 and 168 seconds. It does the calculation to see if the voltage has dropped and then decide to keep chargeing or to stop. It does this repeatedly until the voltage drops. This is kinda what I am after for the different chargers. Something written out in text form or numeric form.
More research, thanks so far for help.
You could probably write your own software for the chargers. It sounds like fun.
I am doing some reading on the maxim controllers and it seems to take a 5 ms sample of voltage then a timed interval between 21 and 168 seconds. It does the calculation to see if the voltage has dropped and then decide to keep chargeing or to stop. It does this repeatedly until the voltage drops. This is kinda what I am after for the different chargers. Something written out in text form or numeric form.More research, thanks so far for help.
That means those charge and discharge curves are done at different temperatures at different charge currents etc etc. Then you write the program that best fits your favorite curve. If like many of us after weeks for charting the chemical make up is understood and the point of chemical change in the battery is clearer than mud [:@] Do some and you become enlighten.
Rich
02-21-2006 | 12:50 PM
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RE: algorithm for charge termination?
Richard,
The really nice thing is that we are not dealing with RF generated noise. If U-dUd keeps to a linear model he will not have to either. Sanyo provides lots of charge and discharge graphs for each of their cells. Have you played with the PIC processors? I'm not saying that circuit layout is not critical at times but it is a lot less than I expected after dealing with dedicated embedded PC's of the early 90's. Lot's of manufactured experimental boards are out there with an area for analog breadboarding with the PIC area already fully debugged and assembled.
One other point power supply design can be a real ***** because you don't know if the load is reactive or inductive in nature. Designing a NiCd or a NiMh charger is simply a lot easier because you know exactly what the load is and your can use a proven power supply to power it. The other simplifying factor is the environment these chargers operate in is not an industrial one with lots of dirty AC but one in a residential setting.
John
The really nice thing is that we are not dealing with RF generated noise. If U-dUd keeps to a linear model he will not have to either. Sanyo provides lots of charge and discharge graphs for each of their cells. Have you played with the PIC processors? I'm not saying that circuit layout is not critical at times but it is a lot less than I expected after dealing with dedicated embedded PC's of the early 90's. Lot's of manufactured experimental boards are out there with an area for analog breadboarding with the PIC area already fully debugged and assembled.
One other point power supply design can be a real ***** because you don't know if the load is reactive or inductive in nature. Designing a NiCd or a NiMh charger is simply a lot easier because you know exactly what the load is and your can use a proven power supply to power it. The other simplifying factor is the environment these chargers operate in is not an industrial one with lots of dirty AC but one in a residential setting.
John
02-21-2006 | 05:03 PM
#17
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RE: algorithm for charge termination?
There are many variables, even on the same battery you can get different results at different times because of charge rate, how fast it was discharged the last time it was used, temperature etc. The reason for the measured voltage change is mostly because of the change of internal resistance as the battery reaches full charge and the oxygen starts recombining at the positive terminal. This is accompanied by an increase in internal temperature which changes the internal resistance even more. The size of the crystals formed inside the battery also effect it and they change with how the battery was used, how deep it was discharged and just pure age. I do not think it is possable to write an algorithm or program which will accomodate all these factors.
02-22-2006 | 09:06 AM
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RE: algorithm for charge termination?
ORIGINAL: JNorton
Richard,
The really nice thing is that we are not dealing with RF generated noise. If U-dUd keeps to a linear model he will not have to either. Sanyo provides lots of charge and discharge graphs for each of their cells. Have you played with the PIC processors? I'm not saying that circuit layout is not critical at times but it is a lot less than I expected after dealing with dedicated embedded PC's of the early 90's. Lot's of manufactured experimental boards are out there with an area for analog breadboarding with the PIC area already fully debugged and assembled.
One other point power supply design can be a real ***** because you don't know if the load is reactive or inductive in nature. Designing a NiCd or a NiMh charger is simply a lot easier because you know exactly what the load is and your can use a proven power supply to power it. The other simplifying factor is the environment these chargers operate in is not an industrial one with lots of dirty AC but one in a residential setting.
John
Richard,
The really nice thing is that we are not dealing with RF generated noise. If U-dUd keeps to a linear model he will not have to either. Sanyo provides lots of charge and discharge graphs for each of their cells. Have you played with the PIC processors? I'm not saying that circuit layout is not critical at times but it is a lot less than I expected after dealing with dedicated embedded PC's of the early 90's. Lot's of manufactured experimental boards are out there with an area for analog breadboarding with the PIC area already fully debugged and assembled.
One other point power supply design can be a real ***** because you don't know if the load is reactive or inductive in nature. Designing a NiCd or a NiMh charger is simply a lot easier because you know exactly what the load is and your can use a proven power supply to power it. The other simplifying factor is the environment these chargers operate in is not an industrial one with lots of dirty AC but one in a residential setting.
John
No John never actually designed using a PIC all have been 68HC11, 8051 and INTEL 16 bit machines. I still teach and our program is 68HC11 in our micro term. The 48V SCR 200amp had a full microprocessor 8085 with 10bit A/D PWM modulation on a star with a inter phase tee. I know when someone talks about phase stability they have been their. But CPU control has two pole due the PS is typically separate. Today’s microcontroller have PWM timers so can to do it all, can get to a single pole shift. The real problem is the predictability of charge if I were to design a termination circuit (instead of plane building
) I’d ingrain a curve projection by using the battery input table therefore knowing capacity an charge rate pin point a spot on the curve an predict the delta rate change before the actual peak voltage. Problem is I used to get paid to think and had a R&D dept build it for me HEE HEERich
02-22-2006 | 09:16 AM
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RE: algorithm for charge termination?
I’d ingrain a curve projection by using the battery input table therefore knowing capacity an charge rate pin point a spot on the curve an predict the delta rate change before the actual peak voltage.
Problem is I used to get paid to think and had a R&D dept build it for me HEE HEE
John
02-22-2006 | 01:47 PM
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RE: algorithm for charge termination?
I like that idea you'd need a fudge factor "hysteresis", but then you'd have to input battery type and many people would balk at that being too complex. Look at the brew ha haw over VCRs. I never had one I couldn't program if I sat down and read the owners manual.
Ya but it would make it idiot proof after one input, only if the battery makers would really tell you what you bought. But theirs only a hand full of us that can read…. A manual. I know when I got the ICE my wifey thought I found another women as I spent to much time with playing with it. On the doing part it’s become more difficult at home to do what I want, I’ll still build a little switcher or linear but to do what I use to it’s not worth the time and I don’t need to prove anything to me that I still can. As we said in another post I’ am trying to keep the Wal-Mart economy low, just use my ideas to fix things now.
Rich
Ya but it would make it idiot proof after one input, only if the battery makers would really tell you what you bought. But theirs only a hand full of us that can read…
. A manual. I know when I got the ICE my wifey thought I found another women as I spent to much time with playing with it. On the doing part it’s become more difficult at home to do what I want, I’ll still build a little switcher or linear but to do what I use to it’s not worth the time and I don’t need to prove anything to me that I still can. As we said in another post I’ am trying to keep the Wal-Mart economy low, just use my ideas to fix things now.Rich
02-22-2006 | 04:57 PM
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RE: algorithm for charge termination?
As we said in another post I’ am trying to keep the Wal-Mart economy low, just use my ideas to fix things now.
Rich
Rich
This is one hobby where I can spend money like water. I might not be contributing to Walmart's economy but me and the hobby shops sure have a good economic boost going! Unfortunately it seems to be only one way from my pocket to theirs.
John
08-04-2006 | 06:13 PM
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RE: algorithm for charge termination?
This is kinda what I was looking for , only for the intellipulse chargers, triton, elite, and ice.
http://patft.uspto.gov/netacgi/nph-P...&RS=PN/6218808
http://patft.uspto.gov/netacgi/nph-P...&RS=PN/6218808
08-04-2006 | 08:44 PM
#24
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RE: algorithm for charge termination?
Perhaps the problem was in communication or definition of the term algorithm which is a mathematical formula to achieve a desired result. I saw a process in the patent application not an alogorithm.
If you really want to have fun doing this use a PIC processor and program your parameters. You can program them in basic which is fairly easy to do. There are some new inline battery monitors that have the capability to dump memory into a serial port for monitoring purposes. For myself I'd use at least a 16 bit AD convertor at a fairly low speed 500 KHz monitoring both current and voltage and cell temperature. It's great you can by MB worth of memory for so cheap. You can store more information on a memory stick than I had in total on my first four computer hard drives.
Later,
John
I saw a process in the patent application not an alogorithm.If you really want to have fun doing this use a PIC processor and program your parameters. You can program them in basic which is fairly easy to do. There are some new inline battery monitors that have the capability to dump memory into a serial port for monitoring purposes. For myself I'd use at least a 16 bit AD convertor at a fairly low speed 500 KHz monitoring both current and voltage and cell temperature. It's great you can by MB worth of memory for so cheap. You can store more information on a memory stick than I had in total on my first four computer hard drives.
Later,
John
08-07-2006 | 07:48 AM
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RE: algorithm for charge termination?
Wow I’ am impressed U-dud that’s a good read but more BS than I’d care to admit. In today’s structure one must submit theses to maintain a status of doing a good job. We had to publish two a year a boy did that become a stress factor. I still get the craps just thinking about it. Hee Hee. Try to remember that there is two different subjects one is in the doing “microprocessor getting good data” and second what to do with it airgo the algorithm. That is that no two manufactured batteries will behave the same over their useful life so it just gets watered down to what just works. Peak voltage… delay check again if less than peak xx volts stop.
Rich
Rich
