Ben, While the current throttle function is in the Elcon manual...... I have never seen it implemented in the software. I have extracted the code from a dozen or so of Elcon/TCCH chargers. If someone has one that does this I would like to get my hands on it to extract the code!
Sent from my iPad > On Jan 5, 2016, at 10:07 PM, Ben Apollonio via EV <[email protected]> wrote: > > Hi Jay, > > I think your approach is good. Some chargers (Elcon, at least) let your BMS > throttle charge current with an external voltage signal. If your charger > supports this, you could try wiring up a comparator and a flip-flop to latch > the signal at 0A when you hit your target voltage at 30A. > > Cheers > -Ben > >> On Jan 3, 2016, at 9:28 PM, Jay Summet via EV <[email protected]> wrote: >> >> I want to charge at maximum current to 80%, and then shut off. My thoughts >> on this subject are listed as text below, or you can follow this link to see >> the images of my charging profiles: >> >> http://www.summet.com/blog/2016/01/03/default-charging-profile-charge-to-80-capacity-quickly/ >> >> I welcome any comments about issues or tricks I may have overlooked. >> >> Thanks, >> Jay >> >> >> >> Because I have a relatively short commute, and rarely anticipate needing my >> full 100% pack capacity, I have chosen to charge my truck to an 80% SOC on a >> daily basis to maximize battery life. One nice thing about the 80% level is >> that most batteries can be charged at a relatively high rate of speed up to >> 80%, and then you need to slow down the charging a bit to prevent them from >> overheating. (This is why DC Quick Chargers will quickly bring an empty >> battery up to 80%, but then slow down quite a bit after that.) >> >> My first attempt at programming an 80% charging profile was very simple, >> just set MaxV to 128.5 and set the TermC (termination current) to 2 amps. >> This works well, it gets the pack voltage up to 128.5 volts and holds it >> there until the battery stops accepting much current. The only issue is that >> it is wasting time, because for a good amount of the charging period the >> current flowing into the battery is less than the maximum 30 amps (4.0 kW) >> that the chargers can produce. The charging curve looks like this: >> >> http://www.summet.com/blog/wp-content/uploads/2015/09/charging_2amp_cutoff.png >> >> >> >> In an effort to speed up my charging, I set the MaxV to a higher amount ( >> 128.9 volts) so that at the 128 volt level the battery pack would still be >> accepting a higher current, and then set my TermC to the highest level my >> EVCC allows (10 amps). This results in a charging curve that looks like the >> following: >> >> http://www.summet.com/blog/wp-content/uploads/2016/01/charging_10amp_cutoff.png >> >> >> As you can see, I spend more time delivering 30 amps before the current draw >> from the pack starts to drop off, and the curve reaches the cutoff point >> much quicker. My EVCC currently limits the TermC parameter to 10 amps or >> less, probably because they have not anticipated somebody trying to charge >> only to 80% as quickly as possible. >> >> If I could set the TermC parameter to 20 or 25 amps it would allow me to set >> the MaxV up higher (131?). The goal would be to find a voltage setting such >> that the pack would be drawing 20 or 25 amps right when it hit the 128.5 >> volt level. So my curve would basically be flat, full on charging at 30 amps >> up until the very end when it would start to taper off and the charging >> would end at 25 or 20 amps. >> I’m not worried about setting the MaxV higher than the actual voltage I’m >> attempting to hit, as it is still much lower than my pack’s actual max >> voltage, and if something were to change with the pack chemistry making it >> miss the TermC cutoff, the MaxV would still stop the pack from reaching 100% >> charged. (and the termination timeout would eventually hit.) >> >> This is the end of my main thought, but you can continue reading for….. >> >> Extra Info about my pack, charging to the 80% level, etc… >> >> The 48 modules from my Nissan Leaf battery pack (LMO/LNO chemistry) are >> arranged in a series of sixteen sets of 3 parallel cells. This gives me a >> 180Ah battery with an absolute maximum voltage of 134.4 (4.2 volts per >> cell). In actual use the 4.2 VPC level should never be reached, if you >> charge the cells to 4.1 volts per cell they are around 99% charged. As the >> extra 0.1 volt difference between 4.1 and 4.2 doesn’t really buy you much >> extra capacity, most people use 4.1 volts per cell (131.2 volts) as a safe >> “full” or 100% capacity on the Leaf Cells. My Mini-BMS units will start to >> shunt voltage at 4.1 VPC, and raise an over-voltage alarm at 4.2 VPC. >> >> However, if you charge the cells to 4.0-4.01 VPC (128-128.5 volts) that >> corresponds to about 80% of their maximum possible capacity. To maximize >> cell and battery pack life, you want to minimize the time the cells are >> fully charged or fully discharged. If you can keep the cells between a >> 10%-80% state of charge (SOC) it will maximize their battery life. >> >> Keeping them above 10% SOC is easy…don’t drive until they are empty. Keeping >> them at or below 80% SOC is also easy, simply turn off your charger when >> they are only 80% charged. This is why the early Nissan Leafs had the >> option to only charge the battery to 80%. (Removed in the newer Leafs due to >> EPA regulations on how maximum range is calculated.) >> >> If you want the extra 20% of range that charging to 100% SOC would give you, >> it is better to charge to 100% and then immediately discharge the pack by >> driving it (as opposed to leaving it sitting at 100% charge all night). >> This is one reason why Nissan Leaf’s have a charge timer, so that you can >> tell the charger to finish just before you start your daily drive. (The >> other reason is so that you can tell it to start charging only after the low >> cost nighttime electricity rates start, if you are on a time of use metering >> rate plan.) >> >> My 2nd charging profile will be a 4.1 VPC full 100% capacity charge, for >> when I feel the need to really go long distances. (or to get the pack ready >> for a top balancing equalization charge, my future 3rd charging profile.) >> >> Jay >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> Read EVAngel's EV News at http://evdl.org/evln/ >> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Read EVAngel's EV News at http://evdl.org/evln/ > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
