If the bike has sat for a while and was unproperly stored, ie long term storage not activated (or whatever term they use, it has escaped me at the moment), or if it has been used and short cycled several times, then YES, the batteries may become unbalanced, and you will need to give it a good long balancing charge.
I will explain in detail, this will get nit picky and fairly long, so iWARNING:
f you are one of those, TicTard educated Z tards, it's over 5 seconds TLDR types, just move on now.
One of the key factors to determine if a battery is properly balanced is comparing voltages, whether it be cell voltages, arm voltages, whatever. As little as a 50 millivolt difference can trigger an 'unbalanced' situation. At this point, the system may try to balance the entire battery pack for ideal performance.
50 mV is NOT a hell of a lot of difference, you will never feel it / see it / taste it/ etc. it is small, but IS important in battery world.
When you charge a battery, the current going through the battery can artificially raise the voltage during charge, (you need volts to PUSH the amps into the battery) The more amps you need to push thru, like a fast charge, the more volts above the batteries terminal voltage you need to push it.
If you are pushing 50 AMPS into your battery, it's impractical to try to measure 50 thousandths of ONE VOLT. Or even measuring the amps you DO push down to 50 thousandths of ONE amp. Besides, the false raised voltage you are putting on that battery is probably 2 or 3 volts by now, probably more, making the measurement of 50 Thousandths of ONE volt you need pretty useless at that point TBH.
So, if you need an accuracy of 50 millivolt, how do you obtain that kind of precision without overshooting it? You use lower amps to charge it. Lower amps means you need lower OVER voltage to push it.
So now, you are only pushing oh maybe half an amp, a third of an amp? Small enough that your amp meter on your dash that has a resolution of 1 FULL amp increments, .. is not high enough to push it to the next number yet, so reads zero amps charging current. BUT current is still flowing
Oh my bike says it's balancing but it's showing zero wtf?
If they had the resolution in the amp meter of say 3 digits, it'd be showing something like 0.225 amps 0.414 amps etc. It don't, so you see ZERO. Get one of those Kill A Watt or cheap power meters off the internet and you can easily see this.
0000000
Back to your battery.
Short cycling them, especially multiple times, and NOT doing a periodic balance is a great way to throw the pack out of balance.
I ride 43 miles back and forth to work every day. My pack goes from 72 to 96 percent charge. Ive done this for a few weeks now without a full on balancing charge. Guess what, your battery is pretty significantly unbalanced ! You probably will not notice it until you start getting to the ends of it's limits, ie your charge is very low, or your power draw is very large. THEN this unbal will start to manifest itself in symptoms. It's sluggish, this alarm blips in and out etc. The longer you cycle it w/o a balance charge, the worse the unbalance will grow until eventually you will have no choice BUT to attend to it.
Charging your battery:
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Charge your battery with the AC charger, not the fast charger. Remember, you NEED something that is designed for and can handle very low amps for that final 'fine tuning' your battery needs. DC does not provide this. DC was not designed for fine charging, DC was designed for bulk / fast charging. USE YOUR AC.
Let's say your battery is at 95 percent. Lets say it sees a 50 ma plus unbalance, THIS is enough to throw it into a balance mode. NOW it tries to fine tune our batteries. Let's say it's using 1 amp charge current (even though it CAN use even a fraction of that).
A 20 KW battery pack, at 95 percent, you need 1 kw of energy into it to get it fully charged. The battery, nominally is at 300 - 330 volts. At one amp you are putting roughly 300 Watts into that battery. NOT KILO watts, just single ole watts. Some fast math, you'll need 3 or so hours to charge it up that final 5 percent.
Oh but wait, you are only putting HALF an amp into it, ok fine, now you need 6 hours, 1/3 of an amp, ok you need 9 hours for that final 5 percent.
Yes this FInal few percent, to fine tune, can take up most of a fine day.
Real life example.
I run my bike on the track, I pretty much go from 72 percent / 75 / 80 percent.... up to 95/96 percent, up and down, again and again and again.
I don't run it to 100 percent, as I need some room for my regen / *engine braking* to go. sp typically stop it from 94 to 96 percent, ideally 95.
I recharge it after every 20 minute session. Max performance each time, each start. One less variable to look at when examining performance.
Your lap time was slow, well battery was at same load, EVERY time, so it's not that, ok moving on.
Doing this for a few weeks, cycling the charge probably 8 times a day, for 3- 4 days in a row, for weeks on end, and no balance charge.
After a month or so, I found myself with the battery wanting to balance itself down to like 82 percent. It'd start off at like 10 amps out of 30, quickly drop tp like 5 amps out of 30 then shoot up and trip the high voltage, ok it's CHARGED and shut down.
WHen I finally DID put an AC charger on it to fine charge, yes, it began balancing at 82 percent,but only took 4 amps. 4 was all it could take w/o pushing over 50 ma ;/ mv on the error. It come up to 87 percent and was running 2 amps. at 90 percent, 1 amp was flickering on and off. From 90 to 93 we were playing 1 amp, then it just went to zero, but every hour or so, we'd gain a percent charge. So it ran, we yapped and drank. It ran... we yapped. finally 4 or sohours later, ding, the battery is finally charged, pull out the plug and you are good
100 percent, battery is charged. Cool, turn it off for the night WELL DONE!!
Your percent charge is very dominant on terminal VOLTAGE. You've been slow cooking this battery most the day, it is well warm, well balanced, evenly warmed thru and thru, at 100 percent. But now, after cooling down from 96 Degrees F down to like 74 Degrees F *your room temp* OOF, the chemical action is a bit slower, we lost some volts, dammit, it's now saying 97 percent charge and I dindu nufffins!! THe battery is BAD !
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NO, the battery is NOT bad, they DO self discharge every day as part of their own diagnostics and monitoring. and chemical reactions. This is normal.
A few percent drop off a fresh charge to an overnight next morning colder reading is normal don't sweat it
A balancing cells message while charging annoying, slows the progress down, but don't sweat it,
A balancing cells showing zero but it's sub balancing, you may want to look into, where are those micro loads coming from? especially if it's happening frequently
THis is a lot but it grows on you with time so you'll get the hang of it pretty quick.
\and if you ever do need to get rid of a batt you pooched Ill gladly take it off your hands.
I recondition and reuse them in my power wall, currently at 232 kw.
Aaron
Author
Topic: Energica should improve charging and system stability (Read 8608 times)