Fórum | MyPower.CZ | Obnovitelné zdroje energie - energetická soběstačnost | Poslední návštěva: úte bře 02, 2021 9:26 pm
bert píše:Zdravim!
Zvyste napatie zdroja naprazdno a prud dajte na maximum. Napatie po pripojeni na bateriu padne na napatie baterie. Ja som pri konci nabijania mal na zdroji asi 7V a omedzenie 2x5A (davalo mi to 11A).
Len je to treba sledovat!
Ale najprv som zacal dobijat bateriu pripojenu priamo do zostavy plnym prudom z nabijacky (60A) + prudom z regulatorov (co slnko dalo do cca 60A), cize do 120A. Takto som dobijal asi 7 hodin so sustavnou kontrolou napatia jednotlivych clankov. Po dosiahnuti 4,00V na najsilnejsom clanku, som to porozpajal a dobijal do plna zdrojom po jednotlivych clankoch. Nakoniec som ich prepojil paralerne, dobil na 4,00V, odpojil od zdroja a nechal prepojene na vyronanie.
Prajem vsetky vela slnka.
abrams píše: ... akorát ten proud (120A) ... nepřekračoval bych 1/10C (C1).
bert píše:Zdravim!
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Ale najprv som zacal dobijat bateriu pripojenu priamo do zostavy plnym prudom z nabijacky (60A) + prudom z regulatorov (co slnko dalo do cca 60A), cize do 120A. Takto som dobijal asi 7 hodin so sustavnou kontrolou napatia jednotlivych clankov. Po dosiahnuti 4,00V na najsilnejsom clanku, som to porozpajal a dobijal do plna zdrojom po jednotlivych clankoch. Nakoniec som ich prepojil paralerne, dobil na 4,00V, odpojil od zdroja a nechal prepojene na vyronanie.
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2. Technical Requirements for Battery Charging & Discharging
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2.5 Individual cell charging float voltage: 3.40V (Charging voltage for the applications in storage
power of photovoltaic energy conversion system, UPS power and automobile auxiliary power.)
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We have previously discussed the difference between "float" and "trickle charge", I saw a related post from Doug out of the EV community. He has done some real testing on the capacity impact of floating LFP for 6 months and measuring capacity before and after.
In this test, no change in capacity was observed. Below is my question and his answer.
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On Sat, Mar 16, 2013 at 8:28 PM, Ebaugh @ DIY Electric Car Forums <Bob> wrote:
Doug,
I read your post over on EVTV. I also use GBS 100Ah cells, but mine are 12P then 4S in a marine house bank. You mentioned floating for long periods at under 3.4Vpc. Have you actually compared before and after capacity by capacity testing?
------- Answer
Yes, but not on the GBS cells. I used the 26650 A123 cells which are about 2AH. I was not able to measure any difference after 6 months of floating at 3.45 volts. I didn't see any reason to test on the GBS cells after the non event with the little ones. I had the little cell in a pyrex oven dish just in case. It would be more difficult to safety the large cells.
------- Not directly related, but interesting:
I don't see this as an issue at all. I did another 6 month test (this one with the GBS 100AH cells) where I fully charged a cell (resting voltage of 3.38v), I half charged a cell (resting voltage of 3.30v) and I discharged a cell to 2.5V (it bounced back to 2.7v resting). I left them sit this way for 6 months and then charged them and retested capacity. I could see no loss in capacity in the fully charged and half charged cells. The one left pretty much fully discharged lost about half a percent of its capacity. A lead acid bank treated this way would have been completely sulfated and ruined. I was quite happy with that small loss. What you are doing is in essence between the mid balanced and fully charged cell test I made.
Doug Ingraham
replied:
1 week ago
I am not Richard and I don’t play him on EVTV. Trickle charging would by definition overcharge all the lithium battery types I am aware of. Instead call it a float charge. This is where you hold the battery at a constant float voltage. The normal meaning of trickle charge is a constant minimum current to replenish that lost due to self discharge. Since lithium cells don’t seem to have a self discharge the correct current for trickle charging would be zero. I have a datasheet for A123 Systems ANR26650-M1 cell which has a recommended float charge voltage of 3.45 volts. I left a fully charged cell connected to a power supply adjusted to this voltage for 6 months and could not detect any degradation of the cell capacity at the end of that time. The current to hold that voltage was less than a tenth of a microamp (this is at the limits of my meter) so not much energy to do any damage. I have a 4S4P pack of these cells in my car as a backup battery for the DC-DC converter. I float the battery at 13.6 volts (3.4 vpc) and have been doing this for about 6 months now. Because of the way I am utilizing this pack I carefully matched the cells such that each module in the series string are within 15mah of each other in capacity and are top balanced. Since it is so closely matched it is essentially bottom balanced as well. It is pretty interesting to watch it go dead. It is almost like turning off a switch as the whole thing dumps at the same time and when charged they all track in voltage right up to the 3.4volts and the current tapers off to milliamps over the next few hours. It should certainly be 100% safe to set a constant float voltage such that the smallest capacity cell in the pack would end up floating at 3.38 volts. And the current will eventually drop to as close to zero as makes no difference.
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