tag:blogger.com,1999:blog-4774014561040227748.post1484923192836104488..comments2024-03-22T10:42:05.161-06:00Comments on KA7OEI's blog: Problems with Lithium Iron Phosphate (LiFePO4) BatteriesUnknownnoreply@blogger.comBlogger16125tag:blogger.com,1999:blog-4774014561040227748.post-89688843169078873532016-06-15T22:38:06.938-06:002016-06-15T22:38:06.938-06:00I've had a Shorai LiFePO for at least three ye...I've had a Shorai LiFePO for at least three years now. The aircraft build was a bit slower than anticipated, so the unit spent its first year in the refrigerator. Soon after being put into service I left the lights on over a weekend, leading to a dead flat, but the plane was started okay with jumper cables, and the battery still seems fine, giving instant starts in all weathers with no signs of deterioration (yet). Maybe I'm wrong to do so, but I happily recommend them whenever I'm asked. Anonymoushttps://www.blogger.com/profile/13400253020693456629noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-34419021748484923882016-06-15T13:47:33.426-06:002016-06-15T13:47:33.426-06:00The LiFePO4 lead-acid "replacements" hav...The LiFePO4 lead-acid "replacements" have proliferated since this article was originally written.<br /><br />In perusing the various vendors of SLA (Sealed Lead Acid) replacements using LiFePO4 batteries very few of them make any mention of the battery itself having any sort of BMS (Battery Management System) that would be responsible for equalizing the charge across cells and disconnecting it on overcharge/discharge. I suspect that reputable branded batteries must have such a thing or else they would fail after only a few accidental over-discharge events - but then again, the cynical side of me suspects that even if not, such an induced failure would likely occur outside a year's warranty for the vast majority users.<br /><br />Thanks for the comment!<br />KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-30502792260035852162016-06-11T15:47:43.701-06:002016-06-11T15:47:43.701-06:00I (and some others in our flying club) use lithium...I (and some others in our flying club) use lithium iron phosphate batteries in our airplanes. My experience is limited to install it and forget it. My engine starts briskly in all weathers. The battery voltage stays up at all times. I have had the battery four years. The first two years (while the plane was being completed) it was stored in the refrigerator. It fits the same holder that was designed for lead acid, but is much (much) lighter. If anything it is too light (!) because that lead (no longer there, of course) was initially intended to provide part of the weight that balances the plane in flight!Anonymoushttps://www.blogger.com/profile/13400253020693456629noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-90122897940861135182013-11-10T01:36:52.065-07:002013-11-10T01:36:52.065-07:00I've had great luck with ping batteries going ...I've had great luck with ping batteries going on 4 yrs and I use them everyday. A 48 -20ah and a 36volt 20ah . still act like new. There being used on electric bikes. That's probably why pingbattery.com has nothing lower than a 5 star rating and customer service is A+ and he is in china. Just a thought.Anonymoushttps://www.blogger.com/profile/18041799545341999717noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-51722769767137581372013-07-22T14:03:19.678-06:002013-07-22T14:03:19.678-06:00Thank you for the comments. As noted in the follo...Thank you for the comments. As noted in the follow-up of this post (links are within the original post) I devised a means of equalizing the cells within each pack.<br /><br />More recently, another commenter to the follow-up article noted the availability of some new protection circuits that do include the ability to force equalization of each cell. Unfortunately, this doesn't appear to be a standard feature and is likely to be of ultimate disservice to both the owner and seller of those packs that lack it!<br />KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-55888243358809862032013-07-07T11:53:49.293-06:002013-07-07T11:53:49.293-06:00LifePO4 batteries require each cell to be 'bal...LifePO4 batteries require each cell to be 'ballance charged' for best performance. The 'off the shelf' 6.6 or 13.2 volt packs with built in charger/protectors do not do this. They attempt to balance after one cell reaches full charge. Actually over full charge, I've tested two different built in controllers and they will charge a single cell to 3.9v instead of the manufactures recommended 3.6. To truly get the life out of an liFe you must buy a pack that has the balanced charger connector and charge with a balance charger. The RC (radio control) guys have this pretty much worked out. Perhaps someday the Chinese will build a good built in lifepo4 charging circuit.Unknownhttps://www.blogger.com/profile/08097116451917372591noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-71840205625948736012013-05-18T19:31:42.402-06:002013-05-18T19:31:42.402-06:00I've recently had time to analyze the battery ...I've recently had time to analyze the battery packs and have determined that they cells within had become grossly "un-equalized". Refer to the <br /><br />May 18, 2013 post for more information about this issue.<br /><br />Thanks for the comments!KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-18582017669665487752013-05-17T17:59:14.720-06:002013-05-17T17:59:14.720-06:00Hi, Glad I found this. I was just about to clic...Hi, Glad I found this. I was just about to click complete order from the same company on 3 packs using the 26650 cells 3.3Ah packs <br /><br />So - what's the work around? And would you recommend a different path? Any battery I get needs to be light - I have no intention of packing an SLA around.<br /><br />I'm a little concerned about pulling the control board which I believe (not positive) keeps the cells from both over charging, and from dropping below 10V which is supposed to be BAD.<br /><br />Any new information would be most welcome. <br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-42767870872234223332013-04-18T12:30:07.487-06:002013-04-18T12:30:07.487-06:00Thank you for the comments!
For testing this - an...Thank you for the comments!<br /><br />For testing this - and other - batteries and cells, I use a "West Mountain Radio" CBA-II battery tester. This is an (older) USB device that provides a constant-current load and allows graphing and logging of the discharge curve while calculating the effective capacity in amp-hours. Regardless of whether or not it is a true and accurate representation of the useful energy stored in a battery, it has proven to be consistent in its measurements and it is in general agreement with the amp-hour ratings of new batteries.<br /><br />In the past when I have had cells go bad - particularly LiIon of various sorts - one sees the voltage drop slowly, and then abruptly disappear as one of the cells in the pack drops below the threshold set by the pack's internal circuitry and is disconnected.<br /><br />These packs, on the other hand, exhibit the behavior of a properly-working pack in the sense that the voltage slowly drops until it reaches the lower limit set by the battery load tester itself. As it turns out, this voltage is slightly above the voltage at which the pack itself would cut off.<br /><br />Now, were one or more of the paralleled cells to drop more quickly than the other over the course of the discharge, I would expect that at some point, the voltage would cut off as those cell(s) went below the circuit's threshold voltage, but the other "good" cells were still at a reasonable voltage.<br /><br />It doesn't do this, however: The fact that the discharge curve decreases gradually throughout the entire test indicates that the cells themselves are fairly equal in terms of capacity.<br /><br />Having said this, when I get a chance I will do more investigation of the state of the cells within the packs, measuring them individually to see how "equal" they are to each other and if there is, in fact, some sort of odd behavior that might be causing uneven charge/discharge of the cells within.KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-22073255554898169412013-04-18T12:28:41.658-06:002013-04-18T12:28:41.658-06:00This comment has been removed by the author.KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-6777327339325410732013-04-13T23:01:00.004-06:002013-04-13T23:01:00.004-06:00Hi !
The problem is most probably the circuit ins...Hi !<br /><br />The problem is most probably the circuit inside the pack.<br />They tend to bleed down one or more cells in the pack to a level where the imbalance between the cells makes the pack almost unuasble.<br /><br />I have had this experience with BMS on LiFePo4 packs.<br />Try to open the pack and measure the cell voltages of each cell.<br /><br />What I have done is to remove the BMS and use the pack without protecting circuits. That way the pack does not get a low constant current draw.<br /><br />I would think that your packs would work just as good if you:<br />1. remove the protect circuits.<br />2. bottom balance the cells in the pack.<br />3. use that charging methods that you did before.<br /><br />You can do some extra voltage check of the cells when your in the later stage of charging to see that the cell voltages dont get to high.<br /><br />REgards<br />/PerPm_dawnhttps://www.blogger.com/profile/11545177173774201204noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-38397254088876573182013-04-04T12:13:47.408-06:002013-04-04T12:13:47.408-06:00According to the manufacturer of this - and other ...According to the manufacturer of this - and other - cells, the charging voltage of 14.2 volts (3.55 volts/cell) is well within the specifications for the LiFePO4 chemistry.<br /><br />Soon after charging was complete, the voltage was removed which allowed the cell voltage to drop - an important point since in contrast to lead-acid cells, the longevity of rechargeable lithium cells is negatively impacted with the constant presence of its charging voltage over a long period of time.<br /><br />Now it is possible that in the 2-3 years since I bought these batteries, experience by users has shown that the lower voltage is more appropriate for maximum longevity, but hindsight is, as they say, 20-20!KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-62945685954330205812013-04-04T10:22:53.489-06:002013-04-04T10:22:53.489-06:00LiFePO4 cells, only charge to 3.4 per cell. sounds...LiFePO4 cells, only charge to 3.4 per cell. sounds like you overcharged them.<br />they operate at a nominal 3.2v, 3.6 is WAY too high.<br />Most EV guys only charge to 3.4 or less.<br />David Lhttps://www.blogger.com/profile/10492458862113816378noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-32566218291030601722013-02-15T01:19:26.295-07:002013-02-15T01:19:26.295-07:00Hi friend,
your blog about problem with litium ion...Hi friend,<br />your blog about problem with litium ion battery is really informative. The energy density of lithium-ion is typically twice that of the standard nickel-cadmium. There is potential for higher energy densities. The load characteristics are reasonably good and behave similarly to nickel-cadmium in terms of discharge. The high cell voltage of 3.6 volts allows battery pack designs with only one cell. Most of today's mobile phones run on a single cell. A nickel-based pack would require three 1.2-volt cells connected in series.<br /><br />Thanks,<br /><a href="http://www.energyholder.com/" rel="nofollow">Rechargeable Lithium Batteries</a>Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-53013017913660616562012-12-29T11:37:46.674-07:002012-12-29T11:37:46.674-07:00The temperature in all of the tests was approximat...The temperature in all of the tests was approximately the same - in the area of 20C-25C so I do not believe that this could explain the >75% loss of capacity.<br /><br />As part of a long-term experiment, I have allowed the three batteries to sit on a basement shelf in a partial state of discharge as recommended by various manufacturers and every 3-6 months or so I will charge them to the recommended voltage and retest: The alarming loss of capacity has continued.<br /><br />In examining the batteries, it would appear that they all use the same make and model of cells. By this time I'm sure that the seller (batteryspace.com) is well aware of the problem as all of the stock using this particular batch of cells must be exhibiting the same problem.<br /><br />KA7OEIhttps://www.blogger.com/profile/01153508130273704727noreply@blogger.comtag:blogger.com,1999:blog-4774014561040227748.post-82207395491443447912012-12-29T02:55:13.539-07:002012-12-29T02:55:13.539-07:00How cold was it at your place at the time of measu...How cold was it at your place at the time of measure. When LiFePO4 batteries drop below +/- 2 degrees celsius they will have more internal resistance and last less long, this problem will cease to exist when temperatures rise again.Anonymoushttps://www.blogger.com/profile/01717440215098201609noreply@blogger.com