Hello guys,

One of my A123 packs got over discharged by mistake to about 1V per cell. when i charged it back up it immidiately jumped to 2.6V per cell, and charged up perfectly normal.

Do you think this pack is still useable ? does over discharging A123 cells cause damage such as in lipos ?
i reckon reading somewhere that these packs are quite insensitive to over discharging.

thanks.

Run a discharge cycle on the now fully charged pack to see how much you are getting out of it. By my experience with A123 ( LiFe) batteries, this should not be an issue and might if anything reduce your packs life expectancy, and at worse case reduce its capacity by a miniscule amount .. These batteries are significantly more resilient over liPo and LiIon type cells .


~V~

Better buy all the A123 batteries you can; I think they just filed for bankruptcy.

A123 is just a brand .. , so no worries on anuyone going out of business ... LiFe is the battery chemistry A123 uses. I myself have been using Hobbico LiFe-Source batteries with a lot of success lately, and I find they offer better size and capacity options. Pricing is great as well



~V~

During the summer I left one of my planes on for 3 weeks before I realized it. The pack was DEAD. It was so dead I had to put some voltage in with an old NiCad charger before I could get my Cellpro 4S to charge it. I've probably had 20 flights on it since then (no redundant battery) without any problems. After 4 flights I still show 83% capacity.

I've run them all the way to 0 a couple times - left them on for days or weeks. Had to pump them up a little on a nimh charger so the Li charger would work. After recharging, they were back up to normal operation. Should cycle them once or twice to be sure. These packs are still flying.

Also make sure they will still hold enough MAHs. I had 2 of those hobbico green batteries loose 75% of thier rated capacity.. Now I only use real A123s.

Always check how many MaHs you put back into them.

After how much use did they loose their capacity ? or is this after over discharging ? I'm definitely curious.


~V~

I was setting up some mixes and messing around with the radio when the battery on the plane started to die. I was like ***? On the next charge on a 1800 mah pack it took only 350 mahs to fully charge it. So I then put it on a discharge and then charged it agian. Only around 350 mahs agian. So I trashed it. I then checked the hobbico pack in my electra and agian it had way less capacity then it should have. So no more green hobbico packs for me.

I learned every now and then we should check our capacity on our flight packs and not just balance charge them after a few flights. I like to charge the flight packs every 4 flights so they always use about the same mah. But you still need to discharge them everynow and then and make sure they still have capacity. I was very close to trashing a plane.

This was after about 1 year of use. These where never fully discharged. I did accidently discharge one of my real A123 batteries but it did not care and charged right back up no problem.

THey dont like to go below 2 v per cell but it really doesnt hurt them much-just dont make a habit of it. I have had a couple of cells go down below one and had to use a few seconds of charge from a 2 cell lipo to get the charger to recognize it and from then on has worked fine. cap is prob down 100 ma or so. What they will not even come close to tolerating is overcharge. If a cell reaches 4.2 it is done , over. Scotty
BTW converted by air pump to a 4 cell 123 even converted my dustbuster!!!

Thanks guys, thats very re assuring !

the charge cycle after running mine down pushed 2256mAh back into this A123 2300mAh pack.
its now discharging...

Discharge to about 2.6V per cell took out 2130mAh.

I think its fine.

A123 uses a proprietary LiNP nano phosphate chemistry that is ONLY available from A123. The negative plate technology is much better and more stable. Life are not the same. When you buy an imported LiFe battery it is not an A123 LiNP that we have come to rely on for high end RC model use. You will likely not get the same long term use and cell quality control A123 uses. Discharge should be no lower than 2.5 per cell under controlled conditions. You can cycle them safely when doing formation charging by discharging at no more than 1 amp down to 2.5 to 3.0V per cell then follow with a full charge.

+1

I was also told that Genuine A123 cells are only available in 1100 and 2300mah capacities.

Tom is correct.
1100 or 2300 and now the Series B A123 is 2500 in the 2300 cell size. But if they are not 1100, 2300, or 2500 A123s they are not A123s.

Is an over discharged A123 bankrupt []

Excellent reading from a well known expert http://hangtimes.com/a123_batteries_for_giants_faq.html

From Hangtimefor those who don't want to read the whole article. <span style="font-family: 'Calibri','sans-serif'; font-size: 11pt"><span style="font-family: 'Arial','sans-serif'; color: black; font-size: 12pt">Yup.. sounds like a short failure on one of your cells in that pack.<span> </span>Uncommon but not unusual.. biggest root cause we found so far relates to 1^st, (most common) a 'run-flat' (severe overdischarge) at some point in the packs history, an incorrect charger sub-routine, such as accidentally triggering a liIon, LiPoly, Nicad/NiMH charge setting at some point in the packs history and/or routinely using a non-balanced charge setting. Repeated non-balanced charging will set up a severe imbalance, results are one cell hugely over voltage on charge and that cell eventually shorting.

Your competitor told me to put it on a NiCd routine for 6-7 minutes to get the voltage up and then switch it over to the LiFe routine. I did and the battery came back up. I used it happily thinking that I had saved the pack. I&rsquo;m also not the best at using the balancing plug. I have a tendency to charge it and fly it. Won&rsquo;t do that again unless I&rsquo;m at the field and putting in an extraordinary number of flights.<div align="center"><font size="3"><span style="color: black"><span style="color: black"><span style="font-family: 'Arial','sans-serif'; color: black; font-size: 12pt">*</span></span></span></font></div><div align="center"><font size="3"><span style="color: black"><span style="color: black"><span style="font-family: 'Arial','sans-serif'; color: #1f497d; font-size: 12pt"><span style="font-family: 'Arial','sans-serif'; color: black; font-size: 12pt">A: &ldquo;Your competitor told me to put it on a NiCd routine for 6-7 minutes to get the voltage up and then switch it over to the LiFe routine.&rdquo;</span><span style="font-family: 'Arial','sans-serif'; color: black; font-size: 12pt">-</span><span style="font-family: 'Arial','sans-serif'; color: black; font-size: 12pt">That didn&rsquo;t do any damage.. it&rsquo;s allowing the cells to climb above terminal voltage further along in that charge process that would damage it.<span> </span>A soft &lsquo;run flat&rsquo; would set the problem up tho; this situation can cause one of the cells to be slightly degraded (impedance and capacity is affected) and from that point on, keeping the pack balanced is very problematic if you don&rsquo;t routinely balance charge.
<p class="MsoNormal" align="center" style="text-align: center; margin: 0in 0in 0pt"><font size="3"><font face="Arial"><span style="color: black">
Q: What's the difference between A123 LiFe packs and LiFe PO4 packs like Hobbico's LiFeSource&trade; packs?</span></font></font></p><p class="MsoNormal" align="center" style="text-align: center; margin: 0in 0in 0pt"><font size="3"><font face="Arial"><span style="color: black">*</span></font></font></p><p class="MsoNormal" align="center" style="text-align: center; margin: 0in 0in 0pt"><font size="3"><font face="Arial"><span style="color: black">Two big differences. First, A123's patented 'Nano' plating technology.. at a molecular level the negative plate material stands like a shag carpet rather than laying 'end-to-end'. This produces an incredible amount of surface area gain for A123's negative plate and it's why A123 can tolerate immense current loading without voltage sag. Another benefit to the nano plating technology is a huge increase in cell life. All stored energy systems consume negative plate over time.. with 100+ times thenegative plate surface area generated by any competitors plating processthe lifespan of the A123 cell is extended immensely. Next, A123's arealuminum cased cylindrical cells withwelded alloy end plates and towers like a Nicad cell. This enablesa rugged welded strap packassembly system (like Nicads) that is exceptionally robust and veryresistant tovibration andhard knocks.TheLiFeSource&trade; packs are built with wafer stacked'bag' prismatic cells.. like LiPoly. And, like LiPoly, they are fragile, thecell link tabs are very thinalloy stripsand the entire assembly is as a result susceptible to rough handling and vibration. Further,the prismatic cellsand their tabbing system are unable to handle anywhere near the current loading the A123 system can tolerate with ease.</span></font></font></p></span></span></span></span></font></div></span></span>

Poking fun at some fine technology.....

One can only hope that the A123 IP will be licensed to a reputable battery company that will do that IP justice. Hopefully the new company willcontine to supply us withidentical technoiogy, which is better than most.

The thing that hurts most is the investment loss. Two years ago A123 stock was 20$. Last Friday it closed at 6 cents.....OUCH!!

Johnson controls bought out a123.. I think they will still produce them, but I do not know to what extent.. they were embedded into the auto industry and when electric cars flopped this year, they were overspent..

I had a discharged 123 pack recently.. it was flat too.. added a little voltage via y cord for literally 10 seconds, and it jumped to 5 volts.. then charged at .5 amps.. the trick is not to hit them hard at lower voltages.. When we first started using 123's, I received several of them from Fromeco for testing.. the only problem I found was when you crossed 4 volts per cell, they gassed and stink.. but at 3.75 volts they were fine..

they wont always fail completely from an over charge, but might hold 400 mah or so, and fool you into thinking they are ok if you dont balance them.. if you balance charge, you will catch it..

Its good to periodically cycle the 123s with a load and take out amperage down to about 500 Mah remaining.. my preferred way is two 1156 light bulbs in parallel with a wattmeter.. I stop at 5 volts. I take em down to half way for winter storage, but they are very resilient.. I have only recently found my first dead cell completely.. it was a twin 1100 pack that gave it up totally and wasn't hooked to anything.. it was one of the very first packs I got over 5 years old. Never had a 2300 fail yet except overcharge.