Arkmundi's saga making & maintaining an A123 AMP20 battery

Are you crazy? I am using the voltphreaks single chargers (16S)' and these single chargers still running solid. It always be exact 3.65V on my fiancee lifep04 pack much better than letting the BMS controlled because the BMS always shoot high as much exceed 3.9V. I was afraid that might shorten lifep04 lifetime.

Lot of ES members recommended this setup due very reliable single chargers. I'm very satisfied with voltphreaks.

arkmundi said:

Voltphreaks?

ejonesss said:

are these ok for charging these cells?

https://p10.secure.hostingprod.com/@www.voltphreaks.com/ssl/catalog/product_info.php?cPath=3&products_id=60

i am using them to charge the lifebatt/psi 40138 cells

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I got one as a trial, tried and discarded as a grade of "cheap chinese chargers" to be avoided at all costs. Invest in quality LiFePO4 cells AND a quality charger! Doing cheap doesn't really work.

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arkmundi i think you

1. got a bad one or or more or got a first gen model

2. you did not observe the correct way to connect them on a power strip and they overheated by either poor airflow or induction harmonics putting an extra load on the pwm circuit and blew it.

4. chroot and me got a good batch or second generation

sometimes first gen products can have problems that are fixed by the second gen.

chroot said:

Are you crazy? I am using the voltphreaks single chargers (16S)' and these single chargers still running solid. It always be exact 3.65V on my fiancee lifep04 pack much better than letting the BMS controlled because the BMS always shoot high as much exceed 3.9V. I was afraid that might shorten lifep04 lifetime.

Lot of ES members recommended this setup due very reliable single chargers. I'm very satisfied with voltphreaks.

arkmundi said:

Voltphreaks?

ejonesss said:

are these ok for charging these cells?

https://p10.secure.hostingprod.com/@www.voltphreaks.com/ssl/catalog/product_info.php?cPath=3&products_id=60

i am using them to charge the lifebatt/psi 40138 cells

Click to expand...

I got one as a trial, tried and discarded as a grade of "cheap chinese chargers" to be avoided at all costs. Invest in quality LiFePO4 cells AND a quality charger! Doing cheap doesn't really work.

Click to expand...

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Voltphreaks is an EXCELLENT charging method to charge these cells. Probably the safest and best way in many respects. Seriously!!! This is well known by many battery/charging experts on ES.

Of course, one should always ideally verify and check your cell voltages with every cycle to verify everything is in working order.

devries how many voltpheaks do you own ?

Cautionary tales of fires
There's been a surge of forum activity this year all relating to battery packs, charging, safety & fire risk:
E+ powered by A123 20 Ah pack UPDATE and the EMS fire/recall disaster

miro13car said:

DISASTER WAITING TO HAPPEN. Remember you ride on LITHUM POLYMER=DANGER.
And it happened, namely fire in bicycle store while charging which triggered recall - very costly operation for EMS .

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Thanks to TheBeastie: Lipo elimination test videos Lipo Explosion Montage | Best lipo battery explosion ever
"LiPO", another "be careful" warning...
Floont's Monzilla - BURNED IN LIPO FIRE AUGUST 11
Lithium Batt House fire Melbourne
Bigmoose's call for a 2013 Li Battery Catastrophic Events - Summary Thread
... and more - do this search for fire in thread title.

It is my firm belief that the A123 AMP20 cell chemistry and construction are as fire safe as can be had in today's market. Part of my awareness of this risk stems from Agniusm's post in his A123 AMP20M1HD-A Battery pack kit thread of this video:
[youtube]FKTJ-1ZJegw[/youtube]
I thought he was crazy at the time, but in retrospect, appreciate his doing that!

I believe the relative risk of these cells is one of the reasons to choose them over others. I said relative because every lithium-ion cell can be abused and thence be subject to degradation and fire. Hence, I'll continue to evaluate my own approach to pack design, charging practice etc, but NOT my choice of the A123 AMP20 cells themselves. My primary objective, however, will be to NOT ABUSE my pack, especially during the charge cycle, not overcharging a single cell at anytime, and periodically doing a balance charge of the pack. I remain BMS-free, even considering.

Still not convinced? Then please see Despicable me - another LiPoo fire.

http://www.youtube.com/watch?feature=player_embedded&v=XymqQ-YlfJ0

And if you need further proof, see above. This is one of the best examples I've seen.

pdf said:

And if you need further proof, see above. This is one of the best examples I've seen.

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Thanks, but that's a HobbyKing LiFe and the only thing I'm interested in, obviously, is the A123 AMP20 cells. Nonetheless, pdf, we share a common perspective on this issue and appreciate your various posts to raise awareness of the fire risks, and discrimination on cell choice. There is nothing that will kill our industry faster than news worthy disastrous fires with lithium-ion batteries as the cause. And the authorities responsible for public safety, WILL NOT differentiate between LiFe and LiPo in making new laws governing their use on the road.

Nice vid with the 20Ah pouch. This is totally consistent with my own experience. The cells can be made to flame out, but it takes extreme effort and often many tries.

the lifepo4 fire was just the shrinkwrap that burned not the cells.

although if you get a bad lifepo4 you can salvage the good cells.

even with beating the dead battery it could not go bang

the only bang you would get if any is the safety vent popping.

Ark how is your problem with the thunder 1220 going ?

ebike fail
Tues-17-Sep-13, ebike stops working in the middle of a ride. Not unusual as the Heinzmann has a thermister in it to shut the motor off when too hot. But the motor is not hot, so what the frack? Couple of hills and walks trudging homeward and finally get back, and what the frack, still no power. Uh oh, so what now? Not the battery - still have a charge, all cells working and adequate voltage. So, its got to be the motor, the controller or the wiring, huh?

Took a while eliminating each part in turn, until I find this:

That's the last connection before joining the motor to the system. Its all black with molten plastic and gummed up. So that's got to be it. Scrape some of the plastic off to get a connection, test, and whalla, that's indeed it. Thank my lucky stars its not the motor or the controller, which would have put me out of kilter for a while. Remember, I'm car-free and a cripple (bum leg), so this is mobility for me.

Cut the junction back to the bare wires and replace with Anderson powerpoles. Good to go and back on the road!

But what the frackisthatjack^%(&%!!???? Why so hot it melts the plastic? I speculate that its the difference in wire gauge. That last little bit of wire to the motor is a higher gauge, so causes a point of high resistance right at the point of connection. So that's where it gets hot.

I doubt that it's the change in wire gauge that caused the thermal rise. If this were the case, the entire length of the thinner wire would be hot. More likely the issue is the impedance across the connector itself. The connector looks like a resistor to the electrons; it thus dissipates power and gets hot. Do you use dielectric grease on contacts like these? Should help enhance conductivity across the tiny gaps where the conductors interface and limit impedance rise. Will also limit the development of corrosion and the accompanying impedance rise that comes with.

A new replacement battery for the new year

There's been a lot of great discussions this year with valuable new information. And it was time to make a decision for staying in the juice. As anyone following my saga may recollect, I'm down to the last two A123 AMP20 cells in my stash. I had attempted to encourage an opportunity at the A123 AMP20 Cells, new, legit, factory direct! thread that might have yielded some additional cells for my dwindling stash, but that didn't pan out. davec almost bit, but decided to opt out, choosing another path. After some consternation, I decided to take another path too. As I said at the A123 AMP20 Cells, new, legit, factory direct! thread:

This has forced to me to reconsider my whole long-term strategy to staying in the juice. This and the A123 20Ah Pressure Thoughts thread, since the AMP20's require some compression methodolgy in the make, whereas the cylindricals are natively already in proper compression. I had not wanted to reconsider strategy, since I had invested in all the paraphanellia for my 12S 36V AMP20 pack and didn't want to start from scratch. But what with the continuing problematic nature of sourcing the AMP20's, I guess its time.

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So, my choice, after a review of many, many different cyclindricals, from Sony, Panasonic, Tenergy and others is the A123 ANR26650 cells from buya123batteries.com. Hence, sticking with the nanophosphate advantage, stepping down to their next hightest capacity cell and in the cylindrical format.

I'll be building it over the next 30 days. In consideration of pack construction:

• its got to be a replicable pack, for a broadening audience, including those taking my ebike workshop
• its got to be relatively simple to source cells & parts, so commonly available
• assembly shoud be straight forward and not difficult, so anyone can attempt the build and succeed, even kids
• the pack should lend itself to disassembly, for inspection and replacement of cells, should any go bad (as they inevitably do over time)
• the cells have got to carry the C rate, and have good amp-hour capacity, and lots & lots of cycles in them
• the cells should be easy to source & buy online

I believe I'll be attempting something so far not covered here at ES, forging new ground. To meet the terms of the above, I wanted to avoid welding and soldering, and make it possible to pop out a dead cell and simply replace it. I'll be using 9V battery snap connectors sourced through Jameco. The snap will be permanently afixed to the cells with high-grade conductive epoxy (i'm getting the expensive silver stuff from Amazon. And in the snap, taking wb9k's suggestion for using dielectric grease. Among other considerations.

So I'll video tape it all in the make and post a new make journal, Arkmundi's saga making & maintaining an A123 26650 battery. Stay tuned, and Happy New Year!

I like spinning magnets Idea of buying cells spot welded up in parellle, Then just making them in series to your liking.

I'm getting the cells from buya123batteries and they don't have tabs. Anyone building packs with cylindricals needs to consider how to create a complete circuit with them. Again, I'm looking for a method that minimizes the steps and is easily replicable. My purchase experience with buya123batteries was great - order online and pay with paypal. So I or any subsequent replicant gets them, then what? I'll produce a video of my experience building a pack with my method. I have full confidence I'll succeed and that the process will be easy enough for anyone to follow, unlike most of the build threads I've encountered here at ES. While I enjoy comments, I'm not at this point seeking advise. Best!

How much money have you spent tinkering with different batteries may I ask??

Jason27 said:

How much money have you spent tinkering with different batteries may I ask??

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http://endless-sphere.com/forums/viewtopic.php?f=14&t=42871&p=674817#p674817

Dude why did you spend that much?

Another dead cell, reduced to zero volts in the middle of a ride. Started out OK, then noticeable loss of power and home, find just the one cell that has given up the spirit and gone to whatever battery cell heaven there may be. No puffing - just leaking electrolyte around the edges. So, did the pack surgery, taking out and replacing just that one cell. I've become proficient at doing it! Anyway, here's a picture:

I don't know why but an amazing thing, something I have never seen for this pack - all the cells were perfectly balanced at 3.31V, all 12, in perfect unison! I did the cell replacement yesterday - see above - and then did a partial bulk charge, leaving off the last part of smart chargers cycle which does a trickle charge to full capacity. This morning in preparation for a ride, I did the remainder of the charge, plugging in my 2 celllogs, so as to monitor that. I do a bulk charge with celllogs most of the time and only occassionally do a balance charge. However, I have never had such a perfectly balanced pack before. If I get all 12 cells within about 0.1V's of each other, its OK by me. So before I turn the charger on I take a look at the 2 celllogs and whaatttt? Perfect balance.

Interesting Arkmundi.
I have a somewhat different experience with my 12S AMP20 pack. It is about 1.5 years old now and needed 1 cell replaced. However It has never been bulk charged, only balance charged, with either a Hyperion1420 or, more often a Thunder 1220. I have had to replace balance wires once and a main wire once due to excessive resistance. I just don't have the confidence that bulk charging would work. I do use Cellogs on our rides, and never discharge over about 70%. We average about 20 miles and use around 11-12AH. Recumbent trikes are quite efficient at <20 mph. The pack still balances at +/- 1/10 of a volt every time with I/R in single ohm numbers per cell.
otherDoc

arkmundi said:

previous .... I wanted to avoid welding and soldering, and make it possible to pop out a dead cell and simply replace it. I'll be using 9V battery snap connectors sourced through Jameco. The snap will be permanently afixed to the cells with high-grade conductive epoxy (i'm getting the expensive silver stuff from Amazon. And in the snap, taking wb9k's suggestion for using dielectric grease. Among other considerations.

Click to expand...

So, after messing around with various makes of conductive epoxy, I have not found it to work and am abandoning the experiment. I found that yes, I could glue a wire to a cell, and yes it would hold current. Unfortunately, it does not adhere to the cell well and has a tendency to break off, so not able to endure the road.

Most fortunately, however, a recent hackerspace - Technocopia - is experimenting with lasers and control systems and is willing to build a laser spot welder for battery packs. I joined and am now on a new learning curve.

I finished the Arkmundi's new A123 26650 battery build today and mounted it. Meaning this is the end for the AMP20. Its still a good battery and all 12 cells seem to be in good shape. But its a spare now, into storage until I need it. I'll be leaving it in 60%<SOC<40% and will check up on it every once in a while to insure it remains there. Ahh, the time I've spent with you AMP20, you're like a dear old friend.

Ark you got the half tab cells ? I got mine from the midwest group sale full tabs with J.R.Holmes and replace one cell in the 24s pack. Yes maybe a little weaker maybe ? Will check over next week for a.h.. they always balance very close.

wb9k commented on the victpower cell failure posted above at http://endless-sphere.com/forums/viewtopic.php?f=14&t=62494&p=934424#p934424