Arkmundi's saga making & maintaining an A123 AMP20 battery

arkmundi

10 MW
Joined
Jul 8, 2012
Messages
3,143
Location
Worcester, MA USofA
Preface
Hello. Thought it would be useful & fun to tell my story here on this forum. And for those interested in building a great ebike, follow the lead. I built a working 500 watt 36 volt ebike without incident, first pass and so can you. It just takes forethought, research, quality components and follow through.

The battery is in my estimation the most costly and prone to error component, so this thread concentrates on building the best of the best - an A123 AMP20, as in 20 amp-hour, nanophosphate LiFePO4 battery pack. Mine is 12S for 36 volts, but it can be 24V, 48V, 72V or whatever your motor demands. See A123 AMP20 Cells, new, legit, factory direct! for sourcing cells.

It became obvious from reading other stories of people building battery packs, looking at their pictures and the comment stream, that life would be simpler with a the right design, parts, tools and construction methodology. Enter Agniusm's A123 AMP20M1HD-A Battery pack kit. The rich picture set, videos and post stream convinced me this was the way to go.

There appeared an opportunity to snag one of these 12S kits in his first engineering run, so on Jul 26, 2012 I first made an inquiry on availability. Sure enough, he had one, and if I acted fast, he'd have it shipped immediately. So, yea, I coughed up the dollars (the magic of Paypal) and got it in the mail a few days latter, adding my name to docnjoj, deVries, ohzee, 999zip999, eva-michael, megacycle and others taking the unique advantage of the simplicity of great engineering, and tacitly agreeing to being guinea-pigs, as Agniusm perfects his desgin & manufacturing

Index
See HERE for the cost of my pack.

To BMS, or not to BMS, that's an important question for everyone. Really, the underlying question is how to keep your battery pack healthy and thereby extend its life. There's a lot of information on the forum. My favorite is BMS-Free, info for the curious on bypassing the BM-mess and dogman's suggestion that a "human BMS" is a valid approach to protecting a battery, the approach I'm taking. Its part KISS, frugal and more informative.

Jump to HERE for information on how I charge my battery pack.

Cautionary tales of fires
 
So, this morning, I wired up the battery to the Heinzmann hub motor, and gave it a half-spin to see all is well! Boy-oh-boy that felt good! Have a great day folks. :p
Wired.png
 
This is very nice of you putting it together for others to enjoy and learn. I have learned a ton here with ups and downs in building stuff. I have few projects comming, cargo bike, foldable scooter and vw scirocco. Keep them comming folks and just maybe bit by bit we gonna shake off adiction to oil. regards
 
OK, have all the wiring done! Here's the image:
WattsUpWorks.png

Shown are the Heinzmann controller, hand-grip throttle, 500 Watt hub motor, the A123 AMP 12S battery pack, and the Watt's Up meter. I ended up using the simple 4-wire configuration of the meter, from the manual, integrating the circuit using 30 amp Aderson powerpoles as connectors.

I had originally thought to mount the meter on my handle bars, like a fuel guage that I could monitor while riding, but for some strange reason, that didn't work. I think the wires ended up being too long since they have go from battery to handle bars and back to the controller since those are mounted on the rack in the back. Maybe it was some sort of inductance problem, don't know. The manual says something about "long wires" and that short wires are best, so I ended up doing that, which means the meter displays on the backside. But I'll collect the data I need on battery performance which is the critical piece.

Next up is using the Watt's Up as single cell analyser - see:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=41274&hilit=watt's+up
 
Preventing Theft
Of all the existential threats to my battery pack, I place theft near the top of the list. When you live in a dense urban neighborhood that borders on some rather poor shabby places frequented by drug addicts, prostitutes and others driven to destitution by their circumstances, then teft if a very real threat. I've invested heavily, the cost of the cells, the kit, the R&D, the time to build the pack and so forth. So gotta deal with that threat. :twisted:

There are three parts: the bicylce rack, the metal cash box that houses the battery, and a way to secure the box to the rack. Here's the image:
rackmount.png


This shows the assembly before the box gets placed. Four bolts, four holes drilled through the box.

Next up: details on the inside of the box.
 
Thanks all for the many suggestions that made this possible. Completed the build and took my first ride today.
myebike.jpg

With the Watt's Up meter, I see 31.18 AP (max amps), an interesting draw by the Heinzmann. That motor peaks at 33 amps and I had thought the controller was limiting it more. Anyway, the AMP20 battery pack is delivering as much as as fast as the motor wants. :mrgreen:
 
Momentum
It takes no time at all to get a full charge with this battery using the 6 amp Smart Charger. Open up the box, disconnect the Watt's Up meter, clip on the leads, let it go to 100% charge, done. About 10 minutes for 10%.
chargeit.png

Notes
  • No comparison to the old SLA battery which LEVT sold me back in April. They really shouldn't be shipping their otherwise great Heinzmann kit with the over-priced crappy SLA they sent me. Fortunately I got a full refund under the 90 warranty and could move on.
  • My next battery was the the AllCell 10ah, because I thought I wanted something being made in the USA and wanted a built pack. That experience wasn't good at all.
  • The AllCell pack had a tendency to cause intermittency when travelling. My motor would just cut out. Give it a few minutes and it'd kick back in. Not good when going up those hills, the primary reason for this whole exercise. Getting a refund from Chicago Electric Bikes where I purchased it was an ordeal, but with persistance and several months, I did get my money back.
  • With this A123 AMP20 12S pack, I finally get what I need in a battery pack. No intermittency like the AllCell. Lot's of zip - its ability to discharge with the motor's draw is phenomenal. :mrgreen:
 
Depth of Discharge before Recharge
I'm still early in the history of this battery pack and have longevity in mind. My trips are all close to home, the maximum depth of discharge so far is less than 25% of nameplate capacity - I don't know actual capacity. So the question comes up: Should I do several trips before recharge, so less frequent charging -or- should I recharge after every trip, so more frequently? My answer comes from:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

The shorter the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles to prolong life... A partial discharge reduces stress and prolongs battery life.
So I'm going with that recommendation for now. It was Table 2 that really convinced me, that keeping DoD less than 25% gives me far greater battery life. :mrgreen:
 
We D/C our current LiFepo4s to about 60% at most. I have run them lower but not lately. The new A123 pack I have built will only be charged on the Hyperion to 3.60 and D/C to approx 14 amps at most. Our bike routes are set up for about 20 miles so it works quite well at about 13 AH.
otherDoc
 
A Request for Congressional Action
So Wednesday night, I went to Beatnicks on Park Ave for the Democratic watch party for Elizabeth Warren. {Please, no political rants - I'm a Lakoff Dem, meaning I'm BOTH liberal AND conservative, as are most people.} So lo' & behold Jim McGovern walks in the door. Like I'm going to miss that opportunity. Jim knows me well because I've been to his office like a billion times on my mission to lower our collective carbon footprint to "safe" levels, 350ppm, per Hansen, McKibben et.al.

So I say 'hey Jim, how about taking a look at my new toy,'' conveniently parked right outside, as the only way I go anywhere, walking the walk or ebiking the bigE, is by ebike, night or day. I've got like 2 minutes to pull this off, so I immediately go into lobby mode for "factory access to A123 cells" {see petition.} I'm like 'we the people have to save this company from Chinesse ownership.' There has been so much technology off-shored so completely the communists end up owning it, for jobs for their people. So anyway, its the usual silence and polite political comment of 'I agree and all, but...'

I'm asking again to sign the petition for factory access in Livona, Michigan. But I'm going to carry the peition first to Jim McGovern. Its like the American people own a piece of AONE, but not really, because of all the direct DOE grants, loan guarantees and tax credits. I've got to get my AMP20 cells from China, recycled? Com'on, give us a break will ya? This has got to be the effort of EVERYONE on this forum, however. Its in our collective best interest is it not? Sign the petition already will ya? Great, thanks! :mrgreen:
 
docnjoj said:
We D/C our current LiFepo4s to about 60% at most. I have run them lower but not lately. The new A123 pack I have built will only be charged on the Hyperion to 3.60 and D/C to approx 14 amps at most. Our bike routes are set up for about 20 miles so it works quite well at about 13 AH.
otherDoc
Thanks for the recommendation, docnjoj. So if I'm gett'n you, keep the AH lower than max on charge and staying in a safe range. If I'm only going to use 5 AH on my trips, make those the 14 AH down to 9 AH? Is that right?
 
I can get 18ah out of my pack for use on a bike. Charge on my 1420 to 3.59v per cell. I don't go down to 18ah. I did it as a test. As at that point the battery feels weak. 3.0v at rest. Don't have a voltage at that point under load. So no bms or alarms Arkmundi ? O.k. I was able to download your thread. You will find a lower cell and put a alarm on those cells.
 
arkmundi said:
docnjoj said:
We D/C our current LiFepo4s to about 60% at most. I have run them lower but not lately. The new A123 pack I have built will only be charged on the Hyperion to 3.60 and D/C to approx 14 amps at most. Our bike routes are set up for about 20 miles so it works quite well at about 13 AH.
otherDoc
Thanks for the recommendation, docnjoj. So if I'm gett'n you, keep the AH lower than max on charge and staying in a safe range. If I'm only going to use 5 AH on my trips, make those the 14 AH down to 9 AH? Is that right?
Not really. You should charge to a reasonable level if for no other reasons than wind or a desire to go further. The figures I gave are already very conservative but take into account possible extra use. I also have a LVC @3.00 built by kfong. Very useful as it cuts off slowly and uses the lowest cell value at that point. Check out his sig in his posts if interested.
otherDoc
 
FYI, just bought a second set of cells from Victpower for $16.50 a piece, half-tab of course. This is a really awsome price for a truly awsome battery. I'm planning to double my range when I need it, which is not often. I'll alternate use of both packs and have comparative data. So, I'm also doubling the life expectancy. I expect this setup will last me 10-15 years. Its also redundancy, should a pack fail for some reason. :mrgreen:
 
First crash test
Coming down Highland and a car coming out of a store parking lot hits me straight on. Me and my ebike are laid out on the pavement. Thank god the battery is OK :!: haha {maybe not true - see below}. All the prep in casing the battery paid off as there is no damage at all, excepting scuff marks. Both wheels are bent, however. My hip took the impact, went to the hospital, took xrays - no broken bones, just a "deep tissue concusion" that requres pain medications.

I posed a few questions on this at http://endless-sphere.com/forums/viewtopic.php?f=7&t=43573, the question being how much for "Pain and Suffering?" I spent the day laid out at home and looked online for information on this. As an "intangible" its up to me to say exactly what that was, so:
  • the actual pain which the doctor says can last upwards to 2-3 weeks
  • a day lost at the hospital, in taxis, at the pharmacist, etc.
  • the "emotional trauma" arising having to be afraid everytime I'm on my ebike having to share it with cars; I went car-free because this outmoded form of transportation is a menace to man and nature; make that "extreme menance and social ill"
  • time the my ebike is in the shop for repair means my primary form of transportation is unavailable
I'm thinking millions :twisted: haha. No, research says an unreasonable claim will be cause for dismisal. Anywhere from 1 times to 5 times "specials" like medical care and lost wages. So I'll wait for a couple weeks, collect all my bills and submit a claim for those plus, I'm thinking 3 times. Anyone with any experience on this? Thanks.
 
Probably time for a lawyer if the person in the car has insurance( or doesn't). Also take pictures of your injuries and the bike.
otherDoc
I'm glad that both you and the battery survived! Heal well.
 
The Third Front
To: The guy who hit me on my bike September 14th on Highland Street (and every other driver of an ICE based vehicle on the road).
You're laid up on pain meds after being thrown to the pavement, what are you going to do? Research how much of a claim to put in with the insurance company for that intangible called "pain and suffering." Being a climate protection advocate that walks the walk and bikes and uses our bus & train system, I gave up the luxury of owning an ICE (internal combustion engine) last year.
The average weight of car is 4000 lbs (http://answers.ask.com/Vehicles/Other/how_much_does_the_average_car_weigh). That's upwards to 2 tons of metal being hurtled down the road, a containment device for explosive forces and protection from collision, protection for you that is. Think about that, the absurdity of it. All that energy, all the injury and death, all those greenhouse gases being released into the atmosphere, all the wars we fight for access to petroleum. All of that is "pain and suffering." In the warmest and most extreme weather year on record, why is everyone not going car-free? We're heading into a world of hurt for our and all future generations.
The true cost has to be added up and passed to those most responsible - drivers who continue to choose this outmoded form of transportation. I believe the future belongs to light electric vehicles. But, only if we can get more on the road and less of those death machines that are a menace to man and nature. So, we need a third front of incurred costs.
The first cost is the cost of the vehicle itself and all those costs to keep it in good repair and on the road. The second cost is the cost of fuel, which will become ever more expensive as we deplete the world of oil. The third cost is the cost of insurance. Its the third front you and every other driver will need to face down as bicyclist like me, on a mission to rid society of this menace, hold out for the maximum amount for "pain and suffering." You see, its not just my pain and suffering, but all future generations of human and non-human that will continue to suffer from your bad choice, society's bad turn.
----
Note: I'm submitting this editorial to my local newspaper - constructive critiscm welcome.
 
Sounds like the pain meds are working! :shock: I suggest you get a lawyer first and hold the editorial till you are feeling better. Seriously.
otherDoc
 
A couple thoughts:
1) There are several places where you can get automobile carnage statistics. I think USC Centers for Disease Control (CDC) has links to an authoritative source. If you poke around you'll find a query able database that tells you just how high the carnage of motorized traffic is: Cars are the top killer of Americans under age 40 - and accounts for about 50% of all deaths in that group (i.e., it kills as many as all other causes combined).
2) Poke around google some more and you'll find that automobiles kill about 94 Americans a day - down from 100 a day a few years ago - and that this ~100 people a day toll has been pretty constant the last 50+ years. In other words, motor-terrorism kills as many Americans each month as the Sept 11 terrorists... only the motor-terrorism happens again and again, month after month.
3) Be clear about what the real enemy is. It's not ICS versus electric, you could have easily been left-crossed by an all-electric Nissan Leaf. The enemy is the absurdity of using 4000 lbs of vehicle to get a loaf of bread. It's true that electric cars are typically lighter than ICE due to battery limitations, but they're in the same weight/size class.

I wish you well on this endeavor.
 
arkmundi said:
First crash test
Coming down Highland and a car coming out of a store parking lot hits me straight on. Me and my ebike are laid out on the pavement. .....

Oh how I feel your pain!!! I just took a anit-inflam/pain killer myself to help with my swollen wrists and hand as I sat down to write this response. I am so sorry you have been hit. :evil:

I don't have any experience with e-bike law suites, but with the amount of ridding I am doing now (20-30 miles per day) I am anticipating learning all about it in the coming years. Please keep us posted on how yours turns out. It could help us all.

It is amazing how the car drivers just don't give a rats-ass about bikes! I was entering a parking lot yesterday on my bike. As with my accident I was in the proper lane following traffic laws. When I entered the parking lot some woman came whipping around a corner of the lot and had to slam on her breaks to keep from slamming into me. :evil: :evil: :(

If I had entered that lot about 1/2 second later I would have been you.

Like you, a good part of my motivation to go electric was to divest my self of oil usage as much as possible. I want to be the change I want to see in the world. (Thanking Gandhi for that!) We may still need tires and plastic parts on our bikes, but that doesn't mean we have to burn oil. It is going to take time to get there, their just has to be enough of us to make trouble for the local city councils to get bicycle-awareness going and get things like dedicated bike lanes.

But even with a heightened bicycle awareness movement, we will still need to protect ourselves from the oblivious drivers who think that they are the only vehicle on the road. :x

Sorry for your pain. I hope you heal soon. And please keep us posted on you law-suite.
 
I feel your pain arkmundi. I had several calls calls with cars. All of them either texting or not paying attention. How fast were you going on your bike ?
 
Hearing a lot more crash stories lately... don't like it...

Umm first up, yah I reckon seriously rethink the open letter/article thing... Rants are best not aired whilst under the fire of fury unless you are well practiced at it... Tend create more Ire than change....

Okies... some other stuff...

Last serious automobile accident I had was on a motorcycle... after 30 years of motorcycling it was my FIRST serious automobile accident.

I survived for so long because no matter how I wanted to educate "cagers" (car drivers) I realised it would never happen... yeah occassionally a car driver will get serious about riding bikes and change their abilities re consciousness of other entities on the road, but it is not the norm.

As such, survival becomes paramount when you are more squashable than your fellow road users.

This means that...ultimately, you need to assume that no-one can see you... full-stop... or "period" as you Yanks say.

this does not mean that riding stops being fun, but it means that you cannot rely on anyone else giving a shit about you, except you.

That don't mean that you wont be seen by ANYONE or NEVER given due courtesy, it happens all the time, but at no stage can you rely on it, and when you are lying on the pavement, your "right of way" is small consolation.


Joe
 
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