A123 - Battery newbie. Some questions.

[inkeeper77]

So I started a thread on SLA batteries and was quickly turned away from them. Due to needing high safety I have basically decided on A123 batteries. Is this based on old information? I will be charging them in a dorm room, and need them to be SAFE.

I am working on setting up a Yuba Mundo build with this kit: http://urbancommuterstore.com/M-Drive-Conversion-Kit-for-Yuba-Mundo-V33-V4-YM-MDRIVEKIT.htm

I read a fair bit of the stickied link to the A123 care and feeding thread ( http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=2498 )

What I have not been able to find has been recent information. That thread is mostly from 5 years ago. Are the 10 cell dewalt packs still the best place for cells? And the links to the chargers do not seem to work anymore. I need to be able to figure out what is the best way to get the safest cells today, and the safest chargers for them. (I want to balance charge them)

Requirements: 36+ volts (preferably more), and high ah high capacity. I will probably be running them in parallel and maybe carrying more along in order to extend range. I will also want to run them in series for speed runs, if they are at 36V. If I could make the packs modular and could change up voltage and also ah capacity at will that would be perfect. I dont mind charging many small packs instead of less large ones.

Is A123 obsolete now?

Thanks!

 

[Joseph C.]

So I started a thread on SLA batteries and was quickly turned away from them. Due to needing high safety I have basically decided on A123 batteries. Is this based on old information? I will be charging them in a dorm room, and need them to be SAFE.

I am working on setting up a Yuba Mundo build with this kit: http://urbancommuterstore.com/M-Drive-Conversion-Kit-for-Yuba-Mundo-V33-V4-YM-MDRIVEKIT.htm

I read a fair bit of the stickied link to the A123 care and feeding thread ( http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=2498 )

What I have not been able to find has been recent information. That thread is mostly from 5 years ago. Are the 10 cell dewalt packs still the best place for cells? And the links to the chargers do not seem to work anymore. I need to be able to figure out what is the best way to get the safest cells today, and the safest chargers for them. (I want to balance charge them)

Requirements: 36+ volts (preferably more), and high ah high capacity. I will probably be running them in parallel and maybe carrying more along in order to extend range. I will also want to run them in series for speed runs, if they are at 36V. If I could make the packs modular and could change up voltage and also ah capacity at will that would be perfect. I dont mind charging many small packs instead of less large ones.

Is A123 obsolete now?

Thanks!

cell_man from http://emissions-free.com/ is the place for new A123 battery packs.

A123 is far from obsolete. There are better cells out there but nothing is available to the public yet to trump them as a consumer product.

 

[dogman dan]

Due to the cost of A123's, plus the need for a large capacity, you might find the most economical solution to be a pingbattery.com lifepo4 battery.

Don't misunderstand, I recomend Cellman constantly, particularly for those who want only 10 ah or so. If you go to A123, and want big range, then talk to cellman about a pack made from A123 pouch cells. That's the gold standard for an Ebike lifepo4.

But chances are, a pingbattery of large size is going to be more affordable. Something like a 48v 20 ah would carry great on the top rack of a cargo bike. Or if you are going 36v, maybe a 36v 15 ah, followed later by another the same size when you can afford it. That would be about 50 mile range.

One last thing, know your A123 supplier. Putting an A123 mark on a 1 buck cheapo lifepo4 round cell is real profitable. Since the seller is in China, have fun complaining about it.

 

[dnmun]

a controller set up to run on 36V will not work at 72V if you think you can swap them into series. the excess costs of having two packs instead of one should cause you to realize it is simplest to just buy the one pack and build the bike around it.

if you wanna go fast, then buy a 48V ping pack.

if you cannot take the bike inside, you will need to protect it from the weather when raining and your pack will have to be removable so you can take it inside to charge.

 

[cell_man]

I agree, pick a voltage and stick to it. FYI 1 of my A123 20Ah pouch packs is about 20-25% more expensive than the equivalent ping. They are at least 10% lighter, cells have much higher discharge current, BMS can accept 10A charge rate, not limited to 5A like the signalab BMS. 36V is enough to go pretty fast with the right motor if you don't need the capacity of a 48V 20Ah pack.

 

[dogman dan]

I have no data on prices of the pouch cell A123 packs. Ability to fast charge is a game changer, but fast chargers do tend to be somewhat expensive and bulky.

Two 48v 15 ah pings would carry rather nice, and since it's two, could be charged at 5 amps each with his larger charger. Charge time, about 3 hours. That would, in effect, charge a 48v 30 ah battery at 10 amps. So you'd have a ride 50 miles, charge three, ride 50 more capability. With the right gearing, 48v will be plenty fast for cargo bike needs.

If you have the cash though, buy at least one cellman 48v 20 ah pouch A123. Then maybe add extra range with a ping, or whatever later. No way to compare the capabilities of a ping vs A123, The A123 wins in every category. But just saying, if you are planning on carrying 20 ah anyway, that gives you plenty of amps for a 1000w bike.

Have you seen Cellmans website? He's definetly on our trusted vendor list. http://www.emissions-free.com/catalog/i29.html
That links to the battery I'd like for a 12 mile ride at 20-25 mph.

 

[inkeeper77]

Thank you everyone! I now have a much better idea of where to find things!

Now, a couple replies: As for switching voltage, that makes sense. I will probably just go with 36v packs then, but I will still be switching them on occasion- I have been talking to the kit manufacturer, and the controller I will be using is programmable. I will not mind having to hook it up to a laptop prior to switching over to a speed setup. He says this will work just fine.

I have already been planning on removable batteries, I am thinking about building narrow battery enclosures that run along the inside of the rear deck, capable of being stepped on. That will keep the weight low and out of the way. (This is another reason for me to consider making my own batteries) - I could easily split the weight evenly on each side of the bike.

I will be taking this bike inside almost all of its life, but it will be in just a parking garage for a couple months. (Batteries will be moved inside when not in use, and I am capable of designing an enclosure suitable)

I think I will have to look into how to build up the batteries myself, as I can solder and do not care about looks. I am not sure yet though. Whatever I do, I will post up a build log!

 

[inkeeper77]

After further googling, I think i have found someone doing exactly what I want. http://www.pedelecs.co.uk/forum/electric-bicycles/5098-building-small-a123-battery-pack.html

Since the cells are only $6 each plus shipping, so I could build 8 of those 6 cell packs for under $300. That seems like a good price to me. I would rather keep away from the BMS circuitry as it seems expensive, and I do not mind being limited to a slow to use balancing charger.

If I did this type of setup I could easily use 6 cell packs normally but also make up a couple 4 cell packs to put into series for a speed run etc- My systems operating range is going to be from about 30 volts to 72 volts. Materials would be rather cheap.

If I wanted I could even use a 2*7 cell pack for a 50v battery. I like this idea, as it fits my modular ideal until I decide what fits the bike best. (Though I think 6 cell packs would be easier to get a balancing charger for)

QUESTIONS:
1) For the balancing, do the balance taps have to be in any particular order? His were all black, but I would normally assume that they would have to be in order, unless the chargers are smart enough to detect what is going on..
2) Chargers. Not a crucial question, I can easily search it, but for any application like this, what should I be looking for? If you have anything in mind that is that you would recommend. (I like the idea of more durable balancing connectors than the ones in the project thread I linked to)

 

[biohazardman]

Nothing wrong with the a123 M1 cells. They are not as easy to find and the prices are a bit higher these days. I have built a few packs and found that they are great near bulletproof long term and seldom need balancing. Once the cells are glued together, without all the plastic, the footprint is smaller so is the way I used them. Found also that building up the voltage with the 36V and 28V packs or a combination of the two was easy as I did not need to alter the original welded on tabs just solder the outputs to parallel or series them as needed. I use them in a 2P 66Vconfiguration at the moment and get very little battery heat generated from my 45A controller. I have built one of the TPpacks V2.3 BMS units, great foolproof unit, and my brother uses it on his 48V system. I keep track of my 66V packs, Check them every month or so now days and balance when needed which is seldom. I have over-charged to 4.2v cell and over-discharged to .8V per cell with what seems to be no damage as yet some year or so later. So, although they weigh more and take up a bit more room than the Lipo packs, I highly recommend them to say the least.

48V with balancing rats nest

52V without balance wires

66V spare pack for the backpack

 

[sangesf]

Inkeeper, for the same price as your a123 cylindrical pack, you can have a ping pack of slightly higher AH (10Ah as opposed to 9.2Ah for the A123s) AND it comes with a BMS AND charger.

What kind of range are you looking for...
With either of those packs, figure only 15 miles at 20mph.

 

[tef]

just my experiences:

In 2009 I bought two 36V 20Ah Ping packs. After max. 30 cycles (30A ebike controller) more and more cells were leaking. A few cycles later nearly all cells were swollen or leaking and I had to throw them away.

I installed 3.2kwh of used A123 18650 and 26650 cells in my scooter and had absolutely no problems so far (11000km). I just installed a lvc/hvc circuit and connect a balancer every 1000km but there is hardly any cell drift.

tef

 

[sangesf]

Everyone's experience is different...
Perfect example is me...
Except for ONE battery (back in 2008), every new "duct tape pack" (not ping, never bought one), I've ever gotten has worked flawlessly and never had a problem....
Some people have 50/50 chance of getting overrated packs, I've been lucky to get underrated ones...
(15Ah has been 15Ah+.. 20Ah has been 21ah+, etc.)
But then again, I never use a pack that's less than 1C then the controller I put it on..
Example: 15a controller on 20Ah batt, 20a controller on 30Ah batt, etc.

 

[dogman dan]

Not suprised that a 20 ah ping got murdered by a 30 amp controller. Those pings are good for 20 amp controllers or less in general.

I nearly killed a brand new 15 ah ping on the racetrack with a 20 amp controller. Just the way I was riding was enough to beat the snot out of it. 13 big fat amp spikes every .8 miles for 12 laps made it sag like the granny's tits.

Fortunately, it rebalanced ok, and is still in use almost 2 years later. But from that day on, it never held a surface charge again. Drops to 56v very quick after removing the charger.

It's not that 2c lifepo4 cannot last. It just has to be used at closer to 1c to count on it lasting. Do the same thing with A123's though, ( discharge at half the specified c rate) and you have a lot more ability to run a big controller. Hell of a lot better C rate. Obviously a high c rate is the way to go, if you want lots of amps from a small pack.