Zippy Flightmax / Turnigy lipo testing

[liveforphysics]

So, would asking for 10s 10Ah packs be a happy medium for you guys? That way it only takes 4 packs to make a 20s 20ah pack, and weenie bike guys could run a single pack as an alternative to the commonly sold ultra wimpy 36v LiFePO4 packs.

I'm guessing hobbycity is just going to want to know the number of packs I'm going to order to see if its worth there time. Then I imagine they will also want to know how we want the cells to be stacked together. There are a lot of ways to stack 20 cells together in a neatly shrink wrapped bundle.

Input on how you guys would like the cells configured? In my own packs I do stacks 40 cells high, one on top of another, just using 8 x 5s packs in a stack. Any special way you guys would want them to be laid out?

[Ypedal]

With 10ah cells, 5s would be my personal preference.. And i'm in at any time for at least 20 cells...

[Hyena]

Yeah I think 10ah packs would be good, even if still in 5 or 6S configuration.
They'd wanna lift their QC game though.

[ktm_paul]

So, would asking for 10s 10Ah packs be a happy medium for you guys? That way it only takes 4 packs to make a 20s 20ah pack, and weenie bike guys could run a single pack as an alternative to the commonly sold ultra wimpy 36v LiFePO4 packs.

I'm guessing hobbycity is just going to want to know the number of packs I'm going to order to see if its worth there time. Then I imagine they will also want to know how we want the cells to be stacked together. There are a lot of ways to stack 20 cells together in a neatly shrink wrapped bundle.

Input on how you guys would like the cells configured? In my own packs I do stacks 40 cells high, one on top of another, just using 8 x 5s packs in a stack. Any special way you guys would want them to be laid out?

10S 10Ah - I would be interested in 8 to 12 of those packs. When do you expect a response from HC?

[mwkeefer]

liveforphysics,

whew... glad HK responded (didn't like their response) but then I did the math, of 30 possible good cells I have currently 24 working re-configured into 2X12S 5AH packs. It is very likely that I can pull the 4 remaining good cells from the 2 puffer 3S packs for a total of 28 working cells of 30. The cost is still 1/3 that of other brands even with the 2 bad from go cells.

I am glad because you have suggested a viable solution to the HK problem. If you can convince them to build / offer larger packs for our demographic market then it serves to reason that the quality control would be higher from HK (we would buy more cells than hobby guys do in the long run, making us a larger target demographic). Add to that your "valued customer" rating and you just might have the trifecto needed.

For one I would be in at 10S or 12S, 5-10-15-20 AH.

Ultimately layout and size(s) should be dictated by mounting locations and ranges so:

On 26" specialized I can cram 12S15AH under the main frame tube (yep right under the family, well u know). I could go a bit wider but length and form of the pack becomes an issue.

If we could come up (I have most of this data and will post if helpful) with minimum average frame tube mounting clearance and crank inner clearances then we could design optimal pack to fit center tube on majority of conversions and builds.

Additionally building some packs as 12S5AH or 10AH into common smaller SLA sizes (as in GoPed ESR 750 EX dimensions) would be great for all the other available mounting locations such as rear rack, side bags, handle bar bags, etc).

I would look at 10S being the most commonly available higher end lipo chargers are designed for 10S at max.

Personally I would prefer 12S at minimum, I know someone else posted in the limits on the 9C style hubs but I have tested and they are 100% a OK running at 50-65v pulling as high as 3000 watts so 12S is actually a tradeoff since these things fly when you run at 15S but cut the charge out at 4.15v per cell (a little lower than what I think you recommended for these so the lifespan should be good).

Please let me know if you are planning a purchase as I would happily go in on it since the quality should be higher if purchased your way or if the packs are intended for "US" ebikers.

Thanks again for all the info!

-Mike

[mwkeefer]

Everyone,

Because of HobbyCity's replacement policy on bad lipo batteries, please:

1.) If a package has any damage to it, AT ALL... REFUSE DELIVERY and RETURN TO SENDER! - This would not apply if you were just ordering gold 4mm connectors, epoxy, etc. but when your ordering lipo, electronics (of any kind) or motors from HobbyCity (or any other overseas operation) your best option is to refuse delivery (and pay with credit card / paypal)

2.) Before charginng anything, before even connecting to a charger... use a digital volt meter and test the discharge plugs of your lipo packs for proper voltage. If you have a pack that tests 0v at the plugs then you have bad pack, move on to the next pack.

3.) If all your packs test within specs at discharge plugs then it's time to check at cell level. Using the same DVM, test the voltage at each tap in your balance plugs. With lipo, each successive cell you read should add between 3v and 4.2v to the total sum voltage. If you find a cell below 3v, you have a bad pack (actually only a single bad cell but if you want HK to replace its all the same) and need to finish testing all your packs then move on to step 4.

4.) If your here... we all feel for you (I am not just saying that).
Because of the HobbyKing return / replacement policy on LIPO packs you need to think about how to proceed very carefully!!!
The safest thing to do is simply contact HK, inform them of the number of bad packs you have received and inform them that you have done nothing with them yet but test the voltage using a DVM. They will instruct you on how to return ship the item(s) to them for testing / replacement.
** (someone should start a thread to report receipt of bad packs, having a public log of bad cells and hobbyking's replacement would be a benefit to all of us))


If you are bold, just dont care or are not about to ship a 30.00 pack back to China on a slow boat (since it would be illegal to ship lipo via Air and ground is not possible - would require hazmat certification anyway) or just impatient and figure you can fix anything then...

Order some aluminum solder and rosin and crack out the high powered soldering iron!!

Most of the time, packs which test as 0v are actually fine and have just been shipped (assuming a non-damaged box was received) with broken solder joints somewhere in the pack. Unwrapping these types of defective packs and resoldering may not even require aluminum solder. On this type of break, normal rosin core solder works fine. Just repair the defective joints and let the packs cool.

On the 0v packs it is also possible that one of the cell tabs (weld tabs, but soldered after crimping?) has broken. This will require aluminum solder and flux to repair (or a spot welder if enough tab is still exposed).

I will publish my personal experience repairing these packs (and blowing two up - ok, puffing them out not blowing them up) along with pictures either to help you repair your packs or (if your smart) to scare you into just sending them back to HK!

Hope this helps, would have helped me!

-Mike

[drewjet]

Either 6 series or 12 series, as 12 is the maximum with the castle HV ESCs.

A bulk buy of bare cells would be sweet too!!

[liveforphysics]

Everyone,

Because of HobbyCity's replacement policy on bad lipo batteries, please:



1.) If a package has any damage to it, AT ALL... REFUSE DELIVERY and RETURN TO SENDER! - Bahh. I've never had a something arive damaged, and all the boxes look like the mailmen used them for a soccer match. Open the box, take a look. They pack my large LiPo orders in multiple layers of foam, wrapped in bubble wrap, and double boxed. The box can look like hell and the LiPos are all fine. This would not apply if you were just ordering gold 4mm connectors, epoxy, etc. but when your ordering lipo, electronics (of any kind) or motors from HobbyCity (or any other overseas operation) your best option is to refuse delivery (and pay with credit card / paypal)

2.) Before charginng anything, before even connecting to a charger... use a digital volt meter and test the discharge plugs of your lipo packs for proper voltage. If you have a pack that tests 0v at the plugs then you have bad pack, move on to the next pack.

3.) If all your packs test within specs at discharge plugs then it's time to check at cell level. Using the same DVM, test the voltage at each tap in your balance plugs. With lipo, each successive cell you read should add between 3v and 4.2v to the total sum voltage. If you find a cell below 3v, you have a bad pack (actually only a single bad cell but if you want HK to replace its all the same) and need to finish testing all your packs then move on to step 4.

4.) If your here... we all feel for you (I am not just saying that).
Because of the HobbyKing return / replacement policy on LIPO packs you need to think about how to proceed very carefully!!!
The safest thing to do is simply contact HK, inform them of the number of bad packs you have received and inform them that you have done nothing with them yet but test the voltage using a DVM. They will instruct you on how to return ship the item(s) to them for testing / replacement.
** (someone should start a thread to report receipt of bad packs, having a public log of bad cells and hobbyking's replacement would be a benefit to all of us))


If you are bold, just dont care or are not about to ship a 30.00 pack back to China on a slow boat (since it would be illegal to ship lipo via Air and ground is not possible - would require hazmat certification anyway) or just impatient and figure you can fix anything then...

Order some aluminum solder and rosin and crack out the high powered soldering iron!!

Most of the time, packs which test as 0v are actually fine and have just been shipped (assuming a non-damaged box was received) with broken solder joints somewhere in the pack. Unwrapping these types of defective packs and resoldering may not even require aluminum solder. On this type of break, normal rosin core solder works fine. Just repair the defective joints and let the packs cool.

On the 0v packs it is also possible that one of the cell tabs (weld tabs, but soldered after crimping?) has broken. This will require aluminum solder and flux to repair (or a spot welder if enough tab is still exposed).

I will publish my personal experience repairing these packs (and blowing two up - ok, puffing them out not blowing them up) along with pictures either to help you repair your packs or (if your smart) to scare you into just sending them back to HK!

Hope this helps, would have helped me!

-Mike

[liveforphysics]

I'm starting to grow fond of the idea of packs of 8s.

Before you start throwing things, it means you can run 24s to make the most use of the 100v FETs, much like Methods does with his 24s setups for hubmotors.

With 10s packs, you can't make full use of IRF4110 modded controllers.

It also gives a fair mid point voltage for regular folks who would want to run a sane 16s setups. The folks who squat-to-pee could even run it at a 29v pack at 8s.

It lets the 1020b charger, which totally kicks ass be used, because it sadly has an 8s limit, unlike it's little brother the 1010b with a 10s limit.


I will see if they will be willing to make 2 types of packs. An 8s 20Ah pack for the nuts who want to run 100v (88.8v nominal) hot off the charger, and 10s 10Ah packs for folks who are looking for 84v hot off the charger (74v nominal).

I will tell them I'm looking to order 20 of each type of pack perhaps? I could front the cash for the order, and show you guys the invoice so you could see that i'm not trying to make a petty profit from this, and then send them to the people who want them. Having them know they will sell at least 20 of each pack right off the bat seems like it would make them more likely to make custom packs for us.

[liveforphysics]

Just to give some very rough ball park pricing, I generally pay ~9$ per 5Ah cell when I buy from them with my special prices.

If I can get them to do ~$8 per 5Ah cell, then a 10s 10Ah pack would cost $180. 8s 20Ah pack would be $256

If I can get them to do ~$7 per 5Ah cell, then a 10s 10Ah pack woudl cost $140. 8s 20Ah pack would be $224

Perhaps wishful pricing, but if we could get $6 per 5Ah cell, then a 10s 10Ah pack would cost $120, and an 8s 20Ah pack would be $192


Battery leads could be a problem though. I use silver plated ultra fine stranded 2awg and 4awg in the packs I build when I combine LiPo packs. This is because I want my packs to handle 400-600amps with minimal voltage drop. The little 8awg stuff they build packs with isn't going to cut it.

[mwkeefer]

liveforphysics,

even at 9.00 per cell, if the cells work... I think everyone could live wih that price point, for 100% alive and useable 5AH lipo cells. If that price could be had lower, obviously that would be better (even an idiot like me can see that) but not really all that important (from my humble perspective) as it would be the additional quality assurance that would more than make the HK cells worth 9.00 ea without question (if the cells were all okay).

In terms of wire, the 3S 20/30C packs I received were all terminated with silicone jacketed 10 AWG but really does it matter even?

Won't we just be building these into mega packs and as such shouldnt we make a new terminator PCB for our packs (to pack them deeper) and then parallel them with a bussbar of some sort (I am partial to 1/8" copper tube, smashed flat in vice and drilled / tapped for discharge leads.)? Not that you are not 100% correct 12 AWG, or even their 10 G will not suffice @ 300-400 amps but again I come back to our needs and for most (myself included) I would think most people wouldn't want to pull more than 100-125 amps max. Just based purely upon available current controllers, 100-125 is approx the theoretical limit of our FETs in applications such as the Infineon and the CC HV110 Controllers... yes you can massage more from them but unless you are drag racing with dual hubs or a terminator RC drive system I can't see the need, use or streetability of larger discharge than 100-125 AMPS.

I am also certain you will correct me on this last part as I know of several people who are running such high amp rates as you speak of, the thing is they are like yourself... elite, the common rider (even agressive or offroad) should not need such high drain rates.

To finish, I think that cell quality needs to be the paramount concern (specifically no DOA packs) followed by higher capacity (10ah) cells if possible, price would be a third concern (at 9.00 per cell non DOA, even for 5AH capacity price is not an issue) finally I would worry about super high discharge ability but the question there becomes... do we trust HK with the final pack assembly (if we don't then discharge or interconnects would be on us and a non-issue since we can do what we want). If HK is to assemble and ship these packs then I would suggest 8G as a starting point that would cover 90-95% of users requirements. Personally I would like the discharge ports to be recessed into the pack and essentially surface mounted to the terminating PCBs, on my rebuilt HK lipo pack (12S10AH) I use4mm gold terminator plugs mounted to the PCBs in this way. To parallel the two sides of the pack (each 12S 5AH) just made a 10 AWG parallel harness with 2x male 4mm on one end and 1x female 4mm on the other. My pack never gets hot (I have pulled peaks of 58 amps through it so far) and ranges between 15-40 AMPS under my average use (30+mphh, huge hills, etc).

What do you think? I mean for "most" of the consumer and enthusiast market, is 300-400 amps really a requirement? You do know this stuff far better than I.

-Mike

[mwkeefer]

Liveforphysics,

Sorry... somehow I missed the 8s / 10s posting above. Yes you are correct about the maximum voltages for 8s vs 10s and even 16s for us sane people. The HV110 still can't really handle much more than 140 AMPS max (in my testing) before blowing fet boards. The modified 9,12 or 18 FET infineon controllers would handle (obviously) the load at varying voltages.

The only real remaing question would be shipping, you are in the states right? So you would hazmat via UPS ground right? That's going to add about 40.00-60.00 us for the hazmat surcharge in addition to normal UPS rates (I am sure you have an account and get a good discount). Would it not be simpler if HK is building the final packs to just have them drop ship to the intended recipients?

No matter what, consider me in for atleast 2 of the larger packs (of the 20 pack order). I will be happy to paypal in advance once you have pricing info.

So far as you making a profit, lets be reasonable... I hope noone here expects you to do this for free, you should make a reasonable profit for this transaction or there isn't any real insentive for you to do it! (that's how I see it, unless you would do it just to get HK making these packs available to us all). Personally if you can get them for $5 ea per cell and offer them to us at $7-8 per cell I think that would be fair and should make it worth your while (in so far as you atleast would glean a few free BIG packs from the deal).

PM me when you have details about payment and I will send $$$. I would suggest anyone else who is serious about getting in on this order posts a similar pledge based upon the initial pricing levels indicated by liveforphysics. If this is going to work, please only express pledge if you really are serious about ordering these packs (as opposed to just interested in them) because non-committal pledges is the fastest way for a deal like this to fall apart.

-Mike

[nomad85]

regarding shipping... why pay more? USPS flat rate... no one has to know whats inside.

For me 10-15Ah cell would be awesome, I would prefer a slimmer profile so I can mount them in my xtracycle freeloaders(side pouches) 5s 10-15Ah packs would be awesome, I would get at least 3. 2 8s packs(16s) would push me over 63v off the charger which is the most my controller will handle, this would be true for many people with more basic controllers.

[CNCAddict]

Hmmm, as for the wiring. Multiple wires are commonly used for higher currents. If you need more current, just solder on additional 8ga wires till you arrive at the resistance you want. Hobbyking isn't going to be an expert on terminating 6 or 4ga wire inside a lipo pack. You can't solder something that large without dumping boat loads of heat into the cell.

I also think this first time we should ask for the absolute minimum, if they even make the 10AH cell for us then we have won. But if we start out asking for the sun and the moon, then chances of them taking us seriously go way down IMHO. Remember, HK is selling almost every pack they can make right now....so convincing them to tool up to make some oddball large cell might not be high on their list of priorities.

[TPA]

USPS flat rate... no one has to know whats inside.

USPS has started asking specifically about lithium in some places.

if you say no and get caught.....federal offense.

[mwkeefer]

The problem in the states with lithium based batteries is that the federal laws changed recently (well not so long ago) and now you must be hazmat certified to ship anything with more lithium in it that basically a cell phone... the exact weight a "normal" person can ship doesn't matter because it is far less than even 1 lipo 3S pack.

You are correct that some post offices are now asking specifically about lithium content but... it doesnt matter if they ask or dont, the federal law is the same and once you have put lipos in the mail (of any kind, ground or air) you have violated at a minimum 1 federal law but more likely 3-5. The feds are funny like this.

In terms of jeopardy, trust me on this... its not worth it. If the NTSB or the FAA (if shipped via air which is illegal anyway) catch you or even catch onto you (as in, you have shipped this way) they will prosecute / fine you. These are not little fines!

As an example an unnamed friend of mine got hit because of this for shipping lifepo style packs using air freight (UPS I think). In either case the FAA is involved and has levied fines in excess of 100,000.00 US against him. No, I'm not making this up... As I have been dealing with Segway lithium batteries for years now and the fight to get the FAA to allow generation 2 (i2) Segways with the Lithium Ion Saffion (basically a lipo) batteries onboard aircraft. They will not budge and those packs have correct UN testing for Hazmat. In either case, since the change in laws... every Segway dealer was required to undergo hazmat certification to be qualified to ship the liion batteries back and forth for repair/replacement to/from Segway USA.

My advice... stay legit, find someone who has Hazmat certification and can safely and legally ship lipo/liion packs via Ground and no matter what take my word on this, Federal law, fines and prosecution is NO JOKE!

-Mike


PS: When coming from HK, no legal issues arise as China and Hong Kong are not subject to US laws and so receiving lipo via EMS or UPS or USPS via HK is not in any way shape or form illegal, return shipping them may or may not be (could not get clarification from postal rep I know) but shipping via air from the US to anywhere in the US or outside would violate the laws and they could come after you for it. Remember the feds are slow, so you may ship batteries now and not get the knock on the door for 2-3 years while they investigate many other alike crimes and build cases against many people to make examples of. This is how the fed works, so if you do go ahead and use USPS or UPS or ship via AIR and get caught... don't say I didn't warn you = )

[spike]

I'm in for at least 2 of the 10s 10Ah packs if they can be shipped to Australia. I can be by PayPal or direct bank transfer.

[BenMoore]

I'm not sure if this discussion includes 10Ah cells or simply new parallel pack arrangements of the 5Ah ones.
It would be good to know HCs minimum order for a 10Ah cell production run. As well as improving 10Ah battery pack simplicity and reliability they could be slightly cheaper and lighter per Wh than the 5Ah cells.
Personally, I'm in the market for at least 700Wh of cells but haven't settled on my new pack voltage or preferred capacity yet and am in Australia also.

[liveforphysics]

I was definately thinking banks of 5Ah cells to make 10Ah or 20Ah packs.

As prismatic format cells get larger, as a rule of thumb, the Ri increases and hence the C rate drops.

This is why the 40c/80c premium 5Ah LiPo packs are actually each made from 2.5Ah cells in 2P, because using smaller format cells enables the specific Ri to be lower.

On the bright side, many of the "5Ah" hobby city cells end up around 6Ah after break-in. They are also the most commonly produced cell size, so I would assume this enables the $/Wh ratio to be kept so nice.

As far as shipping goes, I really hate even going to the post office. I hate the hassle of packaging and mailing things. I don't want to do it. So, I'm thinking it would be best to either have the whole order shipped to somebody on here who likes to ship things, or try to arange things with HC to ship them out to everybody indivdually so I don't have to mess with anything.

It would really be great if I can talk them into just adding the packs as a normal item on the site, so anyone can just order them as they like. But... I'm sure everybody want's the priceing that I get for stuff from HC... So, maybe I can just post my username and PW, and everybody can just log-in as me, get my prices, pay for it themselves, and set it to there own shipping address. Or something like that...

-Luke

[mwkeefer]

Luke,

Too generous - literally. Don't post your user/pass = )

If someone with Hazmat cert and the ability to ship (within the US) is needed to test, plot and then ship the packs... I will volunteer to do it. If people aren't comfortable with me doing it (I am a bit new here after all), then I have sent you a better solution via PM.

The guy I mentioned in the PM has been shipping / receiving liion segway batteries, dewalt cells (a123 i think) and more for years now so he is very well experienced. He also has automated testing equipment to plot the charge / discharge / ir specs of the packs so testing prior to shipping would be solved.

Which ever way you decide to do this, I am sure there are more people besides myself and my associate who are certified for hazmat and capable of handling testing and distribution of the packs (within the USA, I never ship outside but I will check on the requirements to ship international hazmat).

-Mike

[GGoodrum]

I agree, you don't want to get into shipping these things. Too much of a hassle now. The best option would be if you could maybe talk HC into setting up a "special" area on their site, that required signing into, so that the packs could be offered separately, at a special price. That way people would pay themselves and HC would do the shipping.

Regarding pack configurations, until the QC is improved, having a 10Ah pack, even using paralleled 5Ah cells, might reduce the number of interconnections, but if a "cell" goes bad it means you've lost twice as much, in terms of replacement costs. Right now, most people parallel packs at the 5Ah pack level, and charge/balance the packs separately. This has one advantage if a cell goes bad, because it won't kill a cell in the second 5Ah pack, unless the balance plugs are also paralleled. It seems that if a pack is going to have a problem, it shows up right away. Once a pack is used for a bit, they seem to stay balanced and work well. If you buy two 5Ah packs and plan to use them in a 10Ah configuration and one arrives with one, or more, weak cells, only that one 5Ah is affected. If you get a prepackaged 10Ah pack, made from paralleled 5Ah cells, and one 5Ah cell goes bad, it will take down the other 5Ah cell it is paralleled with, so it would be like saying both 5Ah packs went bad, not just one of them. I'm probably not making this very clear, but I'm not sure how else to explain it.

I guess there'd also be a problem with doing packs with double the number of cells in series, like 10s or 12s, if there's still going to be an infant mortality issue with these. If you have a single cell go bad in a 12s/5Ah pack, the whole pack is affected. If you have a single 5Ah cell in a 12s/10Ah pack go bad, the whole pack is now unusable. If the 12s/10Ah pack is made up using four 6s/5Ah packs, you only need to replace 1/4th of the "pack".

The QC problem is really more of a factory issue, not something HC can probably do anything about, except to maybe do some pack cycling ahead of shipping. The problem is if any moisture gets into the cell during manufacture. This is typically what causes cells to fail early. The problem is that it usually takes awhile before the problem manifests itself, so the pack might test fine at HC's warehouse, prior to shipping, but by the time it gets over here, the cell(s) start having problems. Cycling a pack a few times should help weed out these "weak sisters", so I would do this initially, before the packs are used.

To me, these prices are so good, even at the standard "list" price (I just bought six Turnigy 6s-5000 20C packs for $60 each...), that it is tough to complain too much about the occasional bad pack. I'd complain more, however, If I had a single 12s/15Ah pack that became unusable shortly after arrival.

What I'm going to do is cycle these packs individually, about 5-6 times, to make sure they are all good, and then I will connect them in parallel, at the pack and balance plug level, and then in series, to make a single 12s/15Ah pack. The parallel and series connections will be part of a single 12-channel LVC board with board-mounted connections for the main pack leads, and the six JST-XH balance plugs. The output of this board will have one set of main power leads, and one 14-pin VAL-U-LOK PE Series connector that will plug into my 12-channel charge balancer. I'm thinking I will arrange the six packs flat, in a 3 x 2 configuration with the leads all facing out. I'll put the LVC board on top, and then shrinkwrap the whole thing together. That will make a very compact pack that is roughy 2-1/2" high x 6" wide and about 12" long, and only weigh about 10-11 pounds. That is tiny for a 45V/15Ah pack.

If we can ever get past the 50V/12s controller issue, an HC pack configuration I'd like to see for HC packs is a 7s. The reason is that if you use 4.125V as the CC/CV charge limit, as Luke recommends, 7s matches up perfectly with 8s LiFePO4 and 24V SLA packs for charging. So a 14s LiPo configuration would be a drop-in replacement for a "typical" 48V SLA or 16s LiFePO4 setup, and could use the same charger. Three 7s LiPo packs in series, again charged to 4.125V, would be a drop-in for a 72V SLA/LiFePO4 setup.

-- Gary

[mwkeefer]

Gary,

Wow... good insight, especially on the potential issues with larger packs.

I believe we are all hoping that QC will be better if buying larger packs through Luke since he is such a good customer to them already.

From what Luke and others have posted HK essentially owns or controls the production facility although I have been told by others (of experience) that they merely are acting as a reseller and they are not even the ones who have the packs made up. In this instance I doubt if anyone is being dishonest, more likely that there is no clear cut answer from HK (why would they) in regards to this chain of manu/dist.

I also love your foresight into the 7S configuration... it would fit right into existing SLA and LiFePo4 style if only we limit the charge v cutout as you indicated (and as Luke proposes). Currently I charge my 2x12S5AH Turnigy Packs (made of 4x3S packs series then paralleled for discharge) using a 1010B+ which works well enough. A full (per pack) balanced charge takes a bit less than 2 hours (1 hr per 2x 3S cells in series @ 5A). My charging cutout is set at 4.18v per cell and I use trickle charge balance method so I end up with 4.18v per cell and rarely if ever do I see cells overcharge and drain balance (reviewing logs). This is a bit higher than Luke's recommended 4.124v per cell but I am hoping that it will extend the life cycle of the packs a bit. My LVC is pack based currently and configured for 38.5v. So long as I am balanced, I have never seen a single 3S pack go below 3.16 at full discharge cutout. Again that is (I assume) becuase my cells are all balance charged.

All in all, if the QC (just checking for bad packs by voltage and IR) were stepped up prior to shipping from HK... it would eliminate the problems we all seem to have with dead packs.

Of the 30 cells I received, 28 are now salvaged and working. I use my few spare cells (4) in parallel as a 12v 20AH supply for accessories and such although I may make them into 2x2S packs and series them in with my existing 12S 5AH packs to bring them up to 14s.

I guess the ones which puffed upon initial charge must have had moisture or contamination inside the cells (if they did even a single cycle to full charge then back to storage voltage for shipping this would have been caught by HK also, but since these two packs had bad solder tabs they would have failed the simle QC check above so they wouldn't have made it to shipping anyway).

Based on my own experience and that of everyone else here on ES who has posted... if a pack works when it arrives, it will be okay.

-Mike

[Dave-s]

My 2 cents.
Since you can't agree on a preferable battery configuration, wouldn't it be best to ask HK to sell loose 5Ah cells (preferably with copper tabs for easy soldering) and the small circuit board they use for connecting cells in series/parallel?
Then each user can assemble his own pack. This way you also get the benefit of being able to replace a single cell if it goes south (I hope I used the correct expression).
We should also ask HK to carry higher power chargers to charge the bigger packs.
Maybe we can also convince them to carry some more E-bike hardware like controllers/throttles/high current connectors etc.

[mwkeefer]

Dave-s,

Not that your idea is bad, however I see several issues:

1.) Without assembly it would be next to impossible for HK to automate QA testing (IE: Charge / Discharge / Storage V Charge) further increasing the risk of bad cells

2.) Without purchasing as a pack, the price would likely be higher.

3.) The aluminum tabs require special solder and skills, not everyone possesses.

4.) the HK circuit boards are junk. To build a true high capacity discharge pack you would want to get the cells with the tabs unbent and perform spot welds to either a nickle busbar or somthing stronger then the tabs will still protect against dead short (like a fuseable link) while the electrical quality would be 100% better with much less impedance - resistance

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In regards to larger or larger cell count chargers...

You are 100% correct, it would be nice to get 12S 10A chargers and supporting power brick style 13.8 -> 15v @ say 30-40 AMP power supplies. The issue is with quality, believe you me the first 1212B+ charger available I will buy and will be very happy with it.

In regards to deciding on AH capacity and voltage range:

We have reached a consensus:

1.) 10S 5AH Packs
2.) 12S 5AH Packs
3.) 8s 5AH Packs

All the above could also be offered by HK as 2P (2 cells in parallel) x 8,10 or 12S
Finally they could also be offered in 10AH capacities although keeping them at 5AH 1P8-12S will allow for nearly any configuration required to match any existing power chemistry and cell count.

So really I think we have a consensus of what is needed for the vast majority of eBikers (80-90%) right out of the gate with the above configurations. Those can be combined to serve the elite.

The real issue is as it always has been Quality Control.

Great ideas and good insight!

-Mike

[johnrobholmes]

I do like 6s packs for compatibility with the vast amount of charging systems available today.