Soliciting practical advice for a 48V pack

[Chalo]

Hi y'all,

I have had a long time to chew on and think over the possibilities of stepping up from the SLA batteries I have always used up to now, but I haven't done it yet. Many factors have come into play that apply to all the different non-SLA chemistries I have looked at:

- High initial cost
- Exaggerated performance and life cycle claims
- Untrustworthy sellers
- No real recourse from foreign suppliers if goods are not as represented
- Need for BMS and special chargers, cell instability
- Chargers with separate power supplies?! (fail!)
- Need to design and construct and troubleshoot a custom system
- Risk of fire
- Risk of pack self-destruction
- Goofy form factors, fragile construction

... and probably a few more that don't come to mind just now. I'm fully aware of the serious shortcomings of SLA batteries-- low energy density, intolerance of deep discharge, short cycle life. But the list of issues above doesn't apply to them. Reliable 110V smart chargers for them are available in every town. They don't need BMS. They don't burn your bike-- or house-- down.

But now I'm building a practical e-bike for my wife, who should not be expected to trouble herself too much about depth of discharge or time elapsed before recharging. And she should definitely be able to go 25 miles or so without hauling 100 pounds of batteries to do it. So I am in the market for a decent battery and charger of nominally 48V, to drive an X5305 hub by way of a Crystalyte 35A controller.

I can build my own pack if that saves money or avoids quality issues, but I'd rather not have to design my own pack configuration. And the end result must plug and play without any geekery whatsoever, because my wife will not keep her eye glued to a voltmeter, or stash the battery in a blast container, or swap half a dozen different connectors when it's time to charge.

750Wh (that can be drawn out of the battery every time without hurting it) will be enough juice for the job. So anything that can deliver an actual, reliable, everyday 16Ah at 48V is big enough. I would very much like to get it all to my place and make it work perfectly for under $1000 total, and less than two dollars per full charge/discharge. Even these numbers are a little difficult for me to contemplate, except in comparison to the motor vehicle costs that might otherwise take their place.

What would the battery masters of E-S do to meet this set of requirements? In summary:

- 48V nominal, at least 16Ah no-fooling-around actual capacity
- Plug it into the wall and it charges
- No fires, no self-destruction
- No diddling around with a multimeter regularly to see what went wrong this time
- No diddling around with a laptop regularly to see what went wrong this time
- Someone who'll take it back and give me a refund if it doesn't work
- Pack can sit as-is on a bike rack or inside bike luggage without damage
- Less than $1000 ready to ride, less than $2 per cycle

How much will I have to spend, and are there any confidence-inspiring merchants who have what I need? (Grin Tech seems like the gold standard of sellers in this sector, but his selection of batteries seems pretty meh for my application.)

What would y'all do?

Chalo

[amberwolf]

For a drop-in plug-and-play solution, with money to spend, I'd probably ask Cell-man what he's got in A123 20Ah prismatic packs.

For DIY reliable and sourceable parts, I'd go with A123 20Ah prismatics. Given they're 20Ah, if you set yourself a limit of 16Ah, you will almost certainly never unbalance the pack far enough to need a balancing BMS. I would bulk charge, and simply periodically (monthly? bi-monthly?) check the cell voltages at discharged state and at charged state with something like a set of Battery Medics or Celllogs, just plugged into a connector for this purpose when needed. I'd keep one single-cell charger around for any cell that ever did get out of balance. A123 modules are available pre-assembled that you could "hack" to do whatever you want, and probably reuse the cell-mounting hardware, just rewiring it to your needs, more or less.

For the same thing with even better cells (higher voltage per-cell so less total cells for 48V (~60V full), I'd go with EIG 20Ah prismatics. The catch is these are nearly unobtainium. Jay64 got some via an unnamed source, but that's the only known pack of this type on the forum. I think some commercial EVs use them, too. Sangesf was organizing a group buy of these things at one point, but it fell apart and that's the last of that I know of. I don't know if the source he was getting them from was ever made public; if it was you could try to get some directly from them. Methods LVC/HVC setup can be used directly with these cells, for overcharge/overdischarge protection. (not with the A123, though--different cell voltage)


If you don't mind the extra work of first cycling and verifying all of your packs/cells, and either repairing or tossing any that don't work as expected, and then paralleling several packs for each of several sets, and then seriesing those sets together for the voltage you want, RC LiPo can also do what you want well enough. Methods' LVC/HVC setup can also be used with these (it is in fact designed for them, including being made to parallel the packs for you). Then just like the other packs, you can bulk charge, periodically check cell balance, and top off any low groups with a single-cell charger.


I don't know what the cost for any of these options is, so they might all be out of the $1000 budget. But if I had money to go buy new stuff, and needed a pack, one of these is what I'd do--almost certainly the A123 or EIG DIY packs.

[deVries]

If you don't mind the extra work of first cycling and verifying all of your packs/cells, and either repairing or tossing any that don't work as expected, and then paralleling several packs for each of several sets, and then seriesing those sets together for the voltage you want, RC LiPo can also do what you want well enough. Methods' LVC/HVC setup can also be used with these (it is in fact designed for them, including being made to parallel the packs for you). Then just like the other packs, you can bulk charge, periodically check cell balance, and top off any low groups with a single-cell charger.

No, I definitely have to disagree on this idea. (Sorry AW. )

Do *NOT* use LiPo for your wife!

Also, forget the unobtainium EIG cells too that no one can get. Unless Luke LFP is your big buddy... it ain't going to happen. It ain't low cost even if could be bought.

Cell_Man would be turnkey, and you get what you pay for. He is a trusted source on ES.

Personally, I would build my own pack if money is a concern from A123 20Ah cells. Probably could bulk charge with a timer cut-off & specific charge voltage limit.

Could just check cells like AW suggests. Once you know "the system" you rigged, then you might be able to avoid balancing except every year or even less often, if ever!
You can get cell level voltage audible alarms for very cheap that would warn when volts get too low. Some have very low pack drain too, otherwise you couldn't store pack without checking the volts unless you can hear the alarm or remember to check periodically.

[el_walto]

Buy a lifepo4 pack from cell_man (http://www.emissions-free.com) or a 20ah battery from ping (http://www.pingbattery.com)

[999zip999]

Big motor Cellman.

[dogman]

Big motor, big controller, pingbattery = shorter than expected lifespan.

Cellman 20 ah pouch pack for the win, unless, the wife will ride like my wife. At 15 mph max, My wife could easily make the 11 ah round cell triangle pack from Cellman last the 20 miles.

I suppose you could return a pack to Cellman if you weren't satisfied with it, but only an idiot mails a pack back to china for a warantee issue. It's cost prohibitive. I'm quite sure you will recieve 16 tested and good cells in the pack, which leaves only getting a charger or bms replaced as the possibilites. Too easy for Cellman to send you new ones if needed, which they won't be anyway.

[deVries]

So I am in the market for a decent battery and charger of nominally 48V, to drive an X5305 hub by way of a Crystalyte 35A controller. ... I can build my own pack if that saves money or avoids quality issues, but I'd rather not have to design my own pack configuration.

The simplest way to go is buy 16 cells of those A123 20Ah. Keep 2 for spares to use for something else but could be used as repairs to your pack too if necessary. That gives you 46.2v nominal & allows you to use that Hyperion charger I mentioned. Or, use all cells in a 16s & bulk charge... for 52.8v nominal @ 3.3v per cell.

Personally, I would pay the extra to get 14s2p. That's $750 or less for the cells including shipping & 2 spares. $130 for the Hyperion charger & about $75 more for the power supply. Otherwise, go with bulk charging about $100-150 & use something like Fechter has to limit current at end of charge. Get a timer to cut off the power to the charger too.

This is under a $1000 AND with 40Ah of Super Range & enables Long Battery Life too!

Since you have helped so many people with bikes, etc., I would build the pack free (labor) for you IF you wish & know what you want for the case or you could do that part. (PM if interested.)

[Icewrench]

Does she really need to go 25 miles non stop? If so then a 20 amp hour pack is the way to go. But 20 ah packs are large and heavy.
If she has stops here and there along the way then maybe a smaller pack with a carry along charger might work.
My 48v 10ah headway pack is good for @ 18 miles and a 10 amp charger will fill it up in about an hour. Balancing takes longer.
Some days I carry a 2 amp charger and plug in when I stop just to help top off the pack.

[cwah]

What's the price for the 20ah cells?

I understood that the 20ah pack are something like 132wh/kg so that's quite good because you can do 100% DOD with them.

Another possibility is to get the NMC battery at 48V20AH:
http://www.bmsbattery.com/48v/249-48v-1 ... -pack.html

It weight 7kg but it's just plug and play and at 45$/100wh it's quite a good price.

[nicobie]

I understood that the 20ah pack are something like 132wh/kg so that's quite good because you can do 100% DOD with them.

Not if you want them to last.

I don't think that Ping's would hold up with that 35a controller. Cellman or going with single cells a123 and building it yourself really is about your only option. I'd take up deVries offer if your not comfortable doing it yourself.

[Chalo]

Big motor, big controller, pingbattery = shorter than expected lifespan.

Cellman 20 ah pouch pack for the win, unless, the wife will ride like my wife. At 15 mph max, My wife could easily make the 11 ah round cell triangle pack from Cellman last the 20 miles.

My wife rides faster than that on her pushbikes. She also rides an eGo scooter (which she doesn't like very much) as fast as it will take her. On 48V, I reckon that this e-bike will carry 23-25mph on the flat, and that it will spend plenty of time cruising at that speed.

I suppose you could return a pack to Cellman if you weren't satisfied with it, but only an idiot mails a pack back to china for a warantee issue. It's cost prohibitive. I'm quite sure you will recieve 16 tested and good cells in the pack, which leaves only getting a charger or bms replaced as the possibilites. Too easy for Cellman to send you new ones if needed, which they won't be anyway.

Yes, it sounds like Cellman might offer something close to the ideal for my application, and it's refreshing to see all the confident support for his business (even if he's not as accessible as I'd prefer). I'm intrigued by the idea of assembling my own pack, but it's also worth something to me for someone else to have resolved the packaging, thermal, and reliability issues satisfactorily.

Chalo

[dogman]

Good for your wife then. She rides. Mines in the category of would like to make turns without leaning.

Cellman 48v 20 ah then, unless you can live with the shorter range of his round cell packs. Carrying all that will be a problem though, likely a split pack for panniers will have to be the solution.

Or a 10 ah triangle pack, with another similar one on a rear rack. That would allow carrying only one pack on the shorter rides.

[SamTexas]

I understood that the 20ah pack are something like 132wh/kg so that's quite good because you can do 100% DOD with them.

What do the capacity (20ah) and the energy density (132wh/kg) have to do with 100% DOD? NOTHING! You really need to slow down and get the basics well understood first.

[cwah]

I understood that the 20ah pack are something like 132wh/kg so that's quite good because you can do 100% DOD with them.

What do the capacity (20ah) and the energy density (132wh/kg) have to do with 100% DOD? NOTHING! You really need to slow down and get the basics well understood first.

I mean that with A123 (and NMC) you can do 100% DOD when required without problems (I've read something like 1000 cycles at 100% DOD for A123 which is still huge). So its energy density is a real 132wh/kg.

When we compare to lipo that have much higher energie density (150+ wh/kg), if you do 100% DOD the pack would be dead. So most probably you'll only do around 85% DOD. So because you can only use it at 85% DOD, its real energy density is 150wh/kg - 15% = 127.5 wh/kg.

So the so lightweight lipo is in "real world" heavier than NMC and A123 because of the 15% shortage.

That's why 132wh/kg with pack that can do 100% DOD are good. (compare to the ones that can't do that)

[999zip999]

Cellman say's he checks his cells before assembaly and it's plug and play not a hobby battery remenber you can't just run to the store for parts.

[cwah]

Cellman say's he checks his cells before assembaly and it's plug and play not a hobby battery remenber you can't just run to the store for parts.

I didn't know cellman has A123 20AH battery. Do you know what's the price for 1 cell?

[999zip999]

No. Cellman sells made packs.

[dogman]

FWIW, 100% discharge for lifepo4 of RC lipo is not 0v. Both types can do a discharge of 100%, defined as a stated minimum voltage. Both types can be damaged by discharge to that minimum voltage at a high rate of discharge. Both benefit in staying balanced better if you practice 80% dod as much as possible.

You have to email Cellman to ask about avaliability of the 20c pouch pack. But he has supplied them in the past.

The other lifepo4 option capable of supplying a 35 amp 5300 setup would be headways. Personally, I just think those are a bit big and bulky for bicycle carry, unless it's a roomy bike like a longtail.

[cwah]

I'm not sure, look at the A123 pack:


At 100% DOD, you can still have 1000 cycles. But with lipo, I believe you would have less than 100 cycles if you do 100% DOD, so it's more than 10 times difference.

[lcrewse]

Check the for sale section, http://endless-sphere.com/forums/viewtopic.php?f=9&t=39215

I'm selling this battery that meets all your criteria. Will easily handle the 35a. Tested at 30mph (about 1000 watt draw) it delivers about 30 miles of range.

[NeezyDeezy]

edited

[lcrewse]

Allcell's batteries are rated at >1000 cycles (I believe their latest data is 1700 cycles) until 80% DOD and warranted for 2 years. So at a minimum I'd say 3 years of completely cycling the pack daily which would equate to about 30,000 miles on a bike is a pretty decent cycle life. Not Lifepo4 like you said, but nowhere near SLA.

[NeezyDeezy]

I didn't know that, sorry.

[dogman]

Wasn't trying to say A123's have as short a cycle life as RC lipo. Was trying to say the life should be even longer than the 1000, if you practice 80% dod.

Those cycle life tests are generally for a cell. Many many many cells in a pack behaves differently, and keeping them balanced becomes important. 80% dod rarely throws either chemistry out of balance, avoiding the thing that really frocks em, discharging past 100%, or overcharging. GET IT, you pack lasts longer if you don't discharge to 100% unbalancing it.

Go ahead and ignore the herd, it's your money Cwah.

You can go ahead and discharge to 100% when you need to. Just don't plan on doing it every one of those 1000 cycles.

Since allcell just got mentioned, you would need a large pack to power a 35 amp controller, just like with a ping, you'd need about 25 ah.

[Chalo]

Check the for sale section, http://endless-sphere.com/forums/viewtopic.php?f=9&t=39215
I'm selling this battery that meets all your criteria. Will easily handle the 35a. Tested at 30mph (about 1000 watt draw) it delivers about 30 miles of range.

It meets my criteria related to technical specifications.

I hope someone who is more knowledgeable, experienced, and adventuresome than me buys your pack.

As for me, maxing out my budget on a used battery whose condition I am not qualified to assess, from a previous owner I don't know, from a manufacturer I've never heard of... is a little too far out on a limb for comfort. Nothing implied about your battery and especially not about you particularly-- but I can only afford one shot at this purchase at the moment.

A wise man once said, "a used battery is like an open can of beer." (Wise, at least, about the nature of used batteries.)

Chalo