New Batteryspace LiPo packs

[xyster]

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3141
"High Power Polymer Li-Ion Module: 37v 16 Ah (592 Wh) 40 Amp Rate
$895.95"


http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3140
"Hi-Power Polymer Li-Ion Battery Module: 37V 8Ah ( 296 Wh) 40A Drain Rate
$369.95"

Of these two lipo packs, the smaller appears perhaps the most affordable on the market yet. They state the larger has an 80 amp drain rate if the 14 AWG wire is replaced. The larger comes with two, 10-cell chargers, which is why the price is more than double.

 

[Ypedal]

In Stock = N

 

[xyster]

"For Professinal only ; Please allow 3-4 weeks delivery"

 

[Reid Welch]

That's their necessary disclaimer. After all, these things are not bulletproof, and are not fitted into the mandated metal box yet--you do that yourself.

My question: I'm considering buying the 36v 8AH pack, and their recommended 1A charger.

I would put the pack in a metal box, immobilized therein.

Is this going to be relatively safe?
I DO have the intelligence to cut off the discharge at 27V or whatever;
I've got a DrainBrain on this bike, and always see the pack voltage.
(the pack has no automatic l.v. cutoff


What will be the projected voltage sag at say 30A discharge?
I happen to run a 35A brush motor controller.
I never will draw more than 35A, nor want to.

I would trust BatterySpace over some others, only because I've dealt with them before, and have been pleased by their price/values and quality overall. They seem to be really on the up and up.


What do you guys who know, think of this pack? I like the integral, simple battery balancer, which works both on charge and discharge.

I will put a 40A fuse inline with the output

The proposed battery pack

Thank you for your ideas!
If it is a go, and if it works well, and if I want more,
later I'd get another for parallel operation (but oww, the cost!)

 

[xyster]

Here's more on the PCB. The description varies from the description on the battery pack page, and also is contradictory in re charge termination voltage 4.2v or 4.25v . I'm not clear if this circuit, as connected to the pack they sell, provides any discharge protection, or balancing-on-charge at all.

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3248&HS=1

his protection circuit is specially designed for 37 V Li-Ion / polymer Li-Ion Battery pack with 40 A discharging rate. Different with normal PCB, it provides equilibrium function during charging, e.g. PCM will detect each cell's voltage and trim higher voltage until other cell's voltage reach same, therefor allow Li-ion cell has longer service life. Also the PCM will provide the following protections:

Keep 37V Li-Ion Battery pack from overcharge ( 4.2V/cell)
Balance each cell at Max. 4.25/cell ( required voltage tolerance within 0.2V for each cell)
Keep 37V Li-Ion Battery pack from overdischarge ( 2.50V/cell)
Limit 37V Li-Ion Battery pack's discharging current below 40 A.
Features:

Apply for 10 Cells Li-ion / Li-polymer Battery Pack with discharging current < 40A
Internally Trimmed Charge and Discharge Voltage Limits to balance each cell
37A Discharge Current Limit Detection
Dimension: 3.3"(85mm) x 2.3"( 60mm)

From the battery pack page:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3140

PCB is installed in Charging terminal only to protect battery from overcharged

Another consideration: as discussed in the thundersky battery forum, charge termination at 4.25v per cell greatly reduces cycle life compared to 4.2v. As discussed on their blog, the Tesla car charges to 4.15V specifically to provide 5 year real-life battery life.

Lithium cobalt whether li-ion or li-poly is the same in this regard, so for better longevity, I charge my 18650s to 4.1 - 4.15v max.

 

[Reid Welch]

Thanks for that. I do see that it purports to balance the charging:

it provides equilibrium function during charging, e.g. PCM will detect each cell's voltage and trim higher voltage until other cell's voltage reach same

and see that on discharge, it at least -limits- each cell to a max rate of 40A.

As for the charge numbers? I suppose that's a choice the makers will make in justification of energy capacity vs. cycle life?

I dunno. It still looks good to me. At least they are USA-based battery specialists,
well established as ethical, with direct connections to China factories,
so-presumed because B.S. speaks in accented English.


I wonder how many volts sag it will make at high discharge?
I have not yet seen a discharge graph. Need to look for that.

Thanks, Mr. Xavier, sanity saver.



Any other ideas? You Lipo experts are my lifeline now. Maybe literally, ha.

Thanks all,
Reid

 

[Reid Welch]

images and data
from their pages


The 8AH cell



37V 8AH pack
6.3" L x 3.0" W x 3.5" H
1750 gram ( 3.6 Lb)










The pack-integrated cell-charge balancer...
...also limits discharge to 40A.
There is no automatic Low Voltage cutoff. Am OK with that: I watch the meter anyway.








The recommended 1A charger

 

[knightmb]

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3141
"High Power Polymer Li-Ion Module: 37v 16 Ah (592 Wh) 40 Amp Rate
$895.95"


http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3140
"Hi-Power Polymer Li-Ion Battery Module: 37V 8Ah ( 296 Wh) 40A Drain Rate
$369.95"

Of these two lipo packs, the smaller appears perhaps the most affordable on the market yet. They state the larger has an 80 amp drain rate if the 14 AWG wire is replaced. The larger comes with two, 10-cell chargers, which is why the price is more than double.

Here's a 5% discount code if anyone does buy one. I'll take any discount I can get

battery337

 

[Reid Welch]

Here's a 5% discount code if anyone does buy one. I'll take any discount I can get

battery337

Thank you! Now, I will order this thing soon unless I hear of something better overall.

I really like the size, and that I can double it up with a twin if that proves worthwhile.


How best to contain it? I suppose an off-the-rack cast AL project box?
But what of best fire safety? The box should be steel, and cleverly vented(?) (water must not get in)
Should it be vented? I need to learn so much.

----
PS:
thanks for da code, Da Vinci man!

 

[xyster]

I'd write BS, Reid (insert joke) to check specs and ask whether or not it's true that, as the battery page stated, the "PCB is installed in Charging terminal only to protect battery from overcharged". If indeed this is the case, after each charge I'd probe the cells individually to make certain they were indeed within 0.02 volts or so. If the cells are imbalanced more than this, and if you're relying as I do on a whole-pack voltage reading as your DIY LVC, then as the pack nears 80% DoD you could have one or more cells drained to near-reversal while the total voltage reads OK.

Also, I'd plan to cut the ride off at 37 volts absolute minimum resting voltage, which leaves about 11% remaining. Li-ion and Li-poly, for our uses and when not using an integrated LVC, drop their remaining charge very quickly after 3.70v -- I blew up a couple cells when running below 3.7 v. One minute they were at 3.68, the next minute one subpack was at 0, and another at 2.35v!

Lithium cobalt resting voltage vs. state-of-charge chart, which agrees very well with my observations, though it differs from all those charts showing lithium cobalt good down to 3.0-3.3v (which may be true when under load, but not when 'resting'):

http://www.rcgroups.com/forums/showpost.php?p=3272601&postcount=11

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

Capacity below 3.7v "resting" is not usable for flying, it's where the battery voltage dump begins.

 

[Reid Welch]

Thank you again. I heed. So, stop at 37 resting volts and call it a ride.

What'd be good (seems to me): voltage monitoring of all cells during operation. An LCD display rolling the ten cell's figures at half-second long displays in sequence would be a great mind-easer. Then there could be no surprises, ever.

Have to study the links you gave above.
Obliged!

 

[xyster]

How best to contain it? I suppose an off-the-rack cast AL project box?
But what of best fire safety? The box should be steel, and cleverly vented(?) (water must not get in)
Should it be vented? I need to learn so much.

Lithium cobalt cells run quite cool both charging and discharging when not over-extended by either over-current or over-drain. They do not generally need venting. Aluminum w/ electrical insulation would be good, so would plastic of some sort. I think it was ypedal? who's boxing his batteries in polycarbonate. Radioshack carries cheap ABS project boxes in sizes that might be about right.

Disregarding my own advice, I'm using styrofoam and wood I don't have the tools to create odd shapes from other affordable materials.

 

[xyster]

I'd suggest also reading this thread:
http://www.rcgroups.com/forums/showthread.php?t=209187
"Data - Complete Guide to Lithium Polymer Batteries and LiPo Failure Reports"

Thank you again. I heed. So, stop at 37 resting volts and call it a ride.

As an absolute, go-no-further voltage. The pack will live a lot longer if you generally stop at 38 resting volts. Lithium cobalt degrades quickly when sitting around with a full charge, when hot, and when run beyond 80% DoD. 3.8v per cell is about 70% DoD. If you're not riding for a while, leave them about 1/2 charged (3.80v - 3.90v)in the fridge, and if you can, refrigerate them whenever not in use.

Another good resource for lithium cobalt longevity info:
http://www.batteryuniversity.com/parttwo-34.htm
Storage Temp Versus Longevity Decline:

 

[Reid Welch]

I don't think these Lithium-ion polymer cells are cobalt-based.
I don't know though.
I do guess they are manganese-chemistry, or a mix of some sort.

They do appear to have been created just recently, precisely for our needs.

Other pouch-type Li-ion cells I've found on the 'net in the past day of searching
do not spec out at such a high permissible max drain rate.

As I think on these, though, no matter their rating, lipoly, etc, will live longer if I reduce the drain rate by operating two packs in parallel.

According to Buchmann, these things (almost all batteries, really), last longer if run at less than their max drain rates (of course!)

and -if- I could afford a pair of packs, then I'd not be discharging them nearly so deeply,
nor so often deep-drained, than if I get only a single pack.

Again, I am gathering by early reading and by deductive logic
that these are a new variant of lipoly, specifically tailored to our needs.

If the pack will last for a couple of years, then that's OK by me.
We may expect much better batteries yet in time, but heck,
I am weary of waiting, and I want to ditch my lead.

The BS pack may or may not be better than the "mystery pack"* that Knoxie used for his Puma test run at 37V
with such exciting results.

Too bad for me, that unbranded battery is built into a metal box
whose form factor will not fit in my bike's battery cubby.

Whereas, the Battery Space packs can be made to fit the bike here very easily, whether I get one or two of them.
I'd stack them in the latter case, each in its own little metal box.

thanks!

*mystery pack to me, because we don't know who makes it, nor the specs of the cells or of the cell management system,
nor is there a domestic seller who backs the thing up with such resources as Battery Space offers for their customers
(they have a forum!)


Best of hopes,
Reid

 

[xyster]

I don't think these Lithium-ion polymer cells are cobalt-based.
I don't know though.
I do guess they are manganese-chemistry, or a mix of some sort.

They,
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3119
are standard lithium cobalt, and must be treated with the applicable care.

- Far too light for it's ah rating to be lithium manganese, which weighs in between NiMH and Li-ion.

- I've found only one prismatic lithium manganese cell available commercially -- it's being distributed by an RC vendor and is very expensive. Manganese itself is much cheaper than cobalt, but production of the cells has yet to ramp up, so the cells are still much more expensive than li-poly.

- 2.5v recommended cut off is another clue. Lithium manganese and lithium iron phosphate can be safely 100% depleted.

- 300-500 cycle life to 80% capacity is another clue. Lithium manganese is supposedly good for 2000+ cycles -- which is why emoli/milwaukee can guarantee their lithium manganse batteries for 5 years or 2000 charges (the V28 packs have internal circuitry that keeps track of charges)

- 5C discharge rate is too low for lithium manganese, which is good for up to 15C.

- If it was lithium manganese, or some new hybrid, BS would sell it as such at a considerable mark-up, like they do their new 1.3ah lithium iron phosphate cells:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3071

 

[Reid Welch]

OK, man, am I ever causing you to work! Thanks for your patience.
I'll digest your inputs after putting up this update.

I don't think these Lithium-ion polymer cells are cobalt-based.
I don't know though.
I do guess they are manganese-chemistry, or a mix of some sort.

They,
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3119
are standard lithium cobalt, and must be treated with the applicable care.

- Far too light for it's ah rating to be lithium manganese, which weighs in between NiMH and Li-ion.

So you say, but, why don't they? Hmmm...

_______


While you were writing I was posing my newbie questions to the BatterySpace forum; to the site owners, really.

http://forums.batteryspace.com/forums/viewtopic.php?t=8315

Have thoroughly cross-linked our forums so they may look in here and also input if they care to do so.

I hope the cells aren't cobalt based.
I -thought- by Buchmann's essays, that cobalt chemistry is not high rate,
not if you don't want a smoke. :wink:

(will read your posting over carefully starting now).

 

[xyster]

I -thought- by Buchmann's essays, that cobalt chemistry is not high rate,

Canned lithium-cobalt cells are not high rate, but prismatic li-poly lithium-cobalt cells certainly can be. 20-30C lipoly's are still the choice of competitive RC flyers because the other, safer, longer lasting chemistries are heavier.

Here's some 30C lithium-cobalt li-poly's:
http://www.maxamps.com/categories.php?cat=8

 

[xyster]

If you want Lithium Manganese, Reid, Michael at bigerc sells packs of emoli's he gets from a supplier of Milwaukee packs:
http://bigerc.com/index.php?cPath=21_26
from emails, he seems on the up-and-up, and does custom packs.

The price isn't much more than buying Milwaukee V28 packs off of ebay, though as you can see they're much more expensive than canned li-ion cells of similar capacity. I'm thinking of purchasing a 1P20S pack from him, paralleling it to bolster the current capability of my main pack.

 

[maytag]

Reid,
Here's a bigger discount offer, hope you havent ordered the BS pack yet. Prodigybatteries lists an 18.5v/8Ah(40A max) pack for only $130. 2 of these in series makes up the equal to the BS pack, thats $260.00 compared to BS's $370 pack. Prodigy's pack does not come with a bms but is tapped to work with popular RC balancers and Litho chargers which is in my opinion a better charging solution. I was on the edge of ordering 6-packs of these for a 55.5v/16Ah pack but couldnt shake the thought of my ebike bursting into flames while parked in the garage. So I've commited and picked up my 1st Milwaukee v28 pack on ebay today, now I just need 8 more. Guess I'll be spending the next week fishing on ebay for more Ridgid and Milwaukee packs, I need enough to build a 55.5v/12Ah emoli pack (60 cells). I've emailed Prodigy regarding these packs. Says that their RC users are getting around 300-400 cycles but they often run the packs over the recommended discharge rates (5C, 40A) and he would expect probably doubling the cycles if running below the 40A max and proper care. Cant beat it at $26 per cell.

http://prodigybatteries.com/productlist/

Here's a 5% discount code if anyone does buy one. I'll take any discount I can get

battery337

Thank you! Now, I will order this thing soon unless I hear of something better overall.

I really like the size, and that I can double it up with a twin if that proves worthwhile.

 

[Reid Welch]

Thanks! I haven't ordered anything.
I suppose, though, that by the time I buy balancers and chargers the costs would nearly match.

The cells are liable to be about identical, themselves? I guess so.

If I go this route I'll not keep the bike in the garage, or remove the battery packs to store in an outdoor cooler, and also charge them there.

Fire scares me, yeah, but if I run the packs conservatively (half the rated max drain, is what it would be in case I get two of the BS packs), maybe...

well... in a year or so we'll have so many easier options.

I only want to keep the bike light and simple and clean.

The emoli drill packs are nifty. But for me, a bit of a pain to go on a buying search for them. Maybe I'm pound foolish.

Like, the Rigid packs, with Lifetime Warranty, are something to exploit.



Main want is a stiff supply, little sag, and a small and neat form factor.
(D'oh, reid)

An attraction of the prismatic tabbed cells is their few interconnections,
unliable to add much series resistance, as opposed to the many A123 cells' that'd need stringing together if I went that route,

or the plain hard work and awkward factor of any large number of series-parallel strings of small capacity emoli or li-ion canned cells.

Can't beat ten plus ten flat poly pouches for form factor and short current paths.

But oh, the worries. I hate decisions that get any more complicated than culling good potatoes from the bad.



Will think on this! Much obliged to you for your help.

 

[Reid Welch]

In favor of the BatterySpace route, they do document their products.

The cell in question also has an associated PDF file which states in certain terms how "safe" this cell must be:


screenshot:



The most salient thing, is that the cell is purported to not fire even if dead-shorted.

Credible? I hope so. Of course, the cells as used are sandwiched and shrink wrapped; then to be metal-boxed;
that's not in the lab test parameters.

Now, i'd be drawing from a double pack (2x10 cells) less than half of their rated current capacity. Should be good then for longer life, at least 300 cycles---and since this double pack would offer much greater capacity than I really need, then when the capacity declines through aging effects,
I'd still have sufficient reserve for satisfactory running.

That the series resistance is relatively low,
and that this resistance does not appreciably increase with age (yes, true?),

and that the cells are designed to be relatively fire-safe,
and that I'd run them intelligently....

should be a -fair bet-?

Not the longest life in years.
Not the cheapest nor the best technolgy(but the best is yet to make it to market).
This -sort- (cobalt lithium-ion polymer prismatic pouch) is fairly well matured today by manuf. experiences.

I dunno....

Potatoes. I hate sorting $*@*$ potatoes.
They stare at me with such goddamn suspicious eyes.



:x


:wink:

 

[xyster]

Now, i'd be drawing from a double pack (2x10 cells) less than half of their rated current capacity. Should be good then for longer life, at least 300 cycles---and since this double pack would offer much greater capacity than I really need, then when the capacity declines through aging effects,
I'd still have sufficient reserve for satisfactory running.

Smart. The typical 300-500 cycle life is measured to the point where capacity declines 20%. Capacity decline remains fairly linear over time and cycles. Hence, if you start with twice the capacity you need, the pack is usable for you down to 50% it's original capacity, which means 2.5X times the available cycles (750 to 1250 cycles, each cycle to 80% DoD).

The other factor with lithium cobalt, be it canned or prismatic polymer, is calendar longevity. If you keep the cells fridge-temp between rides, and try to limit the time they're fully charged, the tesla blog results (remember their air-conditioned pack?), and other info I've found, suggest a 5 year lifespan.

So with a double-pack, a reasonable lifespan expectation is 5 years, or 1000 full cycles, whichever comes first.

This is a major reason I chose to solder a huge 33ah pack.

 

[Ypedal]

Until the LiFePO4 packs become cheaper and available.... my current plan is to go with big name high-volume " Thunder Power " or " MaxAmps " large AH cells...

I DO have the patience to test 20 cells every charge cycle.. ( 8ah rated at 20 C.. used at 20 amps = 2.5C .. should be a walk in the park for these packs .. )

i do NOT have the patience to test 60 cells every charge cycle ( if using A123 cells ) ...

I should be getting into this by end of June or so... 8)

 

[Reid Welch]

Yes, here too, the small number (ten or twenty, tops, to gain 37 or 74V) is a great attraction.
So is the corresponding reduction in inter-cell connections, and length of those connective paths.

Less series resistance; all that.

Just a shame, though, that there they are,

all bound up and no place to blow...

(there was an old song: All Dressed Up and No-Place to Go)


Buzzz, got links? I don't mean sausage, either.

___________
edit, nevermind. I googled MaxAmps.

The equivalent cell capacity as BS' cellpack,
very high drain-capable,
$120 for a two-cell pack (7.4V)
I'd need five of them, minimum.

More $ than BS. Possibly a much better cell though.
I can't tell by looking.

[/UR

As has been pointed out by xyster, it'd be best to go double the really-needed capacity. The pack will last longer for the lower drain,
and retain useful capacity enough for practical purposes for years or cycles longer.

I just can't swing that much green into the fireplace all at once,
not for this trial.

 

[Reid Welch]

OK, done deal.

I'm forging ahead, have ordered the BatterySpace 8AH pack illustrated on page one.


They make these up from stock cells, so I am able to specify thicker leads,
which I have done (12ga or 10ga), unterminated.

The advertised dimensions are a bit off: the height is 4", not 3.5".
They'll correct the web page soon.

It would be far, far better were I to buy a pair of these packs for parallelling.
Too much moolah for now. So, it won't be as stiff or last as long or get me as far.

Let's see how it does though.. they'll ship it out before the end of the week.

From California to Miami.... maybe 10 or 12 days from now I'll have the wee beastie.

Then, after giving it a trial I guess I'd better get onto that steel box project.

Thanks for the helps. Someone has to try this out.

I just hated the alternative of dozens of small round cells...and all that series resistance.

This should be reasonably stiff, at least while new.

r.

PS: more inventive thought: I'll not be taking the battery box off the bike.

I think I'll refrigerate the steel box instead with the guts of an old transistorized cooler; just velcro foam over the box exterior?
Something like that to slow the aging down somewhat.