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Old 10-17-2012, 01:35 PM   #1
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Default Cordycord's epic tube frame battery

mod note: split off from " Cordycord's epic tube frame build" thread


Oh, and that battery? Epic.

When I first picked it up, my initial thought was "This is a pretty neat mock-up. When will you have a real one available to test?"

That thing really does weigh less than Pusha's ego.

Last edited by Joe Perez; 10-20-2012 at 11:42 AM. Reason: Split
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Old 10-17-2012, 01:37 PM   #2
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That's no big deal. Pusha's ego is as big as a tank.
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Old 10-17-2012, 01:57 PM   #3
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Originally Posted by rleete View Post
Pusha's ego is as big as a tank.
Yeah, but it mostly consists of hot air. The ratio of mass to volume or mass to surface-area is hugely askew.


What really impresses me about the battery isn't actually the size or weight per-se. I think the one I held was 12v(ish) at 16Ah. The battery on my bike is 52v at 11.5Ah, and it probably weighs about 3-4x what the Braille battery does, so that kind of makes sense.

The amazing thing about that battery is the electro-chemical properties.

First, it's gotta be capable of delivering a couple of hundred amps for at least several seconds, and that is *WAY* outside the normal profile for a lithium battery. The LiPo packs that the RC airplane crowd use are similar, I guess, but you don't normally find batteries with 20c permissible discharge ratings in automotive applications.

And the *really* cool thing is that it doesn't appear to require any special provisions for charging. You hook it up, and it charges through the same terminals that it discharges through, just like a "normal" car battery. You can't just hook an unregulated voltage source to a lithium battery and expect it to charge itself normally without blowing up, which is why most lithium batteries have more than two terminals and interface with fancy chargers. (The battery on my bike, even though it has an on-board BMS, still requires separate connections for charge vs. discharge.)

I can't resolve those two features in my head. What kind of circuit can you built that allows for common-port charge / discharge and is also capable of passing 200 amps or more on the discharge phase?




Anyway, I'm threadjacking. Sorry about that.
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Old 10-17-2012, 03:35 PM   #4
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You've shown Joe P the car...and the battery?!?

I think you may have created a monster...
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Old 10-17-2012, 04:21 PM   #5
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ib4 five more pages on joe ranting about batteries.
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Old 10-18-2012, 04:36 AM   #6
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Quote:
Originally Posted by Joe Perez View Post
Yeah, but it mostly consists of hot air. The ratio of mass to volume or mass to surface-area is hugely askew.


What really impresses me about the battery isn't actually the size or weight per-se. I think the one I held was 12v(ish) at 16Ah. The battery on my bike is 52v at 11.5Ah, and it probably weighs about 3-4x what the Braille battery does, so that kind of makes sense.

The amazing thing about that battery is the electro-chemical properties.

First, it's gotta be capable of delivering a couple of hundred amps for at least several seconds, and that is *WAY* outside the normal profile for a lithium battery. The LiPo packs that the RC airplane crowd use are similar, I guess, but you don't normally find batteries with 20c permissible discharge ratings in automotive applications.

And the *really* cool thing is that it doesn't appear to require any special provisions for charging. You hook it up, and it charges through the same terminals that it discharges through, just like a "normal" car battery. You can't just hook an unregulated voltage source to a lithium battery and expect it to charge itself normally without blowing up, which is why most lithium batteries have more than two terminals and interface with fancy chargers. (The battery on my bike, even though it has an on-board BMS, still requires separate connections for charge vs. discharge.)

I can't resolve those two features in my head. What kind of circuit can you built that allows for common-port charge / discharge and is also capable of passing 200 amps or more on the discharge phase?




Anyway, I'm threadjacking. Sorry about that.
To be honest, the battery does require a special battery charger. How special? I dunno, but they say it's required for this particular battery. I'm not sure if a float charger would work just as well.

I can't believe how many people geek out about the battery. Everyone who comes in the shop and sees it makes a comment. One neat thing is that since it charges faster than a standard battery, it takes less alternator draw.

In a few years I think all the batteries will be like the Braille, mainly because it's "green"'; No caustic chemicals. If Uncle Sam can mandate curlie cue bulbs, lead acid batteries will be going the way of the dinosaur before long.
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Old 10-18-2012, 11:04 AM   #7
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Sooooo how do these batteries work Joe?
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Old 10-19-2012, 12:42 PM   #8
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Originally Posted by triple88a View Post
Sooooo how do these batteries work Joe?
Plug 'em in and go. Martin from Monster Miata stopped by the shop last night at around 10:30, and he and his buddy Bill were also geeking out about the battery. Jeez, I have a perfectly good tube frame car sitting 10 feet away, and they just want to pick up a carbon-cased battery.

BTW, averaging three hours of sleep a night for the past three nights. I've got Roman Maguinez down here from LA with "the Davids", which are his two crew members who help him out. I think you can guess their names. David is also my main fabricator for the Catfish, so we have three David's hovering over the car at any given moment.

We went home last night after the car fired up for the first time in the new frame. We hope to make it a roller today.
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Old 10-19-2012, 12:51 PM   #9
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Sooooo how do these batteries work Joe?
PLEASE make it a separate thread.
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Old 10-19-2012, 02:21 PM   #10
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Quote:
Originally Posted by olderguy View Post
PLEASE make it a separate thread.
Fair enough. New thread created, battery related ****-stroking moved.


Quote:
Originally Posted by cordycord View Post
Martin from Monster Miata stopped by the shop last night at around 10:30, and he and his buddy Bill were also geeking out about the battery. Jeez, I have a perfectly good tube frame car sitting 10 feet away, and they just want to pick up a carbon-cased battery.
Hahaha.

I honestly felt a little self-conscious geeking out over the battery (and the secret thing) while I was there, but I justified it to myself by saying that the black frame was busy being worked on, and nobody had had the common decency to install a seat into the unpainted frame before I got there so that I'd have a chance to sit in it.

So thanks for that. (I'm back to judging you harshly mode. )


Quote:
We went home last night after the car fired up for the first time in the new frame. We hope to make it a roller today.
Killer!

That's seriously excellent progress in just a couple of days.



Quote:
Originally Posted by triple88a View Post
Sooooo how do these batteries work Joe?
I wish I knew.

The weird thing is that it only has two terminals. That's totally normal for a lead-acid battery- you shove current back into it through the same terminals that you use to take current out of it, and the battery's ESR automatically takes care of "regulating" the charge. From a practical standpoint, it's pretty much impossible to over-charge a lead-acid battery, and it doesn't require much in the way of regulation. Just limit the charge voltage to about 14-14.5v, and the current will self-limit.

Lithium batteries (of which there are actually several different chemistries) are a bit more complex. You have to very carefully control two specific factors:
  • The charging current and voltage must both be carefully regulated, and
  • They must never be discharged to below a certain voltage.

Break either of these rules and they go from cute little fuzzballs to scary green monsters that rip up the town and drive Mr. Futterman's snowplow right through the front of his house.


Single-cell lithium batteries (of the sort found in cell-phones) typically have a minimum of three terminals, where one is a temperature sensor, and they rely upon the assumption that the phone they're plugged into contains a charge controller and discharge limiter.

Multi-cell batteries are more complicated, since the voltage rules apply on a PER-CELL basis. You can't just sense the voltage of the whole pack, you've gotta make sure that no individual cell within a series string goes above or below the threshohold values.

Cheap LiPo packs, such as those used in RC airplanes, typically rely on fancy external chargers with multi-pin connectors, and they still catch on fire sufficiently often that the manufacturers also sell heavy, explosion-proof charging bags and recommend that you never leave them unattended.

Better LiMn and LiFe packs (such as the one on my bike) have on-board charge/discharge controllers. They take care of the per-cell regulation during the charge cycle, and they shut themselves off if the voltage drops too low during the discharge phase.


This battery confuses me, as it doesn't seem to have affordances for either of those things.

I suppose, in theory, that it could contain a discharge cutoff controller, but that would presuppose that it also contains a bank of MOSFETs sufficiently large and low-resistance that they can pass a couple of hundred amps without exploding.

On the charge side, that's where it really gets weird. Typically, we expect that the charging will be done through a separate port, so that the charge can be regulated and shut down once the battery is "full". But this battery doesn't have separate charge and discharge ports.


So I just dunno. I'm sure it works great, but I'll be damned if I can figure out what's actually inside it.
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Old 10-20-2012, 03:57 AM   #11
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braille sent me some technical information that explains how it works...but I'd have to read it.
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Old 10-20-2012, 04:10 AM   #12
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Anything new beyond what's been available from Ballistic and Shorai (i.e. LiFePo4) for 12+ months?
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Old 10-20-2012, 04:30 AM   #13
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Anything new beyond what's been available from Ballistic and Shorai (i.e. LiFePo4) for 12+ months?
Here's the skinny on new stuff; there's a new battery coming out in December called the G20. It's supposed to retail for around $329-ish, will weigh 3.5lbs (mount weighs 1lb). It's a long-life lithium (7-10 years) and has all the attributes of the ML20C that's in the Catfish. However, the ML20C has twice the capacity and 3x the power. So that's the trade-off.

There is one more battery coming out called the U1R. It's a direct Miata replacement battery that will weigh 5lbs and cost about $369. Perfect daily driver/weekend warrior battery, with all the benefits of light weight, long life, more cranking power, faster recharge (less alternator draw), etceteras.

OK, infomercial over. I've got my kick-*** battery, but it sounds like there will be some new ones coming out very soon that are within reach budget-wise and give the same benefits.
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Old 11-04-2012, 01:47 AM   #14
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Default Here's the new Braille battery

This is what Braille had at the show. It's the same size at the stock Miata battery, yet is lithium and weighs just 6.6lbs. Braille won a SEMA award for it, as on top of all the benefits (10 year life, 900cca, "green" lithium, etceteras) the cost is around $350.

I was at the booth listening to their pitch during the whole show:

--lithium retains a strong charge up until drop-off when it's nearly drained. Lead/acid batteries drain slowly so that your car stops working once the battery hits 10-ish volts.
--charges faster so there's less alternator drain on horsepower
--faster startup
--LIGHT. 6.6lbs. No need to skip that Double Double with fries if you get this battery
--same form factor as OEM--my spendy battery is much smaller, and requires a different battery mount. This one bolts right in with no modifications.
--DOT and Rohs approved, which is apparently impossible for AGM batteries.

This would appear to be the shiznit.
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Old 11-04-2012, 05:06 AM   #15
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Quote:
Originally Posted by cordycord View Post
--DOT and Rohs approved, which is apparently impossible for AGM batteries.
By definition, no lead-acid battery (including AGM) can be ROHS compliant, as lead is completely prohibited by it.

Sidebar: ROHS can suck my *****. Lead-free solder is a pain in the ***.
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