Lithium Ion car starter packs - Page 1
Forum section: electronics / projects

author: Stonent
author_rank: Super Contributor
timestamp: March 07, 2015, 02:52:28 am
content: Has anyone found a teardown or know how those Lithium Ion car starter packs work?They look about the size of two laptop batteries and apparently can supply up to 200 Amps of current.I'm trying to figure out if they are doing it directly with lithium ion batteries or if they are charging a large capacitor for the extra kick.The last time I tested the short circuit current on an 18650 battery I got about 3.3 Amps.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 07, 2015, 03:38:43 am
content: They're just R/C type high current batteries. Much cheaper to just get some at HobbyKing.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 07, 2015, 03:44:57 am
content: The R/C battery industry now has crazy capability. The have much large electrode areas than the standard cell you tested. Internal impedances are typically a few hundredths of an ohm, can be less in higher priced, higher capacity batteries.Hobbyking has some great batteries, but also has a reputation for falling short on their claims. Thunderpower brand is consistently good, but pricey. There are other good brands out there.

author: Stonent
author_rank: Super Contributor
timestamp: March 07, 2015, 05:27:44 pm
content: So there aren't normal 18650 cells inside?

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2015, 08:38:32 pm
content: http://hobbyking.com/hobbyking/store/__25217__Turnigy_nano_tech_1300mAh_3S_45_90C_Lipo_Pack_AU_Warehouse_.html12.6V 1300mah 90C !!!!1.3 * 90 = 117AFor US$13or for $25http://hobbyking.com/hobbyking/store/__11953__Turnigy_nano_tech_3300mah_3S_45_90C_Lipo_Pack.html3.3Ah * 90C = 297A

author: Siwastaja
author_rank: Super Contributor
timestamp: March 07, 2015, 09:06:31 pm
content: Quote from: Stonent on March 07, 2015, 05:27:44 pm"Normal" off-the-shelf 18650 cells from the big manufacturers - Samsung INR18650-25R, Sony VTC5, LG HE2, for example, are typically rated up to about 10C discharge, which is just right for the power tool market, a great tradeoff between energy and power. But if you really want to minimize the starter pack size, something like 20C (real rating, not China rating, equivalent China would be about 50 I guess) would be necessary. On the other hand, the energy density of the 10C power cells is so good that you can just increase the pack size to have enough discharge power, get extra energy storage for running lights/radio/etc without engine running, and still have a small and light-weight pack. The energy density of li-ion is approx. 10 times of lead acid.Note that you'd never want to design it to need a 90C rated battery. You don't want to drain a full battery completely in 45 seconds. You may encounter some starting problems and then you want to have some extra energy (also, you should be able to run some loads for some time without the engine running). I'd think that at least 5 minutes worth of starting energy would be great, and that would only require 12C rating, so you can totally do it with off-the-shelf power 18650 cells.

author: eas
author_rank: Frequent Contributor
timestamp: March 07, 2015, 09:46:10 pm
content: Quote from: Stonent on March 07, 2015, 05:27:44 pmThe PowerAll Rosso I took apart had a 3s1p Li-ion/Li-po pouch packs. The connection to the charging connector was direct/un-protected. The built in charger appears to do cell balancing.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 07, 2015, 09:52:56 pm
content: Photonicinduction tested one - hopefully he'll find some more creative ways to abuse it soon...

author: Ton
author_rank: Regular Contributor
timestamp: March 07, 2015, 10:17:34 pm
content: There are a few 26650 cells LiFePo that fits the billoriginal manufacturerhttp://www.a123systems.com/lithium-ion-cells-26650-cylindrical-cell.htmGerman web shop with specificationshttp://shop.i-tecc.de/akkus/a123-systems-hochleistungsakku-anr26650m1b-2-5ah-das-original.htmlContinuous discharge current 70APuls discharge 120Ainternal resistance less than 6mOhmso a 4S2P pack of those would fit the bill.the A123 system cells are realy high quality item, and as you can see at the german web shop - they do make starter packs out of them.

author: Howardlong
author_rank: Super Contributor
timestamp: March 07, 2015, 11:06:43 pm
content: Quote from: mikeselectricstuff on March 07, 2015, 09:52:56 pmCoincidentally I ordered one of them off Amazon today, might be interesting to see what's inside, although I did buy it to use, it looked quite handy, certainly more convenient than the 17Ah lead acid monster I have. And the one time I wanted to use it recently, it was in the boot/trunk... and you can't plip the boot without battery power in my car, doh!

author: amyk
author_rank: Super Contributor
timestamp: March 07, 2015, 11:13:33 pm
content: Yes, RC lipos really do have such high energy densities.On the other hand, they also have relatively short cycle lives and high self-discharge.The safety aspect is also worth mentioning; these batteries are known to easily burst into flames...

author: Siwastaja
author_rank: Super Contributor
timestamp: March 08, 2015, 01:55:21 am
content: Quote from: amyk on March 07, 2015, 11:13:33 pmOnly if they are from the throw-away bin. Which undoubtedly happens with Chinese RC "lipos", but high self discharge is no way the "normal" behavior. It can result in from contamination during manufacturing. I wouldn't really trust a cell with a noticeable self-discharge (anything more than 1% per month); itmaybe unsafe. But as you say, people don't expect high safety from this type of cell anyway, and work around the risks by using all kind of "lipo sacks" when charging.FWIW, there is no separate technology called "lithium polymer", it's just an empty marketing term. The actual chemistries widely used today are: LCO, NCA, NMC, LMO, LFP. Any of these can be made into cylindrical, prismatic or pouch format, and optimized for high energy density, high power density, or between those. I would guess that RC lipos are NCA chemistry, but this is just a total hunch. Older 18650's, designated with ICR, are LCO and newer, designated with INR or similar, are typically NCA or NMC. LFP had a lot of marketing promise, but it suffers from relatively poor energy density compared to its advantages, but it's still useful, although mostly manufactured by small companies with sometimes dodgy quality control and lack of safety features, relying too much on the "safer" chemistry itself. Oh well, went off-topic, hopefully someone finds this useful.I was a believer of LFP chemistry, but now I wouldn't use it almost anywhere, but, maybe it would make a good replacement as a starter pack, not because of high power (it can be made any power, as can all other chemistries, too!), but because of lead-acid like voltage curve. 4S LFP battery is pretty darn close to a standard 6S lead acid battery, with flat voltage curve and relatively compatible charge voltage.

author: Stonent
author_rank: Super Contributor
timestamp: March 08, 2015, 05:22:00 am
content: Quote from: mikeselectricstuff on March 07, 2015, 09:52:56 pmyeah that's what got me started thinking about this. Unfortunately I couldn't find the video again after watching it.Just wondering because I seem to have a lot of old laptop batteries laying around.

author: Stonent
author_rank: Super Contributor
timestamp: March 08, 2015, 05:22:47 am
content: Quote from: Howardlong on March 07, 2015, 11:06:43 pmYes , please show us what's inside.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 08, 2015, 06:43:34 am
content: Quote from: Stonent on March 08, 2015, 05:22:00 amLaptop batteries are optimized for energy, not power density. They may be able to give out short peaks of 3C, but that would require a hugely oversized pack for starter purpose. Used, old cells are even worse in power handling. It probably would weigh about the same as the lead acid starter battery! Of course you would then get ridiculously huge amount of extra energy if you ever needed to run things without running the engine, maybe for days.For an electric vehicle, they are perfect.Not all 18650's are laptop batteries. Power tools use the "power" variety. The discharge ratings are 2C vs. 10C.

author: Howardlong
author_rank: Super Contributor
timestamp: March 08, 2015, 11:22:44 am
content: Quote from: Stonent on March 08, 2015, 05:22:47 amOK then! It arrived an hour ago, gotta love Amazon Prime.The li-ion unsurprisingly has thick gauge wire going directly to the car battery charge outlet, there's no switching.Other than that, there's a bunch of power mosfets (if you look closely they've piggy backed a pair), a microcontroller and the 8 pin SOIC that might be another MOSFET, MOSFET driver or possibly a standalone USB charge port controller (although these would usually be in more exotic packages), sorry I didn't look more closely.The dimensions of the battery itself is approx. 42 x 26 x 129mm, giving a volume of 0.141l. Based on an optimistic 650Wh/L, at a nominal 11V (assuming 3S config) this is about 8300mAh, certainly not the claimed 13600mAh.

author: eas
author_rank: Frequent Contributor
timestamp: March 08, 2015, 09:32:30 pm
content: Quote from: Howardlong on March 08, 2015, 11:22:44 amThey tend to quote those things like USB powerbanks, so capacity at nominal 1S voltage, which works out to be about 4500mAh cell.

author: Howardlong
author_rank: Super Contributor
timestamp: March 08, 2015, 09:46:38 pm
content: Quote from: eas on March 08, 2015, 09:32:30 pmIf so, then it renders mAh meaningless. Should be using an energy nomenclature like Wh if they choose to do it that way.

author: eas
author_rank: Frequent Contributor
timestamp: March 09, 2015, 12:49:43 am
content: Quote from: Howardlong on March 08, 2015, 09:46:38 pmThat battle happened long ago. We lost.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 09, 2015, 12:59:00 am
content: Dimensions on this battery are comparable to those listed on Hobbyking that have 4000 to 5000 mAH capacity, and discharge ratings in the 25-40C range. The 13000 mAH rating seems wildly out of line.It looks just like the low-mid grade RC batteries, and should be a fair fit for this application. RC batteries are claimed to last 200 charge/discharge cycles. My experience has ranged widely, but is always well above 50 cycles, with some batteries far exceeding the 200 cycle threshold. One thing that decreases charging cycle life is storing them fully charged, which this application does by definition. Still, I would think realistically you shouldn't need more than a few cycles for one of these as a car emergency backup.Self discharge on these things is typically very low, so slow that I have never really noticed it. That is a major improvement on the lead chemistry batteries used on the older generation of these chargers. It is also hard for me to believe that battery life for the lithium chemistry in these things will be worse than that for the lead chemistry batteries. The unsophisticated charging circuit in the lead based ones tends to quickly cook the battery.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 09, 2015, 02:54:07 am
content: As a quick technical recap:Lead acid is really suited for uses where the battery is full 99% of the time, and always recharged right after using some energy. Otherwise, the lifetime will be very short; this technology is not really suited for general energy storage.Lithium ion is really suited for uses where the battery is between 20%-70% full most of the time; general energy storage where you need a lot of buffer - I would say solar installations, electric vehicles, etc. It's a complete polar opposite to lead acid; the lifetime drops if you store it full all the time, although it's not as dramatic as if you store lead acid empty.So li-ion is still "somewhat" suitable when fully stored all the time, but clearly it loses its edge as a long-life, low-cost battery. This is a common problem with laptops that are connected to mains all the time. Running hot makes things worse.Li-ion also has much smaller consequences when the designer makes the energy vs. power compromise. The high-power li-ion products with 10x more power density only cost the designer about a 15% decrease in energy density, and about 30% increase in cost, with no other cons. With lead acid, getting high power totally ruins any cycleability, cycle life, SoC range and energy density. Lead acid starter battery is only good for starting and is destroyed if used for general purposes.Starter battery application requires relatively little energy, but as a short burst of power, so in theory, this could be the optimum case for ultracapacitors. However, they are a little bit too extreme on the "little energy" side and have too much self discharge.So, if there is any decent use for lead acid in the 2000's, it's the starter battery application! That's one of the few where the disadvantages of lead acid don't ruin the picture. UPS is another big one.That being said, lead acid has gotten more expensive due to increasing lead prices (and the huge amount of lead needed in the battery), while li-ion has become cheap and commonplace. Li-ion has so much energy density that simply deciding to put your "100%" at 80% fixes the lifetime problem. (Another option for that lifetime gain is to use LFP chemistry, but it's a 50% loss in energy density for the same result.)

author: Psi
author_rank: Super Contributor
timestamp: March 09, 2015, 07:05:30 am
content: Quote from: Siwastaja on March 09, 2015, 02:54:07 amThe high self discharge is a myth.Well, maybe some supercaps are like that. but others, like maxwell, have a very small self discharge.I have left maxwell supercaps sitting on the shelf for almost a year and the only lost 30% of their charge.So for a car staring application the self discharge is a non issue.Capacity wise, yes, they have around 20 times less usable capacity. So if you want to run your car accessories for more than 5 minutes with the engine off your out of luck.That said, if you don't care about that functionality and have almost zero 'parked' current draw a supercap works great. I've had a supercap in my car instead of a lead acid battery for a year now.The main issue to solve is the car alarm, a normal alarm draws too much power with armed. So you either have to live with no car alarm or design your own without the flashing LED which has uA level sleep current. (quite doable)The second issue is modifying the alternator feed so it doesn't try and pull 40A from an engine at idle and stall it out when you start a car with a supercap in a semi-discharge state.(The ESR is too low)

author: Siwastaja
author_rank: Super Contributor
timestamp: March 09, 2015, 09:58:53 am
content: Quote from: Psi on March 09, 2015, 07:05:30 amSo, I was believing in the myth. This was good news; I haven't played with supercaps, that myth being one of the reasons. Thanks for straightening that out.Sometimes you need the energy storage for extended crank-up; for example, if you run out of gas and have air in the system. Starter motor heating limits your duty cycle, but you still need some energy that ultracaps cannot easily store. But maybe a hybrid with a high energy density li-ion cells (laptop cells, for example) and a DC/DC converter could supply the supercaps. I'm thinking about something like a 100 Wh (0.5 kilogram) 1S li-ion pack with a 100W bidirectional boost/buck converter (which can be very small and cheap; the one I have built here has a part cost of $10 and it's smaller than a credit card) and the ultracaps. This would also supply small things like the alarm and maybe parking lights.

author: SeanB
author_rank: Super Contributor
timestamp: March 09, 2015, 05:10:02 pm
content: I have some 0.47F 5.5V Tokin supercaps from old public call box boards. I charged them up to 5v last year, and they still have around 100mV of charge left on them. Not bad for 12 year old caps that have been living in the outdoors in the sun.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 10, 2015, 10:23:36 pm
content: Supercaps are nice, but the batteries here are in the ballpark of 5 AH capacity. An amp hour is 3600 coulomb-sec, so this battery nominally delivers 18000 coulombs. Assuming a nominal 10 volt operation gives a required C of 1800 Farads. An 1800 Farad, 10 Volt supercap is going to be dramatically larger than the battery in question. And this simplistic calculation actually undersized the cap because it assumes discharge down to zero volts, which won't be practical.

author: macboy
author_rank: Super Contributor
timestamp: March 11, 2015, 01:23:10 pm
content: It doesn't seem that anyone addressed this fact: these "booster" packs do not actually supply the high current needed to turn over the engine. What they do is put some charge back into your vehicle's lead acid battery so thatitcan turn over the engine and start the car. Even the old school booster packs that use a SLA battery do exactly the same thing. You connect the booster pack, wait a minute or two (at least),thenturn over the engine. The wait is the important part, that is where the vehicle battery is receiving the charge necessary to turn over the engine.

author: Howardlong
author_rank: Super Contributor
timestamp: March 11, 2015, 05:50:56 pm
content: Quote from: macboy on March 11, 2015, 01:23:10 pmI take it you didn't watch the PhonicInduction video Mike mentioned then?go to 8:02.

author: eas
author_rank: Frequent Contributor
timestamp: March 11, 2015, 09:41:47 pm
content: Quote from: Howardlong on March 11, 2015, 05:50:56 pmYeah, there are a number of vids of people starting off various starter packs without the main battery connected, at all. Some of them may be shady hype-sters, but this guy doesn't seem to go for that:

author: richms
author_rank: Contributor
timestamp: March 11, 2015, 10:07:02 pm
content: Ive thrown enough charge into a totally flat car battery (as in about 2V came back across it once the car was disconnected flat) by sticking a tiny 4S pack for my RC car across it.Must have put an immeense current into the battery as the cables got hot after about 20 seconds, but it basically got the battery up to about 11v and enough to crank the car over within a couple of mins of been connected. pack came back to 13ish V once the load was removed so I dont think I overdischarged it.Didnt want to crank the car with the pack connected incase it got overvolted by the alternator kicking in. I am assuming that the 3S packs have something inline with them to prevent them from being attempted to be charged by the car once it is running.

author: max_torque
author_rank: Super Contributor
timestamp: March 12, 2015, 12:04:46 am
content: It's worth noting there is a world of difference between just starting a passenger car engine on a normal day, and the actual installed capability of the starter system fitted by the OEMs. Most OEMs mandate an unassisted start down to -20degC!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 12, 2015, 01:01:09 am
content: Quote from: max_torque on March 12, 2015, 12:04:46 amMy experience is that the OEM installed battery doesn't "fail" on a normal day. Its capacity drops gradually, but on normal days no one notices it. The engine starts fine on a fraction of the spec capacity. So the capacity keeps dropping. Along comes one of those bad days, and the battery isn't up to job. The battery required to do the job is bigger than the one needed for a normal day.Even when a failure to start occurs because of a non-battery issue like leaving lights on, a bigger booster capacity may be needed because you need to get a fair charge into that oversized OEM system.