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Old November 1st, 2014, 12:01 AM   #1
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Going extreme light weight on the battery here (<1kg)

How does a <1kg battery sound for anyone trying to do some fat trimming?

With a new battery technology allowing for extreme discharge rates (500a+) from a 6aH battery, these should easily allow the car to be started, with hope.

https://www.hobbyking.com/hobbyking/...Lipo_Pack.html

given they are only 7.4v cells, I'm ordering two in order to make a 14.8 cell. Adding a small constant charger to avoid the overcharging is required but allows for some good data on the battery to avoid blindly using it. My only worry is the alternator will keep the batteries undercharged and shorten the life.

Shipping to me on Monday, will try to install sometime this upcoming week. The adapters that come with these batteries are only 5mm wide, and meant for 10 gauge wire, anyone have ideas on how to bump that to a 4 or 0 awg wire for connecting to the starter?

View My Video

Proof of concept. weighs in at <2 lbs.

Apparently extremely short runs of 8awg will support the current I need to start the car and lights and etc. Still needs a discharge protection circuit.

Last edited by oraclem19; December 19th, 2014 at 11:08 PM..
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Old November 1st, 2014, 12:26 AM   #2
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Will it have enough cca?
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Old November 1st, 2014, 06:22 AM   #3
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question...

do you have a modified alternator?
or stock?
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Old November 1st, 2014, 06:51 PM   #4
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Will it have enough cca?
Our cars supposedly need 600 cca, however I have started mine with a 150cca 12AH motorcycle battery many times when I had the sound system out of the car.
By comparison these batteries should be equivalent to a 540CA 6AH battery. If really neccessary I could put another pair in series for a 12Ah battery or bump up to 4 of the 7.5Ah batteries.
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do you have a modified alternator?
or stock?
240A alternator, although right now it's stepped down with a larger lightweight pulley that probably puts it around 150-180
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Old November 2nd, 2014, 03:41 AM   #5
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Good luck in your search for a lighter battery but I don't think you're gonna make this one work. I'm only saying this cause I fly rc helis in my spare time, one of them being a trex600 which uses something similar albeit smaller to this.
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Old November 3rd, 2014, 07:36 AM   #6
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Good luck in your search for a lighter battery but I don't think you're gonna make this one work. I'm only saying this cause I fly rc helis in my spare time, one of them being a trex600 which uses something similar albeit smaller to this.
Newer tech, before these batteries were limited to about 40C constant discharge. These ones are rated at 90C.
This brings the available amps(at 14.4 volts) from 240A to 540A.

Remember there are videos of Odysseys being started with an airsoft battery and a pair of super capacitors.
Im hoping to not need a set of super caps, but I will likely do it anyway if this works.

After I test this inline with another battery, I'll try it solo. Worst case is I get to use this pack as a super capacitor stabilizer for the sound system. If my calcs are right this pack is equivalent to a 1800 farad near super-capacitor.


Honestly trying this pack solo is just for shiggles and possibly track time. I run a 33lb battery right now so being able to remove that for track is worth a bit.
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Old November 3rd, 2014, 12:26 PM   #7
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amp rating is calculated by C X capacity in amps. not voltage

90C X 6A = 540amps
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Old November 3rd, 2014, 08:31 PM   #8
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amp rating is calculated by C X capacity in amps. not voltage

90C X 6A = 540amps
Mentioned that (@14.4 volts) part because it's used to calculate farads. The power/time of farads gives a direct link to starting a car(no starter starts the first time every time).

Was kind of a note for me too, remembered that the battery should be charging up to that voltage if not 14.8v instead of the 12v that a car battery usually sits at.

Gives a little more oomph for a little longer with that extra 2.8v. When you're dealing with batteries that you should BARELY be able to start the car with twice(maybe) without recharging, I gotta make a note of it.
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Old November 5th, 2014, 05:52 AM   #9
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Mentioned that (@14.4 volts) part because it's used to calculate farads. The power/time of farads gives a direct link to starting a car(no starter starts the first time every time).

Was kind of a note for me too, remembered that the battery should be charging up to that voltage if not 14.8v instead of the 12v that a car battery usually sits at.

Gives a little more oomph for a little longer with that extra 2.8v. When you're dealing with batteries that you should BARELY be able to start the car with twice(maybe) without recharging, I gotta make a note of it.
3.7v per cell is the norminal voltage. The maximum is 4.2*4 which is 16.8v. I think when my battery dies I'll try a lifepo4. Probably a 16 26650 config. Those battery seems to have a more ideal voltage range. 3.2v norminal and 3.65 charged max. Considering most cars only do 14v max charge anyways
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Old November 5th, 2014, 06:18 AM   #10
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3.7v per cell is the norminal voltage. The maximum is 4.2*4 which is 16.8v. I think when my battery dies I'll try a lifepo4. Probably a 16 26650 config. Those battery seems to have a more ideal voltage range. 3.2v norminal and 3.65 charged max. Considering most cars only do 14v max charge anyways
they are, yes, and it is.

I was looking at the number I would be able to reliably find the battery sitting at.
I wanted to recommend lifepo4 for you, however they are a bit pricey unless you DIY. There's a brand that already makes some lifepo4 car batterys in tight little motorcycle battery sized packages, but they're not near cheap(like as much as an engine)
Will try to find the link tonight if I have time. University is wreaking havoc this week.
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Old November 12th, 2014, 12:34 AM   #11
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Old November 12th, 2014, 05:21 AM   #12
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Where's the dyno invcbleduck
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Old November 12th, 2014, 07:25 AM   #13
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^ what he said!
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Old November 12th, 2014, 09:29 PM   #14
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updates.
tiny updates.
tiny wires.
look at these ****ing things.
i need like 5 of them each terminal.
as long as the wires don't instantly explode, they wont be active long enough to heat up.
any ideas to avoid any (more) explosions in my engine bay?

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Old November 13th, 2014, 10:49 PM   #15
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my new battery isnt being that great already in 25-30 degree f weather

NRG-CELL Slim Racing Battery - HeelToe Automotive

think im going lipofe4 soon
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Old November 14th, 2014, 12:42 AM   #16
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my new battery isnt being that great already in 25-30 degree f weather

NRG-CELL Slim Racing Battery - HeelToe Automotive

think im going lipofe4 soon
^^^These are exactly what I'm trying to beat out. Possibly by combining this pack with that little 58farad capacitor kit from another thread in a casing about the shape of those cells. 600 cranking amps does not need to weigh 14 lbs.

Lifepo4 was an option I considered a while back, but the only preconstructed one is a ridiculous price.

However any cell is going to have issues below 60*... except supercapacitors. I think those actually discharge better when colder.
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Old November 14th, 2014, 12:44 AM   #17
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Not edit edit: I think even with the 3000F capacitors, and these batteries, and a charging system, I could still beat 10lbs if need be. The 3000F pack thought is mostly for those of you whose cars get below 50* since the pack itself can start the car as the lipo pack keeps the caps charged over time and adds some extra voltage stability.


As an update, having an issue finding an indoor 12v source for my charger to start conditioning the batteries, so put on hold until the weekend for any updates at all.
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Old November 14th, 2014, 08:47 PM   #18
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goddamnit the expensive LCD charger I bought broke internally in less than 10 minutes.

As a side note, the very inexpensive flashing LED charger i bought is charging just fine. Should only take 7 hours per charge and another 7 per discharge, per battery, for at least one or two cycles to get the batteries in condition. I would prefer four but again, broken expensive charger.

will see if my local RC shop has any alternatives.
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Old November 16th, 2014, 06:15 PM   #19
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Alright so the charger is fine, did not think of diagnosing the banana plugs that connect to the larger charger, apparently they don't hold up to a 3a or 6a charge. (mind you this battery is capable of a 12a charge)

Running battery cycles today and tomorrow if I can. Should be trying some wiring tricks later on in the week to get this power directed correctly. May have found I can use my speaker connections for these terminals, which ramps up to at least 8gauge if not 6 modified or 4 with a splitter/resizer.
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Old December 1st, 2014, 11:36 PM   #20
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I have connection issues figured out, however I now need candidates for testing in colder climates. I have the hot climate here, I need testing into colder climates for a full proof of concept. PM if you have adv. electronics knowledge as well. Could use some verifications of my numbers
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Old December 1st, 2014, 11:52 PM   #21
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I could run in for u. I live in Toronto climate that occasionally see below -20celcius and I park my car out side
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Old December 2nd, 2014, 07:45 AM   #22
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qaz, that sounds like the perfect candidate. PM with what battery you currently run? I think the battery setup im trying to use has a -40 70c range. You're on the brink of that.
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Old December 2nd, 2014, 08:38 PM   #23
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-20 celcuis is around 0 F.
i run a nrg cell slim from heel toe. rated at 480 CCA.
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Old December 2nd, 2014, 10:41 PM   #24
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can't seem to find the aH rating on that battery online... mind checking yours?
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Old December 3rd, 2014, 04:13 AM   #25
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Ive used a smaller lawn mower type battery in my nissan before.. Worked normal... Just went to walmart and picked a smaller batter with same voltage rating and thats it... Bothing functioned any different
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Old December 7th, 2014, 10:37 PM   #26
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always good to have a backup plan though. Three possible arrangements




votes? still not sure how to hold them in place other than the brackets.
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Old December 8th, 2014, 12:13 AM   #27
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How much cca do you expect and how much is this setup? I'd love to try it but being in AK, -30 isn't far fetched.
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Old December 8th, 2014, 12:29 AM   #28
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How much cca do you expect and how much is this setup? I'd love to try it but being in AK, -30 isn't far fetched.
depending on how I do this, 540 to 1000.

-30 centigrade? or are you meaning farenheit? also im not sure where AK refers to but -30f is pretty damn low.
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Old December 9th, 2014, 12:33 AM   #29
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Yeah, -30F... About 200 miles north of me, -60F is Feb weather.
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Old December 18th, 2014, 03:07 PM   #30
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Any issues in extreme cold or heat?
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