Tibo

iTrader: (15)

I have been looking into adding a battery who's function is solely to power the stereo. It would be the typical circuit with the battery in the back seperated with an isolator/ high power relay. I have looked off and on but the added weight of another battery always drove me away. However in the last year lithium ion motorcycle batteries seem to be dropping in price ( and weight ) and increasing in availability. Most claim to be asleep to run between 1.2 and 2.0 liter engines. Power tool manufacturers are also hoping on the lithium ion band wagon and making radios powered by their relatively small 12 volt lions. These batteries are the size of a pistol grip. My Milwaukee radio lasts all day on that battery. Granted My car stereo is much bigger and powerful I am wondering if it is worth trying. I have a 5 channel amp that does 500 watts RMS which converted to amps is 41 amps. 4x6, 6x9 and 8" sub. Any thoughts? or.

84 1LE

iTrader: (9)

Bike battery probably wont have the amps to run an audio system.That said, I use a shorai battery in my Daytona, but shorai (currently) doesnt make a car battery.Thing weighs about 1.2lbs, CF shells, lithium iron (not ion).Will hold a charge for a yr w/ no drain applied....great battery.

Scorpner

iTrader: (4)

From what I've seen you have to be careful how you charge and discharge lithiums. Most of the time it's not a straight up connection to the battery but uses an interface that monitors things like amperage and/or temperature so it can makes adjustments or shuts the system down.
Google laptop lithium fire or lithium thermal runaway boeing.

mudd746

I'm using a stinger spp680 in mine and it is working great I'll post a few pics later if I can find them

browncamaroz28

iTrader: (1)

with a lithium ion battery you have to get one that charges on a normal 12volt circuit. Those will have a battery management system built in and will hopefully prevent you from damaging the battery because it will regulate charge and discharge functions on its own.

Tibo

iTrader: (15)

Yes! I had read that while reading the various articles on Lithium Ion batteries. It seems that most lithium batteries have the circuitry added in which then escalates the cost. I'm starting to wonder exactly how much amperage I need to run a car stereo. Any takers?

Tibo

iTrader: (15)

I agree with your post initially but I disagree with you if you are suggesting that lithium ion batteries are unsafe. Any battery has problems and can present risks to the point of explosion. I did google some stories and found that several of the publicized incidents were caused from faulty repairs, equipment misuse and faulty charging which still leads me to believe that as long as proper procedures are followed there is no real danger.

browncamaroz28

iTrader: (1)

in an ideal world 500watts = 12volt * Amps ..... amps ~42 ish so 50AH pack would play the stereo for one hour at 84% discharge. 60AH would be better per hour used. then just multiply it out for every additional hour played

Scorpner

iTrader: (4)

I was simply making you aware of it. My understanding is that the laptops in question were straight from the manufacturer where they were recalled and eventually ended up changing the design, and then there was an incident with Boeing Aircraft as well. I agree if they are charged and discharged within limits they aren't as likely to fail. However imho you should watch a video or two before deciding that they are as safe as any other battery.

Below is where the issue grounded an entire fleet of aircraft:
http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems
Then a vid showing how they fail and what kind of extinguisher to use.
https://www.youtube.com/watch?featur...482lvMRXUg#t=1

mudd746

You could try a earth x battery it's a lithium and it's a factory replacment for atv's about the size of a atv battery a little smaller like a 1/4" or so. Weighs like 2lb's a lot less then a regular motorcycle or atv battery. Not sure if it will work in a car though you could call them up. It does have the circuitry built on the battery so you can just hook it up. Great replacment for atv's with more cca's and better reserve.

Thirdgen89GTA

iTrader: (5)

Lithium Polymer batteries, referred to as LiPo offer much better energy density than standard battery, however their charging requirements are significantly different and more complex.

With a traditial Pb battery, you can simply feed it the appropriate voltage and it will draw current until its full.

However, LiPo batteries require 2 stage charging. The first method is constant current. The battery is fed a constant current, and voltage rises at a safe level. Once the appropriate voltage is reached (12.6v for a 11.1v 3 cell LiPo) it switches to Constant Voltage charging where it holds the required voltage until current drops off.

LiPo batteries are also multiple cell systems, and require balancing as well. A 12v LiPo battery is made up of 3 LiPo cells, each cell has a nominal voltage of 3.8v, and a maximum voltage of 4.2v. Also, the minimum safe voltage is 3.3v for most batteries.

Going above or below the voltage limits will cause a cell to swell, and possibly catch fire. Once a cell swells thats it, it has to be replaced, or the whole battery scrapped.

I have two 3S1P 11.1v 5000mah LIPO batteries that power one of my RC Cars. BTW, said RC car weighs 11.5lbs and is capable of 0-60 in under 3 seconds with a top speed in excess of 110mph.

Together, these batteries are capable of 3 second bursts of 11.1v @ 400amps, and weigh less than 2lbs. Adding a 3rd would give almost 600amps. It would take 4 of these batteries to start a car safely. But by then you'd have 3S4P, meaning you'd have 12 cells to balance and charge. Complicated. Also, the lifespan on LiPo's isn't anywhere near what a traditional car battery is. Expect maybe 3 years maximum.

I have used the two batteries at times to help jump a car.

Each battery pack is $80, so 4 of them would mean a battery well in excess of $350 by the time you added in the cost of built in electronics to safely charge them.