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Seriously high output lithium battery packs.
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WesleyK View Drop Down
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Points: 90 		Post Options Post Options   Thanks (0) Thanks(0)   Quote WesleyK Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2015 at 3:45pm
While I was also surprised to read that the LiFePO4 was found underwhelming, I can't agree that Lipo's are junk, regarding high current applications, that is. Have you ever seen a small 1:8 or 1:10 RC car accelerating using a good LiPo battery? The power output of these small cells is amazing. ~100-150A bursts, supplied by a 5000mAh battery, quite amazing. I'm sure the same applies when using Lipo's with airsoft rifles. Expect to need to replace them often, though.

Edited by WesleyK - 01 April 2015 at 3:47pm
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With batteries I find it helps to set a budget you're willing to stretch to and consider what the various options available will get you within that budget and what the pros and cons of each are.

In my case I'd like to spend around £150 on batteries for a system, which is apparently enough for a 40Ah LiFePO4 system, but it won't go much further if spent on lipo or li-ion systems - Perhaps 50AH instead of 40Ah and 4.5kg instead of 6.5. Supplemented by high efficiency speakers, high efficiency amps and a substantial solar charging system it should be all that's  needed. Being 12.8v nominal and fully weatherproof is a definite plus.
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Points: 2025 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2015 at 8:28pm
Never mind weather proof. The EV LiFePO4 batteries are crash tested. They're pretty much impossible to physically destroy. Shocks in excess of 3000G is trivial for these batteries.
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slaz View Drop Down
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Points: 2713 		Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2015 at 10:36am
Originally posted by WesleyK WesleyK wrote:

While I was also surprised to read that the LiFePO4 was found underwhelming, I can't agree that Lipo's are junk, regarding high current applications, that is. Have you ever seen a small 1:8 or 1:10 RC car accelerating using a good LiPo battery? The power output of these small cells is amazing. ~100-150A bursts, supplied by a 5000mAh battery, quite amazing. I'm sure the same applies when using Lipo's with airsoft rifles. Expect to need to replace them often, though.


They can work pretty effectively for sound systems also.

I have some HobbyKing-supplied LiPo packs - 6S Zippy branded 5Ah and 4Ah ... and they rock powering a Sure ST508 amplifier. Haven't measured it, but I reckon that combo is strutting a good solid 50-60W/channel -> 4R loads.

I charge em with a Turnigy Accucell 6 - always balanced - and at quite a low charge rate (gut instinct tells me that keeps heat out of the picture .... heat is the enemy of Lithium cells).

Longevity - well I can't say - YET - but I'm happy with em.

I use em external to the speaker box, as housing internally would be a bit of a faff (to make the balance connector externally acessible).




Edited by slaz - 02 April 2015 at 10:37am
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Points: 2272 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2015 at 1:07pm
Standard Li-Ion-/LiPo definitely had it's appeals. Just to throw out one other possible option into the mix: http://www.batteryspace.com/high-power-polymer-li-ion-cell-3-7v-10-ah-9759156-5c-37wh-50a-rate-----ul-listed-un38-3-passed-3-0.aspx/ at 210 grams per cell that makes for a 14.8v nominal 30Ah battery pack equivalent to a 35Ah LiFePO4, in only 2.5 kilos. Costs about £250 though..

On ease/reliability of charging and maintenance it surely falls short, and you pay extra for the privilege, those are not insurmountable design hurdles for mobile audio though, and if high power concentration in a small space and weight are the main priorities LiPo is a good option, that's about half the overall weight for the same output.
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Please note that if you're buying LiPo batteries from the US (ie batteryspace) add import tax and mandatory hazardous goods insurance/handling fee on the shipping.

Hazardous goods shipping handling fee is an extra $62.50 per package regardless of content. This comes on top of the shipping fee.


Import tax for the package of 12 LiPo of the above described would be an extra $98.12

According to this calc (could be a little off but not much) it would be almost £400 for the package in total.


My main beef with li-ion/lipo batteries though is that when used with standard car audio equipment nominal voltage of 3 cells is too low so the useful capacity is only around 60-70% of the actual capacity. And charging voltage of a 4 cell battery is too high (16.8V) for most 12V equipment that does not also accept 24V directly. That's why I recommend LiFePO4 batteries. For this use they are just superior in every way.


Edited by Saturnus - 02 April 2015 at 2:44pm
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lutkeveld View Drop Down
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Points: 517 		Post Options Post Options   Thanks (0) Thanks(0)   Quote lutkeveld Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2015 at 2:47pm
I see a lot of spl competition guys use 8S lead acid, which is 18.4V fully charged. Maybe they use special gear then, don't know.
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http://www.aliexpress.com/item/Universal-3-7v-10Ah-lithium-iron-phosphate-polymer-lithium-iron-phosphate-battery-electric-vehicle-batteries/2048464236.html £137.50 direct from China - opens the usual can of worms about reliability but if you can budget a bit extra say £180-£200 that should be enough to find some relatively premium cells from a reputable source.
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Originally posted by lutkeveld lutkeveld wrote:

I see a lot of spl competition guys use 8S lead acid, which is 18.4V fully charged. Maybe they use special gear then, don't know.

Only to fed the power amps. And the amps they use are specifically rated for up to 24V. They do this to avoid voltage sagging triggering the low voltage shut-down. This is because lead batteries have very significant voltage sagging when delivering very large currents. LiFePO4 batteries do not. They would be better off using standard LiFePO4 batteries.

Also, and this may rough some feathers, SPL competition people are generally ignorant retards.


Edited by Saturnus - 02 April 2015 at 3:10pm
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Originally posted by Hemisphere Hemisphere wrote:

http://www.aliexpress.com/item/Universal-3-7v-10Ah-lithium-iron-phosphate-polymer-lithium-iron-phosphate-battery-electric-vehicle-batteries/2048464236.html £137.50 direct from China - opens the usual can of worms about reliability but if you can budget a bit extra say £180-£200 that should be enough to find some relatively premium cells from a reputable source.

Problem is that they say it's LiFePO4 but it is not. LiFePO4 has cell voltage of 3.2V. Those are standard li-ion (or lipo) cells which has a cell voltage of 3.7V.
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Points: 2272 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2015 at 3:19pm
Not a problem for me :D I hoped they were lipo cells! Car amps that accept higher voltages are often the main powered component in a high output '12v' system unless high voltage chip amps are used. Not all car amps will take that sort of voltage but many will - enough to be worth considering a system designed around that restriction. That's where the vast majority of current draw will be going anyway - a smaller dedicated 12v battery Could be included for anything that absolutely needs 12v and would also double function as a reserve battery for when the main is dead.
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http://www.amazon.com/Cadence-Acoustics-ZRS-C6-Amplifier/dp/B003PJ6TOO Interesting how extreme output 'competition' amps are getting more affordable, if these figures are close to accurate that's not a bad price per Watt, and might turn up on the used market for a good price with a little luck. 15 kilos is a lot of weight to take on for an amplifier - Something half the size/weight/price and half the wattage would be ideal: 3000 RMS or so, running 375 Watts each into 8 drivers with a low-power/higher efficiency backup system running on the same 18.5v rail at around 75 Watts per driver (8x fully bridged class D chip amps) 
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