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| JWM |
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Hi, Just wondering what type of batteries I should be looking at for installing into my boot?
My plan is to run a few amps for a few hours without the ignition on and I will be makeing something to disconect the battery in the engine bay from my audio system so it can still start the car, but re-conect so the batteries in the boot can charge... So I need batteries that dont mind being discharged then re-charged often... I need high amp/hour batteries... ...and batteries that dont need venting or something??? Also, how much power to car amps draw? 1000watt RMS amp? 400watt RMS? Not talking about the $40 amps, more like jaycar amps at >$400. Just need an idea roughly what they draw so I can workout what I need... As you can probably tell, I have no real experience with this stuff, although I am confident with electronics... just not car stuff yet 
Cheers, Jake |
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| Hybrid34 |
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Im no whiz at this stuff,
But I run a pretty powerful system (not like show cars), but I've got; - 800watt Alpine v12 4 channel - 600watt Alpine v12 monoblock - 2 x Alpine type S SUbs 15" rated 300RMS each - 4 tweeters - 4 3x2 150watt pioneer speakers - Tv tuner - Dvd Stacker - Cd stacker - 7" Dvd Screen - Soon another 2 screens (head rests) A sh*t load of lights inthe car (fairlane with extra lighting) And i can tell you it drains a heap outta the battery, If you can afford it, go Optima Yellow Top Deep Cycle (Dry cell), its good for instaling a bttery in a boot or inside the cabbin as its not liquid... If you can't, exide make a good battery, along with centrey. I've got a GSYUASA 480CCA, (just brought), seems pretty good. For a powerful stero system get a capacitor (bascailly creates a massive charge and sends it out to the amps, puts less strain on your alt and you've got respsonsive power)... Also get a good battery, don't go any lower thhan 450cca, and try to get a 80amp - 150 amp battery. (DON"T GET RACV batteries, they've changed hands to the purple colors that are made in Korea, very bad rateing) Hope this helps a bit - Ash
_________________ Sucessful trades with Schmee, Braidy, Niko, The_Ghost, YBHVE4, Stalker
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| Hybrid34 |
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..Oh forgot to Add,
get a nice altenator, pref 110Amp..I've learn't it the hard way n killed my yellow top. If your running a heavy load, a powerful Alt will assist in the power your draining, and it will help the life of ur altenator and battery Cheers - Ash
_________________ Sucessful trades with Schmee, Braidy, Niko, The_Ghost, YBHVE4, Stalker
Last edited by Hybrid34 on Mon Jun 09, 2008 5:22 am, edited 3 times in total. |
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| data_mine |
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I use an Optima Yellow top. Great deep cycle battery, and has a huge RC (reserve current) so last a while.
+ high power density + deep cycle (doesn't mind being flattened - don't leave it dead for too long however) + gel acid (leak proof) + sealed (can be installed in cabin) - heavy - expensive As for your power coupling, try these from Jaycar, good for 500A... http://www.jaycar.com.au/productView.asp?ID=SF2245 Also use some heavy duty power cable, as once you reconnect the flat-ish batteries they'll want to suck ALOT of amps from the main battery. 0 Gauge and a 200A fuse would be the go.
_________________ 1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow |
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| twr7cx |
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Optima Blue Top here - was cheaper than the Yellow.
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| JWM |
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Cool, thanks for the help.
Anyone know how many amps a car amp will draw? my guess would be under 50amps but no idea really... If no one knows I guess I can just experiment and find out how long the batteries last
Oh and thanks for that link to the switch, I was wondering how I was gonna go about disconecting the batteries 
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| nicco |
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i'' let you do the sums on the power drawn:
P=VI P = Power (watts) V = Voltage (volts) I = Current (amps) You will want to include an efficiency too. from pyroays tutes and my memory, it about 65% for an A/B amp, and about 80% for a class D. P=VI/n n = efficiency as a decimal (ie: 0.65) |
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| nicco |
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oh and to add to that for you, car voltage estimate at 13.8v.
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| data_mine |
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depends on the amp. Find out it's RMS rating, mutliply by 12, and add 20% That'll be a worst case draw.
Or check the fuses on it, that's what the maker thinks is worst failure case. In reality it'll be much less, because you won't be pumping it 100% with a test tone. Real music takes less power to reproduce than test tones.
_________________ 1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow |
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| JWM |
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Ah sweet as, thanks for all the help guys
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| relaxed_diplomacy |
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JWM wrote: If no one knows I guess I can just experiment and find out how long the batteries last
Despite the common impression most deep cycle batteries aren't designed to be flattened. Normal car batteries are designed for a quick burst, which might take them to say 90%, and then be recharged. Deep cycle batteries are usually designed to be discharged slowly, to no less than say 70% capacity, and then ideally slowly recharged. Deep cycles will handle full discharge better than normal types but it will still dramatically reduce their lifespan. I don't know about Optima batteries. Where can you get them?
_________________ wrecking 9/97 EL fairmont sedan burgundy 6cyl auto 270k modBAintake |
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| data_mine |
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Specialist battery shops - Battery World for example.
or Car audio shops (not talking your JB HiFi's or Strathfields etc.)
_________________ 1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow |
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| JWM |
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relaxed_diplomacy wrote: JWM wrote: If no one knows I guess I can just experiment and find out how long the batteries last Despite the common impression most deep cycle batteries aren't designed to be flattened. Normal car batteries are designed for a quick burst, which might take them to say 90%, and then be recharged. Deep cycle batteries are usually designed to be discharged slowly, to no less than say 70% capacity, and then ideally slowly recharged. Deep cycles will handle full discharge better than normal types but it will still dramatically reduce their lifespan. I don't know about Optima batteries. Where can you get them? Yeah I was thinking I'd have to cut the batteries out at about 11 volts, so probably a volt meter would be a good idea... or get a capacitor with a voltage display built in... |
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| relaxed_diplomacy |
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Quote: Yeah I was thinking I'd have to cut the batteries out at about 11 volts, so probably a volt meter would be a good idea... or get a capacitor with a voltage display built in...
11 volts might be too low but i'm not sure. But voltage isn't really a safe or practical way to go because the voltage is more a product of load than capacity remaining. For example, if you cranked the volume up for a moment or if there was a big base section the voltage would drop and then rise again afterwards. There are battery regulators that have a microprocessor that measures and displays and exerts various influences on the battery including user defined cut outs. You tell them and/or they compute themself the amp capacity of the batteries and cut out when a certain amount has been discharged. If you use a specialist battery like an Optima then you would also want to find out about them regarding these issues. It might sound like a hassle but is usually less so than battery problems, and cheaper in the long run too.
_________________ wrecking 9/97 EL fairmont sedan burgundy 6cyl auto 270k modBAintake |
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| relaxed_diplomacy |
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Here are some useful links:
http://www.optimabatteries.com.au/ http://www.popularmechanics.com/automot ... 66741.html
_________________ wrecking 9/97 EL fairmont sedan burgundy 6cyl auto 270k modBAintake |
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