battery life and amplifiers

Submitted: Sunday, Apr 15, 2007 at 21:47
ThreadID: 44349 Views:1487 Replies:9 FollowUps:23
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Just wondering if anyone has any idea on what kind of power stereo amlifiers draw from your battery. I am running 1X 800 4 channel and 2x 600 watt 2 channel amps . I seem to flatin the battery in under 20 min .

Would be great to know how many batteries would be needed . I was hopeing to get away with 2X 750 ah
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Reply By: Leroy - Sunday, Apr 15, 2007 at 21:52

Sunday, Apr 15, 2007 at 21:52
All my car stereo gear is sitting on the shelf in a cupboard for the very reason you outlined above. I don't really have an answer but many and lots would be in the answer if you wanted to use the stereo camping all night. Maybe consider a genset

Leroy
AnswerID: 233652

Reply By: joc45 - Sunday, Apr 15, 2007 at 21:57

Sunday, Apr 15, 2007 at 21:57
Is it worth carrying 2 x 750AH batteries to make that level of noise away from home?
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Follow Up By: Sarg - Sunday, Apr 15, 2007 at 21:59

Sunday, Apr 15, 2007 at 21:59
Must be another DOOF DOOF dork???
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Follow Up By: Rock Crawler - Sunday, Apr 15, 2007 at 22:00

Sunday, Apr 15, 2007 at 22:00
Its in the show car Joc . so I guess the answer is yes.

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Follow Up By: Rock Crawler - Sunday, Apr 15, 2007 at 22:03

Sunday, Apr 15, 2007 at 22:03
The stereo is in the caddy not the cruiser Sarg. But I guess I would need to fit a A track in it to join your club lol .And before you jump on the ,this is a 4wd forum , build a bridge and get over it .
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Follow Up By: joc45 - Sunday, Apr 15, 2007 at 22:08

Sunday, Apr 15, 2007 at 22:08
Hi rock Crawler,
That's fine, as long as it's at shows, and not camping areas.
The last guy who entertained us at a quiet camping spot with his doof-doof refused to wind it down so we won out with our air horns.
After that, he was quiet, and we got back to our relaxation.

Suggest that if it's at a show, there must be 240v power, so why not run a cable across, and keep the batteries charged with a hefty regulated and filtered charger.
Gerry
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Follow Up By: Rock Crawler - Sunday, Apr 15, 2007 at 22:14

Sunday, Apr 15, 2007 at 22:14
Most are outdoor , but also be good to know , since I use the vehicle for promotional work. I am sure a elec guru will give me the equation i need to work it out. I have been known to turn up to EO functions with a bit of doof doof lol
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Reply By: hiab - Sunday, Apr 15, 2007 at 22:13

Sunday, Apr 15, 2007 at 22:13
isnt the old formula, watts , divided by volts, equals amperes? if not have a look on the amp. or the spec. sheet
AnswerID: 233661

Follow Up By: Member - Oldplodder (QLD) - Monday, Apr 16, 2007 at 07:44

Monday, Apr 16, 2007 at 07:44
Hiab,

Thats what I thought, 1 x 800 + 2 x 600 = 2000 / 12 = 166 amps on full blast?

Of course, could try putting an ameter in the system.
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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 08:01

Monday, Apr 16, 2007 at 08:01
so your telling me that a multimeter across the battery will register what amps its drawing ? or do you do it the same way as checking for volts drop?
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Follow Up By: Member - Oldplodder (QLD) - Monday, Apr 16, 2007 at 14:56

Monday, Apr 16, 2007 at 14:56
No, a multimeter won't work.
In the old days when I had every gauge you could get, I had an anmeter that was between the battery and every thing else.
Would show if the battery was discharging or being charged.
But it would only read to 60 amps either way.

You can now get induction anmeters that will tell you the current running through a wire. Maybe you could use one of them on your feed to your sound system?

Have you asked a local auto electrician if they can take a reading for you?
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Reply By: Member - Stephen M (NSW) - Sunday, Apr 15, 2007 at 22:14

Sunday, Apr 15, 2007 at 22:14
Hi there Rock Crawler, I have been to a few car shows, sound offs etc and they all seem to be running from 240 volt mains, so presuming they are using invertors or some thing of the like to keep the power up. I only had one pioneer amp in the hilux was 800w 4way with splits up front and 6 inch in the rear doors but could run virtually all day without any probs and still fire the lux up at the end of the day. Obviously it wasnt drawing anywhere near the power you have and if you have the amps that run the fans in them and speed up as you increase the volume then thay would draw a fair bit as well. If you have 240V available might be the thing to look at but if no where around then maybe 3 deep cycles. I would imagine you would have to see what current there drawing at certain levels and maybe approach JCar/sparkie and see what they come up with. Regards Steve M
AnswerID: 233662

Reply By: Member - Olcoolone (SA) - Sunday, Apr 15, 2007 at 22:16

Sunday, Apr 15, 2007 at 22:16
You have about 2000 watts of power consumption, most amps are only about 80% efficent as the rest goes in heat.

If you ran the amps flat out at max power you need about 170 amphours but most amps for music will run at about 70% due to peaks and troughs so you could say you need about 120 amphours.

Now the catch, deep cycle batterys are rated over hours so if you had a100 amphour battery you may only get 80 amps out of it in the first hour before it is totally flat due to voltage stability but over 20 hours you may be able to get say 6 amps per hour giving a total of about 120 amphours.

NO battery is designed to be run totally flat.

Batterys are very hard to explain over the net.

Do you know how big 2 x 750ah batterys are and how expensive.....expect EACH battery to weigh around 250 plus kilo's, measure about 750mm X 500mm X 400mm and cost over $1500 then how are you going to charge them? Expect to pay $3000 plus for a charger.

Don't get amphours and cranking amps mixed up they are differant.

Regards Richard
AnswerID: 233663

Follow Up By: Rock Crawler - Sunday, Apr 15, 2007 at 22:32

Sunday, Apr 15, 2007 at 22:32
this seems to be a common mix up I think. Thanks for the info Richard .
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Follow Up By: _gmd_pps - Sunday, Apr 15, 2007 at 23:06

Sunday, Apr 15, 2007 at 23:06
actually it is not as bas as you describe it ...

I currently have 8x6V 220Ah Concord batteries sitting on my workbench in the shed.
They were 165 US$ each which is in todays money around A$200 ..

I use a Xantrex C5012 Multiplex 3 bank 3 stage charger .. cost US$ 460 ...
It charges at 50Amp peak ...

the batteries are around 30kg each .. which makes it 240Kg
for 1500ah you would need around 14 at 420kg ...

good luck Rock Crawler ... I run 1x800W (4 Channel) and 1x400W mono with
a 12" sub on my Goldwing ... have a 1320W alternator doing 60amp at idle ..

have fun
gmd
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Follow Up By: Member - Olcoolone (SA) - Sunday, Apr 15, 2007 at 23:19

Sunday, Apr 15, 2007 at 23:19
But how big are they each?

Regards Richard
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Follow Up By: _gmd_pps - Sunday, Apr 15, 2007 at 23:29

Sunday, Apr 15, 2007 at 23:29
similar size to a 100ah 12V cranking batterie , just a tad taller ...
well ... in a passenger car you need a stronger suspension .. lol ..
but for a show car ... why not ...

have fun
gmd
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Follow Up By: Russ n Sue - Sunday, Apr 15, 2007 at 23:33

Sunday, Apr 15, 2007 at 23:33
Rock Crawler,

Do you check the welds on the vehicle body very often? I reckon an outfit like that would do more for metal fatigue in one month than the Gibb River Road could do in a year. I trust you don't actually sit in the vehicle while that outfit is pumping?

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Follow Up By: _gmd_pps - Sunday, Apr 15, 2007 at 23:46

Sunday, Apr 15, 2007 at 23:46
the batteries are not all in one place ...

4 are in my slide-on
2 in the rear of the vehicle ( so 6 are carried by the vehicle)
and 2 in my boat ..

the vehicle is a 5.1 GVM dually with a Duramax diesel .. so no problem with the weight.

and they are not used for the stereo :)) ... my truck has a factory Bose system..
not really top but not bad either ... I run 2 additional 10" subs with a monoamp

the other stereo I mentioned is on my Goldwing (Motorbike) and of course I ride it when the stereo pumps :)) ... thats the whole idea to feel the 12" sub in the back

have fun
gmd

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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 00:09

Monday, Apr 16, 2007 at 00:09
it was fun setting up !MPG:9!!MPG:10!
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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 00:15

Monday, Apr 16, 2007 at 00:15
!MPG:11!
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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 00:18

Monday, Apr 16, 2007 at 00:18
!MPG:12!
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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 08:07

Monday, Apr 16, 2007 at 08:07
looks like you went free air sub , I was wondering what enclosure you would have used lol .

I give you 10 points for working in confined spaces lol Great looking bike .
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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 08:12

Monday, Apr 16, 2007 at 08:12
Hi Russ & Sue , yes the quarters do take a pounding. Waiting for some dynamat to take care of the issue , yes more expensive that the best barble in the worls per meter lol . But works very well
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Follow Up By: _gmd_pps - Monday, Apr 16, 2007 at 11:24

Monday, Apr 16, 2007 at 11:24
Rock Crawler,

actually it is NOT a free air sub .. I had a free air 12" LM Traffic sub in there from my BMW 745 I drove in Europe .. I has a slight thin spot in the membrane and
I wanted to save it because there is no such thing as free air here in WA .. I looked but nothing .. I just took a cheapy Sony and increased the power to it ... the trunk is enough enclosure for decent base ...

it's real fun riding it with the quiet 6 cylinder engine .. the only nuisance are Harley riders who can't stand to be passed and have to ride along and their POS spoiling my sound ... lol

have fun
gmd
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Reply By: Mike Harding - Monday, Apr 16, 2007 at 06:34

Monday, Apr 16, 2007 at 06:34
I have a string quartet in the boot :)
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Reply By: Ray Bates - Monday, Apr 16, 2007 at 08:29

Monday, Apr 16, 2007 at 08:29
Sorry Rock Crawler. Didn't hear that but what is the point
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Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 18:22

Monday, Apr 16, 2007 at 18:22
you mean as in why build the system ?

with me assuming this is the question, the answer is BECAUSE I CAN lol

it really is a stupid question , to get you to understand how annoying a question it is . Just think of how annoying it is why people ask you , why do you camp ? why not just go 5 star ? why own a 4 wheel drive . etc. etc. etc.

Why restore a chaddy ? why build a big block. Well bud , its because it's what I love. Much like why you go bush.

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Reply By: Steve63 - Monday, Apr 16, 2007 at 11:04

Monday, Apr 16, 2007 at 11:04
Suspect you have a bunch of issues. First one will be how the power has been reported. Some are by channel others are total split by channel, some are power consumption. If it is true by chanel (normally the way expensive Hi-Fi gear is reported) your 800W amp is really 3200W. Depending on the type of amp it may use 50% of the rating when it is turned on with no signal. Then again, you need to look at the charts for the battery. It may not last long with a 150A draw. You will need to get some specialist gear to measure these sorts of currents.

Steve
AnswerID: 233734

Follow Up By: Rock Crawler - Monday, Apr 16, 2007 at 18:14

Monday, Apr 16, 2007 at 18:14
Looks there are issues with the Altinator , as it stopped charging today. Shame because its less than a year old .
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Reply By: Member - Bradley- Sunday, Apr 29, 2007 at 00:22

Sunday, Apr 29, 2007 at 00:22
Hmmm how long is a piece of string Eric??

Its a hard one as it really depends on the music you are playing, because its so transient in its power demands, ie from a few watts rms to hundreds in seconds, ie lots of low bass rolls etc big power draw as amps approach clipping, easy listening only draws a few amps and barely touches the headroom in the amplifiers.

Check the fuse ratings on the amps this will give you the best indication of the max draw possible, as amps are rated so diffently by different makers. For example my soundstream reference 300 amps are IASCA rated at 37.5w x2, so you can run 2 amps in a comp car and be in the 150 watt class. But these amps switch into high current mode when you drop the impedence load on them, and produce 300w at 1 ohm load, stable to a quarter ohm :-) .. They run a 30 amp fuse.

So its a hard one to judge, my fairlane was good for 30 minutes or so on a n70 size batt. And i used an overdriven 80 amp alternator from a magna of all things !! so the charge rate was up at idle, and seeing as the old ford didnt rev past 4500 it was more than happy being overdriven, i also ran extra 4 guage earth cable from block to batt, and ran 4 guage from alternator to batt. Worked real well.

The best batts to use for stereo work are the optima yellow top version, very low internal resistance so they charge quick and also discharge quickly in response to amp demands. Buy as many as you can afford and fit in. (within reason of course). You can even run an isolator to keep one batt good for starting, just like fridges etc... A lot of yanks seem to run the gmc "ambulance" alternators, about 160 amp with a gilmer drive.

hope that helps a bit.
cheers Brad.
AnswerID: 236520

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