#233933 - 19/09/2004 12:59
Run Empeg on Batteries?
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addict
Registered: 29/06/2002
Posts: 531
Loc: Triangle, VA
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I was curious is it possible to run the empeg on a laptop battery of some kind? And if so what size battery would be needed for a decent length of play time? Thanks!
_________________________
-D
Modifying and Tweaking is a journey,
not a destination................................
MKIIa : 60gig - 040103286 - Blue - v2 + PCATS tuner
MKIIa : 20gig - 040103260 - Blue - v3a8 + Mark Lord Special Edition Cherry Dock
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#233934 - 19/09/2004 14:03
Re: Run Empeg on Batteries?
[Re: SonicSnoop]
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carpal tunnel
Registered: 24/01/2002
Posts: 3937
Loc: Providence, RI
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If you search, I know we talked about this before in the context of for instance running it on a plane (and deciding it would look too dangerous)
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#233935 - 19/09/2004 16:53
Re: Run Empeg on Batteries?
[Re: SonicSnoop]
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carpal tunnel
Registered: 20/12/1999
Posts: 31604
Loc: Seattle, WA
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The only person I know of who's run the empeg off batteries did it with a small 12-volt motorcycle battery. He has reported great success that way.
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#233936 - 19/09/2004 18:30
Re: Run Empeg on Batteries?
[Re: tfabris]
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addict
Registered: 29/06/2002
Posts: 531
Loc: Triangle, VA
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Thanks guys, Ive been reading thru alot of the old posts about it, finding out all I need  sorry I posted before searching. keep forgetting you guys been doing things for a while so you all have thought of just about it all
_________________________
-D
Modifying and Tweaking is a journey,
not a destination................................
MKIIa : 60gig - 040103286 - Blue - v2 + PCATS tuner
MKIIa : 20gig - 040103260 - Blue - v3a8 + Mark Lord Special Edition Cherry Dock
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#233937 - 20/09/2004 03:06
Re: Run Empeg on Batteries?
[Re: SonicSnoop]
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Carpal Tunnel
Registered: 08/02/2002
Posts: 3411
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Laptop batteries wouldn't be any good as they don't usually have 12V.
What I'd recommend is 2 RC car battery packs used in serial to give 14.4V. If you used 3000mAh packs then you would expect 3+hours. I'm not sure if we've ever come to a consensus about curent requirements, but we know that it's under 1A including disks being spun up and the VFD on. With a judicious use of the hijack screen blanker and mp3s with a reasonable bit rate double to triple that 3 hour time should be possible.
You could buy or even make 10 pack cells (=12V) but then you'd need a charger capable of charging them, which would put you into RC airplane territory. I'm also not sure at what voltage the empeg considers to be undervoltage. If it's exactly 12V then you wouldn't be able to maximise the usage of a 12V pack's capacity.
Sticking to 2 six cell packs gives you a wide range of RC chargers (including RatShack's cheapies) and avoids that problem.
The other heavier and bulkier options are either a 12V motorcycle battery (lead acid - ugh) or 9 D cells. IIRC, a Duracell D cell is approximately 8000mAh, so that would give you nearly 3 times the duration of the RC packs, although that would come at the expensive of weight. bulk and the fact that you couldn't recharge them.
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#233938 - 20/09/2004 03:13
Re: Run Empeg on Batteries?
[Re: genixia]
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carpal tunnel
Registered: 24/01/2002
Posts: 3937
Loc: Providence, RI
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Quote:
The other heavier and bulkier options are either a 12V motorcycle battery (lead acid - ugh) or 9 D cells. IIRC, a Duracell D cell is approximately 8000mAh, so that would give you nearly 3 times the duration of the RC packs, although that would come at the expensive of weight. bulk and the fact that you couldn't recharge them.
Sadly, if you're talking about any serious amount of ampere hours, you can't beat lead acid on price. Of course, for this, it's probably overkill.
If they still made em I'd have suggested an Evertroll NiZn battery, which would have given you a pile of play time...
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#233939 - 20/09/2004 13:37
Re: Run Empeg on Batteries?
[Re: Daria]
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carpal tunnel
Registered: 19/01/2002
Posts: 3584
Loc: Columbus, OH
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Would something like this work? With 2000 mAh rechargeable batteries, you could get through many domestic flights.
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~ John
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#233940 - 20/09/2004 13:41
Re: Run Empeg on Batteries?
[Re: genixia]
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addict
Registered: 29/06/2002
Posts: 531
Loc: Triangle, VA
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Thanks for the info. Ok this is what I have been thinking. Maybe you can tell me if this would work or not. Im thinking of getting 4 RC 6cell packs (7.2V 3300mAh each) I was going to try wiring them up in pairs in series so I would have two sets at 14.4V 3300mAh. Then I was going to wire those two up in parallel so I would have 14.4V 6600mAh for extended play time. Am I correct in this? Or would I blow something up?  Thanks!!
_________________________
-D
Modifying and Tweaking is a journey,
not a destination................................
MKIIa : 60gig - 040103286 - Blue - v2 + PCATS tuner
MKIIa : 20gig - 040103260 - Blue - v3a8 + Mark Lord Special Edition Cherry Dock
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#233941 - 21/09/2004 02:03
Re: Run Empeg on Batteries?
[Re: SonicSnoop]
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pooh-bah
Registered: 12/01/2002
Posts: 2009
Loc: Brisbane, Australia
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That should work fine. Charging them could be an issue though. They should be charged as a pack I think and not individually.
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Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)
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#233942 - 21/09/2004 03:22
Re: Run Empeg on Batteries?
[Re: Shonky]
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Carpal Tunnel
Registered: 08/02/2002
Posts: 3411
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Quote:
They should be charged as a pack I think and not individually.
I disagree - you shouldn't charge packs in parallel as it would be possible to undercharge one pack whilst overcharging the other.
The other advantage of charging them separately is that you can use standard 7.2V RC chargers to do so. Charging 14.4V packs is expensive. But you do have to ensure that packs in series are kept at the same level of charge - mixing a fresh pack with a half used pack can kill the half used one. And avoid discharging the cells below 1V per cell, ie 12V for the whole lot. (This should prevent stronger cells in the pack from destroying weaker cells). You may want to build in a small LCD panel meter to pay attention to this.
I'd advise labelling each set of packs clearly. If you can't find heatsink of that large size in multiple colors then use different color sticky tape. Anything to make it obvious which pack belongs with which. Get into the habit of charging two packs together. (Yes, two chargers - you don't need to get expensive with them)
I'd personally build such that there was a slide switch to select between the two sets, rather than leaving them both wired in parallel. This would mean that you are only discharging one set at any moment. It also means that if you use it for say 30% of total capacity, you only have to recharge 2 packs rather than 4.
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Mk2a 60GB Blue. Serial 030102962
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#233943 - 21/09/2004 03:34
Re: Run Empeg on Batteries?
[Re: genixia]
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pooh-bah
Registered: 12/01/2002
Posts: 2009
Loc: Brisbane, Australia
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Hmmm. But as you mentioned what happens if you plug a discharged pack in parallel with a fully charged pack. The charged pack will try and dump as much current as it can into discharged pack, possibly damaging it. At the very least it would get very hot. You probably know how hot a 7.2V Nicad pack can get after 10 minutes discharging in an RC car.
I'm no expert on batteries though.
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Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)
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#233944 - 21/09/2004 04:06
Re: Run Empeg on Batteries?
[Re: Shonky]
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Carpal Tunnel
Registered: 08/02/2002
Posts: 3411
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Well, that would be another advantage to switched banks. Plugging the numbers in (5.6mOhm per cell) gives a peak inrush current of 113A, which I suspect may not be healthy for either bank.
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#233945 - 21/09/2004 05:20
Re: Run Empeg on Batteries?
[Re: SonicSnoop]
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carpal tunnel
Registered: 08/07/1999
Posts: 5549
Loc: Ajijic, Mexico
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Im thinking of getting 4 RC 6cell packs (7.2V 3300mAh each) I assume there is some reason you want to go all high-tech and expen$ive. It is really very easy, very cheap, and very reliable to get a 12V lead-acid gel-cell battery, about 3.5" by 2.5" by 4" that will run your player for 8--10 hours, and cost you about $15--$20. You can spend another $25 or so for a "smart" battery charger that won't overcharge it, or if you have the discipline you can use the battery charger you already have for your car and keep an eye on things while you're charging it, don't let it charge for more than about 45 minutes at a time, otherwise it will overheat and shorten battery life. Avoid deep-discharging, and you'll get hundreds of cycles out of it. Abuse the hell out of it (overcharge, deep-discharge) and you'll still get dozens of cycles out of it, and it's so cheap that if you wreck it you won't care very much. I've been using this setup for the last three or four years when I use my player on my bicycle and am still using the original battery. tanstaafl.
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#233946 - 21/09/2004 10:16
Re: Run Empeg on Batteries?
[Re: tanstaafl.]
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addict
Registered: 29/06/2002
Posts: 531
Loc: Triangle, VA
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Well the main reason im thinking of going with the rc packs is that the area I am mounting everything is going to be pretty small and It would be easier to have multiple little packs that I can spread around the sled then one single big battery.
_________________________
-D
Modifying and Tweaking is a journey,
not a destination................................
MKIIa : 60gig - 040103286 - Blue - v2 + PCATS tuner
MKIIa : 20gig - 040103260 - Blue - v3a8 + Mark Lord Special Edition Cherry Dock
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#233947 - 21/09/2004 12:40
Re: Run Empeg on Batteries?
[Re: genixia]
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addict
Registered: 29/06/2002
Posts: 531
Loc: Triangle, VA
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Quote:
The other advantage of charging them separately is that you can use standard 7.2V RC chargers to do so. Charging 14.4V packs is expensive. But you do have to ensure that packs in series are kept at the same level of charge - mixing a fresh pack with a half used pack can kill the half used one. And avoid discharging the cells below 1V per cell, ie 12V for the whole lot. (This should prevent stronger cells in the pack from destroying weaker cells).
I have a RC Charger that charges at 1/2/4 amp. I can use it in a car or in the house. and it supposidly turns it self off after the battery is fully charged. would this work good? Could I just throw them on it individually and tell it to charge and have it shut off when it thinks they are full?
Quote:
You may want to build in a small LCD panel meter to pay attention to this.
Do you know of an example on a web page showing what you mean?
Quote:
I'd advise labelling each set of packs clearly. If you can't find heatsink of that large size in multiple colors then use different color sticky tape. Anything to make it obvious which pack belongs with which.
So the two batteries I wire together in series should stay together? like label them Bat1, Bat2, Bat3 & Bat4 and keep Bat 1 & 2 together and 3&4 etc?
Quote:
Get into the habit of charging two packs together. (Yes, two chargers - you don't need to get expensive with them)
Is this so that they are on the charges same amount of time?
Quote:
I'd personally build such that there was a slide switch to select between the two sets, rather than leaving them both wired in parallel. This would mean that you are only discharging one set at any moment. It also means that if you use it for say 30% of total capacity, you only have to recharge 2 packs rather than 4.
That makes sense. Thanks!
_________________________
-D
Modifying and Tweaking is a journey,
not a destination................................
MKIIa : 60gig - 040103286 - Blue - v2 + PCATS tuner
MKIIa : 20gig - 040103260 - Blue - v3a8 + Mark Lord Special Edition Cherry Dock
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#233948 - 21/09/2004 15:32
Re: Run Empeg on Batteries?
[Re: SonicSnoop]
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Carpal Tunnel
Registered: 08/02/2002
Posts: 3411
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Quote:
So the two batteries I wire together in series should stay together? like label them Bat1, Bat2, Bat3 & Bat4 and keep Bat 1 & 2 together and 3&4 etc?
...
Is this so that they are on the charges same amount of time?
It's all about making it easy for you to avoid putting a fully charged pack in series with a discharged pack. By keeping the banks distinct and charging each pack at exactly the same time you end up with the situation where that this is _never_ going to happen. Each pack in the bank will be either fully charged or at a similar level of discharge. You're never going to find yourself with one known charged pack and wondering whether you remembered to charge the other, or with on charged pack and wondering which of the other 3 packs is its charged sibling.
It's by no means necessary to do this. You could charge each pack in turn.
Quote:
I have a RC Charger that charges at 1/2/4 amp...
It sounds like this is ideal. It would be useful to know the make/model before I put my neck on the block though. As long as it is a voltage peak cutoff charger and not a timed charger then it should be good.
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#233949 - 21/09/2004 16:44
Re: Run Empeg on Batteries?
[Re: genixia]
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addict
Registered: 29/06/2002
Posts: 531
Loc: Triangle, VA
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As soon as my friend gives me back my RC car ill post the exact make and model of the charger. Thanks!
_________________________
-D
Modifying and Tweaking is a journey,
not a destination................................
MKIIa : 60gig - 040103286 - Blue - v2 + PCATS tuner
MKIIa : 20gig - 040103260 - Blue - v3a8 + Mark Lord Special Edition Cherry Dock
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#233950 - 24/09/2004 23:51
Re: Run Empeg on Batteries?
[Re: JBjorgen]
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carpal tunnel
Registered: 24/01/2002
Posts: 3937
Loc: Providence, RI
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He also points out (in person) that cordless drill batteries offer plenty of power for such an application and can be gotten at the right voltage.
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