Buying the right power pack
Buying the right power pack
(OP)
I am going to be buying a Roland CD-2e recorder and using it in locations where I cannot plug it in.
The tech specs of this unit tells me that it has a current draw of 540 mA, and when using batteries it takes 6 X LR6 (AA) type alkaline batteries - so 9 volts DC, right?
The specs also say I cannot use the AA batteries for CD writing and reading, that the unit must use the AC Adapter.
Therefore I need a portable power pack sized to run this unit, full time, for about 12 hours per day, and then be able to plug it in over night and recharge it so it can do it again the next day, for 4 -5 days in a row.
Many of the power packs I see on the market have auto battery boosters cables, a light, a radio and other accessories, that I do not need, but I suspect I'll have to take. All I really need is the power pack that can be recharged and, I guess, the inverter to run the AC adapter.
Can you folks help me choose the right size of power pack and if you have any suggestions for a specific brand and model, I'd be glad to hear it.
I'd also consider assembling the parts myself into a suitable case, making my own power pack, but I suspect buying the ready made unit will be a lot simpler.
Thanks
The tech specs of this unit tells me that it has a current draw of 540 mA, and when using batteries it takes 6 X LR6 (AA) type alkaline batteries - so 9 volts DC, right?
The specs also say I cannot use the AA batteries for CD writing and reading, that the unit must use the AC Adapter.
Therefore I need a portable power pack sized to run this unit, full time, for about 12 hours per day, and then be able to plug it in over night and recharge it so it can do it again the next day, for 4 -5 days in a row.
Many of the power packs I see on the market have auto battery boosters cables, a light, a radio and other accessories, that I do not need, but I suspect I'll have to take. All I really need is the power pack that can be recharged and, I guess, the inverter to run the AC adapter.
Can you folks help me choose the right size of power pack and if you have any suggestions for a specific brand and model, I'd be glad to hear it.
I'd also consider assembling the parts myself into a suitable case, making my own power pack, but I suspect buying the ready made unit will be a lot simpler.
Thanks





RE: Buying the right power pack
see: http://ww
Assuming that your AC adaptor can source 1 amp at 9V, and assuming 40% adaptor/inverter efficiency, you need to supply about 20 W continuously, which is about 1.7 A at 12V, which requires a 24 Ah battery
TTFN
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RE: Buying the right power pack
What is the labeled OUTPUT of the adapter?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
As for staying in 9 volts DC, that would be the most efficient, wouldn't it. The Roland site does not tell us the OUTPUT of the adapter, and I only assume its 9 VDC. I have a friend who has one of these units and I'll get them to check.
But again, if I stay in VDC, I'll still have to buy an additional charger.
I'm looking at a unit available locally and I'll probably get it unless one of you experts points me elsewhere. Its this unit:
http://ww
Thanks very much for all your help. I love forums.
RE: Buying the right power pack
You need at least twice the required AH. This is why you want the efficiency as high as you can get it because you also need twice the capacity demanded by those inefficiencies.
Look at this: http://www.powerstream.com/daa-1209.htm
You need 540mA x 9V = 4.9W
converter 70% efficiency => 7W
7W/12V = 0.6A
0.6A x 12hrs = 7.2Ah/day
If you charge every night then you should use a 14.4Ah or larger battery.
Common LA size is 17Ah.
See:
http:/
An excellent charge is found here:
ht
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
The battery you mentioned is the Panasonic P174-ND and weighs 14.3 lbs.
The converter only weighs 7 oz. and charger is 3 lbs, so all the parts, plus cables, etc will not exceed 20 - 25 lbs. I can lug that to where its needed easily.
I'll be looking locally for a sturdy, rugged, tool box or something like that, in which I can mount the parts.
Thanks for your help. As the project continues, I'll take some pictures and share them with you.
RE: Buying the right power pack
In use, the battery and converter will be in a building at a trade show.... a convention center.
I see the battery is sealed, so I assume if I carry it at a shallow angle from time to time, it won't damage anything.
When charging, the setup will likely be in a hotel room, getting charged for the next day's work.
Any special environmental issues I should know? Fumes? noise?
Thanks
RE: Buying the right power pack
If I put all these parts into a carrying box of some sort and hook them up together, will they conflict with each other?
The converter is wired to the battery, and so is the charger. Is there any risk of damage to the converter while charging? Is there any risk of damage to the charger while using the battery/converter combination connected to the recorder?
Or will I have to disconnect one element while using the other?? If so, I guess some sort of switch might be handy.
Thanks
RE: Buying the right power pack
Your circuitry should be disconnected from the battery during charging. A typical charger will put out several volts above the battery nominal voltage to essentially "push" the power back into the battery. The higher voltage could potentially damage the inverter, although it should be designed to handle the voltage range.
TTFN
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RE: Buying the right power pack
The DC-DC should even handle running while the charger is powered because the charger should not put out more than 15V which is the input rating of the DC to DC.
There should also be no hydrogen evolved in this case. I would probably NOT ventilate the case unless it will never see rain. Instead I would run it with the lid ajar. Or you can ventilate it and not worry about it.
If you do ventilate it you want some holes near the bottom and some near the top.
You should certainly give it a test before your show. You want to make sure things don't get too hot in the resulting box.
A tool box is a good idea that would allow easy handling. It will also provide storage for the cords.
I would also add a fuse to your output, 1A. So if the cord gets shorted you don't lose everything.
One last feature I'd add would be an in-line set of connectors. The reason is for the unexpected. In a trade show you could easily have someone catch the cord with something. You want the plug to just un-plug not yank the device you're powering off onto the floor. A straight in-line connector set will do this. The one in the device will invariably be at right angles to any pull and NOT automatically unplug.
Good luck.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
I will follow up with info and pics as I get this going.
RE: Buying the right power pack
Thanks
http://www.powerstream.com/daa-1209.htm
RE: Buying the right power pack
Its the second or third one down the list.
Will that one work as well?
RE: Buying the right power pack
http://www.powerstream.com/dc6.htm
RE: Buying the right power pack
Have at it.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
I dunno who said it first, but it appeared several times in the books of one of my favorite authors, Ted Allbeury.
I've been mulling this whole project over in my head today and trying to come up with an idea for a suitable carrying case for it. I had planned originally to use a heavy duty plastic tool box, but in order for the battery to sit upright, I'd have to get a box that is quite long - 20 inches, or so.
So I cast around looking for a box that was sturdy enough to carry the battery and other parts, tall enough so it could stand upright, and with a handle on the top. And finally I discovered the ideal box - an ammo box! With the configuration detailed above, the 50 caliber ammo box will do the job well, I think. Here's a link to what I mean:
http://www
Should work well, no?
Then I started thinking about trade offs. Based on the design above, I'll be carrying this box back to the hotel every night and recharging the battery on the hotel plug in.
What would it take to have a setup that would last the whole show?
Typically;
Friday 12 hours
Saturday 12 hours
Sunday 8 hours
Total 32 hours
Then I went back to KC's calculations, as shown above, and tried to bend my head around it, using 32 hours and using the other multi-output converter.
Here's what I got:
9V @ 2.1A = 18.9W
converter efficiency 73% X 18.9W = 13.7W
13.7W / 12V - 1.14A
1.14A X 32 hours = 36.5 Ah
Double that = 72 Ah and that equals a BIG battery or two smaller ones. I abandoned my math calculations there, and I now assume that if the previous battery is 20 lbs weight, this new configuration is probably going to weight 50 - 60 lbs, more than I want to lug in. I'd probably end up with some sort of wheeled dolly arrangement - just not worth the aggravation.
So, KC, I'm staying with our original design and I'll be carrying the unit back to the hotel Friday and Saturday nights to recharge it.
Can I have your input, comments and suggestions?
Thanks
PeterAL
RE: Buying the right power pack
Gelcells can run in ANY position. So stop worrying about keeping the battery upright.
Now can you use a smaller toolbox?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
RE: Buying the right power pack
25.9W / 12V = 2.2A
2.2A * 32 hr = 69 A*hr
Then, double it...
TTFN
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RE: Buying the right power pack
Thanks
RE: Buying the right power pack
Thanks to you folks, I have a neat little portable power supply for my device. This will give me more flexibility in my work and make life easier. Thanks so much for all your help.
If you have any questions about the components I ended up using, or anything else about this project please feel free to ask.
Here's an album of pictures of the various steps I took.
ht
RE: Buying the right power pack
Ammo Box $20.00
Spray Paint 5.00
Battery 50.00
Charger 45.00
Converter 40.00 (included $22 for shipping to Canada!)
Small parts 25.00
----------
Total 185.00
I could have got a power pack for somewhat less at the local Canadian Tire store, but I really enjoyed doing it myself.
Thanks
RE: Buying the right power pack
Don't try to take it on an airliner...
One point. You obviously have no idea how much energy that battery actually represents
or you would immediately fashion some sort of covers for the battery terminals.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
Hmmm.. it would be nice if there was some sort of material I could heat shrink around the terminals like I did with the joins in the wire..
I'm gonna look for large diameter heat shrink stuff..
Thanks
RE: Buying the right power pack
Keith Cress
kcress - http://www.flaminsystems.com
RE: Buying the right power pack
RE: Buying the right power pack
But, I don't want to take chances and be without power when needed.
I use it 12 hours straight, with stops for a minute or two, every half hour. Then I would not need it until the next day for another 12 hours stint, and the similarly the third day for about 10 hours.
If this battery will last throughout the whole three days, it will save me lugging it back to the motel every night for re-charging. It heavy enough, I'm considering re-working it into some sort of wheeled cart.
So, my question is, is there a gauge I can put on the battery, preferably wired right onto it, to tell me how much is left in the battery?
Thanks for your ongoing help.
RE: Buying the right power pack
You could just measure it with a voltmeter. 12V is dead flat - damage land. 13V+ is charged.
However I suggest you go for the exercise of recharging it as running the battery down below half of its capacity and letting is sit overnight will permanently reduce its capabilities.
I'm surprised you can't find an outlet somewhere nearby that you can charge it at. Not maybe where you use it but still local, even while you're eating lunch or something. The first few minutes really pack on the recharge.
Keith Cress
kcress - http://www.flaminsystems.com