Okay. Wow. This is a mountain of knowledge and experience. Thanks so much. It is currently 2 nights 50 minutes shows with the possibility of more. Maybe I use the internal battery option for those and if we get a regular show from it, then I explore something else more permanent. Thanks again.
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Rechargeable power supply
- Thread starter facethebass
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mAh stands for mA (milli-ampere) times h (hour) and is the energy of one mA (at a given nominal voltage, so that current times voltage = power) delivered during one hour.
So a battery capacity of 4400mAh contains the amount of energy of 4400mA drawn during one hour or 440mA during 10h, etc... Of course the first example is not realistic because that battery may not be able to deliver 4400mA of current.
In the case of OP, he plans to draw about 1022mA, leading to theoretical expectations of 4400/1022= 4.3h=4h18min.
Practically, you may get less than theoretical time because (especially when drawing higher currently or when battery is old) the battery may not deliver the full 4400mAh capacity. And additionally, I suspect they use a small marketing gag: the 4400mAh are related to the battery cells voltage (7,4V) and then the voltage is raised to 9V, so the energy is 4400mAh x 7.4V which would correspond to 3620mAh x 9V minus conversion losses, so that would be a somehow less than 3.5h at 1022mA.
However also, the pedals current requirements are for the peak needs, and for the zoom, the average is actually much lower, so you will probably actually get more battery duration because the calculation is very conservative on the current drawn (meaning overestimating the current consumption). My personal experience with slightly more power hungry setup is that it easily lasts 4 hours (but I never measured until the battery stopped)
This is correct if the rating is based on a 1 hr discharge rate. While that is possible, AFAIK it's not generally how it's done. As I said in my last post, it's common to specify a 20hr discharge rate, but it can vary by battery type...and I don't have the specs for the specific battery used in the OP's power supply.
If you don't know it, I suggest you read about Peukert's Law. Peukert's law - Wikipedia
The time interval the mAh rating is based on is called the C-rate. https://www.dv-power.com/battery-c-rate/
Let's consider a Duracell MN1500. This is their Coppertop AA Alkaline. I believe the common claim is about a 2800mAh rating. The data sheet doesn't give a C-rate but it does have charts that show how the available capacity changes, depending on current draw. [Invalid or Expired Link Removed]
The highest current these show is 1000mA. Note the service hours is about 1hr at 1000mA. So the capacity is only 1000mAh which is way less than 2800mAh.
I believe the 100mA trace bottoms out at about 27 hrs. 27 x 100 = 2700mAh. Still a bit short of the 2800mAh rating, but we are getting close.
Here's a chart for the Energizer Max datasheet https://data.energizer.com/pdfs/e91.pdf
As you see the capacity decreases as as the current rises. At 25mA you get 3000mAh and the run time is 120hrs. At 500mA it looks like you get about 1800mAh and the run time is 3.6hrs
The Energizer seems to perform slightly better than the Duracell.
Here is a datasheet for a 12V rechargeable battery with a 7Ah rating: https://www.power-sonic.com/wp-content/uploads/2018/12/PS-1270 technical specifications.pdf
As you see, the 7Ah rating is specified for a period of 20hrs. This table also shows the capacity and current rate for 10hrs, 5hrs, and 1hr. If it's not clear 7Ah is 7000mAh.
DJmtd
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The website calls the C4 an expander. AFAIK It's not a standalone. You need to feed it power from something else.
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Some laptop power supplies can provide 1A or more w the correct barrel connector for the Cioks 4 and 8.
DJmtd
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You can power it from the usb C inlet, or you can power it with something like a OneSpot, or you can power it with a DC7.
I've used it a bunch with a battery bank, it works perfectly.
Edit to add: I specifically use it to power an HX Stomp alongside 3 other pedals. So, no shortage of power.
Passinwind
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Have you tried powering your C4 with a power bank via USB-C at both ends? IIRC the manual says you need to use USB-A at the bank end, which seems obtuse. I have been contemplating a workaround, but if I don’t need it, all the better!
DJmtd
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I haven't, but I just got a new power bank with a USB C out, so I'll try it tonight!
Passinwind
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I have both those pieces here too and just haven’t tried it yet due to a health setback, but thanks, I’d love to hear how it goes.
FWIW, my planned workaround was to get a 15V USB/barrel dongle and run from the USB-C outlet on my power bank to the C4 barrel inlet, which should get me fairly close to the max current capacity of the C4. I’ve been running off a beefy old 15V/2A laptop line lump for now and that works great for my modest needs, but I really want a rechargeable power solution for my upcoming mini pedal board, and also for my externally powered active bass.
Power Box iSO8 (Rechargeable)
Power Box iSO8 The iso8 is a re-chargeable lithium Ion DC power supply for guitar players with a total output capacity of 2.0 amps at 9v and a battery capacity of 51.8 W-HR. Electrically the iso8 utilizes patented BiWire™, isolated output technology that isolates the positive and negative ground...
bigjoestompbox.com
It's not a matter of need. It's a matter of convenience. Less wiring to trip over and the desire to get rid of the always too short power cables that come with certain pedals and/or power supply units and the extension cords required trying to solve said problem.
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typos
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No worries, I have an engineering background, so I'm used to all these units (and multiples).
I knew about Peukert's law without knowing its actual name, but I never realized it could reduce the capacity so drastically.
Do you know how the different battery technologies behave? I think you showed examples for alkaline and AGM, is the effect also as strong on lithium batteries?
Here are some examples for Lithium Ion batteries in the 1000mAh range.
Ref: https://www.ineltro.ch/media/downloads/SAAItem/45/45958/36e3e7f3-2049-4adb-a2a7-79c654d92915.pdf
Ref: Link Removed
Hopefully I translate the C factors correctly:
3C = 20min
2C = 30min
1C = 1 hr
0.5C = 2 hrs
0.2C = 5 hrs
These suggest battery capacity clusters fairly closely for run times of an hour or more.
Whether this is typical of the batteries we are discussing I can't say.
DJmtd
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USB-C to USB-C worked perfectly fine over the weekend!
Passinwind
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