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Author Topic: literature about UPS battery  (Read 705 times)
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italy
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Could you suggest me where can I find information on the internet about batteries used as UPS for arduino?
Do not answer "you can search on google", I am not supid and not lazy, but I havent' found anything really technically interesting.
I want to learn more about charging values depending on cells, switching systems between power supply AC-DC and battery.
Thanks in advance!
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There's no swtiching involved - run the Arduino from a suitable rechargeable battery pack and have it on constant charge at the same time.

However the charge circuit must supply enough current for the Arduino and charging the battery when its flat, yet not over charge the battery when its full.

I'd suggest looking at NiMH chemistry which is fairly tolerant of overcharging and also can be charged quite well from a voltage-limited supply.  A series resistor from the charge circuit can limit current too, but it wil have to carry the ARduino circuitrys supply current too, which affects the calculations.  For low current use a 9V supply with a series resistor might be enough to run a 6-cell NiMH pack without exceeding its charge rate specs -- these you have to look up in the manufacturer's datasheet.

For high current situations more care is needed.
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For li-ion/li-po type, take a look at sparkfun's li-po charger - they sell one that facilitates charging the battery and powering the device at the same time. I'm not saying that you should use that charger though - it'll be educational to go read about it.
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italy
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thanks to MarkT and mowcius! But if I leave the batteries always connected, is it possible that (dependign on cell technologies involved) battery life will decrease?
There are many links on the web showing li-po charger and arduino but the voltage is always between  3.7V and 4.5V. I haven't found anything similar to 9V.
« Last Edit: March 02, 2011, 09:19:06 am by cantore » Logged

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There are many links on the web showing li-po charger and arduino but the voltage is always between  3.7V and 4.5V. I haven't found anything similar to 9V.
Well you can use a boost converter to get the voltage up to what you require - that is how 5V devices work with a li-ion battery - the voltage is boosted up to 5V.
I haven't seen any that boost to 9V but I haven't ever looked for something that high - There probably are some though.

What do you want 9V for anyway?
If this is for an arduino then you want a nice 5V supply.
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italy
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yes it's for arduino. I use many sensors and they works propely only if the system il supplied in the right range. Reporting arduino uno specs http://arduino.cc/en/Main/ArduinoBoardUno:
"The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts"
If I give arduino only 5V my measures can be affected by an error. For example try to measure an analog temperature if you're under 7V and if you're in the 7-12V range. The value red will be very different. Anyway you're right, I can check out for a "9v boost-up", I only need to check if the value of ampere (max A)after this stuff would be ok for my system. Thanks
« Last Edit: March 02, 2011, 09:28:11 am by cantore » Logged

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"The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts"
If I give arduino only 5V my measures can be affected by an error. For example try to measure an analog temperature if you're under 7V and if you're in the 7-12V range. The value red will be very different. Anyway you're right, I can check out for a "9v boost-up", I only need to check if the value of ampere (max A)after this stuff would be ok for my system. Thanks
You don't want to power the board through the regulator (which is when you need more than 7V) as that would just produce inefficiencies. You want to power directly into the 5V and GND pins (avoiding the regulator) as your boosted voltage will already then be a regulated 5V (exactly what the arduino and your sensors require).

Mowcius
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italy
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You don't want to power the board through the regulator (which is when you need more than 7V) as that would just produce inefficiencies. You want to power directly into the 5V and GND pins (avoiding the regulator) as your boosted voltage will already then be a regulated 5V (exactly what the arduino and your sensors require).

Mowcius

Your observation is great!!!
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