12V ups

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g2c

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Hello, I am looking for a recommended reliable design of a 12V lead acid based ups.
The purpose is to power a couple of arduino boards, and a 12V router modem so as to have an uninterruptable arduinos - Internet connection.
The total current is estimated to 2.5A. The battery would be a ~10Ah one
I was thinking of a ~ 2.5 - 3A current injector based on a 15V linear regulator powered by a 18V laptop power supply. The current would flow untill Vbat ~ 13.5V.
Thanks for your help
 
I'd just use a basic 12V "smart" battery charger with a rating around 5A or so.

A smart charger should adjust the current according to the battery state of charge, so can be connected indefinitely.
eg.

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Just received the one i bought and am awaiting for a 8v-20v to 12v5A stabilizer (pic attached) so that my 12v stays 12v whatever the battery fluctuations. My concern is that the charger is said to operate (also} in 'pulse mode' ans so i may to low pass a the battery to stabilizer path, what do you think?
 
I'd just try it as it is and see if everything works OK - I'd expect it to.
The battery itself should provide enough stability to keep the output in range.
 
Reactions: g2c
Just started testing with the bought parts:
1) "smart" charger named anhtczyx
2) DC/DC converter with 8V-20V -> 12V 5A named fulree
3) 12V to 9V unnamed 9V is the power to arduino through the barrel connector. Another one, 12 to 7.5V is underway

when connecting par 2 and 3 in series we do get perfect 9V output with a very large input voltage window. This is perfect

Part 1) however is disappointing:
- With no AC it draws 67mA from the battery which is unreasonably high
- The fan is noisy and it runs, randomly, even with the battery full. Who needs it? Chances that it wont last long (!)
- the notice says that it is recommended to disconnect once the battery is full and also that for 4-15AH batteries it is recommended to use 'repair' mode

Comments are most welcome
 

@rjenkinsgb​

Finally I did find a "maintenance" smart charger which is quiet (no fan) and appear to be more suitable for my battery.
Big thanks for having suggested this solution which makes most of my project
 

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