Hello again, I am looking at building a UPS to keep the network and a server running during "short" power failures, and ofcause safe shutdown, alarms, temperature monitoring, all the stuff that you dont get from a black box marked "UPS"
My last UPS died out after 3 years service so I have been thinking about making my own.
Since most of the equipment runs on some DC voltage, I should be able to get down to < 50W on the inverter (which I would be running all the time to prevent delay in switching).
Then the rest will run off 12V and a few step up/down switchers for the stuff that cant take 12-14V directly.
I have located a 70Ah AGM battery, and will ofcause try to build the charger my self, using pulse width and a FET (I have read the old threads on the subject).
I can get a 13.8V dc generator (although I might need 2 to handle the load) which will power the charge circuit and the equipment.
(picaxe circuit ofcause on a 5V regulator)
The question is not so much the battery charge circuit, but the backup system.
The easy way is to connect the load "directly" to the battery and the charge system ofcause to the battery also.
However this means the charger has to charge at C/20 + what ever is being used by the system, which is kinda hard to know if the battery is flat.
An alternative would be to use a mechanical relay.
Common ground.
NO connected to the mains adapter.
NC connected to the battery.
Coil connected to the mains adapter.
While mains is active, the dc generator will power the coil and let the equipment draw from the generator directly.
When mails fail the coil is not powered, and NC is connected to the load.
However would this switch be fast enough for all the equipment to survive, im guessing no since the voltage will drop down to maybe 7V before the coil even drops, and this is the same voltage the equipment is seeing ?
I have not looked into which switchers to use for the DC so I dont know if they will accept a 5-15V range, and keep same output.
It would make the charge circuit somewhat easyier since it just have to keep the battery topped (I expect 5 dischages to 80% a year, and maybe 1 "full" discharge every 2years, battery would need replacement in 2-4years since its not top quality name).
The power for the mains regulator will be 230Vac, and the total DC load will be around 150W (So 20A to allow for charge+load).
Any ideas/surgestions ?
Is 15A (C/4.67) too high discharge current for a standard AGM (this quality does not come with datasheets, and is typically rebranded).
My last UPS died out after 3 years service so I have been thinking about making my own.
Since most of the equipment runs on some DC voltage, I should be able to get down to < 50W on the inverter (which I would be running all the time to prevent delay in switching).
Then the rest will run off 12V and a few step up/down switchers for the stuff that cant take 12-14V directly.
I have located a 70Ah AGM battery, and will ofcause try to build the charger my self, using pulse width and a FET (I have read the old threads on the subject).
I can get a 13.8V dc generator (although I might need 2 to handle the load) which will power the charge circuit and the equipment.
(picaxe circuit ofcause on a 5V regulator)
The question is not so much the battery charge circuit, but the backup system.
The easy way is to connect the load "directly" to the battery and the charge system ofcause to the battery also.
However this means the charger has to charge at C/20 + what ever is being used by the system, which is kinda hard to know if the battery is flat.
An alternative would be to use a mechanical relay.
Common ground.
NO connected to the mains adapter.
NC connected to the battery.
Coil connected to the mains adapter.
While mains is active, the dc generator will power the coil and let the equipment draw from the generator directly.
When mails fail the coil is not powered, and NC is connected to the load.
However would this switch be fast enough for all the equipment to survive, im guessing no since the voltage will drop down to maybe 7V before the coil even drops, and this is the same voltage the equipment is seeing ?
I have not looked into which switchers to use for the DC so I dont know if they will accept a 5-15V range, and keep same output.
It would make the charge circuit somewhat easyier since it just have to keep the battery topped (I expect 5 dischages to 80% a year, and maybe 1 "full" discharge every 2years, battery would need replacement in 2-4years since its not top quality name).
The power for the mains regulator will be 230Vac, and the total DC load will be around 150W (So 20A to allow for charge+load).
Any ideas/surgestions ?
Is 15A (C/4.67) too high discharge current for a standard AGM (this quality does not come with datasheets, and is typically rebranded).