Cheap Backup Option for running Modem during Powercut?

Shivam15

Member
Messages
134
Location
Ranchi
ISP
BSNL FTTH
Anyone knows any cheap backup option to run wifi modem during powercuts?? I have frequent powercuts and I want to use some method to run my modem even during powercuts?

I was thinking to buy a UPS battery of 7AH and run modem directly since the modem requires 12V and 0.5A. Any one knows how much Backup it will give if I use it?

Or any option cheap option under Rs.1000 to give atleast 2hr backup?

Thank you.
 

aatuif

the geek in chief
Messages
583
ISP
...
Imho, UPS is a bad choice if you have long outages (over 15 mins) as it will kill the battery in no time.

Recommendations:
1. There are portable mini inverters with inbuild 12V 7Ah battery available online (~50 watt) for ~1.5 k. They have rated backup of 3 hours and are designed for long outages.

2. You can also buy a mini solar powered inverter for close to 2 k.
 

Shivam15

Member
Messages
134
Location
Ranchi
ISP
BSNL FTTH
Hi,

I do not intend to buy a UPS as I already have a double battery UPS.

I meant using a UPS battery directly to run a modem i.e. via DC connection.
 


aatuif

the geek in chief
Messages
583
ISP
...
Hi,

I do not intend to buy a UPS as I already have a double battery UPS.

I meant using a UPS battery directly to run a modem i.e. via DC connection.
7 Ah will last more than 5 hrs easily. How do you plan to charge it though ?
 


Shivam15

Member
Messages
134
Location
Ranchi
ISP
BSNL FTTH
^^ I have a small charger thing to charge battery.

Also, do you know how much Ampere comes out from a 7AH battery? Because our modem requires 0.5A only.
 

tictactoe

Member
Messages
8
Get CFL inverter , you can easily get 3-4 hours back up on Modem with CFL inverter costing around 2k

 

aatuif

the geek in chief
Messages
583
ISP
...
^^ I have a small charger thing to charge battery.

Also, do you know how much Ampere comes out from a 7AH battery? Because our modem requires 0.5A only.
The current draw will be 0.5 A.

Only thing to ensure is that the voltage should match.
 

varkey

Well-Known Member
Messages
2,344
Location
Bangalore | Ernakulam
ISP
Excitel | BSNL
So I have been pondering over this for a while and I came across a seemingly good solution. The problem with the traditional PC UPS is that it simply does DC --> AC --> DC leading to significant and un-necessary losses. As @Shivam15 mentioned earlier, using a 12V battery without the un-necessary DC --> AC --> DC conversions is a much efficient solution.

I came across this power supply with UPS function -- https://www.meanwell-web.com/en-gb/ac-dc-enclosed-power-supply-with-ups-function-psc--60a--c
Costs Rs 1200 + tax, its a 60W power supply and probably is more than required for many of your use cases, but there is a 35W variant too which is probably cheaper.

Anyway this device also comes with a 1.5 A battery charger which means we can use higher capacity batteries, maybe a 12 AH battery. This would require a bit of DIY as you would need to procure the different connectors, casing etc, and even though it might be a bit more expensive, it's would be much more efficient and hence a much higher backup time.

Based on rough calculations, I think we could get maybe around 8-10 hour backup with a modem and a router connected. Will keep the post updated as I make more progress. As of now I have just procured the power supplies.
 
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