[Sutripta]

Originally Posted by cooljais

I'm sorry, but do not have any note for the board. Unfortunately, was unable to find one.

Maybe I'll order one just to lay my hands on the documentation!

Sutripta

[cooljais]

Originally Posted by JithinR

Thanks for providing links to the components too. Could you please let us know how was the delivery time for these sites (robu.in and the other one)? That was one of my points of concern since they might not have a robust delivery setup like Amazon/Flipkart.

The delivery times are good with these. I got the components within a 1 week.

Originally Posted by JithinR

1. For Li-Ion, as far as i know, the nominal voltage comes out to be 3.7V. So three of them in series will give out just 11.1V. Also, as far as i know these BMS boards have an Over discharge voltage range : 2.3-3.0v ± 0.05v (at least this one does : https://www.dnatechindia.com/3S-Li-B...search=Lithium). Assuming the worst case won't we be under-volting the router by a significant margin? My limited understanding is that while over-volting is fine to an extent under-volting is strict no-no.
   
   
   
2. While the batteries are fully charged (Over-voltage range : 4.25-4.35v ± 0.05v for the same board) won't the output voltage cross 13V. I suck at electronics so I am not sure but at this point won't the higher voltage drive more than 1A into your router?

You are absolutely correct here. Under-voltage to an appliance means that the current drawn would be more than the expected. When fully charged, I get an output Voltage of about 13V. Since, I only need it to support for a couple of minutes, the UPS works fine, delivering the essential current. Also, when power is normal, the output from the adapter is directly going to router. The board cuts off the power from cells to output.

When the voltage goes to 13V, the current drops to a little below 1A.

you can use power = Voltage X current.

The rated power of my router is 12*1 = 12W

When the output voltage is 13V, the current automatically becomes 12/13 = 0.92A. So the router is safe. Just that it will try to pull a little extra from the board.

Originally Posted by JithinR

The output of the 2S BMS board can be connected to a boost converter. This is another point of concern for me as far as the 3 Li-Ion cells in series is concerned. In their fully charged state (outputting over 12V) I would have to use a boost/buck converter that seems to be more expensive. Is this correct?

Buck/Boost converters are not expensive. These are easily available on any of the sites mentioned before.

Originally Posted by JithinR

For now I was thinking of using a p channel MOSFET with the gate tied to the ground through a pull down resistor. The battery is connected to the output through the MOSFET and will supply only once the Input DC power goes off.

I have kept a decoupling capacitor at both the output and input (I am not sure if this one is needed) to smooth out any voltage variations.

My calculations are as under (they are at an amateur level right now):

1. Max Power Draw for my router: 12V * 1.5A = 18W
2. Efficiency of the DC boost converter (94%) : 19.4W
3. Current drawn from Li-Ion Cells: 19.14W/7.2V = 2.65A
4. Battery Capacity required (Assuming a 5 min runtime): 2.65A * 5min/60 = 2.20mAh

With two Samsung Li-Ion cells I am hopeful of meeting the capacity requirement (Apparently most Li-Ion cells don't have the actual capacity shown)

Not so sure about the MOSFET to be honest. However, what I do know is the board uses N-channel MOSFET for control.

From the calculations it seems right. Two cells should be able to support fine. For detailed calculations, i might have to dig back into my electronics notes.

[ElonSkum]

Originally Posted by blackwasp

I had created a similar device using a power bank and a DC-DC boost converter. ...

Another idea is to just get a motorcycle battery and connect it to the router using some protection device (fuse, etc.).

I second these ideas!

I had done the exact thing before Jio days. Power Bank -> DC-DC boosted to 9V ( XL6009 ) -> TP-Link MR3220 V2 3G/4G router, with an MTS unlocked EVDO dongle with BSNL sim, in my car. And I was giving free unlimited Internet to my friends in car, when GSM based mobile Internet costed a fortune.

And I faced the same issue as the OP is facing during my apartment days. I put my old, college days, APC to use back then. But, it was an overkill and I often thought that there was a market for such a mini UPS.

I did think of a few cheap, easy DIY solutions back then, perfectly suited for your needs - back-up for a minutes, until the generators kicked in.

But, you need to know the exact amps that your device pulls. The adapter is rated at, maxed at, 1.5A, but it's not necessary that the device pulls that much from the adapter. So, try to get a reading of the amps, at high through-put, using your multi-meter.

Solution 1 - Using those cheap single cell power bank that they sell by the roadside, in trains etc



1. Buy one of these. Shouldn't cost more than 50-70. What we want is the charging module and the enclosure.
2. Check that the module supports pass-through charging. i,e it charges the device connected to it, while it is hooked up to the 5V adapter as well. After you are done verifying, throw the battery out; it is garbage.
3. Get a good, decent capacity old li-po battery from some old dead smartphone of yours, family member , friend etc., that might end up in a landfill otherwise.
4. Solder the respective battery leads to the charging module and you have a decent single cell power bank.
5. Get a DC-DC boost converter. Hook it up with this power bank using some old USB cable and adjust for your required voltage. Wire up the output pins from the boost converter to the required barrel jack.
6. I am sure this would give you a few minutes of backup.

If in case, the charging module doesn't support pass-through charging. You can hook up the boost converter directly to the battery terminals, while the power bank is always on charge with the adapter.

It would be absolutely safe. Much more than the cheap Chinese emergency lights, flashlights, Diwali lights that we use.


Solution 2 - Using TP4056 Lithium charging module

1. Almost the same as Solution 1, except that you hook up the boost converter directly to the battery. In fact the newer TP4056 modules do have OUT+, OUT-, solder pads as well.
2. If going this route, make sure that you pick the newer TP4056 modules that come with micro-USB ports and not mini-USB, to save you on the hassle of ordering extra mini-USB cable. And, do make sure that the board has dedicated solder pads for OUT+ and OUT-

Solution 3 - Using those cheap universal mobile battery chargers.




1. Same as Solution 2. Should cost you anywhere between 50-100 at the neighborhood mobilewallah.

Solution 4 - 45Watts CFL inverter boards. If you need a longer back-up and more output wattage.
1. These are used by the street hawkers, veg vendors. You would have seen these. It's usually in 3CFL, 45Watt configuration.
2. You can buy just the PCB board as well. They are readily available.Depending on your location, should cost you anywhere between 150-300.
2. Pair this up with any old UPS, motorcycle battery and you are all set for a decent amount of backup.

[JithinR]

In case members want to go for the resonate router ups it's back in stock at Flipkart.

P.S: Literally, seconds after posting this, it's out of stock again.

[ElonSkum]

Originally Posted by JithinR

In case members want to go for the resonate router ups it's back in stock at Flipkart.

P.S: Literally, seconds after posting this, it's out of stock again.

Just checked the cost of Resonate UPS. 2250 for such a small amount of power output is daylight robbery IMO.

I would still request you and anyone else here to explore much cheaper DIY options. Or explore much cheaper readymade options in the wonderlands of AliExpress, Bangood etc.

If I have the time, I might as well rig one up with components from my electronics bin and put up a video tutorial here, soon.

[akshay380]

Originally Posted by libranof1987

I have the Resonate RouterUPS at parents' and my place; works like a charm. Got it for 24xx; one supports the modem+router and the other one has a splitter cable to support the separate modem and router. I get about an hour or more of backup but don't need more than 5sec.

Also, I bought it directly from them; look their website up.

Where did you get splitter cable? I got this I think 4-5 years ago when my friend who was friend of company founder posted about the product. No complaints until now.

[libranof1987]

Originally Posted by akshay380

Where did you get splitter cable? I got this I think 4-5 years ago when my friend who was friend of company founder posted about the product. No complaints until now.

They sent this in the box itself; I had ordered directly on their website so when I talked to them before placing the order about my requirements, they included the cable (charged extra).

[Route66]

I would like to share my experience of trying to add power back to my WiFi router.

Similar to other members, i was frustrated with constant network drop because router would restart every time there is a power cut and then again when power comes back due to switching from backup generator to power. Gurgaon being pretty notorious with multiple power cuts didn't help the situation.

I bought an APC UPS thinking i will power the router and my NAS with it.

Then came the first power cut. Router did not restart and my laptop was showing connected to WiFi. But internet would not work. It happened again when power came back.

I started trouble shooting and found that the Switch installed by the ISP in our apartment building is not connected to backup power. So the switch restarts every-time there is a power cut and when power comes back. In the end, money and time wasted and I was back to square one.

I would suggest members to please check with ISP whether the switch in there area is connected to a backup power source.

Thank You.

[dkaile]

Was looking for a solution to the OP mentioned problem and found out that I had a perfectly working 10 year+ old APC 650 UPS lying connected to my now hardly used desktop. Just swapped in a new Exide battery into it for 750 bucks and connected the modem supply (12V 500mA) through it and it's working as a charm on the Binatone modem/router from Airtel Fiber. End of all connection drops on power cuts during the fraction of a second that the house power transfers to the 1500 VA Microtek Sinewave Inverter.

The APC UPS is one tough cookie to be working flawlessly even after switching it on after almost a year. Hope it does not die now in this setup of keeping it always on?





Cheers...

[Simhi]

Originally Posted by dkaile

End of all connection drops on power cuts during the fraction of a second that the house power transfers to the 1500 VA Microtek Sinewave Inverter.

Just curious, does the Microtek Inverter not have a UPS mode? Why do you additionally need APC UPS?

[dkaile]

Originally Posted by Simhi

Just curious, does the Microtek Inverter not have a UPS mode? Why do you additionally need APC UPS?

It does and I tried that too but I believe it's still not as good as the APC for the fraction blip that causes the Internet to break. This problem seems solved on the APC.

[ElonSkum]

Originally Posted by dkaile

The APC UPS is one tough cookie to be working flawlessly even after switching it on after almost a year. Hope it does not die now in this setup of keeping it always on?

A tough cookie indeed it is. I have one, over 15 years old, still doing duty. I am such a fan of APC. Is the model, which you have, a smart UPS? Does it have RS232, RJ45 or USB port?

How does the APC work with the sinewave inverter? It works well? I am looking for an upgrade to a sinewave inverter as well.

[dkaile]

Originally Posted by ElonSkum

A tough cookie indeed it is. I have one, over 15 years old, still doing duty. I am such a fan of APC. Is the model, which you have, a smart UPS? Does it have RS232, RJ45 or USB port?

How does the APC work with the sinewave inverter? It works well? I am looking for an upgrade to a sinewave inverter as well.

Yeah, it has a RJ45 ports on the side for surge protection, though never tried it. Model is ES 650. Works perfectly with a sinewave inverter and also my Mahindra silent diesel genset.

Cheers...

Link to user manual - https://www.google.com/url?sa=t&sour...7M0ArPZABOx5wQ

[ElonSkum]

Originally Posted by dkaile

Yeah, it has a RJ45 ports on the side for surge protection, though never tried it. Model is ES 650. Works perfectly with a sinewave inverter and also my Mahindra silent diesel genset.

Cheers...

Link to user manual - https://www.google.com/url?sa=t&sour...7M0ArPZABOx5wQ

Thanks for the user manual. Just glimpsed to through it. So, according to the manual, besides the surge protection for phone lines (2 RJ45s) , the ES650 also has an extra RJ45 that would connect to your computer for UPS monitoring and control, using the APC Powerchute Application. Have you tried it? I am guessing the APC protocol for your UPS would be "Smart Signalling"; mine's older, only supports "Simple Signalling".

I doubt if UPS manufacturers provide such smart features in their home series, these days.

[fordday]

Originally Posted by cooljais

1. 3S BMS board – Output 12 V up to 15 A. Board regulates automatically. (https://robu.in/product/3s-15a-18650...tection-board/ )

Above mentioned board is not available. Do you think this board will work ? Link