Router Battery Backup

cavedog said:
Yes indeed. I want to go from 12v to 19v probably not very efficient as the laptop has one build in that charges the battery but there is nothing I can do about that but it should be better than an inverter or UPS.

The specs shows 3A so it's more than enough when I looked at my laptop charger max is 2A so 3A converter is more than enough. I bought 2 in case I need to run other stuff that is not 12V from a battery :)
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I would be careful about. It is probably suitable only for smaller loads like a router. Whenether it is popular LM2577, or other, they typically give a MOSFET I_max rating. In boost application it applies to the input current, not the output current. Considering no radiator, you will have to deploy derating curve, resulting @19V no more than 2A is expected.

There is a little bit stronger module rated 4A in Communica:
R45: https://shop.communica.co.za/products/acm-dc-dc-boost-adj-mod-5-35v-4a

Or more universal R69, but expect a lower maximum current: https://shop.communica.co.za/products/acm-dc-dc-buck-boost-1-25-35v-4a

Download datasheet for the chip XL6009, you will see an application note for 18.5V step up converter. The output current is only expected up to 2.5A (actually less without radiator)
 
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sajunky said:
I would be careful about. It is probably suitable only for smaller loads like a router. Whenether it is popular LM2577, or other, they typically give a MOSFET I_max rating. In boost application it applies to the input current, not the output current. Considering no radiator, you will have to deploy derating curve, resulting @19V no more than 2A is expected.

There is a little bit stronger module rated 4A in Communica:
R45: https://shop.communica.co.za/products/acm-dc-dc-boost-adj-mod-5-35v-4a

Or more universal R69, but expect a lower maximum current: https://shop.communica.co.za/products/acm-dc-dc-buck-boost-1-25-35v-4a

Download datasheet for the chip XL6009, you will see an application note for 18.5V step up converter. The output current is only expected up to 2.5A (actually less without radiator)
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According to my laptop plug it's rated at 19.5V and 2.31A max so I don't think the laptop would draw more than the laptop power plug max. So if I take the plugs max and work on that I should be fine working out a solution for it. I have decided against adding it to my existing setup I will look at getting a separate setup for it with the dc buck you suggested.

20190415_201019.jpg
 
cavedog said:
According to my laptop plug it's rated at 19.5V and 2.31A max so I don't think the laptop would draw more than the laptop power plug max. So if I take the plugs max and work on that I should be fine working out a solution for it. I have decided against adding it to my existing setup I will look at getting a separate setup for it with the dc buck you suggested.
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Isn't it a plug like there?
https://www.amazon.com/719309-003-721092-001-854054-002-854054-003-854054-001/dp/B00OZVOUBK
The plug has outer and inner cylinder supplying power and pin ID in the middle. You would have to pull up this pin to VDD with some extra components to create a voltage on this pin. Laptop load some current from this pin and based on a resulting voltage decide on the maximum power to draw. You can google for details. It is easy to fool laptop by giving a wrong information, so be careful.

In addition you must remember what I pointed out before that 45W with 90% efficiency (I take it as an example for a clean picture) dissipate 4.5W on the small PCB that do not have a radiator of its own, you will have to make one in my opinion.
 
quick question, I have obtained a Mecer UPS from work, and put a new 7Ah battery in it. Its a Mecer ME-850-VU.
Will this switch off when it reaches 50%? I don't want it to run all the way down to 0%.
 
Ares1000101 said:
quick question, I have obtained a Mecer UPS from work, and put a new 7Ah battery in it. Its a Mecer ME-850-VU.
Will this switch off when it reaches 50%? I don't want it to run all the way down to 0%.
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It will switch off when battery voltage (meassured under load) drops typically between 10.6V and 10.0V. Some versions have a timer to switch off after 10 minutes it is independently to the battery protection.
 
Battery cut out probably at 75% DoD. There are LEDs on that device, so you could check the manual and see when it cuts out.
You could have replaced the battery with a 9AH without pushing the charger over it's capacity.
Don't think there is any adjustment available for you to be able to set the limit.
At 10.7 Volt, the DoD will have reached 90%, which is not a good idea for extended battery life.
 
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Found a manual on the internet which suggests that the battery voltage monitor LED will change to yellow at 75% DoD and cut out will then be at 90%.
 
Geoff.D said:
Battery cut out probably at 75% DoD. There are LEDs on that device, so you could check the manual and see when it cuts out.
You could have replaced the battery with a 9AH without pushing the charger over it's capacity.
Don't think there is any adjustment available for you to be able to set the limit.
At 10.7 Volt, the DoD will have reached 90%, which is not a good idea for extended battery life.
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I just chose a 7Ah cos it was a lot cheaper than a 9Ah.
Thanks. hopefully it doesn't drop too low.
 
We recently had fibre installed and received an Mikrotik router board and wireless access point. With the current mess wrt poer in Kempton, I was keen on implementing some of the solutions for switching the netwok equipment to a 12v backup system. In my case however the ONT is on a 12v supply whilst the router board and wifi access point is both on 24v supplies with different amp ratings. have anybody come up with a solution for this? Current backup is via deep cycle battery and inverter.
 
If you're only using your current back up system to keep your network alive, I guess the easiest would be to get another 12V Deep Cycle battery. This way you can power your 24V devices from the 2 x 12V batteries (in series) and the 12V ONT from one of the batteries (By connecting it only to one).
Then you can ditch the inverter and will have longer supply during power outages.
You don't have to worry about 'the different amp ratings'.
 
IcemanMike said:
This way you can power your 24V devices from the 2 x 12V batteries (in series) and the 12V ONT from one of the batteries (By connecting it only to one).
You don't have to worry about 'the different amp ratings'.
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Would running the 12V on only one of the batteries not drain that battery faster?

FotoJet 12-24v.png
 
airborne said:
Yes, you would probably need to charge the batteries seperately or have some battery management system to compensate for the different states of discharge.
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Or run it parallel for the 12v load and in series for the 24v load?
 
Andre ND said:
We recently had fibre installed and received an Mikrotik router board and wireless access point. With the current mess wrt poer in Kempton, I was keen on implementing some of the solutions for switching the netwok equipment to a 12v backup system. In my case however the ONT is on a 12v supply whilst the router board and wifi access point is both on 24v supplies with different amp ratings. have anybody come up with a solution for this? Current backup is via deep cycle battery and inverter.
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Are you using PoE with the Microtik router?
 
The current draw of these devices is pretty low. If you measure it we will be able to assess if drawing power from the battery bank in that fashion is a bad idea or not.
I am more concerned about what happens when the batteries are being charged, and the devices remain connected to the batteries while the batteries are being charged.
 
Andre ND said:
We recently had fibre installed and received an Mikrotik router board and wireless access point. With the current mess wrt poer in Kempton, I was keen on implementing some of the solutions for switching the netwok equipment to a 12v backup system. In my case however the ONT is on a 12v supply whilst the router board and wifi access point is both on 24v supplies with different amp ratings. have anybody come up with a solution for this? Current backup is via deep cycle battery and inverter.
Click to expand...

Are you running a 12v dc to 230v ac
inverter?
 
My backup is finally going to get some good testing with new wave of loadshedding. :)
 
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