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Building a 12v battery.

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Much like @sunset1's post regarding a 48v battery, how would you build a 12v battery?

 

So the stuff I have so far:

- 4x 18650 2400mAh 3.7V Li-ion

- 1x 4S 40A Battery Balancer

 

What else do I need?

@WannabeSolarSparky, you mentioned I should charge at 14,6v?

How would I accomplish that?

 

 

 

I have made several threads on here, trying to do solar with a (very) tight budget. I have now settled just to get the basics running. 

The idea is to have the Rain Outdoor 5G Router running (19v), a Unifi Access Point (24v) and a Mikrotik (9-28v).

If the battery is large enough, I would like to run two 5w LEDs as well. 

I have a 200watt solar panel I use for camping with a PWM charger. Would this work with the battery? The PWM looks like this:

image.png.85133f2b67e650e7e4ec14cc53951adb.png

48 minutes ago, McGuywer said:

Much like @sunset1's post regarding a 48v battery, how would you build a 12v battery?

 

So the stuff I have so far:

- 4x 18650 2400mAh 3.7V Li-ion

- 1x 4S 40A Battery Balancer

 

What else do I need?

@WannabeSolarSparky, you mentioned I should charge at 14,6v?

How would I accomplish that?

 

 

 

I have made several threads on here, trying to do solar with a (very) tight budget. I have now settled just to get the basics running. 

The idea is to have the Rain Outdoor 5G Router running (19v), a Unifi Access Point (24v) and a Mikrotik (9-28v).

If the battery is large enough, I would like to run two 5w LEDs as well. 

I have a 200watt solar panel I use for camping with a PWM charger. Would this work with the battery? The PWM looks like this:

image.png.85133f2b67e650e7e4ec14cc53951adb.png

The 4 x 18650 cells are only good for a few hours for one of your routers. Also I would not draw more than about 3A load from them. Thus mostly good for LS of 1 router. 40A battery balancer can damage those 4 cells. Normally a laptop uses 6 or 9 of them.

PWM due to higher voltage pulses should not be used on lithium. Rather get a solar controller with lithium profile or at least with many settings that can be used for lithium.

 

1 hour ago, McGuywer said:

What else do I need?

@WannabeSolarSparky, you mentioned I should charge at 14,6v?

How would I accomplish that?

As you are using LiIo the specs and method would be different to what I mentioned as I was referring to the LiFePo4 on that thread earlier.

For LiIo you would go to 3s configuration with a 3s bms.
Also like @Scorp007mentioned, 4 cells are going to be a bit light for a small backup solution for your router.

You should look at doing either 1 of the following:
1 - 3S3P and a nice 3s BMS - Least losses i.e. more efficient
or
2 - 9P -with a nice boost regulator and a simple LiIo charge controller - less efficient but simpler to build

You are also mentioning higher voltage devices

1 hour ago, McGuywer said:

5G Router running (19v), a Unifi Access Point (24v) and a Mikrotik (9-28v).

You would be better suited to rather go for a 5s configuration and then use something like this:
https://www.bidorbuy.co.za/item/552643751/5S_18_21V_20A_Lithium_Battery_Pack_Battery_Charging_Protection_Board.html?srsltid=AdGWZVT_pj263sLr35kVlur7JvkSrFF5c_mmp9rQ0tjK40UulwABPsnTcW8

You would also need to add more parallel cells to boost the available amp hours, minimum should be at least 3P on the 5S

Running a few parallel paths should be OK with 3 in series to give 11.1V. Most 12V items would work fine. The reason is the 12V LED lights will be using the most power. One can then use a boost converter to get to 19V for the Rain 5G. Then another booster to 24V for the Unifi AP. It seems like the Mikrotik can work from the 12V, 19V or 24V. By actual testing one might find the Unifi AP, Mikrotik and Rain 5G all can work at 19V? This means 1 boost unit and it could be a low current unit.

I have found my WiFi routers needing 12V works OK down to 8.5V.

  • Author
1 minute ago, Scorp007 said:

Running a few parallel paths should be OK with 3 in series to give 11.1V. Most 12V items would work fine. The reason is the 12V LED lights will be using the most power. One can then use a boost converter to get to 19V for the Rain 5G. Then another booster to 24V for the Unifi AP. It seems like the Mikrotik can work from the 12V, 19V or 24V. By actual testing one might find the Unifi AP, Mikrotik and Rain 5G all can work at 19V? This means 1 boost unit and it could be a low current unit.

I have found my WiFi routers needing 12V works OK down to 8.5V.

Thank you, I did get a boost converter as well.

 

So the idea now is to just run the Rain CPE and see how long it holds.

While waiting for your replies, I stopped at the hobbie shop and got 4 18650 2400mah cells and a 4S 40A Battery Balancer.

I followed this diagram:

https://www.mantech.co.za/datasheets/products/BMS-40A-4S_SGT.pdf

I broke my soldering iron just before I could start, so I will go get a new one tomorrow and will solder the wires as per diagram.

I hear what you guys are saying regarding the capacity, I will test a bit and go from there.

 

 

In other news, I have also started with my first ESP8266 project. 🙃

14 hours ago, McGuywer said:

In other news, I have also started with my first ESP8266 project

DIY esp32 esp8266 they are so cool to play around with and in the solar world there are so many cool stuff to do with them :)
I use an esp8266 to control my cooling fans reading temperature data from the inverter and then sending the data to my ThingsBoard portal :)

 

come-on-summer-sunsynk-monitoring-portal-ver5RC004.jpg

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