NewStats: 3,265,241 , 8,186,107 topics. Date: Saturday, 14 June 2025 at 03:26 AM 684r6o

iraybuju:


Where’s the inverter ? Did you build it yourself ?

It's at the top right corner. Build myself? What part?

saint2ace:


Nice one bro, this looks cool. Care to explain the circuitry ?

Thanks. The circuitry is very similar to previously described small power station. What's new is the external battery and comm via wifi. Two groups of mosfet switch between external and internal bus, and both never selected at the same or any time. A lot of care went into code and circuitry to make sure both never activates same time.. and if at all they do, physical safe kill activates. Interesting stuff I must say...

Queed:
New build: 3s32p, 864Wh, 500W pure sine wave power station with external battery and monitoring via wifi. Just finished server and front end side. More updates coming in..

Two microcontrollers ( Esp01 and Atmega32 ) are used. The atmega32, though having a much less capable processing power does most of the job.. does all the job to honest, while the Esp01 collects data from the atmega, do some clean up and processing, then serve a browser/app/client etc.

Upon connecting an external battery, external battery mode can be activated manually, or automatically when internal battery gets low or fully charged or external battery sudden disconnect.. it's being tracked closely, you wouldn't even notice the switch.

Aside the external battery , similar board architecture as discussed previously for the the small power station.

Software:
Atmega32 - p
Esp01 - p/html/css/JavaScript(AJAX)

Find internal and final look below

New build: 3s32p, 864Wh, 500W pure sine wave power station with external battery and monitoring via wifi. Just finished server and front end side. More updates coming in..

dollarnaira:


Inverter board only
No brand

Could you share a pic, where did you get them?

dollarnaira:


Testing at the moment

Nice nice, waiting for the capacity results.. I know that the tetra guy sells good cell, but my fingers crossed with 3.2Ah, 3.6v on a 18650 size. Awaiting your result update.

dollarnaira:


You can drain more energy from the 12v than from the 24v. Cut off for the exact set up above is 9v while the cut off of the 24v is 21v ( with great capacity left undrained).

It the same. Standard li-ion 24v is 7s, that's 3v per cell cut off( 3v *7cells is 21v ). While standard li-ion 12 is 3s, being 3v per cell cut off ( 3v *3cells is 9v )

psucc:
Please what's the meaning?

It's a very small storage setup original ment for charging of mobile devices. Yes any suitable solar less than 40v can be used ( for example a 250W, 24V ), and how long it last depends on the connected load. It's a 224Wh (battery) @200VA (inverter) device.

psucc:
What can this power?
2. How long can it last after sundown?
Does it come with Solar , what wattage?

https://nairaland.macsoftware.info/7902446/diy-lithium-ion-like-minds/58#134897722

edobor108:
please what type of charger are you using,i try to use laptop charger but it got burnt

I used a suitable laptop type charger, together with a built in buck converter.

I assume you connected the charger directly to battery? This will cause most adapter to blow out, or enter protection mode (for more quality power adapters).

To safely / properly charge your battery, you will have to find a way to do away with the excess voltage and there are different method to do this.. if interested I could give further notes on this but I guess I have already answered your question.

officialfestus:
Impressive, How did you build the automatic changeover?

Two relays are used to switch the live and neutral lines individually. These are energised by a DC power source, which can be derived from either mains or generator... depending on the configuration... and this acts as the master control.

Although a single two-in-one relay could have been used, this setup was chosen as the most suitable based on trade-offs between cost, size, and power handling capacity.

Queed:
A friend have been on my neck for some time to build a power station for him. He works remote and has limited budget, wanted something for his Lights, phones and Laptop and Modem / MIFI etc.

After long persuasion from him, I decided to come up with a Li-ion 3s8p 12v / 224Wh, 150W portable power station ( small bobo )

After I delivered it to him and he saw it could power his self-con, he suddenly wanted a more permanent place to install it...and still be able to take it on the go if needed. (Lol, man being insatiable! )

So, I had to come up with both a manual and a very simple automatic changeover solution to that problem (which, honestly, could’ve been built into the system itself).

Sas4lyf:


I would love something like this. Location and price please

This exact one would cost you nothing less than 85k.

But you can get 300W, 449Wh, 8A charging, twice the size for just 150k.

Location is Lagos. Can ship to any other state tho.

officialfestus:
wow, where can I get this board?

Custom made by me. You need one or something more specific?

I need 4 nos of 50A LFP cells for immediate purchase. Any seller here?

officialfestus:
impressive.
How does the control board works?

At the heart of the control board is the microcontroller Atmega8.
It measures voltage of each cell, the charger, current flowing into the battery and also the power (servers also as control) button.

Processes it and uses the result to determine certain actions, for example:

stop charging if battery voltage up to max.
stop inverter and usb if battery voltage below min, or if any of the 3series cell below minimal cell
Start top balancing if charging and cell difference beyond minimum level, reduce charge current if necessary.
Maintain charger current to defied soft / fast
Display the right colour LED based on measured voltages, charging, and/or predefined current.

The beauty of the board is scalability. I could use this same board for say a 2KVA, 2KWH system and all I need change are the surrounding dependencies: Use 2KVA inverter, Use bigger buck converter ( or more in parallel ), use 2KWh battery etc. but the board it self remains the same!

Below is an example of processed data outputs of the controller

Obnoxious2001:

Nice...

Good job

Just interested in the charging regulation, how does the microcontroller controls the charging current?

It still send signal to the buck converter?

The micro controller measures the current via a hall effect sensor, processes it and then sends control signal to the buck converter.

Final look

Charging current can be selected for 4.5A (soft) or 7.5A (fast)
Accepted Charging voltage from ( current battery voltage + 1v ) to 40V max
USB 5V 2A
200VA inverter
224Wh battery
USB only mode save battery by shutting down inverter, reduced fan speed.
LED for status indication (soft/fast charge, battery level, usb only, mode switch)

A friend have been on my neck for some time to build a power station for him. He works remote and has limited budget, wanted something for his Lights, phones and Laptop and Modem / MIFI etc.

After long persuasion from him, I decided to come up with a Li-ion 3s8p 12v / 224Wh, 150W portable power station ( small bobo )

Veew:

I was hoping the fan inside the charger would expel the heat from the diode.

I did say it stopped the reverse current, but I think the charging might be slower now because of the voltage drop.

Still wear am small heat sink. Yes it might be slower but the difference may not be much.

Veew:

I got the 10a rectifier diode, open up the charger and solder it to the positive wire. It did stop the reverse current flow but when I take the voltage reading from the charger mouth, the voltage dropped from 14.6v to 13.7v. I understand it's due to the internal resistance of the diode but I want to know if that will be a problem for the BMS on the long run

Hope you included a small heat sink for the diode?
Because 10A at 1V drop out is 10W and it's a lot of heat power for a free running diode. The voltage drop is topical for diode (0.3v to over 1v depending on lot of factors). The diode should fix the reverse current issue, perhaps it's faulty or not properly connected. Finally, the 13.7v would not be a problem for the BMS.

officialfestus:
the fan from the sachet inverters spin faster and noisy whenever I put on my laptop.
Thank you so much for your input, I'll try another hdmi cable to see.

You are welcome. I meant Electrical noise though ( like unwanted frequencies, like signal pollution ).. not the type of noise that comes out from your fan.

officialfestus:
Good morning house.
I noticed if I run my tv and laptop (my laptop is connected to my tv via hdmi cable) on my house inverter setup the display is very smooth and sharp just like the grid.
But if I run same tv and laptop on a sachet inverter, the display start flickering continously either (pure or modify sine wave). I even decided to plug only the laptop on my house power source, and tv on the sachet inverter, vice-versa the issue persist.
My house inverter runs 50/60hz while the sachet inverter runs 50hz only.
My tv and laptop display is set to 60hz. Could frequency be the problem?

Dollarnaira penuelseun

Its a noise problem. HF inverter are usually noisy especially the cheap ones (not having adequate EM shield/ filters).
Your device ( tv / laptop in this case ) internal/external power unit may also not be well equipped to handle such level of noise.
Your hdmi cable could also be the cause, for a test, try a very short hdmi cable, if it works well then buy an original longer cable, like those with ferrite beads and proper shielding. Frankly speaking, we all know that the inverter is the source of the noise here, but other connected devices should be able to reject the noise to some reasonable extent.

tetralogyfallot:
you should have used a bigger adaptable box for more spacing and ventilation sir.

The idea is for it to be able to fit into sizeable laptop bag. Next version will be smaller and same specks.

officialfestus:
congrat on your build, please what did you use to cut the adaptable box?

Hot Cutter knife

Queed:
Finally.

Red and black connector are for external battery. Li-ion, LFP and LA are supposed. The device switch automatically to external battery once the Internal battery is low, or fully charged, and vice versa from external to internal battery. External battery can also be set manually. The right external battery type have to be selected (at least once) otherwise the system will reject the switch over, even if it acknowledge the presence of an external battery.

Although Interface is via the two external switches and four LEDs (for battery level indication, soft or fast charge select, USB-only or inverter mode, and also for external battery type select), if you have a serial to USB converter, you can hook up the Rx and Gnd pins and view logs from the device.

Finally.

Red and black connector are for external battery. Li-ion, LFP and LA are ed. The device switch automatically to external battery once the Internal battery is low, or fully charged, and vice versa from external to internal battery. External battery can also be set manually. The right external battery type have to be selected (at least once) otherwise the system may reject the switch over, even if it acknowledge the presence of an external battery.

Although Interface is via the two external switches and four LEDs (for battery level indication, soft or fast charge select, USB-only or inverter mode, and also for external battery type select), if you have a serial to USB converter, you can hook up the Rx and Gnd pins and view logs from the device.

Everything connected together

Placing the inverter and main board into the enclosure.
Inverter is 500VA (375W) modified sine inverter
Main board comprised of:
15A Pwm solar control
15A DC mains charge control
30A current sensor
1A top balancer
Microcontroller etc

Planning the interior of the power station.
I prefer using large fans as they are less noisy, I can slow them down and they will still push good volume of air. Heat management is one of the top priorities when I build stuffs like this.