Dui ni shuo de dui
10 kW
Hi Everyone,
As I received a nice little suitcase together with my FarDriver Controller, I decided to use it in order to make a 48V battery system.
The main goal here is to have a backup battery to power fridges and other important equipment during a power outage, and to have it compatible with a future solar panel installation that I intend to build later. I settled for 48V for this reason, because the inverter will likely integrate a MPPT 48V charge controller.
Here is the thing that started this whole project:
What I want to achieve here is to have a system that I can easily monitor and maintain. I'd like to be able to replace a defective string module in a few minutes in case there's anything wrong with it, and be able to relatively easily change a defective cell if I need to. For the monitoring, the battery will have a smart BMS, which will have bluetooth as well as usb connexion. It is a 60A BMS because I won't need a crazy aount of power on this battery. It is actually a copy of the Daly BMS, so that should be interesting to see how it performs.
I'd like to be able to use relatively standardized string modules so that I could just take some modules and drop them into different batteries.
Today I need 14S 1P, but I could just reorganize the modules to make various configurations. This way I could have a reconfigurable battery that I could use in the 48V system most of the time, but that I could dismantle and reconfigure for a 72V go kart, a 12V backup backup battery or whatever I want in just a few minutes by bolting this modules in a different configuration.
I started designing this thing last week, so far here's my design:
It has 14 modules in series. Each module is 10 cells in parallel, so each module is 3.7V and right now the cells I'm using are 2500mAh, so each module is 25Ah. So, if my math is correct, this battery should be a 48V 25Ah battery.
On the right side of the box I've left a space for the BMS, the wires and the connectors.
Each module is made of 10 cells in parallel, which are to be spot welded with my little, very cheap (but very effective) spot welder. These modules can be made in any lenght, the only real limit is the size of your 3D printer. Here I was limited by the size of the suitcase.
There are copper tabs on each side in order to conduct the current. Each tab is bolted directly onto bus bars which are integrated into the outside shell.
The outside shell is the most complicated part. It doesn't look very complex on the pictures but it has to integrate all the pathways for the bus bars and for the balancing wires. There are also some keyways to ensure I plug each module the right way so that should be idiot proof. This is the only part that needs to be custom made between different batteries.
So, anyway, I started building the thing, making a small 3S test sample.'
First assembly of a module:
Making the copper tabs:
Installing the tabs:
The first prototype module completed:
Next, printing a small 3S sample of the outside shell:
Test fitting of 3 cells + the BMS :
Test fit in the suitcase:
So far everything seems to go well according to plan. I'm now printing all the parts (there are a lot!), hopefully I should finish printing everything this weekend, or next week. It's really easy to assemble and there's no major difficulty. The only "difficult" part is to make the copper tabs, but it's not really super difficult, just a bit tedious.
So far it has been a very interesting and fun build, I hope the final product will work well!
As I received a nice little suitcase together with my FarDriver Controller, I decided to use it in order to make a 48V battery system.
The main goal here is to have a backup battery to power fridges and other important equipment during a power outage, and to have it compatible with a future solar panel installation that I intend to build later. I settled for 48V for this reason, because the inverter will likely integrate a MPPT 48V charge controller.
Here is the thing that started this whole project:
What I want to achieve here is to have a system that I can easily monitor and maintain. I'd like to be able to replace a defective string module in a few minutes in case there's anything wrong with it, and be able to relatively easily change a defective cell if I need to. For the monitoring, the battery will have a smart BMS, which will have bluetooth as well as usb connexion. It is a 60A BMS because I won't need a crazy aount of power on this battery. It is actually a copy of the Daly BMS, so that should be interesting to see how it performs.
I'd like to be able to use relatively standardized string modules so that I could just take some modules and drop them into different batteries.
Today I need 14S 1P, but I could just reorganize the modules to make various configurations. This way I could have a reconfigurable battery that I could use in the 48V system most of the time, but that I could dismantle and reconfigure for a 72V go kart, a 12V backup backup battery or whatever I want in just a few minutes by bolting this modules in a different configuration.
I started designing this thing last week, so far here's my design:
It has 14 modules in series. Each module is 10 cells in parallel, so each module is 3.7V and right now the cells I'm using are 2500mAh, so each module is 25Ah. So, if my math is correct, this battery should be a 48V 25Ah battery.
On the right side of the box I've left a space for the BMS, the wires and the connectors.
Each module is made of 10 cells in parallel, which are to be spot welded with my little, very cheap (but very effective) spot welder. These modules can be made in any lenght, the only real limit is the size of your 3D printer. Here I was limited by the size of the suitcase.
There are copper tabs on each side in order to conduct the current. Each tab is bolted directly onto bus bars which are integrated into the outside shell.
The outside shell is the most complicated part. It doesn't look very complex on the pictures but it has to integrate all the pathways for the bus bars and for the balancing wires. There are also some keyways to ensure I plug each module the right way so that should be idiot proof. This is the only part that needs to be custom made between different batteries.
So, anyway, I started building the thing, making a small 3S test sample.'
First assembly of a module:
Making the copper tabs:
Installing the tabs:
The first prototype module completed:
Next, printing a small 3S sample of the outside shell:
Test fitting of 3 cells + the BMS :
Test fit in the suitcase:
So far everything seems to go well according to plan. I'm now printing all the parts (there are a lot!), hopefully I should finish printing everything this weekend, or next week. It's really easy to assemble and there's no major difficulty. The only "difficult" part is to make the copper tabs, but it's not really super difficult, just a bit tedious.
So far it has been a very interesting and fun build, I hope the final product will work well!