jonathan_winters
New Member
- Joined
- May 25, 2022
- Messages
- 22
Like many others here, I've been putting together plans for a DIY "milk crate" build.
I feel pretty comfortable with the choices I've made so far, though I'm happy to get input (I haven't purchased anything other than the battery yet so there is still time to edit):
My main question here is about fuse and wire sizing for the connection from the battery to the inverter.
With a 1200w inverter, I calculated upwards of almost 120 amps when the battery voltage gets to the lower SOC:
So I was just about ready to go with 1AWG wire to the inverter (which I think goes up to 150A) and fusing it at either 125A or 150A. Even though I don't believe I'll ever use the full 1200w of the inverter, I want to make sure the wires and fuses are sized for the worst-case scenario.
But then it hit me that this AmpereTime 100Ah battery has a 100 amp BMS (with over-current and short circuit protection). So is it even possible for the battery to discharge more than 100A, even when the battery runs down to ~12v?
If 100A is the absolute max output from the BMS, then it seems like I could size everything based on that 100A max output (even though the Inverter could technically want to draw more), meaning I could go with 2AWG wire to the inverter (or technically even 4AWG based on the chart I was using) and fuse it at 100A at the battery. Does this sound right?
And then the final question (assuming the above is correct about the 100A output at the BMS): Is there any harm or damage that I could do to the inverter or the rest of the system by using a 1200w inverter? It seems like I'll just be limiting the max capacity of the inverter to ~1000w, but is there something else that I should be aware of by using an oversized inverter?
I feel pretty comfortable with the choices I've made so far, though I'm happy to get input (I haven't purchased anything other than the battery yet so there is still time to edit):
- AmpereTime 100Ah Battery
- Giandel 1200w inverter (I will only rarely push it up to even 1000w, but wanted the larger size to have options, even though it means I have a higher no load current)
- BougeRV MTTP 40A solar charge controller
- 2x 100w solar panels (will be adding more after this build is done)
- Various 12v plugs (car charger and USB)
- Blade fuse block to fuse the DC plugs
- DROK (or other similar) AC charger
My main question here is about fuse and wire sizing for the connection from the battery to the inverter.
With a 1200w inverter, I calculated upwards of almost 120 amps when the battery voltage gets to the lower SOC:
- 1200w inverter
- 12v at low voltage
- 0.85 efficiency drop
So I was just about ready to go with 1AWG wire to the inverter (which I think goes up to 150A) and fusing it at either 125A or 150A. Even though I don't believe I'll ever use the full 1200w of the inverter, I want to make sure the wires and fuses are sized for the worst-case scenario.
But then it hit me that this AmpereTime 100Ah battery has a 100 amp BMS (with over-current and short circuit protection). So is it even possible for the battery to discharge more than 100A, even when the battery runs down to ~12v?
If 100A is the absolute max output from the BMS, then it seems like I could size everything based on that 100A max output (even though the Inverter could technically want to draw more), meaning I could go with 2AWG wire to the inverter (or technically even 4AWG based on the chart I was using) and fuse it at 100A at the battery. Does this sound right?
And then the final question (assuming the above is correct about the 100A output at the BMS): Is there any harm or damage that I could do to the inverter or the rest of the system by using a 1200w inverter? It seems like I'll just be limiting the max capacity of the inverter to ~1000w, but is there something else that I should be aware of by using an oversized inverter?