What size fuse for Giandel PS-2200kar

[GuydeMtl]

Bonjour All,
I'm building a milk crate solar generator to use on the road. From what I can read, I need to put a fuse between the batteries and the busbar or inverter.
Here the parts:

• 4 Basen (Eve) LifePO4 3.2v LF280K-896Wh
• 1 BMS JBD SP04S034-L4S-200A
• 1 Giandel PS-2200kar, came with 2 DC POWER CONNECTION FLEXIBLE CABLE 600V 1X35mm² PVC 105°C

I'm not sure what size and type of fuse to install. The largest appliance I will use is a 1800W Portable Induction Cooktop.

After reading a lot, I think the purpose of this fuse would be to protect the cable.

Any advice would be appreciated.

Merci !

 

[GuydeMtl]

Well, one month and no help what so ever: thank you community !!!

 

[GLC]

Fuses protect wiring, we need to know what voltage is your inverter to determine wire size and fuse size. If your batteries an inverter is 12 volt and you are pulling 1800 watts, that is 150 amps so you are looking at 175 to 200 amp fuse. You wire will also have to beefy too but we need to know how far it is from your inverter to know the wire size.

 

[rmaddy]

Assuming a 12V 2200W inverter that would be up to 220A being pulled from the battery. Your BMS can only handle 200A. The 1800W load from the cooktop will pull about 180A from the battery.

The 35mm² wire is way too small. You need 70mm² (or 2/0AWG) wires between the battery and the inverter to support the full load. Throw away the wires that came with the inverter and use properly sized wires. Be sure you use high quality marine grade pure copper stranded wire.

You should use a 250A Class T fuse close to the battery.

The biggest fuse you should use on the 35mm² wire that came with the inverter is 150A. You wouldn't be able to run the cooktop since the fuse would blow every time you turned on the cooktop.

 

[GuydeMtl]

Fuses protect wiring, we need to know what voltage is your inverter to determine wire size and fuse size. If your batteries an inverter is 12 volt and you are pulling 1800 watts, that is 150 amps so you are looking at 175 to 200 amp fuse. You wire will also have to beefy too but we need to know how far it is from your inverter to know the wire size.

Thank you GLC, I read a lot and I think I have figure it out.
My battery and inverter (2,200 watts) are 12 volts. The inverter Input low voltage shutdown is 9.8 volts, so from what I understand I use the following formula: 2200 watts / 9.8 volts /0.8 = 280 amps. I will use 2/0 AWG cable with a 250 ANL fuse. I'm using a 200 amps BMS on my 280 amp battery. The battery and inverter are less than 2 feet apart.

 

[rmaddy]

2200 watts / 9.8 volts /0.8 = 280 amps

80% is a bit low. Your inverter probably isn't that inefficient. 85% would probably be better. I use 12.0V in the calculation because I never want my LiFePO₄ to ever get below 12.0V. But if you plan to let your battery get so low that the BMS will shutdown the battery then using 10.0V (0% SOC for LiFePO₄) is low enough.

So you have:

2200W / 10V / 85% = 260A.

But again, your BMS can only handle 200A so you can't power a 2200W load down to 10.0V. At 10.0V your BMS can only handle 1700W which is less than your cooktop uses. Your 1800W cooktop will pull 200A from the battery when the voltage gets down to about 10.59V. That's roughly 2.5% SOC. It's best to avoid letting your battery get that low.

 

[GuydeMtl]

80% is a bit low. Your inverter probably isn't that inefficient. 85% would probably be better. I use 12.0V in the calculation because I never want my LiFePO₄ to ever get below 12.0V. But if you plan to let your battery get so low that the BMS will shutdown the battery then using 10.0V (0% SOC for LiFePO₄) is low enough.

So you have:

2200W / 10V / 85% = 260A.

But again, your BMS can only handle 200A so you can't power a 2200W load down to 10.0V. At 10.0V your BMS can only handle 1700W which is less than your cooktop uses. Your 1800W cooktop will pull 200A from the battery when the voltage gets down to about 10.59V. That's roughly 2.5% SOC. It's best to avoid letting your battery get that low.

rmaddy, my mistake in the formula. The efficiency in the inverter documentation state "Approximate 90%". The 0.8 in my formula was the headroom.