Hi! We live near the fire that happened in Paradise and I am making Wills solar box and plan on putting it on a dolly so we can move it around to help my inlaws and our family when the power goes out. I have 2 solar panels and about 170ah of agm batteries. Which i think will be good enough to keep electronics and our fridge (limping along) as well as a cpap machine for my father inlaw. I was hoping someone could double check my wire size and fusing before I plug it to the battery (i just finished). Also can i get away with 4g wire to link my batteries together or should i use 2g? I have six of these little batteries (i get them for free so i want to use them). Thanks so much for helping me!
Check me please!
- Thread starter Rene
- Start date
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,847
Is that block diagram accurate? Just wondering as it looks like your Victron batteryprotect is across the 200 amp breaker. The BP should be inline with the load that is to be automatically disconnected on low battery voltage.
Are your batteries in parallel or some other arrangement?
When determining the wire gauge to use you have to work with the lowest voltage the battery will be supplying to the load, and the expected draw by the load. Suppose your 1500 watt inverter is running full tilt. You might find that it actually draws 1700 watts due to losses in the inverter. If your low battery cut off is 11.5v that means about 150 amps (1700/11.5). The 2g from the battery to the breaker will cope with that. The current will exceed the 4g wire rating so you can expect it to heat up more than the insulation may be good for. Keep in mind that this is only with the inverter at full power. If it is only at that level for a short time that won't be a problem.
Is the intent of the 30 amp fuse between the CC and the battery to protect the wiring if it becomes shorted on the run between the CC and be fuse? If not, ie it's there to protect the CC, you could do away with it since the only fuse that will blow will also limit the power output from the CC. The Victron CC already limits its output current to 20amps.
The 10g from the CC to the battery is fine. It will only ever be carrying a maximum of 20amps.
You don't have a breaker in line with the solar input on the CC so when it comes time to disconnect the panels you should cover them up to avoid arc damage on the CC's input terminals or panel plugs.
Is the fuse block a 12v connection point for DC devices?
Are your batteries in parallel or some other arrangement?
When determining the wire gauge to use you have to work with the lowest voltage the battery will be supplying to the load, and the expected draw by the load. Suppose your 1500 watt inverter is running full tilt. You might find that it actually draws 1700 watts due to losses in the inverter. If your low battery cut off is 11.5v that means about 150 amps (1700/11.5). The 2g from the battery to the breaker will cope with that. The current will exceed the 4g wire rating so you can expect it to heat up more than the insulation may be good for. Keep in mind that this is only with the inverter at full power. If it is only at that level for a short time that won't be a problem.
Is the intent of the 30 amp fuse between the CC and the battery to protect the wiring if it becomes shorted on the run between the CC and be fuse? If not, ie it's there to protect the CC, you could do away with it since the only fuse that will blow will also limit the power output from the CC. The Victron CC already limits its output current to 20amps.
The 10g from the CC to the battery is fine. It will only ever be carrying a maximum of 20amps.
You don't have a breaker in line with the solar input on the CC so when it comes time to disconnect the panels you should cover them up to avoid arc damage on the CC's input terminals or panel plugs.
Is the fuse block a 12v connection point for DC devices?
Thanks gnubie!
1. I dont understand how the low voltage should be connected can you explain more. Maybe a picture?
2. My batteries are going to be in parallel.
3. I Plan on running the inverter for about 4-6 hours at a time (at night for a cpap machine) and then seperatly during the day for about 1-3 hours at a time for the fridge. I know that the fridge will cycle on and off trying to cool itself. So do you think I should upgrade my wires to 2g for the inverter to circut breaker? I will keep an eye on the heat for sure.
4. The 30a fuse to the CC is because Will did one in his solar box project and I just copied that. Guess it is overkill but i am gonna keep it, seems like a good idea.
5. yes i got that right
6. I have 2 solar Renogy 100 watt suitcases (total of 200 watts) i will make sure to plug them in before opening them. If i did want to breaker it what size would you Reccomend?
7. The fuse box is a blue sea 6 circuit box that is connected to 1cig port 2 usbports a volt meter and a switch to turn the power to the ports on there. Its super small draw just for phones and radios ect. I had it laying around from my truck so i used it.
Thanks for all your knowledge!
1. I dont understand how the low voltage should be connected can you explain more. Maybe a picture?
2. My batteries are going to be in parallel.
3. I Plan on running the inverter for about 4-6 hours at a time (at night for a cpap machine) and then seperatly during the day for about 1-3 hours at a time for the fridge. I know that the fridge will cycle on and off trying to cool itself. So do you think I should upgrade my wires to 2g for the inverter to circut breaker? I will keep an eye on the heat for sure.
4. The 30a fuse to the CC is because Will did one in his solar box project and I just copied that. Guess it is overkill but i am gonna keep it, seems like a good idea.
5. yes i got that right
6. I have 2 solar Renogy 100 watt suitcases (total of 200 watts) i will make sure to plug them in before opening them. If i did want to breaker it what size would you Reccomend?
7. The fuse box is a blue sea 6 circuit box that is connected to 1cig port 2 usbports a volt meter and a switch to turn the power to the ports on there. Its super small draw just for phones and radios ect. I had it laying around from my truck so i used it.
Thanks for all your knowledge!
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,847
My drawing skills aren't too flash so ... What I've done there is change the wiring so the + from the battery to the load (inverter and the aux fuse block) passes through the batteryprotect. It will be able to turn off the load if the batteryvoltage falls too low.
The inverter still runs through the 200A circuit breaker to allow you to open the circuit and remove power from the inverter completely. The other side of the breaker goes to the 175A fuse for protection.
The charge controller goes direct to the battery to allow it to remain connected to the battery regardless of the load and actions of the batteryprotect. The manufacturer of your CC advises that it must never be disconnected from the battery and still have power coming in from the solar panels.
The negative wiring can still be hubbed off the negative terminal on the inverter.
Someone else might have a better scheme so don't leap out and assume this is the best way of doing it
Do you have a link to the suitcase panels? That way I can see the voltages involved for the right type of breaker.
The inverter still runs through the 200A circuit breaker to allow you to open the circuit and remove power from the inverter completely. The other side of the breaker goes to the 175A fuse for protection.
The charge controller goes direct to the battery to allow it to remain connected to the battery regardless of the load and actions of the batteryprotect. The manufacturer of your CC advises that it must never be disconnected from the battery and still have power coming in from the solar panels.
The negative wiring can still be hubbed off the negative terminal on the inverter.
Someone else might have a better scheme so don't leap out and assume this is the best way of doing it
Do you have a link to the suitcase panels? That way I can see the voltages involved for the right type of breaker.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
no disconnect, breaker (better imo) or fuse between panels & charge controller ? Certainly would consider that.
Also if you want the panels to be detachable / unpluggable you'll want to disconnect them nicely before yanking plugs and you'll want a good solid plug for the solar wires. I saw one DIY setup and the fellow used a small Anderson type connector to accomplish that for 3x300W panels. I don't know if there would be something slicker & as solid as an Anderson connector though.
A personal thing though, I rather prefer to oversize the battery to inverter wires and have a definite preference to using high quality welding wire, like Excelene which is fine copper wires and seriously tough and always use the heavy lugs. REF: https://www.wireandsupply.com/www_wireandsupply_com_welding_cable_s_22_htm_s/22.htm none of the cheap kits on ebay, amazon etc are this grade. I've seen too many cheap or coarse grade copper wires fail, especially with Big DC and I won't take that kind of risk. It is not THAT much more expensive to get high end wires but the peace of mind & safety has a lot of value.
A Case in point. When I switched from my 3KW Inverter/Charger to the Samlex EVO4024 I had to change from 2/0 to 4/0 (ouch $$$ that could have been avoided IF I had just bought 4/0 at first) the cost difference between the two NEW is only $40 but now I have $200 worth of 2/0 sitting there next to the decommissioned 3kw inverter. A Line to always remember.... Penny Wise, Dollar Foolish and of course, Dollar Wise & Penny foolish.
Also if you want the panels to be detachable / unpluggable you'll want to disconnect them nicely before yanking plugs and you'll want a good solid plug for the solar wires. I saw one DIY setup and the fellow used a small Anderson type connector to accomplish that for 3x300W panels. I don't know if there would be something slicker & as solid as an Anderson connector though.
A personal thing though, I rather prefer to oversize the battery to inverter wires and have a definite preference to using high quality welding wire, like Excelene which is fine copper wires and seriously tough and always use the heavy lugs. REF: https://www.wireandsupply.com/www_wireandsupply_com_welding_cable_s_22_htm_s/22.htm none of the cheap kits on ebay, amazon etc are this grade. I've seen too many cheap or coarse grade copper wires fail, especially with Big DC and I won't take that kind of risk. It is not THAT much more expensive to get high end wires but the peace of mind & safety has a lot of value.
A Case in point. When I switched from my 3KW Inverter/Charger to the Samlex EVO4024 I had to change from 2/0 to 4/0 (ouch $$$ that could have been avoided IF I had just bought 4/0 at first) the cost difference between the two NEW is only $40 but now I have $200 worth of 2/0 sitting there next to the decommissioned 3kw inverter. A Line to always remember.... Penny Wise, Dollar Foolish and of course, Dollar Wise & Penny foolish.
