My First System - For My RV - 24v - 9kW LiFePO4 - 2500w Inverter

[SolarAntics]

Hi y'all,

Getting closer to finishing my designs and could use some guidance. I am building a system for my RV and I unfortunately have not the most ideal components to work with and want to build with what I have. Batteries are miss matched a little, but the ones in series are the exact same. This should be a 24v system. Inverter and chargers are rated at 24v. Please see the diagram

I really don't want to add more bus bars than I need to, but unfortunately the charge controllers will need to be in a separate compartment, so bus bars there. Also, I can't connect the three negative cables from the banks to the shunt, so I figure I need a bar before that. Can confirm?

As far as fuses and breakers go I think I got all that I need. The 120v charger is for emergency generator charging only and is going to be disconnected unless in use (will cut off the MPPT when that is in use manually at breaker). The 120v charger has its own fuses.

Also am wondering about grounding. My understanding is to ground the batteries and the inverter for the AC side. As well as the panels would need grounding, but I think they are all set considering that they are the 400w Renogy solar suitcases (that's why I didn't add a ground there). I need to dig into documentation on that, and possibly a ground is needed at the solar charge controller. Thoughts?

Grounding Plan UPDATE: The manuals are giving me jack squat for answers or no answers at all - - at best they say ground if necessary. I think I should ground the MPPT and AC Charger with 8awg to their own negative bus bar; which goes to the main - and use 4awg to ground the inverter to the main - bus bar and then 4awg from the bus bar to the RV chassis. Logical?

Thank you for all y'alls help!

v5 - Decided to add a kill switch to terminate the batteries since these breakers at each bank likely will not be good enough to act as a cut off (worried about repeated use will eventually wear them to failure - they're cheap with 1/4" lugs so I imagine the rest of components are skimpy too)

(Previous designs in attachments)

v4 - put grounds to bus bars
v3 - added balancers
v2 - made some silly corrections and added data
v1 - lost in the aether

 

[time2roll]

The 200 amp breakers on the battery seem redundant. 300A class T seems rather large. I would be closer to 150 amp. Keep in mind a class-T will pass 2x rating for close to a minute before it opens. No need for allowing for surge performance. And there is very little to no start surges with an RV, really only the A/C.

 

[B-ManFX4]

I would replace the battery breakers with battery switches. Being able to quickly and easily disconnect battery power when working or troubleshooting is handy.

 

[SolarAntics]

I would replace the battery breakers with battery switches. Being able to quickly and easily disconnect battery power when working or troubleshooting is handy.

Can't a breaker be used as a switch?

 

[SolarAntics]

The 200 amp breakers on the battery seem redundant. 300A class T seems rather large. I would be closer to 150 amp. Keep in mind a class-T will pass 2x rating for close to a minute before it opens. No need for allowing for surge performance. And there is very little to no start surges with an RV, really only the A/C.

I oversized them because the purpose was to prevent an extreme current causing arcing past a regular fuse or breaker. They are so expensive, I can't really afford for it to blow, only when it absolutely needs to prevent catastrophe.

 

[chrisski]

May need a battery balancer to avoid 12 volts from getting out of balance.

For the grounding batteries and AC of the inverter, just wire it as the inverter says. Easiest way for me was to plug the three wire AC from the inverter onto shore power with a plug I made from hard wired port to a shore power adapter. The case gets grounded to chasis. I did not tie any of the three AC wires to bus bars. That seems dangerous.

With 800 watts of power, I’d plan on 3 kWh of production on the shortest day of the year around the AZ latitudes if you move them twice to face the sun on a clear shortest day of the year. Could be 1.6 kWh if not moved and less if they can’t be out all day. That should be enough if you don’t use electric heat or electric refrigeration, or electric water heater.

With AC to DC conversion losses and the inverter maxed out like the propane heater on with the microwave on and a couple other things, could push more than 100 amps and trip the breaker.

 

[SolarAntics]

May need a battery balancer to avoid 12 volts from getting out of balance.

For the grounding batteries and AC of the inverter, just wire it as the inverter says. Easiest way for me was to plug the three wire AC from the inverter onto shore power with a plug I made from hard wired port to a shore power adapter. The case gets grounded to chasis. I did not tie any of the three AC wires to bus bars. That seems dangerous.

With 800 watts of power, I’d plan on 3 kWh of production on the shortest day of the year around the AZ latitudes if you move them twice to face the sun on a clear shortest day of the year. Could be 1.6 kWh if not moved and less if they can’t be out all day. That should be enough if you don’t use electric heat or electric refrigeration, or electric water heater.

With AC to DC conversion losses and the inverter maxed out like the propane heater on with the microwave on and a couple other things, could push more than 100 amps and trip the breaker.

Thank you, I forgot about the balancers. Am planning on using them for the series banks. My plan is to plug my shore power cable into the inverter. My system is not connected in anyway to the RV system aside when I do that. Will that provide the grounding? Do I still need to ground the inverter case (Is the case grounded already by the negative terminal to DC side? I suppose I should check manual..)?

 

[chrisski]

Thank you, I forgot about the balancers. Am planning on using them for the series banks. My plan is to plug my shore power cable into the inverter. My system is not connected in anyway to the RV system aside when I do that. Will that provide the grounding? Do I still need to ground the inverter case (Is the case grounded already by the negative terminal to DC side? I suppose I should check manual..)?

Check the manual.

All my RV type inverter have the case grounded to chasis. I forget the exact size, but I connected the chassis ground on the inverter to metal on the RV that I drilled and put a star washer between the ground lug and RV chassis to maintain a tight fit.