Inverter and battery BMS question

buckeyestargazer · Apr 12, 2024

I'm planning to add a whole RV inverter and could use a little help figuring parts of it out. I'm planning to use the Renogy 3000W inverter to power everything except for the A/C. I have a 230AH LiFePO4 battery. Right now, the BMS limits the discharge current to 100A. I might need to update that?

-Renogy told me to use a 400A ANL fuse between the battery and inverter.
-Just for an example, let's say I need 2000W power constant. I believe that translates to about 167A, so I would need a BMS that is capable of at least 167A, correct?
-If that figure approaches 3000W then I would need a 250A BMS?
-The Renogy can surge to 6000W which is a crazy high current of 500A?

Basically, what BMS do I need and what size ANL fuse?

Rocketman · Apr 12, 2024

The BMS can only supply 100a (or so depending on the model) to the inverter- to get 200amps you put two batteries in parallel. If you need 250a you put three batteries in parallel.

The fuse size depends on the wires.

To get that many amps into an inverter you need 4/0 cable or two sets of 1/0 cable (two positives and two negatives).

That surge is only a moment.

buckeyestargazer · Apr 12, 2024

Rocketman said:
The BMS can only supply 100a (or so depending on the model) to the inverter- to get 200amps you put two batteries in parallel. If you need 250a you put three batteries in parallel.

The fuse size depends on the wires.

To get that many amps into an inverter you need 4/0 cable or two sets of 1/0 cable (two positives and two negatives).

That surge is only a moment.

Right, but you can buy a BMS that can supply 200A or 250A. I believe my battery is 1C so theoretically it could supply 230A(?). I'd rather buy a BMS for $100 than another battery for $600. It's entirely possible I'm not thinking about this correctly.

I was planning to use 4AWG silicone wire which I thought could handle up to 300A but please correct me if not.

robbob2112 · Apr 12, 2024

It would be better to run a 48v or 24v battery/inverter/MPPT and just get a 48/24 buck converter to run your 12v loads.

Smaller wires, lower current, and much higher capacity. And you can get a dc-dc charger if you. Want to keep a 12v system topped up.

And were it me I would reconsider Renology and go with victron or other quality system.

Rocketman · Apr 12, 2024

buckeyestargazer said:
Right, but you can buy a BMS that can supply 200A or 250A. I believe my battery is 1C so theoretically it could supply 230A(?). I'd rather buy a BMS for $100 than another battery for $600. It's entirely possible I'm not thinking about this correctly.

You really need more than one battery for an inverter of that size.

buckeyestargazer said:
I was planning to use 4AWG silicone wire which I thought could handle up to 300A but please correct me if not.

Nope not even close… it might be able to pull that much but the voltage drop would shut the inverter down as you heated the wire up. Especially in a 12v system voltage drop is not good.
Look up “Blue sea wire amp chart” you will find 4awg wire is for 100amps.

For my Victron 12/3000 inverter it wants dual 1/0 cables - which will pass more than a 4/0 cable, but my rig was wired with 4/0 so that’s what I use. It also recommends a 400a of battery and a 400+ amp/hour battery with a 400a fuse. Yes drawing that much power in 12v is massive amps! It really is better to have a 24 or 48v battery and inverter and then convert down to 12v.

If your RV has a 50a plug look at the Victron 12/3000 2x120v or the 24v model.

buckeyestargazer · Apr 12, 2024

Alright, thanks for the info. I wasn't even thinking about adding batteries. I figured 230AH would be enough. I built this 4S battery with EVE 230A cells. Let's say I get 4 more 230A cells and make a 24v battery. How does that then feed the 12v inverter?

Rocketman · Apr 12, 2024

Your inverter and your battery must be the same voltage- both 12v or both 24v.

What equipment do you already have?

buckeyestargazer · Apr 12, 2024

Rocketman said:
Your inverter and your battery must be the same voltage- both 12v or both 24v.

What equipment do you already have?

The renogy 12v 3000w inverter and the 12v 230A battery. The inverter is new and I could probably return it. The battery has a Daly 100A bms. Also an auto transfer switch.

I don't have the camper yet but it it comes with a 12v/24v MPPT charge controller.

Rednecktek · Apr 12, 2024

Since it's a camper and already has a native 12v system, I'd recommend sticking with 12v and either making room for more batteries in parallel or making your own higher density batteries. I can tell you from personal experience that a 4s 304ah build with BMS and heater pad and thermostat fit nicely into the Noco Group 29-31 boxes.

3kw is a LOT for a 12v system, you'll need 3 batteries in parallel to feed that and you'll have 30ish watts, or 750ish watt-hours a day just to exist.

If you go to a 24v system you're really not going to gain anything. The battery will take up twice the space, and you'll have to have a big enough converter to kick back down enough amps to feed all your 12v stuff. The only benefit is smaller wires to the inverter. The converter is likely to be more expensive than what you save in copper.

MisterB1959 · Apr 12, 2024

I have a 12v 304Ah lithium and a Renogy 3000w inverter in my motorhome (RV).
I can run the kettle and microwave at the same time, which is what I wanted to be able to do, though it rarely happens. I am more than happy with the setup and am slowly migrating to reducing the use of onboard LPG by cooking and heating on electric (Inc BBQ with a George foreman). One of the plus points with the Renogy is that when I hook up to mains (grid/shore) power the Renogy automatically allows everything that is usually fed by the battery to be fed by the mains!

buckeyestargazer · Apr 13, 2024

MisterB1959 said:
I have a 12v 304Ah lithium and a Renogy 3000w inverter in my motorhome (RV).
I can run the kettle and microwave at the same time, which is what I wanted to be able to do, though it rarely happens. I am more than happy with the setup and am slowly migrating to reducing the use of onboard LPG by cooking and heating on electric (Inc BBQ with a George foreman). One of the plus points with the Renogy is that when I hook up to mains (grid/shore) power the Renogy automatically allows everything that is usually fed by the battery to be fed by the mains!

What specific inverter do you have? I was planning to use an automatic transfer switch to feed the converter/charger from either the inverter or shore power. But it sounds like your inverter has an integrated transfer switch?

MisterB1959 · Apr 13, 2024

buckeyestargazer said:
What specific inverter do you have? I was planning to use an automatic transfer switch to feed the converter/charger from either the inverter or shore power. But it sounds like your inverter has an integrated transfer switch?

It's the Renogy 3000w take a look on YouTube. It has a 'pass through' facility which negates the need for an ATS

buckeyestargazer · Apr 13, 2024

MisterB1959 said:
It's the Renogy 3000w take a look on YouTube. It has a 'pass through' facility which negates the need for an ATS

You must have the inverter/charger. I just have the inverter, which does not have AC input for pass through.

MisterB1959 · Apr 14, 2024

buckeyestargazer said:
You must have the inverter/charger. I just have the inverter, which does not have AC input for pass through.

Def NOT inverter charger ?

3000W 12V to 230V/240V Pure Sine Wave Inverter With English Standard Socket (with UPS Function)

Renogy 3000W Inverter transforms the DC electricity stored in batteries into standard household AC power. Free Shipping!

uk.renogy.com

2000W 12V Pure Sine Wave Inverter with UPS Transfer Switch and Built-in Bluetooth

Help power your cabin with Renogy's 2000W 12V Pure Sine Wave Inverter. This inverter helps you run electricity through your off-grid system. Free shipping

www.renogy.com

the US version only seems to be in the 2000w version for some reason?

if its what you need, is it worth trying to sell your current inverter and buying the pass through version? i assume the same thing is available in the US and as you mentioned, can you send the new unused inverter back in exchange?

buckeyestargazer · Apr 15, 2024

MisterB1959 said:
Def NOT inverter charger ?

3000W 12V to 230V/240V Pure Sine Wave Inverter With English Standard Socket (with UPS Function)

Renogy 3000W Inverter transforms the DC electricity stored in batteries into standard household AC power. Free Shipping!

uk.renogy.com

2000W 12V Pure Sine Wave Inverter with UPS Transfer Switch and Built-in Bluetooth

Help power your cabin with Renogy's 2000W 12V Pure Sine Wave Inverter. This inverter helps you run electricity through your off-grid system. Free shipping

www.renogy.com

the US version only seems to be in the 2000w version for some reason?

if its what you need, is it worth trying to sell your current inverter and buying the pass through version? i assume the same thing is available in the US and as you mentioned, can you send the new unused inverter back in exchange?

I don't need the inverter AC pass through as I already have an automatic transfer switch.

robbob2112 · Apr 20, 2024

I use this along with a 12v200ah plus battery for the UPS for my media server and desktop computers. It keeps the battery charged and auto transfers the load in 5ms if power goes down. That is with it set for AC priority. Withit on DC priority it uses battery power until 40% then charges back up.

12V 2KW Pure Sine Wave Inverter Charger

Rated Input Voltage: 12V Rated Output Voltage: 110V Efficiency: >90%

www.expertpower.us

I plan to add a mppt with a few panels on it to make the server 'off-grid'

And Renogy has a pretty bad reputation. If it works fine, if you need service or warranty work they wear you down and take months to let you mail the failed unit to them so they can evaluate. If they don't find an issue from a defect you have to pay to get the bad unit back.

corn18 · Apr 21, 2024

Is your RV going to be 30A or 50A shore power service?

Inverter and battery BMS question

New Member

Solar Wizard

New Member

Doing more research, mosty harmless

Solar Wizard

New Member

Solar Wizard

New Member

Solar Wizard

Solar Enthusiast

New Member

Solar Enthusiast

New Member

Solar Enthusiast

New Member

Doing more research, mosty harmless

Village Idiot

Similar threads