Ground a charge controller?

How do I ground my charge controller via the little screw on the side? I contacted Victron directly about which charge controller I should go for according to the setup and I’m now pretty much ready to switch everything on – it’s just grounding the controller that’s left? I emailed them again asking if I should wire that little screw up to the metal frame on the shelving that’s holding my batteries (metal frame standing on rubber matting on a wooden floor) and their reply was “Well its supposed to be connected to the common ground, where also the AC distribution is grounded”. That’s all they said? So I’m still clueless really. The AC distribution is the inverter, yes? The inverter doesn’t tell me it needs to be grounded so I’m confused. Please can anyone shed some light? Thanks!!

With no tie in to any electrical system simply connect the inverter chassis ground to the controller chassis ground.

Shouldn't those cells have some compression?

Texas-Mark said:

Shouldn't those cells have some compression?

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Not necessary.

This subject has been beat to death on the forum.

Calendar aging will kill them way before compression issues.

Joe run the wire to a stake that’s 3 ft into the earth.

Your house grid system will have an earth rod somewhere. Thats were they are saying to attach it.

JoeHam said:

Not necessary.

This subject has been beat to death on the forum.

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Then why are there always threads about bloated cells and people say their compression technique was wrong? And why do nearly all of the pictures posed show them compressed?

I do a 3000 watt inverter on a 24 volt system with Victron equipment on an RV build and I ground with 8 AWG stranded wire to the chassis.

A smaller crate build with a 300 watt inverter with Victron equipment is not grounded.

If it’s practical in your area, I like the idea of a grounding rod, but drilling a hole through the house will make a difference.

The three inverters I’ve used have all called for grounding.

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I have other things I want to comment on the build, but that will distract fro the grounding question.

JoeHam said:

Not necessary.

This subject has been beat to death on the forum

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Everyone can make reach their own conclusion. I do not have the luxury of space like that picture posted above. I have 48 cells in two rows of 24 each and to save strain on terminal tops and bus bars I chose to follow a suggestion in a manufacturer sheet and concluded that compression would work for me even though it might not be "necessary".

Ampster said:

Everyone can make reach their own conclusion.

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I agree.

Your money, your choice but I stand by not necessary.

Texas-Mark said:

And why do nearly all of the pictures posed show them compressed?

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I don’t think that’s true.

For example, take a look at the 8:53 mark here :

JoeHam said:

I don’t think that’s true.

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I was talking about build pictures posted here. I don't think I have seen any that were not compressed until now. Granted, I have not seen every single post, and that is why I asked. and as i said, there have been plenty of threads about cells bloating.

In any case, i did not want to distract from the grounding question, just thought it was worth mentioning.

Equipment 'earths' can improve safety and prevent fire and electric shock.
What is the building where the equipment is installed, does it have utility power?
What are you going to connect to the inverter?.

Important safety points.

You need a master fuse at the battery positive, the breaker you have fitted is designed for car audio. Ther are unreliable and catch fire.
Your cells need some sort enclosure to prevent accedantal shorts.
There seems to be no BMS connected to the cells

mikefitz said:

Equipment 'earths' can improve safety and prevent fire and electric shock.
What is the building where the equipment is installed, does it have utility power?
What are you going to connect to the inverter?.

Important safety points.

You need a master fuse at the battery positive, the breaker you have fitted is designed for car audio. Ther are unreliable and catch fire.
Your cells need some sort enclosure to prevent accedantal shorts.

Click to expand...

I wanted to mention some of those and need to add:

I also think the wiring is a bit skinny for a 24 volt system.

Appears that 3000 watt inverter is connected to a 100 ah 24 volt battery pack. Not much time to power a lot of equipment.

A 3000 watt inverter is a bit over sized for a 24 volt system if it is run full out for long periods of time.

mikefitz said:

Equipment 'earths' can improve safety and prevent fire and electric shock.
What is the building where the equipment is installed, does it have utility power?
What are you going to connect to the inverter?.

Important safety points.

You need a master fuse at the battery positive, the breaker you have fitted is designed for car audio. Ther are unreliable and catch fire.
Your cells need some sort enclosure to prevent accedantal shorts.
There seems to be no BMS connected to the cells

Click to expand...

Thanks so much for this. I’ll definitely make a plan for earthing.

No utility power just a shed, we rent so must be movable.

An extension runs into the kitchen so the plan is to run as many kitchen appliances as possible. It’s only the fridge that’s a concern as it runs all the time, well maybe 60% of the time if it powers down when the temp is reached. All other items, with exception of the washing machine, are only used for a minute or so a couple of times a day. Dunno, I may only connect the fridge and see how it goes and then add bit-by-bit. But I do want all kitchen LED lighting sorted.

I will get a better master fuse for the inverter. Others have mentioned this as well. It’s such a good thing I posted here.

I will look into an enclosure for the batteries. A BMS is a very good point I originally became aware of when buying the batteries but have overlooked since so good point! I found one here that I see connected to 16 batteries but may have to get shorter bridges to pack them closer as in this link, and considering enclosure my shelving might not work then. Mmm

https://www.amazon.co.uk/Lithium-Ma...652330&sprefix=lifepo4+bms+24v,aps,75&sr=8-43

chrisski said:

I wanted to mention some of those and need to add:

I also think the wiring is a bit skinny for a 24 volt system.

Appears that 3000 watt inverter is connected to a 100 ah 24 volt battery pack. Not much time to power a lot of equipment.

A 3000 watt inverter is a bit over sized for a 24 volt system if it is run full out for long periods of time.

Click to expand...

Thanks! It’s 16x 200ah 3.2V batteries (8 in series for the 24 (well 25.6) and another 8 in parallel for bank).

I went with the same size cables as came with the solar panels. Looks like 8awg. Then way thicker for the inverter. The cable that concerns me is the one running from the wind turbine controller to the battery bank that could be 12awg, even though, and I could be mistaken, turbines don’t really generate that much power? There are 2 fuses here, a 20A trip from the turbine before the controller and another 25A from the controller to the battery bank. That said what if power surges back from the battery bank! It’s a minefield to figure all this out.

Yeah, I did pause on the 3000 before getting it but then figured with the number of batteries along with 800W of solar and 400W of wind it might be suitable. Dunno, still trying to figure this out. It’s taken 9 months to get to this point buying stuff bit-by-bit and realised I still need to get more items, change a few things, and rearrange a lot so still not there! Mad

mikefitz said:

Equipment 'earths' can improve safety and prevent fire and electric shock.
What is the building where the equipment is installed, does it have utility power?
What are you going to connect to the inverter?.

Important safety points.

You need a master fuse at the battery positive, the breaker you have fitted is designed for car audio. Ther are unreliable and catch fire.
Your cells need some sort enclosure to prevent accedantal shorts.
There seems to be no BMS connected to the cells

Click to expand...

Can I ask what size fuse you think I should get for the inverter to the battery? My research tells me it’s the power draw of the inverter which is 3000, divided by the voltage of the battery bank which is 24, which comes to 125? The audio fuse I used here, which I will replace, is 150A?

Fuse size = inverter wattage / low voltage cutoff / inverter efficiency * 1.25 headrom

220 amps =3000 * 20 / .85 * 1.25

For my system, 24 vdc and 3000 watt inverter, I use 4/0 wire and a 225 amp class t fuse.