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BMS 120Amp to Inverter question

John Frum said:
"Daly BMSs have very load capacity to balance your batteries.
Most of the cells that folks purchase here would not stay balanced with a Daly BMS.
That means adding an active balancer which is a whole other kettle of fish."

Ya. I'm not planning to go the active balancer route, from the bit of research I did ..(Will's videos) I didn't feel inspired to go for that kind of option. Maybe it sounds good more than it performs well? ?
 
In that video I shared, he's multiplying the 120a from the bms to "12.8 nominal". I suppose that # is just the voltage of the pack?
The nominal voltage is the voltage that when multiple by the rated amp hours indicates the rated watt hours.
Nominal is weird word and its meaning is heavily contextual.

1500 ac watts / .85 conversion factor / 12.8 volts low cutoff = 137.867647059 service amps.
Still exceeds the rating for a 120 amp bms.

I'm guessing you are using a Giandel inverter because you mention 2200 watts.
The reason why I use 10 volts is because your Giandel inverter has a hard coded low voltage disconnect of ~10 volts.
The lower the voltage the higher the amps to cover the same wattage.

1500 ac watts / .85 conversion factor / 10 volts low cutoff = 176.470588235 service amps.

I don't mean to offend you or sound like I'm not listening to your advice John.
None taken.

For a mobile installation I suggest you consider a quality inverter_charger.
This one is good
This is the hardwired version

An inverter/charger is actually an inverter, ac2dc charger and an automatic transfer switch.
 
John Frum said:
"Daly BMSs have very load capacity to balance your batteries.
Most of the cells that folks purchase here would not stay balanced with a Daly BMS.
That means adding an active balancer which is a whole other kettle of fish."

Ya. I'm not planning to go the active balancer route, from the bit of research I did ..(Will's videos) I didn't feel inspired to go for that kind of option. Maybe it sounds good more than it performs well? ?
I'm not a fan of the Daly BMS and I don't believe most of their claims.
 
In that video I shared, he's multiplying the 120a from the bms to "12.8 nominal". I suppose that # is just the voltage of the pack?

I don't mean to offend you or sound like I'm not listening to your advice John. I'm all ears! This is just the exact video and segment that got me to start questioning my inverter size/bms size.

You say potato and I say potato. The numbers that are used in a formula should be adjusted for your situation. The inverter efficiency number varies from inverter brand to brand and model to model and even within a utilization amount (2000 watts of a 3000 watt inverter may be more efficient than 2800 watts of a 3000 watt inverter).

The voltage number in the formula (10 volts) is the lowest voltage a system might see. Not all of us have our systems programmed to allow the batteries to reach 10 volts. My inverter cutoff is around 12 volts. LiFePO4 batteries typically spend most of their time above 13 volts.

What John presented is a worst case scenario with the numbers in his formula. It's a safe approach when sizing components for folks that are new to this. An experienced designer may choose higher values that produce a lower amperage rating.

I'm with John on not recommending the Daly BMS. There are just too many issues seen with it (here on the forum). The Overkill Solar BMS that you have already is a very good BMS, as long as it is used within specifications.
 
I design based on the assumption that the teenage son or daughter of the DIYer will be using the system.
 
I design based on the assumption that the teenage son or daughter of the DIYer will be using the system.
Would there be something to look out for (in a smart brain) that would prevent any issues from forming with a 1500w inverter? What precautions would need to be taken do you think? I really don't think I would test its limits at all, but I just wonder.. what kind of operation would be required? Just don't test that 1500 watt max of the inverter?
 
Would there be something to look out for (in a smart brain) that would prevent any issues from forming with a 1500w inverter? What precautions would need to be taken do you think? I really don't think I would test its limits at all, but I just wonder.. what kind of operation would be required? Just don't test that 1500 watt max of the inverter?
Can you restate you question simply and directly?
 
Lets try it this way.
What do you want to run that requires a 1500 watt inverter?
 
Actully what do you want to run with a 1500 watt inverter that won't run on a 1000 watt inverter?
 
Actully what do you want to run with a 1500 watt inverter that won't run on a 1000 watt inverter?
That's pretty genius! Well, I think the convenience of having more options with higher wattage appliances just seems appealing, that's all. I can't think of anything specifically that I would use with high wattage. The PS5 in the future, but those are below 1000 watts.
 
I predict that you will learn about inductive vs resistive loads and in-rush.
A 1200 watt microwave probably won't run off a high frequency 1500 watt inverter.
I also see you learning about Low frequency vs high frequency inverters.
 
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Generally best to start with requirements and build the system to meet or exceed them.
 
@Shep would you like to start over?
We can help you build a system that meets your requirements.
 
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