Inverter to battery communication? Important or nice to have?

[davekra]

I"m building a UPS system for my mother-in-law to power some medical equipment in the event of a grid outage.
I'd like to use an all in one 48 volt inverter/charger and a server rack battery.
Is it worth spending a little extra to get both from the same manufacturer to get communication between inverter/battery?
Can equipment from different manufacturer communicate?

Any help would be appreciated.
Thanks.
davidk

 

[cs1234]

Is it worth spending a little extra to get both from the same manufacturer to get communication between inverter/battery?

Some people think it's dangerous to not have it.. One of the battery/inverter manufacturer/resellers on here even described it as "open loop insanity" to not have comms.

Can equipment from different manufacturer communicate?

Yes, if they use a compatible standard. There are a few different standards out there for battery comms. Check the spec sheets on your desired products.

 

[davekra]

Thanks for the tips.

 

[DIYrich]

Is it worth spending a little extra to get both from the same manufacturer to get communication between inverter/battery?

Depends upon the inverter. If the inverter plays well with generic batteries, then IMHO, voltage mode for LiFePO4 batteries works just fine. Otherwise, you may be stuck with the high cost of the one battery that works well with your system.

I would do a small off-grid sytem. They tend to be ok with any battery. SOC drifts overtime, so unless you are charging to 100% on a regular basis, you can't rely on SOC. LiFePO4 doesn't like to be at 100% and not used. If the UPS is used infrequently, then I would buy a system that can keep the battery charged around 53.0v (about 75%), and call it a day. Once every month or so, charge to 100% to keep the cells balanced, and then discharge back to 53.0v

 

[davekra]

I understand the LiFe cells not liking to be at 100%. The LiPo batteries I use in my radio control hobby always get storage charged at the end of the day.
I was thinking of getting the Growatt SPF 4000t. A low frequency split phase inverter. The total running watts I'm trying to protect is 3600 with inrush watts of 5600. Not all of that is on all the time. Maybe 1500 watts continuous.

So, if I'm reading the manual correctly, the float voltage on this inverter can be set to 48 to 58 volts. If that's true would this do what you're recommending?
And rather than a no maintenance system, this would be manually charging to 100% to balance and manually discharge to 75% once in a while.
Are there UPS systems that would be more appropriate for this use case? Maybe a different forum to pose questions? I came here because Will's videos were very informative although I'm not looking to do any solar.

Thanks,
davidk

 

[Ampster]

Is it worth spending a little extra to get both from the same manufacturer to get communication between inverter/battery?

Yes, I think it is worth the money to get communications. In my case they are different manufacturers but the BMS communicates more acurate voltages and SOC estimates than my Inverter. That is the value.

Can equipment from different manufacturer communicate?

Not in all cases. I checked with the inverter manufacurer if my Orion BMS would communicate with the inverter.

 

[davekra]

So, reading the manual of a PowMr inverter it talks about setting hours for grid charge or PV. Now, thinking of my UPS setup and exercising the battery, would it be something to explore disconnecting the grid on a regular basis?
If the inverter doesn't have a program for that I could use a contactor and timer to disconnect the grid. Maybe then use the generator start feature (if it has one) to reset the timer and reconnect the grid. Do this once a week or month?
I don't think I would want to use the 'battery first' program as that would be cycling them multiple times a day.

Thanks.
davidk

 

[JoeHam]

I’ve used various LiFePO4 batteries with various inverters for a decade now and haven’t seen a need or developed a want for communications.

To each their own.

 

[zanydroid]

Now, thinking of my UPS setup and exercising the battery, would it be something to explore disconnecting the grid on a regular basis?

In theory leaving at high SoC is probably bad for durability.

LFP batteries will probably exceed the service lifespan of the inverter already. Even taking a 50% haircut off what the spec sheet claims.

So if you believe this then worrying about degradation may not be worth the complexity

 

[ksmithaz1]

LFP batteries will probably exceed the service lifespan of the inverter already. Even taking a 50% haircut off what the spec sheet claims.

A friend has been running a Midnight Solar inverter I think for about 10 years, I'll have to ask. He's on his 2nd set of FLA's. I'm not sure why you would think any battery would outlast an inverter?

 

[zanydroid]

A friend has been running a Midnight Solar inverter I think for about 10 years, I'll have to ask. He's on his 2nd set of FLA's. I'm not sure why you would think any battery would outlast an inverter?

1) I was referring to a HF AIO, lower tier than MidNite. Not a buy it for life inverter

2) LFP cycle count and calendar age spec exceeds 10 years, sometimes by 2x. And my primary point is that I’m not sure if following the optimal average SoC for longevity matters, they would have in either case likely deviated way short of their spec sheet, and I might even be more upset at this if I had spent a lot of work babying the batteries.

We will see.

 

[davekra]

Thanks for the replies. I think I'm close to making a decision.
I'm starting to think that for my use the BMS/Inverter communication isn't critical.

Instead of the Growatt I'm might choose the SunGold Power 4000watt split phase inverter https://shorturl.at/hmnH3
And either the SunGold SG48100p https://sungoldpower.com/collection...-server-rack-lifepo4-lithium-battery-sg48100p
or ExpertPower https://www.expertpower.us/products/48v-100ah-lifepo4-ep48100
They both seem to have a relay that can send a signal on low voltage. I can find specs on the SunGold and you can adjust the low voltage alarm point. Can't find the same on the ExpertPower. The SunGold is $350 more. Anyone know if the low voltage alarm can be customized on the ExpertPower?

With these two pieces and an Arduino I think I can put together a system that will exercise the battery on whatever schedule I want.
What do you think?
Thanks,
davidk

 

[Laura Hanson]

Working with installers/manufacturers using Victron, it's amazing how much a system is limited (or let loose to do its thing) due to the coms. Put another way, the system is only as 'good' as the battery it is paired with because the battery is the foundation of a power system. If it's a dumb battery, you get a dumb system (and sometimes that's all you want!) But if you're choosing a top-tier inverter/charger because it's reliable and intelligent, taking a shortcut on the batteries is never a good idea. We get a ton of battery communication and battery-inverter compatibility questions and have turned those into a blog series that's intended to be a resource for installers, builders, etc. Included are stories and scenarios of what happens when battery coms is there, imperfect, or completely absent.

Battery Communication: Closed vs. Open-Loop Communications
https://icmontana.com/blogs/technic...ation-closed-loop-vs-open-loop-communications

Active Management: Expect More From Your BMS
https://icmontana.com/blogs/technical-articles/active-management-expect-more-from-your-bms

Bad, Better, Best: Battery-Inverter Communications & Compatibility
https://icmontana.com/blogs/technic...battery-inverter-communications-compatibility

How to Manage the Temperature of a Lithium Battery Bank: Heated Lithiums, Relays & Custom Controls
https://icmontana.com/blogs/technic...y-bank-heated-lithiums-relays-custom-controls