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Growatt SPH 6000 and DIY LiFePo4 16S battery

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brum

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I'm working on the design of my residential solar system. The Growatt SPH 6000 seems like a good fit. I'm aware of the service issues and I'll be getting from a local supplier that will enable warranty claims directly to him under the local jurisdictions (I'm in Bulgaria). All other options cost twice and over, so I'm likely going for it.

The question that I'm unable to answer is can I use It with a custom LiFePo4 16S battery (EVE 160Ah cells) and what are the drawbacks if the battery BMS doesn't communicate with the inverter.

In the manual, I see that I can adjust a few parameters for lead-acid batteries that are likely to enable the use of LiFePo4 batteries. There are CV, LV, and CC params. If I'm correct these are max charging voltage (CV) battery cut out voltage (LV) and max charging current (CC).

What would be the drawback if I use a 16S LiVePo4 battery configured as lead-acid with CV of 56V (3.5V per cell), LV of 48V, and CC of 60A. The PV power will be at most 3000W, so 60A charging current is unlikely to be a problem. The voltages are a bit on the safe side, but I'll try to cycle the SOC from 10% to 90% with a goal to extend the battery life.
 
brum said:
I'm working on the design of my residential solar system. The Growatt SPH 6000 seems like a good fit. I'm aware of the service issues and I'll be getting from a local supplier that will enable warranty claims directly to him under the local jurisdictions (I'm in Bulgaria). All other options cost twice and over, so I'm likely going for it.

The question that I'm unable to answer is can I use It with a custom LiFePo4 16S battery (EVE 160Ah cells) and what are the drawbacks if the battery BMS doesn't communicate with the inverter.
Click to expand...

It can operate without any BMS comm.

brum said:
In the manual, I see that I can adjust a few parameters for lead-acid batteries that are likely to enable the use of LiFePo4 batteries. There are CV, LV, and CC params. If I'm correct these are max charging voltage (CV) battery cut out voltage (LV) and max charging current (CC).
Click to expand...

Be sure to check the limits on these settings so that it will work within the desired CV and LV.

brum said:
What would be the drawback if I use a 16S LiVePo4 battery configured as lead-acid with CV of 56V (3.5V per cell), LV of 48V, and CC of 60A. The PV power will be at most 3000W, so 60A charging current is unlikely to be a problem. The voltages are a bit on the safe side, but I'll try to cycle the SOC from 10% to 90% with a goal to extend the battery life.
Click to expand...
I looked over the spec sheet https://www.ginverter.com/upload/file/contents/2020/08/5f2cf9a46bc2d.pdf

Have to wonder why the AC backup power is only 3000w.
 
Don't know, but the same applies to the Victron Multi Plus II. The output power is quite a lot more than the power in "backup" mode.

Victon and SMA are the other options I've considered, but the price difference is quite serious.

Regarding the limits - CL is from 42 to 50 volts, CA is from 55 to 60 volts and CC is up to 60A. So they do cover the LiFePo4 requirements. This is what raised the question about the drawbacks.

The 60A charging limit is not because of the lead-acid battery. The charging power is 3000W and at 50V this is exactly 60A.

Not sure if this charming approach (without boost voltage) will impact cell balance in long term, but proper BMS should be configurable and should be able to take care of that at lower cell voltages.
 
brum said:
Victon and SMA are the other options I've considered, but the price difference is quite serious.
Click to expand...
Apparently the SMA battery inverter can use lifepo4 batteries using the lead acid settings, but the system requires a specific bms.
Rec, Batrium and seplos. The problem here is each cost around £250+ each + the cost of each battery. Unfortunately we can't use off the shelf ready made batteries with sma.
 
Fingers said:
Apparently the SMA battery inverter can use lifepo4 batteries using the lead acid settings, but the system requires a specific bms.
Click to expand...

What do you mean by "specific bms"? Can the Sunny Island work with LiFePo4 batteries on open-loop mode and proper settings or not?

Asking this in a bit of high urgency, cause I ordered an SMA Sunny Boy and was planning to extend in the near future with one of their battery invertors...

I just opened the manual again and I see "7.6.2 Adjusting the Battery Management to the Battery". And there are options to boost time, charge voltage, and so on. Last time I was looking at these I decided, that as long as the voltages are suitable for LiFePo4 batteries I should be good to go with their battery inverter and DIY battery.

Moreover, I recall seeing posts in the forum about SMA with LiFePo4 batteries in an open-loop mode.

And a bit off-topic, but does the price of the SMA pay off in the long term? People here are trying to change my mind and push me for a cheap China brand inverter. The statement I get is that the SMA has been a good brand 10 years ago, but now the cheap options can provide better value for the money. And I have some concerns that this may not be true in the long term.
 
Last edited:
As far as I know there are no factory settings for lifepo4 batteries. Only lithium iron or lead acid.
Sorry I do not know what open-loop is; I'm new to lifepo4 and battery systems other than a car battery and pwm charger.
I have asked owners of sunny island that say specifically Rec, Batrium and Steplos are the bms to use.

This is why I'm selling my unused sunny island 4.4m-11, and sunny boy sb360 tl-21.
If I went ahead, I'd also have to buy a sunny manager @£600 and an electrician to fit it to the meter tails, also a sma remote control which would be more mega bucks that is if I could find one, plus the bms and batteries. Way too much.

Also the system will not work in a power cut. The sunny boy will not charge the batteries, and the sunny island will not work in a power cut. You can wire it all up in a clever way for off grid mode, that would work, but that would be even more cost.

Just for info: External charging will turn off the sunny islands charging automatically, if done with a charge controller or mains charger etc by using a shunt on the neutral battery cable. This info took me yonks to find.
 
The more I'm reading, the more I'm convinced that the SMA Sunny Island can work with DIY LiFePo4 batteries. Open-loop means that you don't connect the BMS to the inverter.

If I'm getting it correctly you use should configure lead-acid battery type and set proper voltages and capacity. And if you have compatible BMS you can set the battery type to lithium and connect the BMS.

Don't know what is the remote controller, but I'm building on-grid system. From SMA I need:
* Sunny Boy PV inverter
* Home Manager 2.0 where the main fuse in the house is
* (optional) - Sunny Island with DIY LiFePo4 battery

Check your sources of information. To me it seems like you are getting incorrect information.
 
brum said:
Open-loop means that you don't connect the BMS to the inverter.
Click to expand...
Ah ha! This is a bit of information that I was missing. Thank you for that.
Almost all lifepo4 batteries that I have seen didn't have a communications socket, and I didn't understand how batteries could or should communicate with the inverter. Humm now I know :)

Ah ok, so your going to set up open-loop the same as you would for lead acid, but what are you going to do about the float current; or doesn't that matter?
 
Don't know in detail. But let's say the boost voltage is 3.6V to 3.65V per cell. Then the float voltage would be something between 3.3V and 3.4V.

If I recall correctly there was a dedicated thread on LiFePo4 charging voltages somewhere in the forum.

And by the way - lithium iron is LiFePo4. And Seplos is not a bad option for a BMS. If you are giving 2000+ USD for the cells it makes sense to invest 10% of that for proper protection. I'm kind of surprised that these are expected to be able to communicate with the SMA Sunny Island.

P.S. The post about setting SMA SI in open-loop mode with LiFePo4 batteries is this one - https://diysolarforum.com/threads/sunny-island-chargery-issue.22177/ . So it should be doable. Even if the affordable BMS models don't support the SMA SI protocol.
 
Last edited:
brum said:
lithium iron is LiFePo4
Click to expand...
Do you mean a lithium iron battery is the same as a lifepo4 battery? Or do you mean that the SMA inverter settings are the same for both battery types?

Yes I get what your saying about bms protection. But I do not want home made batteries, I want off the shelf car battery branded looking jobs - nice an neat.
Building regulations, no certifications and home insurance are at the fore front of my mind.
 
Lithium iron phosphate batteries are the so-called lithium iron batteries and the chemistry in them is LiFePo4.

Regarding regulations - here in Bulgaria we don't have such issues :) .
 
brum said:
Lithium iron phosphate batteries are the so-called lithium iron batteries and the chemistry in them is LiFePo4.
Click to expand...
Lets get this right because I'm getting confused as hell here;
your saying people (or sma) are calling Lithium iron phosphate (which has LiFePo4 chemistry), Lithium iron?

I know most inverter manuals state lithium, as the manuals & inverters were manufactured way before Lithium Phosphate batteries were invented; and they are to damn lazy to change the pdf manuals or write ups, or up date software / firmware. Or their inverters are just not intended for phosphate batteries, but they will happily sell you the inverter on the back of this misunderstanding.


Sorry I'm hijacking your post here.
 
No, I'm saying exactly what I said:
Lithium iron phosphate batteries are the so-called lithium iron batteries and the chemistry in them is LiFePo4.
Click to expand...

In the SMA Sunny Island manual, I see references to lithium-ion batteries. Not lithium iron. At least in the one that I was reading.

Lithium and lithium-ion are different types of batteries. The 3V coin cells are lithium batteries and they are not rechargeable.

Lithium-ion batteries are rechargeable and there are different types of lithium-ion batteries. Different chemistry, cell voltages, discharge current rate, and cycle life. The LiFePo4 stands out due to a few reasons - high cycle life, safety, affordability, and similarity with lead-acid due to their voltage ranges.
 
Ah, I get what you mean.
So sma accept lithium ion the older explosive batteries that I didn't want to use, and sma are not designed for lithium iron lifepo4.
Yes that's what I thought :)
 
LiFePo4 is a lithium-ion battery. But not all lithium-ion batteries are LiFePo4.

As far as I'm getting it the SMA manual refers to batteries lithium-ion, but they are mostly considering that these will be LiFePo4 batteries.

In the end, if you can set the charging parameters you should be able to use most kinds of batteries. Both lead-acid and lithium-ion batteries utilize the CC-CV charging approach with some time constraints. And these are configurable in the SMA.
 
brum said:
I'm working on the design of my residential solar system. The Growatt SPH 6000 seems like a good fit. I'm aware of the service issues and I'll be getting from a local supplier that will enable warranty claims directly to him under the local jurisdictions (I'm in Bulgaria). All other options cost twice and over, so I'm likely going for it.

The question that I'm unable to answer is can I use It with a custom LiFePo4 16S battery (EVE 160Ah cells) and what are the drawbacks if the battery BMS doesn't communicate with the inverter.

In the manual, I see that I can adjust a few parameters for lead-acid batteries that are likely to enable the use of LiFePo4 batteries. There are CV, LV, and CC params. If I'm correct these are max charging voltage (CV) battery cut out voltage (LV) and max charging current (CC).

What would be the drawback if I use a 16S LiVePo4 battery configured as lead-acid with CV of 56V (3.5V per cell), LV of 48V, and CC of 60A. The PV power will be at most 3000W, so 60A charging current is unlikely to be a problem. The voltages are a bit on the safe side, but I'll try to cycle the SOC from 10% to 90% with a goal to extend the battery life.
Click to expand...
I have in use the sph6000 and diy lifepo4 batterry.
I use the lead-acid battery seting for this , but i manage the xharging/ discharging and protection with a daly bms.
If you will use this pair ,be sure to have the cut charge and disharge of the inverter set in such way that the inverter will stop the process and not the bms.
If the connection is intrerupted by bms you will have to manualy reconect.
I have used for 5 monts, not big problems till now.
I will not recomand to people who prefer plug-in and forget about it.
 
Last edited:
@2muschi I have the same setup as you (200Ah + Daly BMS+ Growatt SPH 5000). Can you share what your CC, CV, and LV settings are? Mine's working OK but I'm having trouble getting the Growatt to charge the battery until it's almost empty. Even when the Daly is reporting a SOC of 48% the Inverter thinks it's full.

My CC is 60A, CV is 55.2, and LV is 50. That gives plenty of space inside the Daly's high and low range of 3.65 and 2.7. But I'm wondering if the LV and CV values change the growatt's interpolation of battery state.

I've got some RS485 adapters coming and I'll eventually put some code together to make these work together.
 
Just out of interest; How is your Growatt wired up?
Incoming mains: Tails out of the electricity meter, tails in to a small trip box, tails from trip box to the Growatt, and then tails out of Growatt to the main consumer unit (fuse box/trips/distribution box. Different names for the same thing)?

Or, is it wired directly to the consumer unit (fuse box/trips/distribution box)?
 
We don't have fuses, we have RCDs (residual current safety switches) and breakers (trips I'm assuming). The distribution box and meter are all in the same box with non tamper links on the active wiring on the grid side of the meter (single phase system). The diagram goes something like.

Grid
|
Electricity Meter
|
Main Breaker
|
CT Sensor
|
|- Solar 20A Breaker------ Growatt SPH 5000/ battery / 4.5KW Panels
|
Loads

It's actually a little more complicated than that becasuse there's also an EPS switch that allows me to dissconect from the grid and plug a generator into the main box. I live in the bush and when there's a fire, the first thing we loose is power. I'll be setting the EPS port on the Growatt to perform that function instead, which will be a lot more convenient than a genset.
 
The main breaker, contains rcd's, and from there, cables to lighting, sockets, Growatt?

Here in the UK we use different terminology; when RCD's were invented we had to think of a name to replace "fuse box", so we thought "Consumer unit" would be a good name for it.
Consumer unit, ha, sounds like a robot or some thing out of a science fiction film. RCD distrabution box would have been a better name for it.

So your Growatt is by-directional (same cable to feed power to your house, and charge your batteries)? So in a power cut, does the Growatt use a different cable to power your house?
 
We just call them a "Power box" or "Distribution Panel" (If its inside). Us Aussies are a rather literal bunch :)

Yes, there's two AC outlets on the Growatt, an AC Grid connector (for grid tie operation), and an EPS Connector (Emergency Power Supply). The manual takes great pains to state that the two should never be connected together. Like crossing the streams in Ghostbusters.

I already have a grid isolation switch and two 15Amp outdoor sockets on the side of the power box to connect a generator. It's a DPDT arrangement so it's impossible to accidentally connect the generator to the grid. So I'm just going to wire a short cable with two 15 Amp sockets to the Growatt supplied EPS connector and I'll be good to go.

It'll be a manual operation to switch to EPS, which I'm fine with.
 
the only thing you really need to run lifepo4 on a sunny island w/o communication is a shunt. the sunny island needs a shunt to track battery soc. The manual makes these seem optional, But if you are running the system offgrid-THEY ARE MANDATORY for all battery types unless you have a bms that will communicate with a sunny island.
 
chopwood said:
We just call them a "Power box" or "Distribution Panel" (If its inside). Us Aussies are a rather literal bunch :)

Yes, there's two AC outlets on the Growatt, an AC Grid connector (for grid tie operation), and an EPS Connector (Emergency Power Supply). The manual takes great pains to state that the two should never be connected together. Like crossing the streams in Ghostbusters.

I already have a grid isolation switch and two 15Amp outdoor sockets on the side of the power box to connect a generator. It's a DPDT arrangement so it's impossible to accidentally connect the generator to the grid. So I'm just going to wire a short cable with two 15 Amp sockets to the Growatt supplied EPS connector and I'll be good to go.

It'll be a manual operation to switch to EPS, which I'm fine with.
Click to expand...
HI Sorry to jump on this post, but we have had issues with fridges and freezers and a water pump blowing. we think this has happened when the system has switched to eps, the installer has an automatic switch automatic switch to isolate the grid if the power cuts, the EPS then cuts in but is connected to the same cables from the ac out of the inverter to the distribution board, this means that everything then tries to run of the eps which is limited to 3kw/h, do you think this could be the cause of the issues as we are trying to draw more than is available? (we have disabled the EPS now so that this can't happen)
 
Given that my Growatt has a sticker on the front that says not to connect EPS and AC Out together. I think your install might have done someone hokey. My EPS is going to the generator in on the meter board. Inside there's a switch that allows grid OR generator (not both).
 
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