Hey folks

Anyone here running these Sunsynk batteries: https://powerforum-store.co.za/collections/batterys/products/sunksynk-battery-lfp-wall-mount-5-12kwh-51-2v

In my opinion they are the best of what's around at the moment for a few reasons

1. They are using 16s
2. They are using LiFePO₄
3. Decent rating on discharge current
4. Bonus you get extra warranty on your Sunsynk inverter

Compared to some other brands, here are my reasons to prefer the Sunsynk battery over the respective brand; on paper at least

• Hubble: They don't use LiFePO₄ and there are too many threads with issues around their battery technology and their response to customers
• Pylontech:  They seem to use 15s and their discharge current, from what I saw, was somewhat lower

There is plenty of data on how Hubble deals with warranty, not much on how Pylontech deals with it (but from what I saw it can be somewhat hostile?).  Obviously using a suitable chemistry and having good testing means you can almost certainly have fewer reasons to have a warranty return in the first place (hence why I like their use of LiFePO₄ and 16s).

TL;DR

• What is the experience like with Sunsynk batteries so far?
• Any problems and when there are, how has the warranty situation been?

Edited October 5, 20223 yr by Gnome

There are 2 versions of the Sunsynk battery, one with CATL cells, and one with BYD cells. And they have slightly different specs.

Even though the datasheet says Max. Continuous Discharging Current - 100A, it looks like the BMS reports the Standard Discharging Current - 50A to the inverter, so they are effectively also 0.5C, just like Pylontech.

If you want a 1C battery, you can also look at BSL or FreedomWon

39 minutes ago, P1000 said:

There are 2 versions of the Sunsynk battery, one with CATL cells, and one with BYD cells. And they have slightly different specs.

Even though the datasheet says Max. Continuous Discharging Current - 100A, it looks like the BMS reports the Standard Discharging Current - 50A to the inverter, so they are effectively also 0.5C, just like Pylontech.

If you want a 1C battery, you can also look at BSL or FreedomWon

Ok good to know, that is disappointing because even 2 of these batteries is not enough to carry a 5kW SunSynk at full load

Have a look at Greenrich batteries as well. For the price so far they are crazy nice batteries. 

Now I'm looking at just building my own battery again.  It is just SO much cheaper for what you get, capacity wise.  But obviously I can't install that for my parents. (too far away, warranty, possible problems and such comes at a price and probably worth the price)  Sigh.

Edited October 5, 20223 yr by Gnome

According to Sunsynk's BYD web page, the max charge/discharge is 100A. So don't only go on what you see on 3rd party web sites. Maybe the specs shown on other web sites are still the old specs? But no, other than the official web page I have no detailed knowledge about these batteries. I would like to know more about them myself though.

Edit: I've now noticed that the BYD version has extra lights top left which the old model doesn't have?

Edited October 5, 20223 yr by p_i

@Powerforum Store Maybe you guys can answer some of the questions around the Sunsynk batteries (https://powerforum-store.co.za/collections/batterys/products/sunksynk-battery-lfp-wall-mount-5-12kwh-51-2v)

1. How many batteries do you expect a customer to have to support the 5kW SunSynk inverter?
2. What are the conditions of the installation in order for the warranty to be valid?

1 hour ago, p_i said:

According to Sunsynk's BYD web page, the max charge/discharge is 100A. So don't only go on what you see on 3rd party web sites. Maybe the specs shown on other web sites are still the old specs? But no, other than the official web page I have no detailed knowledge about these batteries. I would like to know more about them myself though.

Edit: I've now noticed that the BYD version has extra lights top left which the old model doesn't have?

What are you going on about? On that page the nominal charge/discharge is 50A. The question is what does the BMS tell the inverter, because that is the value that matters.

5 minutes ago, Gnome said:

@Powerforum Store Maybe you guys can answer some of the questions around the Sunsynk batteries (https://powerforum-store.co.za/collections/batterys/products/sunksynk-battery-lfp-wall-mount-5-12kwh-51-2v)

1. How many batteries do you expect a customer to have to support the 5kW SunSynk inverter?
2. What are the conditions of the installation in order for the warranty to be valid?

Question 1 actually not something that can be answered without a load profile like how many units are used a day. How many units for cooking after 16h up to 09h when PV kicks in? What size is the PV side?

We tend to give answers based on our own use and powering the equipment we use.

May be just my way of thinking?

Just now, Scorp007 said:

Question 1 actually not something that can be answered without a load profile like how many units are used a day. How many units for cooking after 16h up to 09h when PV kicks in? What size is the PV side?

We tend to give answers based on our own use and powering the equipment we use.

May be just my way of thinking?

I think he wants to know how many batteries to use the full capacity of the inverter - 5kW.

3 minutes ago, Scorp007 said:

Question 1 actually not something that can be answered without a load profile like how many units are used a day. How many units for cooking after 16h up to 09h when PV kicks in? What size is the PV side?

We tend to give answers based on our own use and powering the equipment we use.

May be just my way of thinking?

Ok let me rephrase, how many batteries are required to run a 5kW load continuously, at 100% duty cycle until the battery is depleted.

Runtime is trivial to calculate with Lithium batteries, so the calculation factor here is, what number of batteries do you need to meet the SunSynk inverter specifications of 5kW continuous load.

EDIT:

1 minute ago, P1000 said:

I think he wants to know how many batteries to use the full capacity of the inverter - 5kW.

Exactly.

Edited October 5, 20223 yr by Gnome

Just now, Gnome said:

Ok let me rephrase, how many batteries are required to run a 5kW load continuously, at 100% duty cycle until the battery is depleted.

Runtime is trivial to calculate with Lithium batteries, so the calculation factor here is, what number of batteries do you need to meet the SunSynk inverter specifications of 5kW continuous load.

A 5kwh will run for about 50min in order not to totally discharge it.

21 minutes ago, Scorp007 said:

A 5kwh will run for about 50min in order not to totally discharge it.

Yes but the battery has a maximum discharge rate.  I'm not sure why I need to spell this out, but let me do that then:

A typical household with have loads that run for minutes to tens of minutes that push the load at near the 5kW limit (ie. hair dryer, kettle, etc.).  A battery stating that it is rated for 50amps continuous would thus not be able to supply that load, regardless of how full the battery is or how many minutes you need it.

Yes you need to calculate the number of runtime minutes you need, but before you can even get to that number you need to be able to meet the maximum short term load of the household.  Although 5-10 minutes seems short, it is an eternity for a battery and you can't simply write that off as "peak".  That would fall into its continuous load specification, unless they explicitly call out for how long it can handle a "peak" load.  Peak loads are usually measured in seconds up to a minute.

EDIT: Going even further with this, if you buy 2x of those batteries and indeed they can only supply 50 amps, that means even a 5kW inverter cannot truly supply 5kW continuously for even just for 30 minutes because at 5kW load, factoring in the realistic efficiency of 85%, we are sitting at a continuous load of 6kW for 30 minutes.  At their nominal voltage of 51.2V that means it is roughly 117 amps.  Thus to supply 5kW continuously for any real load length of time, you need 3 of these batteries, even if you just wanted to run that load for 10 minutes.

UNLESS they have a chart that maps runtime to discharge rate that makes it possible to get more accurate on the what the continuous vs maximum load means.

Since Peukert's law doesn't apply to Lithium batteries, runtime length is a walk in the park to calculate, you just simply take your load average for an hour or two and there you go.  The challenge is if your load maximums within that hour can be met by the battery.  And for that you can ignore capacity and only look at the continuous amp rating.

Btw. any installer that doesn't take the above into account has no idea what they are doing and I would say 100% they don't have the knowledge required to be installing equipment for customers.

Edited October 5, 20223 yr by Gnome

24 minutes ago, Gnome said:

EDIT: Going even further with this, if you buy 2x of those batteries and indeed they can only supply 50 amps, that means even a 5kW inverter cannot truly supply 5kW continuously for even just for 30 minutes because at 5kW load, factoring in the realistic efficiency of 85%, we are sitting at a continuous load of 6kW for 30 minutes.  At their nominal voltage of 51.2V that means it is roughly 117 amps.  Thus to supply 5kW continuously for any real load length of time, you need 3 of these batteries, even if you just wanted to run that load for 10 minutes.

At a high level, if you buy two batteries, each can supply 50A, in other words the inverter receives 100A total at 51.2V, and the Sunsynk 5kW will basically be able to supply its full rated capacity at that point. Two of those batteries would provide 10kWh of storage, which could run for 2 hrs at full load. Of course there's the real-world efficiency to consider, so you can de-rate that accordingly by 10-15% or whatever value is applicable.

2x batteries at 50A discharge each will give you your 5kw

1 minute ago, GreenFields said:

At a high level, if you buy two batteries, each can supply 50A, in other words the inverter receives 100A total at 51.2V, and the Sunsynk 5kW will basically be able to supply its full rated capacity at that point. Two of those batteries would provide 10kWh of storage, which could run for 2 hrs at full load. Of course there's the real-world efficiency to consider, so you can de-rate that accordingly by 10-15% or whatever value is applicable.

 

Just now, Chris_S said:

2x batteries at 50A discharge each will give you your 5kw

No.  The efficiency is not 100%  That is basic electronics theory, the specification states the maximum efficiency but that number is typically at a target of 80% load.  So the standard electronics principle of add 10-15% applies.  Thus you can take their efficiency and drop it by 10-15% and use that as a realistic number of the true efficiency of the inverter

Edited October 5, 20223 yr by Gnome

1 minute ago, Gnome said:

No.  The efficiency is not 100%

Yes and the sunsynk battery BMS will go over 50A if needed. 

1 minute ago, Chris_S said:

Yes and the sunsynk battery BMS will go over 50A if needed. 

🤦‍♂️

You are going in circles.  It cannot supply over 50A for a realistic load time period, so it cannot supply 5kW continuously. 

Edited October 5, 20223 yr by Gnome

Clearly I'm too sober to participate any further in this thread 🤣

🤦‍♂️To whoever wants to run their inverter at max continually off of batteries 

2 minutes ago, Chris_S said:

🤦‍♂️To whoever wants to run their inverter at max continually off of batteries 

What do you consider continuous?

Also have you actually setup your inverter to be inline with the maximum draw of the battery?

So if you install a system for a customer, do you set it up to keep it within the specification of the battery?  Or do you just put it all together and walk away hoping the customer doesn't ever have someone say running a 5kW load for 10 minutes during their load shedding?

3 minutes ago, Gnome said:

What do you consider continuous?

Also have you actually setup your inverter to be inline with the maximum draw of the battery?

So if you install a system for a customer, do you set it up to keep it within the specification of the battery?  Or do you just put it all together and walk away hoping the customer doesn't ever have someone say running a 5kW load for 10 minutes during their load shedding?

5kw until batteries are flat. 

Best thing you can do is as follows

2x 1C batteries or

3x 0.5 batteries. 

Discuss that with your customer if he wants 5kw in UPS mode. 

Just now, Chris_S said:

5kw until batteries are flat. 

Best thing you can do is as follows

2x 1C batteries or

3x 0.5 batteries. 

Discuss that with your customer if he wants 5kw in UPS mode. 

Rarely will customers have a continuous load of X watts.  The two data points of concern are

1. Continuous load in watts over a period p
2. Maximum load in watts during that period for duration d.

Your battery kWh specification informs 1 for the period p. The battery continuous rating informs 2 for the duration d.  Unless d <= battery maximum rating duration you need to use the battery continuous rating.

Last but not least, as with ANY installation you derate your equipment by some well established efficiency factor (not even just electronics, every aspect of building design incorporates this, AC, fresh air fans, etc.).  In the case of inverters 85% is a fairly typical efficiency rating, so your actual load calculations should incorporate that amount.  Thus the customer load can be taken as 1.15 * rating of 1 and 2

1 minute ago, Gnome said:

In the case of inverters 85% is a fairly typical efficiency rating

9 minutes ago, P1000 said:

Hahaha.  I know it seems naive to assume that, but coming from electronic engineering side of this, let me tell you that a lot of these ratings inform customer buying.  So they always take the most enthusiastic value.

They'll typically give the efficiency rating the data sheet at the most optimistic ambient temperature with the most ideal input battery voltage with the most ideal load percentage.  Those 3 components together can cause an enormous shift in efficiency.  You can actually see this, for example, from the Victron inverters where they have a crazy efficiency rating but when you look at the actual data closely you'll notice they use a very high input voltage and very rapidly derate based on temperature.

If you want a really good example of this that is REALLY moving fast, take a look at computer power supplies.  They are years ahead of inverters, they are using GAN FETs and have really incredible efficiency ratings and even more impressive claims.  When the devices are actually tested you realise that the maximum rating rarely applies and when it does apply it is for an incredible narrow band.

Unfortunately I don't see a good amount of independent reviews where the efficiency claims are tested and an efficiency graph is generated.

Before this kind of testing became common place with computers the manufacturer outright lied, all of them without exception.  And even now that it is very tightly controlled by specifications they still only claim the best they can achieve which is very far off from worst case.

Inverters are not special, they operate on a lot of the same principles and have all the same constraints and have most of the same common components.  And since people buy using that single value, it is important to give the most optimistic value there or you are hurting your company when the competitors are all doing it.  This is true for all electronics, they all work like this.

Edited October 5, 20223 yr by Gnome