Notifications

Clear all

Battery disconnected

Eliuccio · 2025-10-25T09:52:47Z

I apologise I have missed already a relevant thread on this. I essentially feel a bit desperate as it is more than one week now that my 2x Growatt 2.56kWh LiFePO4 battery cells are disconnected (with all the financial loss that is coming with it), and I could not come up with a simple solution. First, the installer basically dodged me as the 2-years workmanship are expired. Now it's clear they are not interested in helping. I did switch off and on the inverter, hoping that it would see the battery again. I also tried to check any physical damage to cables but it's very difficult to visualise the back and side of my batteries because they are really near the extarnal wall of the house encased in a wooden cabinet (pictures and video attached). Remote whatsapp support from Growatt was better, but essentially stopped when they asked me to open the battery and check if it was powered. I didn't feel confident doing that and asked my electrician to come. He couldn't so far, hence I will have to call someone else. I thought I would anyway post here in case someone else had a similar experience and would share how they handled it. Thanks in advance for any feedback!! Elia

Page 3 / 3 Prev

Energy Storage

Last Post by Transparent 2 hours ago

30 Posts

6 Users

3 Reactions

166 Views

RSS

Transparent

(@transparent)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 2655

27/10/2025 2:44 pm

Posted by: @agentgeorge

↑

This 0.5v is stated in the instructions you linked to.

Indeed, on p.19

That's the same page I was referring to earlier, where the connection of the power cables suggests that the battery packs are being connected in parallel.
But that still conflicts with Growatt referring to the ARK system as high voltage.

It's interesting that Growatt gives no advice to an installer as to how they should go about changing the State of Charge of a battery such that they do indeed match to within 0.5v

Given that they have their own dedicated Control Unit, and a BMS in each battery box, they could've included a feature by which that would be done automatically.

Posted by: @agentgeorge

↑

last time I enquired, the cost of a 5kW pack had dropped to £1800.

So that's two more battery units, right?

It's an expensive way of having battery storage in the home.

Most of the price is being taken up with:

a steel case
BMS for each unit
high-current cabling
installer's on-site time

... and very little on the actual LiFePO4 cells.

Save energy... recycle electrons!

ReplyQuote

Eliuccio

(@eliuccio)

Trusted Member Member

Joined: 8 months ago

Posts: 38

Topic starter 27/10/2025 2:49 pm

Posted by: @transparent

↑

The key issue at the moment is whether there is any voltage on the battery connections to the inverter.

Depending on whether the Growatt ARK design puts the batteries in series or parallel, I would expect to see 52v or 104v DC.

I am pretty sure he assessed both.

What I can report is that I emailed Cahill and Growatt asking them to pay a visit and assess the battery (on warranty). No reply as yet.

Thanks everyone for the input so far!

ReplyQuote

AgentGeorge

(@agentgeorge)

Estimable Member Member

Joined: 9 months ago

Posts: 56

27/10/2025 3:44 pm

@transparent yup, the cost no longer has VAT, but installer cost, for 2 people is £300-400, profit for company 50%

so battery wholesale cost is around £700 which includes the BCM and sexy magnolia metal case, oh and some big cables

High Voltage is anything over 12/24V, PV at 48/52 and Hybrid batteries 48V in cars are all covered under HV regulations for approved installers

Traction batteries at 400-800V are just plain lethal. They have batteries in series and parallel to achieve the voltages. Some cars can “fold” their batteries so an 800v architecture can look like 400v to a charging station.

ReplyQuote

Toodles

(@toodles)

Illustrious Member Contributor

Joined: 3 years ago

Posts: 2203

27/10/2025 4:03 pm

@agentgeorge High Voltage means different things in different circumstances; as an audio engineer, I used 48 v. DC to power microphones and this is known as ‘Phantom Powering’ but does not require high voltage warning labels etc. I also did some work for a telecomms company who required a test rig that supplied 50 v. DC for ringer circuits and this was technically referred to as High Voltage! Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

ReplyQuote

AgentGeorge

(@agentgeorge)

Estimable Member Member

Joined: 9 months ago

Posts: 56

27/10/2025 4:32 pm

My take on it is microphones need mAmps whereas cars need Amps. although both work on 48V, one will give you a buzz, the other will launch you across the room. Hence why in cars HV wiring and connectors are orange

ReplyQuote

Transparent

(@transparent)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 2655

27/10/2025 4:36 pm

Posted by: @agentgeorge

↑

High Voltage is anything over 12/24V

I think that is going to cause confusion.

And for that reason I ought to state what other 'authorities' use for high/low voltage.

The UK grid operators use Low Voltage (LV) when referring to anything below 1000v AC.
That makes sense because 1000v is the rating for the insulation level on tools used by 'domestic' electricians.

75v AC is usually regarded as the voltage level at which you must employ an accredited electrician to work on electricity wiring and hard-wired devices within the home.
However, that value isn't stipulated in law. The regulatory view is that an electrician is required when there is a risk of danger to life.
I like that because it's based on safety rather than analysing a voltage waveform!

Below 50v (AC) or 120v (DC) is referred to as Extra Low Voltage (ELV).

ELV is further defined in specific legislation which recognises three variants