I have a Gen 3 Hybrid Inverter with a gen 2 9.5kwh battery.
I`m looking at adding a second 5kwh battery to the installation - does it matter if the new battery is a gen2 or a gen 3 and what considerations are there do this decision? Thanks.
The inverters will handle gen 1, 2 and 3 batteries. Makes sense to buy the newest gen as that has the latest firmware and fastest response times.
The Gen 1 5.2kWh battery was 80% depth of discharge, the Gen 2 is actually 5.12kWh but its 100% DoD so you get more capacity
If you have mixed battery sizes, the largest battery has to go first in the chain and the inverter sees the combined capacity as one larger battery. What you will find is that when one of the batteries in the chain reaches full or empty then the entire battery chain stops charging or discharging. The first battery in the chain takes more of the load but you will find with dissimilar battery sizes you wonāt get the full capacity you expected.
Personally if you have a 9.5 I would buy the same again. You get more capacity for your money and have less of the above problem
Wow. Thats a game changer. If GE`s firmware / BMS design cant independently manage the batteries, I wont bother.
It is the way theyāre electrically wired I believe.
Hereās an example just posted on the other givenergy customer forum Batteries failing to supply power when they hit 35% - GivEnergy
I have the same problem with my 2 x 5.2 kw batteries not balancing properly. Charge will stop when the first one reaches 100% and the āsystemā capacity thinks itās 100% but the second is still at 90%. Same problem on the way down but worse, it stops discharging when the āsystem capacityā says itās 4% but the individual battery capacities can show 20 or 30% and they are not balanced either.
There are BTW two givenergy customer forums. The original one, and this which is a beta of new forum software, but at the moment the two forums run in parallel and the old one hasnāt been migrated over. The other forum is busier than this one.
Appreciate the followup. If the design doesnt allow independent control and monitoring of state of charge / discharge, then as far as I`m concerned its a complete waste of money.
ROI is marginal enough as it is without the system design kneecapping real world usable capacity
ROI on batteries is an interesting calculation. Iāve come to the conclusion that you need some battery storage to see you through peak rate periods, but adding more gets to rapidly diminishing returns. You donāt even need enough battery storage for the peak period, just enough to ātake the edgeā off peak import.
I have 13.5kWh of batteries, would dearly love to add more, but every time I run the calculations I end up with 6 to 22 years payback depending on the assumptions I make!
On the battery management, newer versions of the Givenergy battery firmware do improve on earlier versions, but it is still something to be aware of
How does one access this legacy forum? When I follow your link, it takes me to an empty forum with no contentā¦
Hi thereā¦I am not sure about the largest battery being āfirst in the chainā. However, I have the same inverter but with two Gen 1 5.2kWh batteries. Three weeks ago I had a Gen 3 5.4kWh battery added. This had to be primary battery (i.e. connected directly to the inverter with the other two in the same chain but as 2Y and 3Y. This was all achieved with new cables and alteration of the requisite dip switches. BUTā¦at the same time I updated the firmware for the batteries to 3022 for the Gen1 and 4010 for the Gen3ā¦after a bit of messing and hardwiring the inverter via ethernet cable to my router all is working perfectly. It is important that a full SOC battery discharge and charge is done to ensure the whole system works properly.
Thatās whatās stated as being required in the Givenergy installer manual, and thatās what your installer did.
The Gen 3 battery is 5.12 not 5.4kWh GivEnergy Gen3 5.12kWh LiFePO4 Battery but its 100% depth of discharge so you get 5.12kWh usable whereas the Gen 1 5.2kWh batteries are 80% depth of discharge, so around 4-4.2kWh usable.
And yes you need a full recalibration discharge and charge when a new battery is added. The newer BMS versions are better at keeping batteries in line with each other.
Sorry - was a typoā¦and yes its 100%ā¦
Whatās the best way of initiating a āfull recalibration discharge/chargeā after adding a new battery?
go to my inverterā¦then up at the top right you can see an on/off button then to the left of it is a āsettingsā wheel - for remote control..press it..then go down to the Battery section and you can see the place to schedule a recalibrationā¦depending on the battery total size you have it can take quite a long time. So schedule it so you can take advantage of using the electricity while discharging and cheaper electricity periods when charging.
2 Likes
I thought about doing just this. Couldnāt make the maths stack up for it though. Needed the installer back as well. Think cost was circa Ā£2k for the 5 and Ā£3k for the 9.
Thank you!
What exactly does the battery calibration do? Am I correct in assuming that it will force-discharge all batteries to 0%, then immediately force-charge to 100%?
yes - more or less then your inverter system knows the relative charges of your batteries
1 Like
Thank you!
Currently, my 2x 9.5kWh Gen2 batteries are within a couple of % of each other; worth doing a calibration?
I noticed that one seems to reach 100% when charging earlier than the other, which ends charging at ~96%ā¦
personally I wouldnāt botherā¦but I am no expert..
1 Like
no, if they are that close then a calibration wonāt make any difference, and since the batteries hold less charge when cold you may well find doing a calibration reduces your usable storage capacity
the primary battery will always take more of the load than the secondary battery, and when one reaches full or empty then the entire chain stops charging/discharging so you loose a bit of available capacity as a result. Its just the way they work
1 Like
Thanks, helpful to know.
With regards to charging: I understand itās best practice to charge to 100% periodically; my 5-hour overnight cheap rate window and 3.6kW inverter can only get the 2x 9.5kWh batteries to ~95%; would it be worth scheduling a longer full charge to 100% once a month/fortnight?
it is best practice yes to fully cycle the batteries through the entire soc range from full to empty, that helps the battery management system to keep track of the soc (which is estimated based upon battery voltage, it canāt be directly measured).
With regard to your question, yes I think it would be good to fully charge the batteries every couple of weeks. Its not going to use a great deal more energy at the day rate to achieve that. Either start your overnight charge a bit earlier or let it run on a bit longer.
Iād also suggest when the batteries are reporting 100% full, leaving them on charge for a bit longer, as what can happen is that the battery voltage drops a little and then the battery can charge a bit more into it. All this helps the BMS to learn what the soc levels really are. Also be aware that the charge rate drops off as the battery nears to 100%, this is normal, so donāt expect it to charge at 3.6kWh all the way to 100%
1 Like