My system consists of 8 solar panels, a MultiPlus II GX and 4 12 V 110 Ah GEL batteries (type BAT41201104).
It has been in place for 3 and a half years, installed by the company Mon Energie Autonome (which has since gone out of business, leaving me without support).
10 days ago, we noticed a strange smell in our utility room, which was quickly identified as coming from the batteries. One of them is hot and swollen. Following this, over the course of a few days the batteries charged beyond 85% and now barely discharge at all (the smell has disappeared). We are now operating solely on the electricity directly from the panels and from the EDF grid.
I assume I need to replace the swollen battery? How can I refine the diagnosis and find out the condition of my batteries? And then, how do I find a battery dealer? When replacing one battery out of four, are there any particular precautions to take?
In short, as you will have gathered, I’m a complete beginner …
As it’s a 12V battery bank with 4 batteries connected in parallel, you can “simply” remove the faulty battery from the configuration. A photo would be helpful.
Since one battery is already swollen … it’s probably faulty … the others will follow soon …
Which MultiPlus 2 is it?
The Multi would have to be switched off for this, and the fuses BEFORE the batteries switched off … remove the faulty battery and put the system back into operation. Cover ALL battery terminals and insulate the tools … if necessary with a rubber glove or a plastic bag, to prevent unnecessary short circuits. After that, the setting for the “new” capacity would still need to be adjusted.
However, you should definitely consider replacing the AGM batteries with LiFePO batteries. At the moment, an EVE 12V 320Ah battery costs around €280. Unfortunately, AGM batteries are only suitable for systems like this to a limited extent. Things may have been somewhat different 3.5 years ago.
One thing at a time. … I’m curious to see how this gets translated with the new system
If a lead-acid battery smells of rotten eggs and/or gets hot, failure is not far away!
In such a case, disconnect the batteries immediately!
In your case, the other batteries have already been damaged as well and will not have much life left either, especially if they were not connected in a crosswise configuration (do you have a photo of the battery bank?)
I promise, I’ll take a photo tonight when I get home and share it with you. And I’ll disconnect the battery pack. I suspected this would end up with replacing the whole unit…
And the charging voltages should be checked. There is a very high probability that the voltages are set too high and the absorption time is too long. Which charge controllers are being used? Is a temperature sensor attached to one of the batteries?
Apart from the circuit breakers, the solar panels and the grid connection, my installation boils down to these elements. I don’t take voltage measurements at regular intervals; perhaps I should start doing so from now on.
Since the batteries are connected in series … unlike assumed above … you obviously can’t simply “remove” one battery.
The damage pattern is typical of AGM batteries that have been operated without a balancer. Chemically, all batteries are slightly different, and eventually one battery ends up receiving too much charging voltage and “boils dry”. The cells swell up, and then you get a result like the one you have. At least a temperature sensor was installed … it may have prevented the worst by adjusting the charging curve …
What does the system power in your case? Or is it simply connected in parallel with the grid, with no loads connected to the AC output?
Okay, that was a 48 V system made up of Victron batteries. It’s a shame you didn’t install three balancers there; they would have helped keep things balanced. Battery Balancer | Victron Energy
As it was, the slightly different cell chemistry caused one block to drift out of balance, which boiled the cell dry.
You can either install lead-acid batteries again or switch straight to lithium batteries. Have a look around and let us know what sort of loads you have and what ambient temperatures are involved!
You have a MultiPlus 2 “GX”, which means that a GX control unit comparable to the Cerbo GX is already built in.
You can connect it to the local network and also link it to Victron Remote Monitoring (VRM). You can see a great deal of information in VRM.
I recommend switching to a 5 kWh (100 Ah) LFP battery with a BMS, for example from Pytes. At present, you essentially also have 48 V/110 Ah. Other manufacturers also offer 10 kWh and 16 kWh batteries. However, you can also connect several 5 kWh Pytes batteries in parallel or add more later.
Pytes is officially supported and is therefore well suited for “beginners”.
Together with the GX (Venus OS) and VRM, you’ll have far more information and get much more enjoyment from the system.
Please also take some photos of the wiring, battery isolator and fuses.
