jumper

The only inverter I know of is the Axpert King models that use double conversion on AC in to smooth the voltage. They are sold specifically for areas with unstable grid supply. Just be aware that you will have to run everything 'through' the inverter so you will be limited to the max output of the inverter. There may be other brands I am not aware of.

I agree, I think some detergent is necessary, I just use sunlight soap, but be careful with high pressure on solar panels, you might damage the silicone seal around the edge of the glass over time which can cause water ingress and electrical shorts. I use the same, but I find the telescopic handles a bit cheap and flimsy, I have attached a wooden broom handle instead.

It might be that you don't have timed absorb, in that case you can use the equalization setting at 56.4V for 1 hour, it'll do the same thing.

This is likely because the inverter is not staying at the absorption voltage for long enough and going to float before the battery is at 100% and not allowing cell balancing to take place. At 96% is usually when the battery is balancing and needs up to 1 hour for it to hit 100% and the BMS to stop the charging. I am not sure if SA actually controls the inverter to keep charging until 100% or merely reports what is happening, but it doesn't look like it keeps it in absorb until 100%. First thing I would do is change the absorbtion voltage to 56.4V, I needed that to get the battery to 100% and then change the timed absorb setting to 60mins and see if it manages to get to 100%. While it is balancing the battery will look like it is switching on and off, but it will be changing from charging to standby and back for quite a while before hitting 100%, this is because the BMS will be limiting the charging current while balancing. It also won't climb up, it will jump from 96% to 100%.

I would place the setup towards the front of the garage regardless of temps as it will be less likely to be damaged when accessing the vehicle. Also consider what would happen if the door gets left open (by accident) in the heavy rain or sunshine.

Could it be possible that it might be switching off due to a cell undervoltage protection? Being a second life battery the cell voltages might sag unevenly under load which might be why the document I found suggests a low voltage of 49.5V and not 48V.

FYI this is not the best time to look at the difference as batteries 2&3 will currently be in balancing mode (over 98%) and the BMSs will be physically limiting the current to those 2 batteries which is why there is a lot less power flowing into them. At this stage batteries 1&4 should charge faster to catch up, but I'm not sure what happens when batteries 2&3 reach 100% as their BMS will stop charging and I'm not sure if that will also stop batteries 1&2 from charging before they reach 100%. I agree with @mzezman, the batteries seem to be quite far apart, were they all at 100% when originally hooked up? I would suggest disconnecting batteries 2&3, charge batteries 1&4 to 100% and then disconnect them and connect only batteries 2&3 and charge them to 100% and then hook up all the batteries again. Then observe from there to see if they start to drift apart again.

These seem pretty decent, I have the same one from takealot. There is a little voltage regulator screw on the left of the terminals which can probably be used to increase the voltage to charge the cells to full. I've not tested how high it can go though.

Have you tried to re-calibrate the BMS yet? This can usually be done by discharging the battery until the BMS low voltage cutoff (sets SOC to 0%) and then charge it back up to the overvoltage cutoff (sets SOC to 100%) and it will then calculate the capacity and SOH from how much charge it gets into the battery. It is important to do this without comms to the inverter so the BMS doesn't stop the charging due to incorrect calibration. I would do one battery at a time, get them to 100% and then hook them both up in parallel again with comms.

I keep seeing this with this ICM software, I think it is a problem with the display of the values, but I don't know if it affects the balancing or not. It's a little disconcerting that so many people use this software and there is still such a blatant error.

Not sure where you are buying from, but just make sure you are getting the new V3.0 version of the BMS, the older versions had all sorts of comms issues, but the new version comes with bluetooth and a phone app to monitor the battery and change all the settings.

Here's a link I found which looks like your battery, it seems to have the same specs... it suggests a battery cutoff of 50-49.5V. https://revov.co.za/wp-content/uploads/2020/05/Specs-and-recommended-settings-by-REVOV.pdf

Master and slave 1 are correct, slave 2 needs to be dips 1&2 on, not 3.

It does not matter whether the master has the positive or negative cable. What matters is that the CAN comes from the master battery with the correct dip settings as in the image.

Great news. Just remember when running only 1 of those batteries you will need to manage your loads manually as you can only set the max charge amps, not max discharge amps, so limit your loads to a max of 2.4kW or you will trigger the battery BMS to go into protection.

From the manual it says you need only dip 2 on for the axpert. Most likely that is going to tell the battery to use RS485 comms to the inverter. On the inverter you are most likely going to need to change setting 5 to PYL or LIB or LIC to get it to speak the correct protocol and use RS485.

Thanks @BritishRacingGreen, I had exactly the same 120V battery voltage fault on my old 5kVA clone. I think it was caused by running my panels in 3S with 136.6Voc. It would always trigger the error in the evening or early morning when the PV was switching on and off in low light and cold temps, so i figured it was the panels. At the time I was told it was probably my gel batteries because "the plates can bend and short circuit causing high voltages" which turned out to be a load of hogwash causing me to waste another 22k on a new lithium battery. Could high pv voltages cause this failure at all or would that be more likely to fry the mppt board?

Hi @drummer, unfortunately most of us on the forum are from SA so it is difficult for us to judge your situation and prices in the UK. In SA we have constant outages due to load shedding and we have a lot of sun, so solar makes a lot of sense, but as i understand it most people in the UK use batteries and inverters to game the tariff structure and save money. What is your situation, why are you wanting to install solar? Do you have many outages or is it just to try to save on bills? I'm also not sure how profitable panels are in the UK due to the lack of sun in Winter and the short days, but maybe it is made up in Summer when the days are super long. Are you able to sell electricity back to the grid? That may affect the returns quite a lot because most panels sit idle for most of the day once batteries are charged.

This is from the website, maybe it helps "With all the battery models below, if an inverter is already reading them via CAN then SolarAssistant can not read them via RS485 at the same time. Set SolarAssistant to "Use inverter values"... rentech is in the list https://solar-assistant.io/shop/products/shoto

If it is this inverter then it looks like a genuine rebranded Axpert MKSII https://solarsolved.co.za/product/axpert-mksii-5kw/ If it is then you should be able to get a replacement mppt board from somewhere like shumata. Best way to know is post an image of the sticker on the side also showing some of the screws and someone like @Coulomb should be able to identify it. If you are looking for someone to do board level repairs then @BritishRacingGreen should be able to help out.

I think this is extremely important information. People generally think that "Deep Cycle" means you can do it all the time (I did in the beginning too), but it is really meant for emergency situations, like getting your boat to the harbor before dark or something like that.

Looks like these panels produce approx 13A at Pmax, so in 2S3P, you should be getting around 3x that, around 30A. From you inverter specs this is the correct wiring and it can easily handle that many amps. It looks to me like there is a problem on 2 of the parallel strings... maybe fuses or wiring issue in the combiner box?

Thanks for this info. Shuang Deng is Shoto, so I guess this is their own software.

@Muzammil, have a look here, this is the same battery as you and it seems they use a different software to access it that does both RS232 and RS485. He has the cables etc. working, but the seplos software didn't connect, I guess it needs different software, maybe PBMSTools will work.

Yeah I think so too, it also has the dry contacts shown in the manual I posted which the new battery doesn't have.