Igubu

Glad you have a workable “workaround”- at least 10Amps gives you 500W approx- so should be able to fill up the sunsynk batt in 8 hours or so.. if you can get 20Amps min your golden! yes it’s incredible that the same issue exists years later. out of interest: the diy comms cable..? Does the inverter not have can bus interface and are you using rs485 or usb? I know the sunsynk batt CAN cable is just a normal flylead- unsure about the inverter, not up to date with them. * found a link! Think rs485 might work as well with sunsynk batt - unsure. You’d need at least 3x 545 panels to work nicely https://www.mecerpc.co.za/pdf_downloads/20/206710_PDF1.pdf

If it’s for a cottage- probably more remote- so self built batteries not the best idea- as they tend to be slightly cheaper, but have a lot more returns/issues. The builders sort you out eventually- but if you don’t want the hassles, pay a little but more for something proven. Victron good reliable kit for sure- think exsolar in Somerset West are one of the main guys. They also sell FreedomWon batteries- more expensive- but built to last- so a lot of over engineering- again might be the right choice for a cottage if it’s remote.

BU is old school yes… don’t think they are updated with latest developments in new batteries… Lithium absolutely wants to be charged to 100%- lifepo4 anyways… the older ncm based ones used in EV’s preferred the 20%-80% band, but more so for the “fast charge” portion… they are very different to lifepo4 ‘s used for solar storage… It proves the point there is a lot of miss-information around, lots of outdated articles etc, and a lot of confusion with acronyms etc. Most people just think “Lithium” of “LFP” is enough to indicate what it is- but it’s not unfortunately. Biggest impact on your Mercer's is rate of discharge/charging and temperature. The inherent chemistry will give you the cycles it can - but remember they are already used/2nd life and even “cycle count” is calculated differently between manufacturers…

Apologies, based on you currently running 2x 100a’s thought you’d replace with 2x. Purely based on AH, yes 1x could do- but remember there is a big difference in how lead acid and lithium’s “percentage full” (SOC- state of charge- lets learn the lingo ) are measured. Your trolley inverter only understands Volts- and the decharge curves are completely different. In layman’s terms- you will get less actual capacity with the Lithium compared to the LA with the same settings- especially under load.. glad to explain in more detail if you want to- but it becomes a long post then

Not anti any Brand, there are more than 20 different rebranded versions of this same battery on the market in SA… I’m offering advise based on experience…you are lucky to get 2 years, but have you actually ever load and capacity tested them? New and now? I’ve said this a few times- people that don’t understand the technology just look at one thing: Price. They think a mecer/any brand of these cheap lithium’s @ Rx thus Rx per kW are way cheaper than another brand based on selling price only…. Surprise surprise it’s untrue. There is a very small niche market where these could be used, ie LA replacement- think gate motors, alarm backup etc, where very low current is required, and cycling doesn’t happen - so NOT a solar system in SA where we load-shed constantly. There are many Technical reasons- you can speak to installers who’s in the business for many years- or educate yourself a bit- simple few google searches to explain the basics of batteries, chemistries, BMS and comms control systems etc. The correct battery will give you 6000+ cycles and retain 70-80% after that- thats many years… vs your cheap lithium that will probably not even give you 100% capacity on day 1 (they use 2nd life cells that are already years old) and degrade to 30% in under 3 years… So purely advice to not waste money in the short term…

I see hubble has a s-200 now… also prismatic lifepo4, and online around R12K. Would be much better option than 2x mecers. I know you said cashflow is an issue, but you are wasting a lot of money long term sitting with old 12V inverters and batteries. Also lose at least 30% of usable capacity because of not using CAN interface between the battery and inverter. a hybrid or even off grid 48V inverter with a 48V battery will be much better in the long run, and you could even add 3 or so panels (which you can find 2nd hand) and at least get some money back… not sure if thats an option. As an example you could buy a proper Dyness 5.5kW for around R26K, and a small 3kW kodak around R10k or so (i’d recommend a sunsynk hybrid of course but it’s a lot more) Add a few panels and you could run most things with a bit of management….

Are you happy with the trolley as such? Also are you CT based or elsewhere? not sure if the s-200 has also moved to lifepo4 like the new am’s - if not i’d look for something that is… I could send you to somebody that manufactures these- but he’s CT based- might save you some cash. also unsure if the mecer’s have perhaps changed to prismatic lifepo4 cells, maybe try and find out. I’d wager all manufacturers are moving to it as the old pouch cells all fail after around 3 years… Another option perhaps- look for somebody who has some 2nd hand ones and buy a couple on the cheap (around R1500 each)- stick 2x or even 4x together and at your modest 600W load they might be good for another few years.

Update perhaps? Have a similar issue at a friends house… change wiring, RCD’s etc, neutral/earth bonds with relay all perfect, only thing not changed/removed is the CT… but that is needed to block export, worth a test I suppose? Still fine your side? I’m assuming no CT installed?

If you scroll to page 9 - the “workaround” from HermanD was given: ”Hi Smirresa, Yes, setting 11 set to 2A and setting 16 set to CSO. In CSO the inverter will only charge from utility in bypass mode when there no solar. If you are in bypass mode, but there is solar (cloudy day with batteries low), then the AC charge will not occur. If you are running from batteries and no solar (at night time) then the AC charge will not occur. AC charging will only work when you are in bypass mode and no solar.” Also on the same page 2 posts of the pcb and some arabic text (use google translate” and pictures of a possible fix- but nobody tried and replied that it worked ever- so would try HermanD’s workaround first.

There might a few reasons - these axpert inverters really weren’t great, but if you read the 4Y + history of error 8 and ALL the rebrands using voltronic powers’ pcb, they all had the same issue, utility charging has a design flaw and the bus V shoots up to 600+. There is a long forum post history about it, many things were blamed- seemed to happen when it was raining, so panels and joins were mentioned, but coincidentally was because of rain batteries ran low and utility charging were used. Some clever engineers explained why, how to physically modify the pcb, or add a “push button bypass” to reset the issue manually- but it all came back to the same old pcb design flaw. When I say all- any of the axpert,rct,mustek,growatt etc rebrands - they all used the same mainboard with that 145V mppt limit… maybe newer models have fixed it. Only workaround that was confirmed by many in the field to help , was limit grid charge to as low as possible- or disable if it’s an option. The logic of grid charging at 2A when raining is flawed for sure- you’ll never get the batteries charged during these multiple loadshed days, but that’s what you were stuck with. I remember a year or so ago somebody sat with the same issue- the best advice- sell the inverter for somebody that uses it for ups mode only, and buy a decent one- small sunsynk 5kW hybrid comes to mind…even the newer versions of this- but if you consider a kodak 5kW for R14K- save up and buy a hybrid sunsynk for 20k- worth it for many many reason, but not tue correct page to explain the differences and advantages of proper bi-directional hybrids vs “off grid” ups style cheapies like axpert/kodak. If you are desperate to fix this- and cannot disable/limit grid charge, scroll through the history of error 8 and, somewhere the post with engineering changes required by somebody in Saudi I think was posted- but this involves opening up, and soldering- some surface mounts, so obviously for somebody that’s comfortable doing that kind of thing..

Hi Stormpie, It’s not a fixable issue, inherent design issue. Only work around is to set grid charge to min, think 2 amp or something, or disable charge from grid in CSO if possible.

All the best - please report back here

Hi Rochelle, Seems it’s been a journey! My first solar system 9 years ago was 2x old axperts and 4x 200ah gels - worked well for a few years - inverters anyways… somewhere in the last 2-3 years axpert changed design, possibly outsourced something to get it made cheaper.. and they started supplying numerous other companies with the same flawed design.. (kodak,mecer,rct,growatt the list goes on….) I’ll give you the correct advise, but not what you probably want to hear. The error 8 will not go away, firmware will not help. Loadshed etc is going to be a thing for many years- nobody wants to struggle. The rest of your components are very good (hubble has CAN as well)- get rid of the cheap axperts- return the one if you can, sell the other one to somebody for a few grand, and buy a proper hybrid inverter. With a little management , maybe not even, a single 8kW sunsynk will make all your problems go away. You will be able to get at least 20% more usable capacity out of your 10kW battery bank because of CAN, and the mppt’s themselves will probably generate 10-20% more power from the same panels - they really are that much more efficient than axperts! Yes the 8kW is around R34k, yes somebody (preferably a master installer - sunsynk has a list of them in SA) will charge you again to install- but probably the same as just changing things back. Simplify things, no more split db boards, EVERYTHING on one inverter via 1 main DB. Dont stress about it- solar is a journey, we all learn as we go, but believe me it’s not worth struggling with Axperts. Happy to explain anything around additional benefits and options around Sunsynks ( Have one myself)- but many others will also recommend them as the only worthwhile option. * just read the old Post from a while back… see I repeated a few things :).. btw your SBU has to be on CSO, but read the old post on what that means. Also forgot to mention your sunsynk has 2x mppt inputs, split into 4x string inputs- so you can use both your pv arrays with one inverter, installer just needs to check string sizing-wiring, which will be different compared to Axperts..

Sure it’s not just no loadshedding last week or so? It’s the discharge/charge from util that triggers it when adding loads.

@TimCam Fantastic to hear somebody doing it the correct way. Bus-Bars should really be part of any install - most installers dont do it - or if they do, completely undersize the copper in width and thickness. Always find it amazing that it takes 1 internet search to see what size wiring for size of battery bank is needed - say 50mm for 200Amps - yet people insists on using 25mm - "because it works". Same applies to fuses and bank sizes...how many "standard" 160A DC fuses are used on battery banks of 200,400,600 Amps!? The exact same applies to Bus Bars (Buzzbars? there are so many different spellings!) - a small 10mm wide by 2mm thick is NOT sufficient.... And that age old argument - " A proper bar is another R1000 - and thick battery cables are "expensive" - another R500 more!" .. after you have just spend R150-R250k on something that needs to last for years. When an electrician (a good one anyways) tells you you need an xyz breaker in your DB and it costs R1000 - nobody cares.. but when people install PV systems they choose the R150 cheap breaker... Maybe take a picture of it if and share for others to see what we are talking about?