Eishkom Inverter setup dilemma

[Gravedigger]

As per thread title,

My poor AGM batteries is now tapped after two years of service. Suspect the inverter's to blame...
How long is a AGM battery supposed to last for?

Bought a expensive piece of kit two years ago from GeeWiz, a 3kW MUST inverter with 2x100Ah AGM batteries, making up for 24V.

When the system was new, I could get at least 4-6 hours of lifetime out of the batteries, but now, only like 1 hour, with minimal load, which is not good for my WFH setup. I pull less than 100 watts.

Voltage readings between inverter and batteries were out of whack, sometimes like 0.3V to 0.6V, no matter how much I tried to set the float voltage and limits, the system were never calibrated properly, and I think that may have damaged my AGM batteries?

Should I take the plunge to buy a proper replacement Voltronic Axpert inverter, smous the other one off, and give the AGM batteries a second chance? I seriously cannot buy a new set of AGM batteries after two years of light use. That stuff is expensive, yo...

I discharged them every month, to give the batteries a proper charge-discharge cycle, or should I look for other alternatives?

Sound off in the comments...

 

[ld13]

When the system was new, I could get at least 4-6 hours of lifetime out of the batteries, but now, only like 1 hour, with minimal load, which is not good for my WFH setup. I pull less than 100 watts.
...
I discharged them every month, to give the batteries a proper charge-discharge cycle, or should I look for other alternatives?

4-6 hours of runtime till they were flat? When you discharge them, do you take them to 0%?

 

[Paul_S]

My poor AGM batteries is now tapped after two years of service. Suspect the inverter's to blame...
How long is a AGM battery supposed to last for?

I discharged them every month, to give the batteries a proper charge-discharge cycle, or should I look for other alternatives?

Sound off in the comments...

Firstly if you've been deep discharging any lead acid batteries repeatedly then they will die very quickly. It doesn't matter if they are AGM deep cycle or not - lead acid batteries will not last long when deep discharged. Even a couple of hundred deep cycles is a lot for decent brands.

Do yourself a favour. Get rid of the lead acid batteries and purchase lithium based batteries. If your inverter/charger doesn't have charge settings for lithium based batteries then toss it and switch to a 48V battery system while you're about it.

 

[TheChamp]

Firstly if you've been deep discharging any lead acid batteries repeatedly then they will die very quickly. It doesn't matter if they are AGM deep cycle or not - lead acid batteries will not last long when deep discharged. Even a couple of hundred deep cycles is a lot for decent brands.

Do yourself a favour. Get rid of the lead acid batteries and purchase lithium based batteries. If your inverter/charger doesn't have charge settings for lithium based batteries then toss it and switch to a 48V battery system while you're about it.

No point to switching to 48V for 100W of load? It will just increase the costs, unless of course he has the funds. Even any basic 12V system that can charge lithium batteries would work. But the Must should be able to charge lithium batteries, it's an Axpert based inverter.

 

[AlphaJohn]

As per thread title,

My poor AGM batteries is now tapped after two years of service. Suspect the inverter's to blame...
How long is a AGM battery supposed to last for?

Bought a expensive piece of kit two years ago from GeeWiz, a 3kW MUST inverter with 2x100Ah AGM batteries, making up for 24V.

When the system was new, I could get at least 4-6 hours of lifetime out of the batteries, but now, only like 1 hour, with minimal load, which is not good for my WFH setup. I pull less than 100 watts.

Voltage readings between inverter and batteries were out of whack, sometimes like 0.3V to 0.6V, no matter how much I tried to set the float voltage and limits, the system were never calibrated properly, and I think that may have damaged my AGM batteries?

Should I take the plunge to buy a proper replacement Voltronic Axpert inverter, smous the other one off, and give the AGM batteries a second chance? I seriously cannot buy a new set of AGM batteries after two years of light use. That stuff is expensive, yo...

I discharged them every month, to give the batteries a proper charge-discharge cycle, or should I look for other alternatives?

Sound off in the comments...

AGM she no like going bellow 40% SoC / 50% for Lead acid.
Your once a month deep cycle most likely killed it and not the inverter.

Anyway, toss the Lead. Get Lithium. If your Inverter doesn't have charge settings, look for Lead replacement type's in the form of Hubble S range.

 

[Lupus]

You killed them with the discharging them and recharging them. Lead acid of any variety are tricksy and they don't like being used . With your setup look at a 24v lithium battery it would probably be about 12k for a 100ah version which would essentially cover your 100w load for 20+ hours.

 

[Mista_Mobsta]

I have exactly the same 24V MUST trolley system with the AGM batteries - thus far mine is still going strong but I have never taken the batteries below 60% SOC. You have to monitor those AGM's and always make sure you set the cutoff voltage of the inverter before the batteries get to 50% SOC. Mine is set to cut the batteries at <12.4V per battery. The MUST inverter does have a charge cycle that caters to the Lithium batteries + built in MPPT so maybe save up a bit of dosh and get 2 Lithiums + 2 solar panels.

 

[Neuk_]

Two years for AGM is pretty much average currently in SA.

 

[Lupus]

Two years for AGM is pretty much average currently in SA.

It's actually pretty good, generally anything over a year on AGMs is considered good, I've got 2 AGMs I sold that I did warn the guy they were 2 years old, but they literally were used to keep a monitor, laptop and speakers running during shedding and even on 4 hour sheddings of 2020 it never went below 75%.

 

[PsyWulf]

at least 4-6 hours of lifetime out of the batteries

There's your problem,I assume you drew more than 150watts?

 

[Gravedigger]

There's your problem,I assume you drew more than 150watts?
View attachment 1335066

It depends, usually drawn like light loads, just to survive load shedding, 100-150w usually...

 

[Gravedigger]

You killed them with the discharging them and recharging them. Lead acid of any variety are tricksy and they don't like being used . With your setup look at a 24v lithium battery it would probably be about 12k for a 100ah version which would essentially cover your 100w load for 20+ hours.

Which lithium setup would you prefer?
Seems everyone is going for them litthies..
Atm, I can replace those two AGM with Gel, 200Ah for R10k, (secondhand deal, know a guy that ran with the batteries for 2 months, before going lithium)
Or I can spend the dosh for a 24V lithium setup, which will probably be the best setup...

 

[PsyWulf]

It depends, usually drawn like light loads, just to survive load shedding, 100-150w usually...

150watts for 6hours is past 50% discharge and is already pushing what most would recommend,this shortening lifespan is batteries being overdrained repeatedly

 

[Mista_Mobsta]

Which lithium setup would you prefer?
Seems everyone is going for them litthies..
Atm, I can replace those two AGM with Gel, 200Ah for R10k, (secondhand deal, know a guy that ran with the batteries for 2 months, before going lithium)
Or I can spend the dosh for a 24V lithium setup, which will probably be the best setup...

For that price, rather go with Lithium.

 

[wingnut771]

There's your problem,I assume you drew more than 150watts?
View attachment 1335066

I'm not following? He has a 100Ah battery and used 50% after 6 hours. Not sure why he's running it for 6 hours though.

 

[AlphaJohn]

Which lithium setup would you prefer?
Seems everyone is going for them litthies..
Atm, I can replace those two AGM with Gel, 200Ah for R10k, (secondhand deal, know a guy that ran with the batteries for 2 months, before going lithium)
Or I can spend the dosh for a 24V lithium setup, which will probably be the best setup...

People seem to go for em Hubbles or Blue Nova...

Personally I bought similar to these:

https://www.solarimports.co.za/product-page/48v-100ah-lithium-ion-battery

Wholesale for around R10800 & basicly forgot there is such a thing as LS or that I have an inverter.

 

[PsyWulf]

I'm not following? He has a 100Ah battery and used 50% after 6 hours.

50% is the bare minimum to just keep some form of reasonable-ish cycles,the available Ah will drop then still
Given his inaccurate voltage readings earlier,likelihood of an accurate wattage usage without some direct measuring and the shortening span i'd wager it's gotten a beating a few times and it's cascading now.

It just takes once to do massive damage to the capacity

(Also other maintenance considerations like charging the batteries to full separately before joining them on the inverter to prevent sudden changes in voltages when balancing)

 

[Lupus]

Which lithium setup would you prefer?
Seems everyone is going for them litthies..
Atm, I can replace those two AGM with Gel, 200Ah for R10k, (secondhand deal, know a guy that ran with the batteries for 2 months, before going lithium)
Or I can spend the dosh for a 24V lithium setup, which will probably be the best setup...

Ouch okay so 24v batteries are getting pricey, you'd have to extend it to R15k but look at a Pylontec 2000

 

[Lupus]

People seem to go for em Hubbles or Blue Nova...

Personally I bought similar to these:

https://www.solarimports.co.za/product-page/48v-100ah-lithium-ion-battery

Wholesale for around R10800 & basicly forgot there is such a thing as LS or that I have an inverter.

I use my camera to see if the street lights are on , though I also could just check my meter.

 

[wingnut771]

Which lithium setup would you prefer?
Seems everyone is going for them litthies..
Atm, I can replace those two AGM with Gel, 200Ah for R10k, (secondhand deal, know a guy that ran with the batteries for 2 months, before going lithium)
Or I can spend the dosh for a 24V lithium setup, which will probably be the best setup...

Just get 2 S-120's. They wont care about inverters inaccurate voltages.