Mecer 2400VA Inverter (Community Support) - Part 2

wingnut771 said:
No that's fine. Size isn't the issue, it's the recharge time. With a 20A charger, 200Ah will take 10 hours from 0 to 100%.

A 500W load would take 4 hours to deplete the battery, then you need 10 hours to recharge.

If you have smaller load then you not using too much capacity and recharge time with be shorter then you can use 10A setting for less noise, but then why get a 200Ah?
Click to expand...

I have two 200Ah lithium batteries - what you're saying makes sense. But on most days my batteries charge fully again on 10A in about two hours.

The Mecer doesn't give reliable discharge numbers for lithium, so maybe I just don't discharge them much at all? My battery balancer no longer gives me voltage readouts, so I'm in the dark here.

Power was out yesterday from 7.30am, local fault fixed just before midnight and then we had another four hours of load shedding. Mostly just one laptop and some lights running, but batteries still recharged again in less than three hours although I pumped 20A for a while
 
impracticaldogg said:
I have two 200Ah lithium batteries - what you're saying makes sense. But on most days my batteries charge fully again on 10A in about two hours.

The Mecer doesn't give reliable discharge numbers for lithium, so maybe I just don't discharge them much at all? My battery balancer no longer gives me voltage readouts, so I'm in the dark here.

Power was out yesterday from 7.30am, local fault fixed just before midnight and then we had another four hours of load shedding. Mostly just one laptop and some lights running, but batteries still recharged again in less than three hours although I pumped 20A for a while
Click to expand...
Thing is, i'm looking to pull 500 watts constantly for around 2 hours minimum. Lot of things to power. Which Mecer are you using?
 
impracticaldogg said:
I have two 200Ah lithium batteries - what you're saying makes sense. But on most days my batteries charge fully again on 10A in about two hours.

The Mecer doesn't give reliable discharge numbers for lithium, so maybe I just don't discharge them much at all? My battery balancer no longer gives me voltage readouts, so I'm in the dark here.

Power was out yesterday from 7.30am, local fault fixed just before midnight and then we had another four hours of load shedding. Mostly just one laptop and some lights running, but batteries still recharged again in less than three hours although I pumped 20A for a while
Click to expand...
Yes, you can't use voltage to determine SOC with LFP. So you must be using (10A x 25.6 x 2 hours) 512Wh during your session out of your 5120Wh capacity.

You need to get a shunt to count Wh from your battery, something like this:
1677080156062.png
 
wingnut771 said:
You can increase that to 20A.
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Ok, so before I do order. My biggest concern is the battery low voltage cut off. Iv'e read some batteries do it so you dont damage them, some don't etc. I DO know however that the Mecer I have cuts off at around 10volts which is obviously a problem.
 
ClarityJuice said:
Ok, so before I do order. My biggest concern is the battery low voltage cut off. Iv'e read some batteries do it so you dont damage them, some don't etc. I DO know however that the Mecer I have cuts off at around 10volts which is obviously a problem.
Click to expand...
The only problem if it happens is that the BMS in the LFP will go to sleep preventing you from turning on the inverter. All that needs to be done is to take a small 7Ah alarm battery and parallel it with the LFP so the BMS sees 12V and wakes up. Then you can turn the mecer on again and everything is back to normal, no trainsmash, nothing damaged, just a bit of a faf.
 
wingnut771 said:
The only problem if it happens is that the BMS in the LFP will go to sleep preventing you from turning on the inverter. All that needs to be done is to take a small 7Ah alarm battery and parallel it with the LFP so the BMS sees 12V and wakes up. Then you can turn the mecer on again and everything is back to normal, no trainsmash, nothing damaged, just a bit of a faf.
Click to expand...
Thanks alot. Really appreciate the help here. Looking to order one of these. Hope they are decent. https://www.takealot.com/mecer-lifepo4-12-8v-200ah-lithium-battery-sol-b-l-m200/PLID91577930
 
ClarityJuice said:
Thing is, i'm looking to pull 500 watts constantly for around 2 hours minimum. Lot of things to power. Which Mecer are you using?
Click to expand...
Can't say about the sizing - someone else attached a calculator app. I'm using the 24V 2400 Mecer. So batteries are in series. I also have a battery balancer with Bluetooth all, but it's on the blink atm
 
impracticaldogg said:
Can't say about the sizing - someone else attached a calculator app. I'm using the 24V 2400 Mecer. So batteries are in series. I also have a battery balancer with Bluetooth all, but it's on the blink atm
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Yes, a 24V will charge twice as fast as a 12V.
 
wingnut771 said:
It should go from 0 - 100 in 10 hours as 100Ah / 10 = 10.

The think that concerns me is that its not going higher than 12.9V. It should go up to 14.4V-14.6V. Also the SOC display is based off LA so should be ignored completely.

Okay, run it now see where voltage gets to. If it hasn't moved much, run it down to 12V, then recharge.

It sounds like something is happening with the cell balancing and the BMS is not letting it go past 12.9V for now. Maybe in time, the cells will balance out. I would use it normally for a week and see if it slowly improves. Just keep monitoring the battery voltage. At the moment it's looking like you got a faulty battery.

Here is the resting voltage for this battery type:
View attachment 1479559
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Hi Everyone - I have made some progress on my issues of lack of charge on my lithium 100A battery.

When charging off the Mecer 1200VA my resting voltage never goes to 13.0V after a day of charging and not using the inverter. Strangely I bought this battery as my 100A AGM battery also took around 2 days to charge to 100% full.

I have now bought a 5A Victron charger and set it to lithium ion. After 10 hours of charge on that as well as the Mecer(both connected to battery) my resting voltage is 13.2V. So the battery is good. I think there is something wrong with the Mecer's charge function as I am clearly getting 2-3A instead of the needed 10A. This is since I bought it and I just thought this was how long it took to charge the battery.

Based off of the above and considering it is still under a year I want to take the Mecer in to get tested. Of course this would mean not having an inverter so will try do it in a stage of lower load shedding.

Do my comments make sense? does this point to the inverter being a problem in terms of charging?
 
nickst3r said:
Hi Everyone - I have made some progress on my issues of lack of charge on my lithium 100A battery.

When charging off the Mecer 1200VA my resting voltage never goes to 13.0V after a day of charging and not using the inverter. Strangely I bought this battery as my 100A AGM battery also took around 2 days to charge to 100% full.

I have now bought a 5A Victron charger and set it to lithium ion. After 10 hours of charge on that as well as the Mecer(both connected to battery) my resting voltage is 13.2V. So the battery is good. I think there is something wrong with the Mecer's charge function as I am clearly getting 2-3A instead of the needed 10A. This is since I bought it and I just thought this was how long it took to charge the battery.

Based off of the above and considering it is still under a year I want to take the Mecer in to get tested. Of course this would mean not having an inverter so will try do it in a stage of lower load shedding.

Do my comments make sense? does this point to the inverter being a problem in terms of charging?
Click to expand...

Do you have access to a Watt meter?

On my 24V system I can clearly see the unit using an extra 1A over 240V (240W) on 10A setting and 2A over 240V (480W) on 20A during bulk phase.
 
AlphaJohn said:
Do you have access to a Watt meter?

On my 24V system I can clearly see the unit using an extra 1A over 240V (240W) on 10A setting and 2A over 240V (480W) on 20A during bulk phase.
Click to expand...
I don't no - I'll ask my brother in law - he may have.

Are you think I need to prove this beyond a reasonable doubt? Surely Mecer could test this all for me?
 
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