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Growatt 24 Volt system

scotts24V

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Feb 8, 2021
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I have the Growatt 3000TL LVM-24P controller and I was working on it last week. I inadvertently left it unplugged ( no solar yet so there was NO power coming in) and today noticed the Growatt is off (no display, no blinking status light). It is connected to 2 100 Watt hour 12 V batteries in series to give it the 24 Volts.
Question is - with no load on the unit, is it normal for the batteries to be so low it wont even power on the unit when I plugged it today from sitting unplugged for about 3 days? ie- the unit itself pulled all the power from the batteries in less than 3 days. yes, it has been cold in the garage these past three days to. Thermometer shows around 40.
Thanks for any info.
 
Welcome to the forum.

Inverters have an idle consumption even when no loads are applied. These can be surprisingly large.

The data sheet lists a standby power consumption of 2W. If standby is NOT enabled, their power consumption is likely on the order of 20W.

Assuming standby was enabled, even at 2W over 72 hours, that's 144Wh consumed just sitting. That's more than your 100Wh batteries.

Have you measured your 12V batteries for voltage? I recommend you get them on a charger ASAP.
 
Thanks. The voltage is quite low on the batteries. I tested them but the tester was quite cheap and I couldn’t get a good read.
Isn’t the Growatt a battery charger as well?
 
What were the readings? If you were reading single digits, you likely got a good read, but the batteries were excessively discharged.

Yes, it's a charger, but I believe it must draw power from the batteries to power itself. It might be able to be powered exclusively by AC input, but I don't know. It's not designed to bring batteries back from the dead.
 
Batteries are dead. Voltage is under 8 on one battery and under 11 on the other. Thanks for your help. Now to find a battery charger... Ugh
 
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Wire them in parallel and use any 12V charger. Their internal BMS should protect them if there are any issues with the charger. A 10A charger will take longer than 20 hours. They should be fully charged in parallel before they are put in series again.

To prevent future occurrence, disconnect batteries when Growatt is not in use, or attach Growatt to AC source for charging.
 
Thanks. Yes. The reason I was working on my system was to put in a battery disconnect switch. I just forgot to get it plugged back into power when I finished.
 
He said what but he meant amp he's got multiple kilowatt hours supposedly if his second specification is the accurate one. Because the grow watt system is not a USB support system but a mppt inverter I think we are dealing with expensive triple digit amp hour multi battery investment. This is one of the reasons why people pay for lithium titanate oxide because if you short it out and charge it in the wrong polarity etc there's still good to go. If you do the math again even the 20-w drain would have been insignificant. That's two days per kilowatt hour easily because it's a 50th or 2% and he has four days of batteries and I think something was mentioned about three days unplugged LOL but for future warranty claims having a third party certify the batteries are not as of now damaged sounds prudent. Just call battery Plus and discuss it with them even if they're not local they won't know that

New LFP typically ship at 50% SoC, so a 3 day 20W load would tap out the batteries. I'm also being generous with 20W, these are not known for their idle power efficiency. 12.8 * 100Ah * 2 * 50% = 1280Wh. 3 days at 20W is 1440Wh.

These batteries have a BMS, so there's no reason to believe they are damaged. A key function of a BMS is short circuit protection, so I'm not sure how your LTO comments are relevant.

Why on Earth are you mentioning Batteries Plus?
 
Batteries are dead. Voltage is under 8 on one battery and under 11 on the other. Thanks for your help. Now to find a battery charger... Ugh
The growatt has a battery charger included. You can charge off grid or AC generator power. The unit will also power up via solar input from pannels in order to charge the battery. Once the battery has charged to the votlage you have specified it will turn the inverter back on.
 
Thanks. Too bad it’s overcast today. How would using the solar be different than using the shore power?
 
right.. so going back to the original post.. when I turn on the switch on the Growatt nothing happens. The batteries are to far discharged to power it on (even with shore power plugged in). So I have disconnected the batteries from the system, separated them and am in the process of charging them up to voltage to get them to work with the Growatt. We have no sun in the forecast for the next several days.
Thanks for the forum to be able to discuss various ideas and solutions. Still lots to learn.
 
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In case anyone else cares. I left one battery on a charger all night. Then this am I put it on the other one to charge all day. Got home and both batteries were over 13. So I put them back in series and connected to Growatt. It powered on!! Then went ahead and plugged it in to charge batteries and hopefully won’t have this issue again. Plug it in!!!
 
Of course we care. Otherwise, we wouldn't bother responding to your questions.

Glad to hear it's alive.

Note that I had recommended you charge the batteries in parallel, not one at a time. If you didn't have those batteries on the charger for equal amounts of time, or they did not fully charge, they are not at the same state of charge. You should monitor them as 12V when you start charging them with the SCC to confirm they are at the same voltage/SoC. If they are not at the same SoC, you will not have your full capacity available and one 12V might trip its BMS before the other one is full.

Personally, I would yank them, parallel them and charge them to full overnight. Then reinstall as 24V.
 
Thanks for the info. Yes. I will be getting them at the same voltage! I just wanted to make sure they were going to work again. Thanks.
 
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