EG4 24v unbalanced? Wont charge?

[RebelWithoutACausey]

Hey gang,

I have installed the electrical components for my school bus build, and while im fairly electrically literate, im playing with a far bigger system than anything im used to installing. That said, I’m scratching my head here.

My battery bank consists of two EG4 Lifepower 4 24v batteries, currently being charged by the victron MPPT 150/100, with a solar array of 6 panels wired 2S3P. The ither charging method is through the Victron Quattro, but I haven't programmed it yet and have not used it at this time. Parked at the shop here, there is no shade and we have had 3 clear, sunny days since I flipped the switch.

One battery displays a full SOC (4 of 4 LEDs) and isolated at the terminals, shows 26.2v. The second battery displays 3 of 4 LEDs, and the terminals show 28.3v. Both of them are connected to the system with equal length 4/0 cables into the victron lynx power in.

The reported SOC of the batteries vs the voltages at the terminals does not make any sense to me.

Further, it appears that they aren't accepting nearly as fast of a charge as I expected. My array is rated for 2400 watts, and while I didn't expect to get the full rated output, from the victron app it seemed to be charging at around 1100 watts. I set the parameters in the victron app per the suggested figures in the manual, maybe there is something else im missing? At the current rate, a full day of sun wont be enough to recharge the batteries fully if I deplete them through the night.

Im confused, so any resources or advice on how to get all this new expensive equipment to play nice together would be GREATLY appreciated.

Thanks!

 

[sunshine_eggo]

Please post a screencap of VictronConnect detailed view that shows daily production and voltages.

99.9% of all new batteries arrive imbalanced because that's how the world works. It's going to cause weird stuff to happen.

If you have a data cable between the two batteries, remove it.

Recommend you lightly discharge them to 26.4V nightly.

Set absorption to 27.6V, Expert settings, fixed absorption time to 4 hours, and float to 27.5V, charge daily.

Repeat discharges/charges for several days. Balance should improve, and you can try higher voltages.

2400W array almost never produces rated power - especially not a week from the winter solstice while you're in the Northern hemisphere.

Flat panels on a roof generate about 50% of summer output in winter, so 1100W on 2400W with the Sun about as far South as it gets with panels flat on a roof sounds about right.

Additionally, if there's nowhere for the power to go, they will only produce as much as is needed. If your battery is full or approaching full or not accepting charge for some other reason, you won't get anything more than that.

Best way to test your array performance is to wait until high noon, hit the system with > 2400W load and see what the array does.

 

[RebelWithoutACausey]

Is this the screen you wanted?

There is no data cable between the two batteries. Oddly enough, I tested them last night and the voltages match now, but the second battery still displays 3/4 SOC.

As it stands, the only loads I have while im building the interior is 30w of lights. I suppose I could get the AC outlets going and put some higher loads on it.

With the proper settings, are you saying the batteries should balance themselves?

 

[sunshine_eggo]

Is this the screen you wanted?

Yes.

There is no data cable between the two batteries. Oddly enough, I tested them last night and the voltages match now, but the second battery still displays 3/4 SOC.

I think the 26.X battery was in over-volt protection reading a lower voltage reported by the BMS rather than the actual battery voltage.

As it stands, the only loads I have while im building the interior is 30w of lights. I suppose I could get the AC outlets going and put some higher loads on it.

30W left on 24/7 should be more than enough to cycle the battery.

With the proper settings, are you saying the batteries should balance themselves?

yes, set per above recommendations to help expedite balancing.

BMS reported SoC on a new battery is generally unreliable. The lights reporting SoC on a new battery is even less reliable. Getting it balanced will improve SoC reliability.

 

[RebelWithoutACausey]

Much appreciated!

So all I need to do is set the recommended parameters in the charge controller and inverter, leave the lights on 24/7, and let the batteries figure themselves out? Sounds easy enough, easier than I was expecting.

 

[sunshine_eggo]

Much appreciated!

So all I need to do is set the recommended parameters in the charge controller and inverter, leave the lights on 24/7, and let the batteries figure themselves out? Sounds easy enough, easier than I was expecting.

Yes.... provided you have a surplus of solar to replace everything you use and hold at absorption/float for a few hours or more.

 

[RebelWithoutACausey]

I’ve given it some time, and the second battery still has yet to display a full SOC.

The bus is inside the shop for the week, so no sun, but I am finally coming around to programming the Quattro. I’m going to charge them off of shore power for the week.

I've searched around and can’t find any good info on what those settings should be for the 24v system. The manual doesnt provide much info, any pointers?

 

[sunshine_eggo]

28.8V absorption for 1 hour.
27.0V float

If you find that you're triggering charge protection, set absorption to 27.6V for 4 hours and set float to 27.5V. After a few days, revert to 28.8V abs/27.0V float and check if you can charge to that voltage without charge protection.

 

[RebelWithoutACausey]

Roger that, thanks again!