12000xp open loop battery voltage bounces between float and bulk after batts are full

EG4 Eric

@eg4eric 6x Midnite Solar powerflo-5. I do NOT want to use closed loop comm cables, which is why I set parameters as shown in top post to enable the inverter to manage charge control by voltage setpoints.

Interesting note is that charge voltage absorb -> float looked fine when there were no Loads after I set the EQ voltage= float. However, once the system was operational with "real" loads, the voltage keeps returning to end-of-charge (absorb) voltage.

I suspect that there is faulty programming when running "open loop" which needs to consider that return to EOC is not required after small dips below float of short duration in the same day... System should just return to float voltage, not EOC voltage. They probably need to open up the allowable sag a little to create logic that the system doesn't need to return to EOC voltage unless voltage drops to "operational" voltage for a minute or more to account for temporary cloud cover or momentary sag from heavy output.

dtbaker61

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November 10, 2025 11:45 pm

I had the same problem with the first 6000xp I installed.... and it was eventually resolved with a firmware update. I would have hoped the same logic is used with all models when running off-grid, self consumption, open-loop... Lithium battery charge curve "faked" with EQ=float=0 days, 0time

Krzysiek_KTA

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November 11, 2025 1:39 am

Are you positive the issue was resolved?

I had some issues with my EG4 Wall Mount battery BMS comms with 6000xp (finally resolved) and was forced to run in open loop (Lead Acid) mode for months. Below is an sample screenshot of the battery voltage throughout the sunny day when the PV array production exceeded the demand and the battery was topped up during the day.

NOTE that I used AC Grid to charge it overnight and there was no issues whatsoever with maintaining the Battey in float voltage as set in the 6000xp

That issue was main driver for me to fix the BMS comms issues and go back to closed loop comms (Lithium Battery type 1) where the voltages are managed better - see below example of sunny day when the PV array production exceeded the demand and the battery was topped up during the day:

NOTE that no overnight AC Grid charging.

I run the latest firmware ccaa-191011

Just my 5 cents.

Brgds

This post was modified 3 weeks ago by Krzysiek_KTA

dtbaker61

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November 11, 2025 4:15 am

@krzysiek_kta I don't want closed loop comms, I want to program voltage setpoints. This is working correctly finally on a 6000xp system that is offgrid, with no AC-in available. Same settings are NOT working on an off-grid 12000xp

Krzysiek_KTA

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November 11, 2025 12:59 pm

Got it.

Yet it seems when in Off-Grid mode with open loop comms during the day my 6000xp did not maintained 54v float voltage as programmed and voltage behaved as in OP 12k case. See example below.

My point is that even with latest 6000xp firmware the Off-Grid voltage management in open loop comms does not work as programmed.

I wonder how bad it could be for batteries if one has over-paneled PV setup and it stays fully charged most of the time ....

Brgds

dtbaker61

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November 11, 2025 3:06 pm

@krzysiek_kta it is not great for LFP to hold at 56v, and its hard on the BMS and charge controller to cycle on and off. There needs to be a reasonable hysterisis (like float -1.0 v) to be lithium-friendly. I'd be fine with seeing "float" bounce between 53.0-54.0... knowing that as soon as the sun sets, 53.3 or so is still "full".

More importantly, holding at 100%, or bouncing up to EOC many times in the afternoon increases the chances of overvoltage, killing the internal BMS, and fires.

some brands of batteries have this worked out internally, but you have to have closed loop for that to work. My point to EG4 is that the inverters all need to be able to have internal charge control managing by voltage setpoints as well to accommodate batteries that do not have closed com.

I don't like to used closed comm in many off-grid situations because I don't trust the durability of cat5 cable or port in a typical off-grid shed or even an RV/camper with vibration from the road long term. I want the inverter MPPT charge control to work predictably as programmed with a LFP friendly charge curve and float.

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dtbaker61

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November 13, 2025 3:45 pm

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@eg4eric , the charge curve and behavior we really want to see for open loop charge control of Lithium batteries is a simple CC-CV curve where:
- daily (PV voltage comes up to minimum) charging happens at max current until "Vfloat", and then
- switches to CV= Vend-of-charge once a day, and then charging stops, and allowed to drop to Vfloat, and is maintained at Vfloat for the remainder of the day as detected by the presence of PV voltage available.

typically there is some bouncing +/- float as loads and pv available vary thru the day, but a good charge controller algorithm controls that pretty tightly, always seeking to return to Vfloat for the day as long as PV power is available. When PV voltage drops < operational, the controller considers that as "night", and resets charge curve to shoot for Veoc the next "day".

Unfortunately, what I see with EG4 inverter charge control (open loop), is the Battery voltage bouncing between float and EOC and sometimes holding at EOC despite settings for 0 time and 0 days for EQ voltage.

What we want to see is 56.2 once a day, and float targetting 54.0 for the remainder of the day with minimal bounce to be expected depending on PV available versus loads

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Krzysiek_KTA

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November 22, 2025 2:27 am

Maybe new firmware will offer an alternative - look at the latest for 6000xp - new battery type 30 for lithium batteries in open loop added (if I read the changelog correctly).

I am reluctant to try it yet, but maybe similar version for your 12000xp would eventually do...?

Brgds

dtbaker61

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November 22, 2025 4:05 pm

@krzysiek_kta most of the xp series I have installed have been way off-grid with no wi-fi available, which makes firmware updates after install difficult without easy delivery from a local laptop, and expensive for the clients if I have to make a physical trip and charge them for it.

I do have one 6000xp, and one 12000xp, with wifi access for firmware updates.... but it can be difficult to do remotely if the system has to be put on standby and the residential modem is on a circuit that gets de-powered. Most clients can't get thru the process on their own to power the modem from a secondary source during an update; so it becomes a time consuming (expensive) process.

I'd want to be very sure that the update is "worth it". I'd want to see a written report, video, or something to show the results.

Krzysiek_KTA

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November 22, 2025 5:54 pm

I have two 600VA UPS units - one powering the wi-fi and the other internet gateway.

All firmware updates I have done were in off-grid mode thorough EG4 monitoring website.

When all went well the power loss when inverter restarted was just few seconds and easy handled by UPS.

The longest it always took for the Wi-Fi dongle to come back online (couple of minutes).

So in theory such setup can be upgraded remotely.

But.... errors can happen (my first hand experience) and I am always on site when performing upgrade. Just in case.

Good luck

Brgds

dtbaker61

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November 22, 2025 11:19 pm

@krzysiek_kta aha.... see.... what if the customer doesn't have a separate UPS for their wifi ?

don't you have to turn off EPS to inverter in standby to initiate a remote update of the inverter via app or portal ?

This means if the customer doesn't have a separate UPS for wifi, I HAVE to go on site with one, and execute the update while I am on-site. That is the time consuming (expensive) part for the client.

The only other way around it would be a "bypass" circuit from the generator that skips the xp completely to keep all loads powered up while the update is in progress. This would be a great thing to build into the xp since they are intended for off-grid use, but currently you'd have to design/build a bypass in externally.

Krzysiek_KTA

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November 22, 2025 11:26 pm

Well,

As hobbyist BETA tester I always build backup plan. I do have externals bypass transfer switch separating Inverter from the house power and allow grid or other more conventional power source to be available to power the house independently - that was the first think I did starting my Inverter/battery project journey....

Yet the power blips issues with EG4 inverter/battery (read my other posts) made me invest in multiple UPS and even it home Surge Protector in my main load panel....

I was just sharing my experiences with 'remote firmware updates'. I think the UPS for WiFi and Internet gateway is a MUST for any Off-grid setup. Just my 5 cents.

Brgds

This post was modified 1 week ago 2 times by Krzysiek_KTA

dtbaker61

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November 22, 2025 11:54 pm

@krzysiek_kta The issue with planning for UPS for the wifi is problematic whether the install is grid-tied, or off-grid, since normal functionality desired by clients is to have the wifi modem on a normally protected Load circuit.

The two best (least expensive for client) solutions would be:

1. adding a "bypass" switch from either/both the AC-in and Gen-in terminal blocks to power the Load breaker directly for updates, or if the inverter fails completely and you are waiting for a replacement.

2. providing firmware updates (and instructions) as files that can be uploaded from a laptop thru the Dongle or rs-232 port or BT local connect WITHOUT internet. i.e. connecting a laptop to the dongle wifi and doing updates from a laptop locally rather than worry about www internet connection.

Krzysiek_KTA

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November 23, 2025 12:23 am