Victron BMV712 not syncing on Solar

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bikerchic49 asked Oct 5, '22

Victron BMV712 not syncing on Solar

I have 400 watts Renogy solar, the Renogy mppt controller and Victron BMV712 and Costco 6V Golf Cart batteries

1) My Victron BMV712 is not returning to 100% when not connected to shore power (shows changing output on the trends over past week)

2) When plugged into shore power it returns to 100%

I've attached a screen shot of the trends

So summary ...

when I'm on shore power everything works as it should (meaning if I disconnect shore power and run battery's down to say 65% then plug in to shore overnight then it resyncs every time). The problem I'm having is when I'm not hooked to shore power with nothing on its not resyncing even though the voltage is clearly meeting the set voltage criteria on victron and it is clearly receiving proper solar input (shows on victron "trends" graph).

victron community

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Mike Dorsett commented · Oct 05, 2022 at 06:42 PM

? screenshot?

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Modifications Space

Node Red Space

Answer 1 · 2022-10-06T01:43:05Z

bikerchic49 answered · Oct 06, 2022 at 01:43 AM

This is yesterday (charged on shore with oem charger, always returns to 100%) and today (ran battery down last night and allowed to rest until this morning before turning solar back on and still not returning to 100% or any increase but appears fine looking at the graphs)

These are the settings specific to the battery's installed per interstate battery engineer.

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Answer 2 · 2022-10-06T01:44:00Z

bikerchic49 answered · Oct 06, 2022 at 01:44 AM

This is from the Renogy controller.

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Answer 3 · 2022-10-06T07:36:13Z

JohnC answered · Oct 06, 2022 at 07:36 AM

Hi @bikerchic49

First things first. I think your wiring from both chargers may be incorrect, because charge isn't incrementing SOC upwards. If the negative wires from both chargers go straight to the battery rather than the load side of the shunt, then that is the problem.

Regular syncing from down as low as ~70% SOC isn't normal, and a properly tuned BMV might never need more than a 1% SOC tweak at sync, depending on how long it last saw 100.0%

I think you need to sort this first. Please ask if you need help. And oh, charge Amps are part of the sync process, so it will help if you provide that too.

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kevgermany ♦♦ commented · Oct 06, 2022 at 07:56 AM

I'm sceptical about the recommended voltages/charging parameters for these batteries. Shouldn't we be seeing absorption /fully charged quite a bit higher?

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Answer 4 · 2022-10-06T19:20:53Z

bikerchic49 answered · Oct 06, 2022 at 07:20 PM

This is how I currently have it hooked up

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klim8skeptic ♦ commented · Oct 06, 2022 at 07:46 PM

Better swap the "solar ground" to the oyher side of the shunt.

You can probably tweek the bmv settings a bit also. BMV Youtube tutorial.

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Stefanie (Victron Energy Staff) ♦♦ commented · Oct 07, 2022 at 08:43 AM

@bikerchic49

Just as a side note; installing the shunt in a location like that will eventually cause problems. The shunt is not suitable for outdoor installation and only corresponds to protection category IP55.

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Answer 5 · 2022-10-06T19:24:11Z

bikerchic49 answered · Oct 06, 2022 at 07:24 PM

These are the settings that the main engineer from interstate battery recommended in order to get the most life and usage of these batteries

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Answer 6 · 2022-10-06T19:29:55Z

bikerchic49 answered · Oct 06, 2022 at 07:29 PM

Renogy settings

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Answer 7 · 2022-10-07T01:52:34Z

JohnC answered · Oct 07, 2022 at 01:52 AM

@bikerchic49

Nicely labelled wires. And proof that the "Solar Ground" is connected to the wrong shunt terminal. Shift it to the one marked "Main Ground" (or it's busbar). The BMV manual is clear on this. Your SOC will then be able to register increases as it charges from the solar cc. The same applies for your shore charger.

Those batteries appear to be generic GC2 pattern floodeds. Same as I use (but different brand). These are the charge parameters I use (for 48V)..

Victron's Absorption is the same as Renogy's Boost. Don't Equalize them, and Abs shouldn't need more than about 1.5 hrs (the Victron mppt can terminate Absorb by the Tail setting, in my case 7A into 225Ah, so about 3%). They shouldn't need your 14.8V, except maybe in cold weather where Temp Compensation might push above 14.4V.

My shunt settings..

Fair bit different to yours, so you have some tuning to do I think..

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Answer 8 · 2022-10-07T03:13:16Z

bikerchic49 answered · Oct 07, 2022 at 03:13 AM

So BOTH connections need switched? (Battery & solar grounds on right side and main ground on left side)

Thanks for all the help so far.

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ludo commented · Oct 07, 2022 at 03:27 AM

No, only the solar charger needs to be changed from left to right.

And, in the bmv battery parameters you should set "full" to 14.8v to properly synchronize the systems.

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kevgermany ♦♦ ludo commented · Oct 07, 2022 at 04:08 AM

Yes for connection reply.

No, this voltage setting will prevent synchronisation to 100% with @JohnC recommendations

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JohnC ♦ kevgermany ♦♦ commented · Oct 07, 2022 at 05:47 AM

Thanks Kev. Yes, my Charged V is quite low at 13.5V (equiv), and I may need to drop it even further in summer heat. This is so it will sync under Float. I terminate Abs at 3% A/Ah, which is about 99.0% SOC, so I pick up the last 1% doing it this way. Running this low there's a risk of false syncs with passing cloud, so that's why the CDT is 5 min.

These are plain flooded cells, and 14.8V isn't necessary. They'll still charge pretty fast at 14.4V.

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Answer 9 · 2022-10-11T20:53:01Z

bikerchic49 answered · Oct 11, 2022 at 08:53 PM

So I made the changes that you suggested and it appears to be working properly now, it was the solar wire on the wrong side. The only other thing I'm in question about is the voltage that Renogy is showing in the app. As I have four 100 watt panels mounted and wired parallel. ( I know you can test each panel individually by crawling on roof and testing with multi meter, but doesn't the Renogy app that shows the voltage coming in not a good indicator without testing with multi meter? )

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JohnC ♦ commented · Oct 12, 2022 at 03:10 AM

@bikerchic49

Good you've found the issue. Not sure what your concerns are with the Panel V, but as long as that stays a little above Battery V and shows Amps then it should be ok. This can vary depending on light, temperature and load, so usually only becomes a thing when there's no Amps.

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