question

cmorewood avatar image
cmorewood asked

Help getting the best out of my sodium (salt water) batteries

The System 5.2Kw PV with a Fronius Primo 4-1 inverter interfacing with a Victron MultiPlus 48/5000/70-100 an a CCGX Gateway, 2 x Aquion S30-0080 48v batteries.

I'm new at this. The batteries have only been up and running for 2 months so I'm learning about them every day. I'm trying to get the most out of them, that is charging to 100 % and discharging to near zero every day. However the Victron unit is, I'm sure, preventing this as It's not designed to work with sodium batteries.

My problem is that unless the batteries have a 100% SOC for at least an hour during the day they will only discharge to a relatively high percentage SOC.

In the summer where the batteries have a 100% SOC every day the batteries will discharge to about 11%. ( I was hoping for lower)

At this time of year I'm rarely getting a 100% SOC via Solar and so have to use scheduled charging. However as soon as the charging is finished the discharging starts . But only to about 60-70%.

I'm beginning to think that there is a battery life protection built in to the Victron unit even though it is disabled in the CCGX.

My options/questions:

How do I enable scheduled charging and get the SOC to remail at 100% for at least an hour?

Is there a battery life protection built in within Victron?

Can I turn off battery life protection within the Victron?

As you can see in the first image, as soon as the SOC is 100% for about an hour (10-1100 )the battery will discharge more, down to about 40%. the other attachments show what happens if I can't get that magic hour of 100% the discharge is between 60 to 70%.

If the battery doesn't achieve 100% SOC the I'm left with about 80% SOC

I am planning in the winter to charge the batteries with cheap grid electricity at night, but if I cannot get the !00% SOC to last for more than a few minutes the batteries will never discharge fully, which is one of the reasons I chose the sodium batery.

Any advice gratefully received.

Thanks,

Chris

screenshot-20191020-194346.png(61.5 KiB)

Battery Protectdischarge levelAquion
screenshot-20191022-075544.png (62.2 KiB)
screenshot-20191019-101300.png (58.6 KiB)
screenshot-20191020-194346.png (61.5 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

4 Answers
JohnC avatar image
JohnC answered ·

Hi CM. Aquions are a bit of a rarity here, and I'm guessing too.

But I'm sure that custom settings in the Multi charger can do what you want if you define them correctly.

Your SOC worries me though. Unless you've a BMV (or some unknown bms), then you're likely sourcing that from the Multi (via the GX). That's not really adequate for total reliance, as it's quite coarse, and even then would need setting up to suit your batts.

Nor can I find sense in what it's showing. On your centre graph, it's even rising with loads on?? What's happening there??

I'd ignore SOC, and maybe delve deeper into VRM Advanced to select more useful graphs ('widgets' if you've never done it). Voltage, and time spent there is what you want to see for batt health.

But come back, plenty help available here with full info. Most of us don't like guessing, so mostly we don't..



2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

cmorewood avatar image
cmorewood answered ·

Thanks for your reply John,

The center graph is showing a sheduled charge plus the usage from the heat pump 2200 and 0530 which just happened to be at the same time on that day. ( I forgot my system time is setup on GMT) I try to keep the large useage events apart to avoid the high peaks, but I'm still educating the family as we've just moved from gas and this is the first Autum of the new regime.

I understood that the Aquions didn't need a battery monitor and they could be left to their own devices as no harm comes to them when they're discharged fully. I wanted simplicity which is partly why I chose them.

I don't have full control over the Victron System. I merely have monitoring control so there's only a few parameters I can change, The installation engineer has full control and as this was his first sodium installation, he's experimenting with the settings as well. I believe he has used the settings which Victron recomend for the Aquion and Greenrock batteries.

I thought I'd try to find out if there was anyone ion the Victron site who was having siimilar problems and how they'd solved them, so I could then pass on the information to the engineer. He's busy enough without me bothering him all the time with problems. If I can give him solutions to the problems, we can both learn.

I've attached the advanced page from the last 24 hours. I think this is what you were after John.

It has the scheduled charge times of 2100 0400 and 1100. I'm trying the 1100 to get at least an hour of charge into the batteries using the most productive solar period, so that I can increase their yield in the evening but as you can see, today, even with over an hour of 100% SOC the discharge stopped at 60.5%.

Unfortunately John I'm completly new to this and although I enjoy a challenge, this is a steep learning curve for what I thought would be the simplest of battery setups.



24-hr-graphs.jpg (72.4 KiB)
2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

JohnC avatar image JohnC ♦ commented ·

Ta Chris. The pics help, and you've selected them well. My random gleanings:

* Your Multi is cutting out at 41V, and your loads are then reverting to grid supply. 41V is awfully low, and (without looking it up) insufficient to keep it operating.

* Hence your SOC halts it's decline. It may not be at the point you desire to see, but it's being overridden by V.

* You (or your installer) could adjust the calculation parameters of the SOC in the Multi. Maybe lessen the batt capacity, or tune it's sync point under charge. You can make it show anything you want, as it's a calculated figure. I'd ignore it for now..

* Your system likely has ESS assistant installed. Bedtime reading for the benefit of your learning curve: https://www.victronenergy.com/live/ess:start

Victron pulled it's Aquion compatibility page, but this remains: https://www.victronenergy.com/live/battery_compatibility:greenrock

Maybe someone else with Aquion experience can chime in..



0 Likes 0 ·
cmorewood avatar image cmorewood JohnC ♦ commented ·
Thanks John, Yes I have been reading the ESS manual and trying to understand the new terms. The batteries should be switching off at 37.2 V so perhaps that is the problem? Meanwhile I have resorted to trying another method to keep the batteries charged during the day by manually switching on the Keep Batteries Charged function during the day and off again in the evening. If there is a battery protect operating covertly within the Victron system ( after the visible battery protect is turned off) then this should find it.

I've forwarded the thread to the installing engineerso he can have access to it.

Thanks for your suggestions John,




0 Likes 0 ·
cmorewood avatar image
cmorewood answered ·

Success!! I think I've proved that if I force the batteries to stay charged for a few hours I can get a deeper discharge, 37%SOC yesterday as opposed to the 60-70%SOC not using the technique. There must be a battery protect built into the ESS programming even when it is switched off?

I'll now delay the 2000 sheduled charge to see if I can achieve a deeper discharge today.


24-hr-graphs-1.jpg (81.7 KiB)
24-hr-graphs-2.jpg (31.8 KiB)
10 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

JohnC avatar image JohnC ♦ commented ·

Please try to be clear here. There is no 'battery protect' at play. The inverter is simply cutting out at that dreaded ~41V, and reverting to grid. It's still doing that.

Your 'success' is simply the longer length of time the batts have been under charge, and in better condition for the SOC to start it's decline.

If you really *must* look at SOC, try setting it's 'State of charge when Bulk finished' away from the default 85% (and I think I can see a kink @85% in your SOC graph under charge), say down to 50% as a test. Then you can watch it rise if the batts are still charging usefully. If the charge curve flattens at say 80%, adjust the 50% up by the shortfall (20%) to 70%. That should bring you closer at least to a little more meaningful figure.


0 Likes 0 ·
Show more comments
cmorewood avatar image
cmorewood answered ·

I found this manual online for the Aquion S series.

www.altestore.com/static/datafiles/Others/Aquion_S30_M110_Installation_Operation_Manual.pdf


Thought it might help someone

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Victron BatteryProtect product page

Additional resources still need to be added for this topic