Multiplus- make it not charge batteries?

[pda1]

I've got a Multiplus 24 2000 and it works very well.

The problem I'm having is I lose all of the solar generated energy at the end of the day (let's say 2 kW) after switching from "Inverter" to "On". "On" will fully charge the battery and supply AC loads simultaneously. That's fine but I'm gaining nothing energy-wise as at the end of the day the Multi fully charges the batteries thus offsetting any solar gain. It would be best, I suppose, if the batteries weren't fully charged at the end of the day (or a certain SOC or battery voltage)

My only thought is there must be a solution to this problem.

How can charging be prevented when the batteries get low in SOC (any value but zero)?

I think the ideal would be to run on inverter throughout the day and then at the end of the day (no more sun) switch to Grid but let the batteries remain at whatever charge level they are at the end of the day then let the following day's sun charge them back up.

Any ideas?

 

[Adam De Lay]

I use the generator start/stop of the cerbo to control when the inverter uses grid power. I also wired another Cerbo relay to control when charging from the grid is enabled.

With both of these options, I can ensure I’m using all my solar power first (down to 15% SOC) before ever switching to the grid.

 

[pda1]

In my configuration whenever I use the Cerbo (Rsp Pi) I switch the Multi from "Inverting" to "On". Once it has been set to the option "On" it immediately starts charging the batteries and supplying AC to the loads. That's not what I want to do. I don't want the Multi to charge the batteries until they can be charged by solar the following day. However, I do want it to run the AC loads in the mean time.

 

[Adam De Lay]

Here’s how mine is configured.

You can use the rpi like I did, but it will take some extra work since the pi doesn’t have any actual relays on it.

Have you looked at the new “solar and wind” priority option?

Venus OS v3.10 - Solar and wind priority, Generator start/stop, ESS - Victron Energy

Good morning! Per just now released, a new version of Venus OS, the software on our GX monitoring product range such as the Cerbo GX, and the recently launched Ekrano GX. Lets get into the highlights of the v3.10 release: Solar and wind priority This is a new feature, designed for boats, vans...

www.victronenergy.com

 

[Checkthisout]

Looks like you just need to update your software.

 

[pda1]

My Rsp version, Venus os, is 3.11 and multiplus is 506.

 

[pda1]

Here’s how mine is configured.

You can use the rpi like I did, but it will take some extra work since the pi doesn’t have any actual relays on it.

Have you looked at the new “solar and wind” priority option?

Venus OS v3.10 - Solar and wind priority, Generator start/stop, ESS - Victron Energy

Good morning! Per just now released, a new version of Venus OS, the software on our GX monitoring product range such as the Cerbo GX, and the recently launched Ekrano GX. Lets get into the highlights of the v3.10 release: Solar and wind priority This is a new feature, designed for boats, vans...

www.victronenergy.com

Adam, in one of your videos you mentioned turning the charger off. I think it's the first video above. Where's that option located...in Assistants or Virtual switch options?

 

[pda1]

Honestly, I think I'm asking the wrong questions. This is so darn confusing.

 

[Adam De Lay]

Adam, in one of your videos you mentioned turning the charger off. I think it's the first video above. Where's that option located...in Assistants or Virtual switch options?

To completely turn off the charger, there's a checkbox in VE Config under the charging tab.

 

[Checkthisout]

The problem with your question is that why would the battery charge up again the next day if it's dead at the end of the day after the sun has gone down?

 

[pda1]

The problem with your question is that why would the battery charge up again the next day if it's dead at the end of the day after the sun has gone down?

When the batteries are low, in terms of SOC, I click the Multi's "On" box in the VRM and the Multi immediately starts charging the batteries and load with full grid power. During the day that's fine when I'm inclined to bring them to full charge. However, it would be nice to have AC pass-thru (I think that's the correct term) at will just like the following options in VRM;

The Multi in VRM allows me to select;

"On" (which provides grid charging supplemented by the SCC)
"Inverter only" all power supplied by the batteries and SCC
"Charger only" which provides AC to charge the batteries and loads
"Off" (I guess that turns the Multi off)

 

[pda1]

The problem with your question is that why would the battery charge up again the next day if it's dead at the end of the day after the sun has gone down?

I wouldn't let it go dead. (I hope). I want the sun to do all the work in providing (most of) the electricity. Charging the batteries with grid accomplishes nothing in energy saving, as I mentioned before, if the PV provides 2 kw during the day but I have to recharging of the batteries to full, or any level of charge, consumes 2 kw or more.

So, at the end of a nice solar day I'd switch to grid alone so that the grid doesn't charge the batteries and let PV charge the batteries to some level the following day.

Does that make sense?

 

[Adam De Lay]

When the batteries are low, in terms of SOC, I click the Multi's "On" box in the VRM and the Multi immediately starts charging the batteries and load with full grid power. During the day that's fine when I'm inclined to bring them to full charge. However, it would be nice to have AC pass-thru (I think that's the correct term) at will just like the following options in VRM;

So you're trying to charge up your batteries to full every day, regardless of whether it's from solar or AC IN?

 

[pda1]

So you're trying to charge up your batteries to full every day, regardless of whether it's from solar or AC IN?

I think I'm senile. No. The idea is to get the multi to not charge the battery to full once switched to "On" in VRM (that's a specific option in the Dashboard at near the top right of the VRM screen). Once the Multi goes in to Bulk the grid power really gets dumped into the batteries and I have to pay for that. Each day, it's not much, but that's not why I have solar- so I don't want to pay for excessive grid usage.

I want free power and don't want to pay the grid to recharge the batteries once the "On" is selected as mentioned above.

The more I think of it, it seems I'm trying to create a AC pass-thru and let the solar charge the batteries OR let me decide using VRM, when to charge the batteries with grid.

 

[Adam De Lay]

Then it sounds exactly like how I set up my environment in the two videos I shared. The only difference is that you're using the pi instead of a Cerbo and you would have to add your own relays to the pi.

You CAN program the inverters using the VE Config software when you want to Ignore the AC IN but outside of using the VenusOS Generator start/stop, I'm not aware of any other way to control those things using the VRM or the Remote Console.

 

[Adam De Lay]

I'm working on a video showing how you can perform the same tasks that the Cerbo can by adding relays to the Raspberry Pi/VenusOS.

 

[Brucey]

I think I'm senile. No. The idea is to get the multi to not charge the battery to full once switched to "On" in VRM (that's a specific option in the Dashboard at near the top right of the VRM screen). Once the Multi goes in to Bulk the grid power really gets dumped into the batteries and I have to pay for that. Each day, it's not much, but that's not why I have solar- so I don't want to pay for excessive grid usage.

I want free power and don't want to pay the grid to recharge the batteries once the "On" is selected as mentioned above.

The more I think of it, it seems I'm trying to create a AC pass-thru and let the solar charge the batteries OR let me decide using VRM, when to charge the batteries with grid.

Set it to this instead of On?

"Inverter only" all power supplied by the batteries and SCC

 

[Checkthisout]

It sounds like you want solar and battery until battery is down to say 10% and then you want the multi to kick on and allow pass through without charging the battery?

The cheat I would do would simply turn the charging amperage down to like "1" in the multi.

There are also some relays on the multi that can be linked to lots of different settings that could be used to activate a relay that controls incoming grid.

 

[bdbugbee]

Set it to this instead of On?

"Inverter only" all power supplied by the batteries and SCC

I've taken a little different approach to limiting when the Multi charges my battery. I use the AC In to serve loads when PV is not available and batteries drop to 20% SOC, but I don't want to charge my batteries too much from "AC In" so I simply lower my Absorption and Float voltages on the Multi's battery charger (my Absorption and Float are both set to 26.3V on a nominal 24V system). This floats the battery at around 25% SOC. I set Absorption at 28.4V and Float at 27.6V on my solar charge controllers so when the sun comes up they are doing the heavy lifting in charging the batteries. Then I switch the "Ignore AC In" function on the Multi by using the Cerbo Generator start stop function based on battery SOC (I "Ignore AC In" when battery SOC is above 30% and don't "Ignore AC In" when it drops to 20%). Adam De Lay has shown how to do that in his "Ignoring AC Input" video above. This gives me plenty of room in the batteries to maximize my PV output.

 

[pda1]

My thinking is that you're closer to understanding what I want to do. Now, I'm running the Rsp Pi and fiddled a bit with the Generator start and stop function but was too scared to try it for fear of seeing smoke pour from the Multi.

In truth, I've been watching VRM-ALL-DAY-LONG every few seconds (no, I'm not kidding) and then changing from Inverting to "On" when the loads increase to a wattage that'll drain the batteries faster than I want.