Multiplus 24v 3000va dc input restart value

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th3p4rk2 asked Feb 23, '19

Multiplus 24v 3000va dc input restart value

I have a multiplus 24v 3000va

It runs off of 4 x 210ah deep cycle AGM

When we are on sites we run the unit on mains power and leave our air conditioner running.

Last week someone tripped over the cable whilst we were out, losing mains power and so when we got home the batteries were completely flat.

Now the multiplus has an inbuilt function to prevent this occurring.

I have the cable and the VE configure 3 software.

I go to the inverter tab and the ‘Dc Input low shut down’ is set to the default value which is 18.60v. (Completely flat battery)

I want to change to 23.80v which should be between 35-40% of my battery capacity because going below 50% damages them and reduces life.

So I change the value to 23.80v. (35-40%)

Now there is also a value ‘dc input low restart’

This means if the inverter shuts off because the batteries drop below 18.6v, the inverter won’t work until they have been charged up again to this value.

The problem is the minimum possible value is 25.80. (Higher than a full 24v battery bank!)

When a 24v battery bank is full (100%) it should read 25.46 so the only way to reset the inverter is to have it plugged into mains charging.

Now this is a great idea in theory, it forces me to charge my batteries up completely if they become exhausted below my desired cutoff value of 23.80v.

The problem is, the low light switch is activated just by switching off the inverter. When you turn it back on, the low battery light becomes activated and the only way to restart the inverter is to plug into mains even though my battery bank is 100% charged. (Reading 24.56v)

Obviously not ideal on a Motorhome which is often 200km from the nearest PowerPoint.

Why can I not set this value below 25.80? I would like the inverter to begin to function again when the batteries are maybe 80% (25v).

Thanks in advance,

Tony

SOC

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Answer 1 · 2019-02-23T09:25:08Z

Paul B answered · Feb 23, 2019 at 09:25 AM

you cant do this because of voltage bounce it goes low on load that once the load is remoived the voltage bounces back up.

maybe use a BMV-712 and us the relay on that to open the remote switch.

or setup a assiatant in the multiplus to turn of when SOC gets to a nominated figure

you would have to turn on the internal battery monitor and this only really works if you don't have and other DC draws off the batteries.

here is a link to some assistant setup options

https://www.victronenergy.com/live/assistants:introduction

https://community.victronenergy.com/questions/8933/example-of-using-assistants-partial-off-grid-boat.html

the above maybe of help

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Answer 2 · 2019-02-23T11:27:00Z

JohnC answered · Feb 23, 2019 at 11:27 AM

Hi T. This issue seems to also be of concern to the Li people particularly. Maybe we can expect future improvements? Anyhows, some thoughts..

@ 24V, you have a min 2V to play with between min & restart. So do your best to find the right range.

I note you switch off the inverter. Fair enough to dodge the standby load. But when you switch it back on it will want to 'preload' it's caps, etc. So expect a downward spike on batt V when that happens. It can be fast, like a spark, but may influence what you see. (There's a clumsy way to workaround that, just ask if it's an issue).

Any sort of charge at all will soon lift batt very quickly if it's mostly charged, even a single panel.

If you're 'headin bush' though. maybe consider easing your settings before you leave. Given you may need ac to do that, hey.

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th3p4rk2 commented · Feb 23, 2019 at 10:12 PM

Would installing a ‘victron battery protect’ BP 65 fix this issue? I was hoping not spend more money on another product particularly given the inverter should be capable of doing this already but happy to order one if it will fix the issue.

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Answer 3 · 2019-02-23T23:40:08Z

th3p4rk2 answered · Feb 23, 2019 at 11:40 PM

Right, set back to default settings and will purchase a ‘battery protect’. Not happy that I have wasted $100 on the overpriced USB cable to use a setting that is essentially defective.

Now I have to spend another $70 on a product to do something I should already be able to do. Not impressed really, won’t be recommending the multiplus to others.

Feels like an apple product, buy the bare bones and then buy all the extras to keep the revenue coming in.

There’s no reason why I should not be able to have the unit cut out when the batteries reach 40% and then be able to either automatically restart or manually override when the batteries exceed my desired voltage, without the need to screw the front off and connect my computer to it.

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Answer 4 · 2019-02-24T02:06:18Z

JohnC answered · Feb 24, 2019 at 02:06 AM

I can sympathize with you getting 'excited' about this. Please try to understand it's the very nature of Pb batts that causes the issue and can easily show a 2V variation depending on load when the batts are not under charge. It's not an issue confined to Victron kit either.

I considered suggesting a BatteryProtect, but I didn't think it would help you muchly. You don't want to spend more, and I appreciate that too. An open budget would suggest a BMV, GX box, www, portal access, and email warnings. Nice, but I'm not suggesting that either.

In the washup, bigger batts may be the only real 'cure' for this.

But for now, you have kit that can at least be adjusted, and there will be an optimum point that may come close to suiting you. Have a go trying to find it.. good luck too.

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Answer 5 · 2020-06-16T01:21:45Z

Michael Riley answered · Jun 16, 2020 at 01:21 AM

I have a similar issue and live on a sail boat. Victron 24v/2 x 200 AH LIPO connected to a 24/5000 MultiPlus (+ Battery Protect x2, Venus etc.). The 'DC minimum restart' value is the issue. Updated to lastest VE.configure (90.04.220) running through CrossOver on a MACBOOK Pro via Victron Remote so do not need to unscrew the front panel. There is 'plenty' of energy left in the LiPO bank at 26.35V which is the 'minimum' value able to be set in VE Configure. Why? I understand that it should not be 'easy' to simply put in any value but as I understand it from Victron own doco/info the damage to this battery does not occur until cell voltage at 2.8 (22.4 V) and I am happy to run regularly down to 3.16 (25.3V) so why cannot the DC restart be say... 3.16v/cell (25.32 V). This information is available from the battery (Smart) or total from Lynx or Venus on my system. The MultiPlus appears to need to get into bed with the rest of the smart sibling devices and operate as part of the Victron team. It should be a simple enough matter to change the minimum value to '<read XX> from your minimum pre-alarm value set on the same VE.Configure page.

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Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 16, 2020 at 10:34 PM

Hi @Michael Riley

I don't really understand what you are writing, but...what firmware are you running on the inverter?

older firmware has some limitations on delta between shut-down and restart voltage, but shouldn't be an issue with LiFePO4 batteries...what shutdown and restart voltage are you using now?

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Michael Riley Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 17, 2020 at 12:57 AM

@Daniël Boekel (Victron Energy Staff) Perhaps it is my poor english. See attached (2 images) s/w for multi is 2614430 and the correct term is 'DC input low restart'; showing 26.35V. When I try to set lower limit it gives and error and states that minimum value is 26.35. Trust this assists.

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multi-24-5000-sw-version.png (265.7 KiB)

multi-dc-input-low-restart.png (133.9 KiB)

Daniël Boekel (Victron Energy Staff) ♦♦ Michael Riley commented · Jun 17, 2020 at 07:14 AM

Hi @Michael Riley

yes the restart-value moves with the shutdown value.

when you upgrade the firmware of the Multi, and use the latest version of VE.Config (or VictronConnect) you should be able to have these values closer together.

https://docs.victronenergy.com/victronconnect-vebus.html#firmware-updates

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Michael Riley Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 19, 2020 at 12:54 AM

@Daniël Boekel (Victron Energy Staff) I am happy with the explanations and reasons for the restart value being higher. Further, I understand that it moves as you change the value of the low DC. What I do not understand, and what you have not answered, is why with 400AH of LiPO (Victron Smart battery 24/200V x 2) 26.35 this is insufficient. This is approx 72% SOC and I believe this is sufficient level of energy to restart surely.

Put another way, are you telling me that I cannot effectively run my 'system' between 90% SOC down to say, 35% SOC, as is a 'typical' LiPO cycle, because on day 2 the inverter will not start (at approx 72% and therefore I have to wait for it to charge from solar before I can commence Day 2. Day 3 has a similar issue depending upon the solar yield the day before and my wife's cooking. I am on a sailing vessel, it is the middle of winter here in AUS. This seems to be more of a 'system' issue related to new technologies (LiPO) but see my next paragraph - which refutes this a little.

Can you state for me what would be the minimum 'restart' DC value for a 2,000 AH LiPo4 system (all Victron and all 'Shared Voltage Sense' available to the various components, as a comparison? I think that you are going to tell me it is the same value!!

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Michael Riley Michael Riley commented · Jun 19, 2020 at 12:54 AM

@Guy Stewart (Victron Community Manager) Hi Guy, are you able to wade in here also?

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Daniël Boekel (Victron Energy Staff) ♦♦ Michael Riley commented · Jun 19, 2020 at 09:29 AM

Hi @Michael Riley

Please don't @ mention extra people

recommended settings:

-shutdown voltage: I use 23 volts

-restart voltage: I use 25,5 volts

these values can be changed upon different systems, if you have a large battery bank, you generally don't reach such low voltages, but that's fine.

I don't understand what you mean by not being able to run between 90% SOC down to say, 35% SOC.

if you want to shut down on SOC, that is also possible in ve.config, but generally there is no need to do this.

basing SOC on voltage is not smart, as the voltage (especially under load) also varies on battery temperature.

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Michael Riley Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 19, 2020 at 06:21 AM

@Daniël Boekel (Victron Energy Staff) @Guy Stewart (Victron Community Manager)

Daniel, What a day I've had. With reference to your advice above I looked to update my 24/5000 Multi using Victron Connect. Getting my MacBook Pro to talk to the unit was a hoot because in updating the Multi you have to (according to Victron Doco) disconnect all other devices. As soon as I disconnected the VE.Bus BMS cable power was disconnected from the BP's and of course the Multi went dead - couldn't talk to anything. Took a lot of working around but as I have a secondary 12/3000 Multi I bypassed the 24/5000 and used this with the generator (remember I am on a yacht) and eventually I got the Multi powered and the USB Ethernet working at which point Victron Connect found the Multi.

Updated the unit via 'Product Info' and then started to check the configurations. Buried in the middle of these steps is the note about limitation of Victron Connect when using VE.Bus BMS and LiPo. Sort of got me going as you can imagine particularly when there is no warning about this limitation and you and others (Guy in video) generally indicate we should now use Victron Connect for updates. All sorts of lights flashing on the Multi and no charging or inverting.

Backed out of local and reconnected to VRM and at this point I got the error reporting 'no BMS Assistant found'. Hadn't connected to email so did not get VRM email warning of same.

So booted CrossOver and launched VE.Configure on MacBook Pro. Got update notice and updated VE.Configure - found no assistant in VRM downloaded settings so imported the assistant, changing the 'Bulk' setting SOC% to 98%, used the lowest DC restart setting and closed (saved). Uploaded this rvsc file via VRM and it all appears to be working fine. My Multi is now on ver 473 and will check tomorrow on how the restart looks. All's well that ends well but better doc on what the actual limitations are would have helped my heart rate a bit there for a while.

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Answer 6 · 2020-06-19T06:32:33Z

Michael Riley answered · Jun 19, 2020 at 06:32 AM

@Th3p4rk2. Sorry if your post got a bit hijacked there by a 24/5000 lithium issue on DC restart value for Multi. My apologies. Hope you are progressing your issue satisfactorily.

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