Victron Venus OS and a Rasberry

steveh57 said:
Hi Hoovie. Sorry long night escaping Devon. You're of course correct there is no smart networking with the Orion Smart-Tr. I currently have the SmartShunt, no BMV 700 . Just wondering whether I could/should automate the low temperature charging cut off to the Lithium Battery
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OK,
questions would be:
First... Does the BMS in the Lithium Battery have a GENUINE low-temperature charge-cutoff? If yes, then you are sorted. If no (and I say *genuine* as many cheap Lithium Batteries claim to, but don't really) or you are not sure, then something to consider for sure.

Next ... How to add? (And what I am about to say is part of the reason why I moved away from using a Raspberry Pi running Venus OS to a Venus GX and then a Cerbo GX)
You have a Smartshunt that you can use to provide Temp info to the entire connected setup via the DVCC options
This is mine - I use the Temp Sensor #4 as the Battery "system" temp - you would select Smartshunt Sensor in your example.
1627637661166.png

That will let your MPPT controller use the accurate 'dynamic' temp sensor.
The Victron MPPT internal temp sensor is not that useful - it reads once on controller wakeup, sets the parameters according to that temp and that is it until the next wakeup to get the next reading (a day later usually). The Victron Bluetooth SBS fixes that but is not compatible with DVCC as it needs smartnetworking - and DVCC won't allow that (at least currently. it might change?)

So that sorts the MPPT, but the B2B?


If you want a Solution to prevent the B2B from charging a Lithium at Low Temp, get a descrete setup. Something like this unit- https://amzn.to/3l8DXZj - and connect the probe to the battery and the relay output to the B2B (for example, replace the existing jumper with a pair of wires that go to the two relay connections on the device in the link, and set it so the relay opens when temp drops below 5C say.

The other - more expensive - option you have is to replace the Smartshunt with either a BMV-702 (not a BMV-700) or a BMV-712. you can then use the built-in relay on the 702/712 to send a control signal to the Smart B2B to turn off if the temp drops below 5C (or whatever you choose).
The relay on the BMV is not part of the DVCC setup and so cannot be remotely controlled by the Venus system, just directly on the BMV (via display or VE.Connect).

If you had a Venus GX unit or similar (Cerbo, CCGX, etc) with a programmable Relay, then you could set it up with an "Alarm" option to activate on various alerts (not tried that, so can't be sure of that).
With the Pi you would need to add this physical functionality. This kind of limitation, the cost of proper VE.Direct to USB cables and the extra features like multiple temp sensor inputs, tank sensors and digital IO inputs makes the genuine Victron GX units actually better value than the cheap RPi option.
(PS. yes, you can make DIY VE.Direct - USB cables; no, they are not reliable. For testing stuff, ok (and I still use them on my Venus/RPi test kit) but on a proper installation, you need a reliable setup.)
 
Thanks everyone, I'll look a bit more in depth when I've had a nap
 
If it was possible, a better solution might be to set the 'Limit Charging Current' menu option to a very low value (I've seen 400mA on some advanced BMSs) instead of just cutting off the battery completely with a relay. I'd imagine that below zero was exactly the time you most needed battery power, so cutting it off is less than ideal.
 
Maybe is just me, but how can you charge in sub 0 with the B2B? You will be driving at the time and the van will be warm already. A simple switch when B2B is not needed is more than enough. The BT temp sense works well networked with the solar charger. That’s all you want, not to charge when you not there. But once in the van, you warm up and flick the switch once the solar started charging. I have actually used the B2B less than 3 months since October 2019 when I installed it.

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Raul said:
Maybe is just me, but how can you charge in sub 0 with the B2B? You will be driving at the time and the van will be warm already. A simple switch when B2B is not needed is more than enough. The BT temp sense works well networked with the solar charger. That’s all you want, not to charge when you not there. But once in the van, you warm up and flick the switch once the solar started charging. I have actually used the B2B less than 3 months since October 2019 when I installed it.
Click to expand...
In winter, when it is cold and you get into the van outside the house to drive it it is not warm already, so VERY easily.
and if the battery compartment is outside and so not getting any heat from the interior, even more easily.
You maybe say "well, the battery won't need charging as it is parked up"? but if charging is disabled from solar and/or mains due to cold temp and it will accept charge, then the B2B will happily provide it when the engine starts, won't it? Opps, there goes another Lithium Battery!

Down Amersham way it doesn't get quite as cold as the more northern climes of the UK (up here we have the heating on 8 months of the year), but it still gets below 5C for a fair proportion
I don't have any external low-temp charging on my lithium as it has integral heating pads so it takes care of itself, but if it was a nomal lithium battery I would do.
 
Hoovie said:
In winter, when it is cold and you get into the van outside the house to drive it it is not warm already, so VERY easily.
and if the battery compartment is outside and so not getting any heat from the interior, even more easily.
You maybe say "well, the battery won't need charging as it is parked up"? but if charging is disabled from solar and/or mains due to cold temp and it will accept charge, then the B2B will happily provide it when the engine starts, won't it? Opps, there goes another Lithium Battery!

Down Amersham way it doesn't get quite as cold as the more northern climes of the UK (up here we have the heating on 8 months of the year), but it still gets below 5C for a fair proportion
I don't have any external low-temp charging on my lithium as it has integral heating pads so it takes care of itself, but if it was a nomal lithium battery I would do.
Click to expand...
Perhaps you jumping into conclusions to much. When is parked up, it doesn’t turn a wheel. When you board or before you board you do your checks for the vehicle like any responsible driver does, specially for winter driving. Like windscreen defrost. The switch is off anyways when you parked up, so it starts with off, not the other way round. If you really worried, this switch can be a thermostat to give you the extra comfort. Yes a simple analog boiler stat will work. I use a simple switch as I do my pre checks. If battery is above 85% soc I will not want the B2B to kick in, I control and decide when I want the help of the B2B. As for my winters, hm, my last was -22C, and when I left at the end of March, there was 8” of snow still on the ground. Amersham is the UK home only. We do travel to cold climates, more than others, and my battery bms does not have a cold temp protection charge. The solar does via batt sense. No better place to take temp reading then the batt itself. My bmv is next to the inverter charger that makes heat even if I boil a kettle. Again, you misunderstood this function. Nothing stops it charging when temp resumes above 4-5degC. At this time the B2B can be switched on. Since it’s only a 30a to a 400ah bank it’s quite mild rate at 4degC, and have plenty of loads if I’m driving. The fridge freezer and electrical gizmos draws around 100w easy. I have dvcc enabled and the SCS on another installation, but not for the reason you imply. It monitors the current going in the battery from bmv reading, and separates the current eaten by loads, by the current that makes it to bat, until tail current value is met. The charges haven’t got a clue where the current goes, with the SCS enabled via GX hub can achieve this. If my tail current is 2a, and loads are 2a, nothing is going in the battery. After the time set, the charger thinks is done, but it ain’t. Similar to midnite solar chargers with wizbang shunt. Much more precise .
 
Raul said:
Perhaps you jumping into conclusions to much. When is parked up, it doesn’t turn a wheel. When you board or before you board you do your checks for the vehicle like any responsible driver does, specially for winter driving. Like windscreen defrost. The switch is off anyways when you parked up, so it starts with off, not the other way round. If you really worried, this switch can be a thermostat to give you the extra comfort. Yes a simple analog boiler stat will work. I use a simple switch as I do my pre checks. If battery is above 85% soc I will not want the B2B to kick in, I control and decide when I want the help of the B2B. As for my winters, hm, my last was -22C, and when I left at the end of March, there was 8” of snow still on the ground. Amersham is the UK home only. We do travel to cold climates, more than others, and my battery bms does not have a cold temp protection charge. The solar does via batt sense. No better place to take temp reading then the batt itself. My bmv is next to the inverter charger that makes heat even if I boil a kettle. Again, you misunderstood this function. Nothing stops it charging when temp resumes above 4-5degC. At this time the B2B can be switched on. Since it’s only a 30a to a 400ah bank it’s quite mild rate at 4degC, and have plenty of loads if I’m driving. The fridge freezer and electrical gizmos draws around 100w easy. I have dvcc enabled and the SCS on another installation, but not for the reason you imply. It monitors the current going in the battery from bmv reading, and separates the current eaten by loads, by the current that makes it to bat, until tail current value is met. The charges haven’t got a clue where the current goes, with the SCS enabled via GX hub can achieve this. If my tail current is 2a, and loads are 2a, nothing is going in the battery. After the time set, the charger thinks is done, but it ain’t. Similar to midnite solar chargers with wizbang shunt. Much more precise
Click to expand...
you are jumping to the conclusion I am commenting about YOUR setup (even though I know nothing about it) and how YOU like to operate (again, I have no idea). I honestly have little interest in YOUR setup and it was not YOU who was asking the question I was answering.

Now to get back on topic, but with a bit of reference to YOUR input...
A manual switch can be forgotten about - so you either charge when it is a bad idea as you have forgotten to turn it off. or you are not charging at all as you forget to turn it on (that is a generic "you", not YOU btw).
I don't like relying on manual switches personally and think an automated enabler based on the conditions that are relevent (i.e. Temperature) is a much better idea. But each to their own
 
You missed the thermostat, switch works for me and others uses to, as it was suggested in the past, and I adopted the idea. Not for you? No problem. I let everyone decide for themselves, to their abilities and convenience.
 
Raul said:
You missed the thermostat, switch works for me and others uses to, as it was suggested in the past, and I adopted the idea. Not for you? No problem. I let everyone decide for themselves, to their abilities and convenience.
Click to expand...
I did miss it. All your stuff blurred into one very long paragraph (try a few line breaks occasionally?)

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Hoovie said:
I did miss it. All your stuff blurred into one very long paragraph (try a few line breaks occasionally?)
Click to expand...
PAX guys! This is a great thread that I am enjoying for the most part, very informative for many Victron enthusiasts.

I now have my Supersense tank sensors feeding into the Cerbo. I am looking for a way to get my Ruuvi sensors (in fridge and Freezer) onto the Cerbo too??

Screenshot (37).png


20210221_113148.jpg
 
Very nice looking run of CUs there :) My installs never end up looking that neat :(
If you find a way to use the Ruuvi, post it up! would be useful. I ended up just running a standard Victron Temp Sensor out the floor, across the van underneath and up again, then across, up and back again to get a Fridge Sensor. A wireless one would have been so much more preferable
 
Ruuvi have a gateway launching (I have paid my forward order) and I was thinking about linking it into the Cerbo through Modbus, but you can do it with your Pi, Here maybe. I have only gone the standard OEM route so when I come to sell I have a system that doesn't frighten the natives and that said the Cerbo has all the ports I need.
 
Hoovie said:
If you want a Solution to prevent the B2B from charging a Lithium at Low Temp, get a descrete setup. Something like this unit- https://amzn.to/3l8DXZj - and connect the probe to the battery and the relay output to the B2B (for example, replace the existing jumper with a pair of wires that go to the two relay connections on the device in the link, and set it so the relay opens when temp drops below 5C say.
Click to expand...
I do have a spare one of those relays somewhere, I was thinking that I could incorporate the D+ feed to the B2B into this relay.
 
steveh57 said:
I do have a spare one of those relays somewhere, I was thinking that I could incorporate the D+ feed to the B2B into this relay.
Click to expand...
any reason why you are using a D+ signal into the Victron Smart B2B?

You could easily use the D+ and the Temp relay together. Have the D+ go to the COM, and the NO then goes to the H line on the B2B.
 
Hoovie said:
any reason why you are using a D+ signal into the Victron Smart B2B?
Click to expand...
Thanks, Rightly or wrongly I assumed D+ was a better way of controlling the B2B than engine shutdown detection. Are you suggesting that engine shutdown detection is all that’s required or indeed something else
 
steveh57 said:
Thanks, Rightly or wrongly I assumed D+ was a better way of controlling the B2B than engine shutdown detection. Are you suggesting that engine shutdown detection is all that’s required or indeed something else
Click to expand...
it is not a bad thing to do by any means, it is just not a requirement for this B2B to work fine.
where it (D+) does work well is when you have a mains charger on the starter battery (maybe you need to give it a boost say), and if you are relying purely on voltage levels to activate, a B2B can come on and actually start to drain the starter if the mains charger is lower power than the B2B (don't ask how I know this :( ).
with the Victron B2B it is nice and easy to use the app to disable of course to get round that if not using D+ or an ignition signal.

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Hoovie said:
Very nice looking run of CUs there :) My installs never end up looking that neat :(
If you find a way to use the Ruuvi, post it up! would be useful. I ended up just running a standard Victron Temp Sensor out the floor, across the van underneath and up again, then across, up and back again to get a Fridge Sensor. A wireless one would have been so much more preferable
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Shelly have some wireless sensors which are wifi not BT like the Ruuvi tags, however they are like golf balls in size. I know some have used them fed into Grafana however my previous caveat applies. I was not happy with their size and vulnerability in the fridge and freezer. Returning to your DVCC implementation my reading of the feature was that it only works with can bus compatible batteries on the Victron list, am I missing something from the manual?
I am attaching a sheet from the Victron forum which I collated on the subject of ESS implementation. This is very useful where you are on a site with electric that is charged by the kW and you want to have all the benefits of EHU combined with UPS as well as utilise all the solar that your regulator can harvest. I have not implemented this yet and will look in depth this winter. However you may find its content thought provoking.
 

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sallylillian said:
.... Returning to your DVCC implementation my reading of the feature was that it only works with can bus compatible batteries on the Victron list, am I missing something from the manual?
...
Click to expand...
So on this point, a picture speaks a thousand words so they say?

Enable DVCC and turn on STS, and then choose your Temp Sensor
1627741103286.png

My Battery Temp Sensor is on input 4 of the Cerbo. For these screenshots, I changed the designation of the Fridge Sensor (on input 4) to "Battery" so I could select it (DVCC only lets you select Sensors that are flagged as "Battery")

1627741248639.png

So Red is Fridge, 'proper battery is Orange ....

My setup as it usually is ...
1627741370166.png



Change STS Temp sensor to Fridge for fun :)
1627741350416.png


So does DVCC work on devices that are not can bus? I would say yes. I think it is connection type agnostic.

Do the batteries have to be can bus for DVCC? I can't see any connection or relevance of DVCC to Can Bus specifically, or even to batteries of any type whatsoever to be honest.
The main purpose of the Temp Sensor is to adjust the voltage output of a charger to compensate for temperature changes*. That affects the charger setup only and is nothing to do with the battery setup. So in the example above the Absorption and Float voltage targets will have gone up at the lower temp as I have temp compensation enabled.

(*or to set a charge cut-off temp for lithium, yes).

sallylillian said:
I am attaching a sheet from the Victron forum which I collated on the subject of ESS implementation. This is very useful where you are on a site with electric that is charged by the kW and you want to have all the benefits of EHU combined with UPS as well as utilise all the solar that your regulator can harvest. I have not implemented this yet and will look in depth this winter. However you may find its content thought provoking.
Click to expand...

I have not really done anything with ESS as my use of Victron (and other makers) kit is not in static sites but exclusively in Leisure Vehicles/Boats and used primary for off-grid wild camping purposes.
I'll have a look at the doc mind as I do like to understand as much as I can on the kit :)
 
My mind was following the management of low temperature cut off for Lithium, if the BMS was not up to it, as back in other posts and was therefore engaged on that principle, where the Cerbo becomes active in the charging algorithm not passive.

On the ESS front the outline is a mobile proposition, I know that ESS is for Grid connection assistant but the ESS assistant can create the priority of solar over EHU if set up correctly, which is ideal for my mobile environment. Not a Victron approved solution I believe.

By the way I am not a professional, unlike yourself, I am working at the edge of my skill set and learn from others like you and what I read, and the mistakes I make. So thanks.
 
sallylillian said:
My mind was following the management of low temperature cut off for Lithium, if the BMS was not up to it, as back in other posts and was therefore engaged on that principle, where the Cerbo becomes active in the charging algorithm not passive.

On the ESS front the outline is a mobile proposition, I know that ESS is for Grid connection assistant but the ESS assistant can create the priority of solar over EHU if set up correctly, which is ideal for my mobile environment. Not a Victron approved solution I believe.

By the way I am not a professional, unlike yourself, I am working at the edge of my skill set and learn from others like you and what I read, and the mistakes I make. So thanks.
Click to expand...
I think I tried something with the ESS assistant a few years ago but can't recall what! (I have an terrible memory :( )
My approach to prioritsing Solar over EHU is fairly simple and basic, but does seem to work ... set the charge voltage slightly higher on the MPPT than on the EHU (or the B2B). This ends up with the EHU going into float (or storage even) earlier and any residual demands tend to be delivered by the Solar.
In reality it likely makes very little saving in costs, but I like the idea of using the 'free power' when it is there :)
 
You can have dvcc enabled on batteries that are not managed, the settings are just different, only what applies to your situation. DVCC is just a comms platform turning your GX into a managing hub. I use it on stationary Lead bank to control the current of solar chargers, shared voltage and temp sensor on ve buss.

The ESS does not work well in off grid, a mobile is off grid with generator and shore power support. You can implement the power assist and power control to prioritise solar harvest. In fact, when I have the generator on, it only takes what’s the deficit from solar in that present demand. The ESS assistant is intended where grid is present all the time. But things do change, since last time I used. Thinks do get added up on updates.

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Need a bit of advice with the DIY Ve Direct cables.

I made mine up with PL2303TA USB to TTL RS232 and not what Steve used ( PL2303HX USB to TTL RS232 ) and it does'nt work, anyone know what the difference is between TA and HX?
I have double checked the pin configuration and that is ok, do I need to power off/on the Solar charger for it to see the VE direct cable and Rpi instead of the dongle thats there at the moment?
 
Diabalo said:
Need a bit of advice with the DIY Ve Direct cables.

I made mine up with PL2303TA USB to TTL RS232 and not what Steve used ( PL2303HX USB to TTL RS232 ) and it does'nt work, anyone know what the difference is between TA and HX?
I have double checked the pin configuration and that is ok, do I need to power off/on the Solar charger for it to see the VE direct cable and Rpi instead of the dongle thats there at the moment?
Click to expand...

Could not find any specific info on the net setting out the difference between the PL2303TA and the PL2303HX.
Should be no need to power on/off your solar charger for the Pi to pick up the data flow.

Are sure you are using the correct pin out?

1639475751495.png
 
yes the same as your picture, the USB to serial shows up on my PC as Prolific USB-to-Serial comm port so that seems to be working at least on Win10.

I'm going back up the Van shortly to give it another try as I didn't have much time last time to faff about last time and brought it back to check the pin outs.
 
Not sure I can be of much help, I didn't deliberately buy the HX version, I just plugged the cables in and booted up the RPI. Looking at the MPPT the only setting I can see that would effect matters is the RX TX settings but why would they have been changed from their defaults anyways. I'm still on an earlier version of Venus OS 2.72. Do the devices appear in the device list on the remote console, is VRM online portal two-way communication enabled?. I assume Venus OS will log events so you should be able to tell whether the PL2302' are active- don't ask me how but presumably accessible via ssh. The PL2302 do require some power but I'm using 3 USBs on an RPi 3+ with a 2amp feed

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