DIY Lithium

xsilvergs

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Looking more I will have monitoring with the daly app. what I am short of is as you say " getting the BMS info out into the wider world." Until someone hacks the Daly BMS!
Despite its cost the only way to get automatic action seems to be the victron bmv 712 with its programmable relay, with added Ve direct to usb. Is the RPi just for setup of the bmv and better monitoring than the little bmv screen

Look at Node-Red you can read ALL VE.Direct data from Victron devices and then control relays.

Node-Red is a graphical programming language so little code writing necessary.

List what you think you want to do.
 

Derekoak

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Hi xsivergs thanks,
I think I want to control charging from my 160 watt solar and alternator, both of which are processed through my ring rscdc 30 b2b at maximum 30 amp output. I think I have plenty of Ah at last, so I do not want to use the top and bottom of capacity. I think the b2b cannot be cut off from the battery so at a certain SOC I am thinking that both the solar and alternator feeds to the b2b should be switched off. That is 1 signal to 2 relays. Perhsps at a lower SOC they should switch on again. If 2 signals were available I could,treat the sources differently but I do not see the need.
I may want to switch off the sources for different safety reasons too maybe over or under temperature . Whatever those reasons are the same relays would work
I also have heat pads to warm the cells if they are too cold. A thermostat and relay might stop the b2b charging and heat the pads until a good temperature more simply than involving the Victron.
I would want the Soc settings to change depending on what we are doing. So for example maybe during lockdown a set of rules that kept the battery at 50% SOC.
when away in the camper charge off at say 80% on at 50%.
Maybe another set if after this drive we predicted not driving for days.
 
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Nabsim

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Looking more I will have monitoring with the daly app. what I am short of is as you say " getting the BMS info out into the wider world." Until someone hacks the Daly BMS!
Despite its cost the only way to get automatic action seems to be the victron bmv 712 with its programmable relay, with added Ve direct to usb. Is the RPi just for setup of the bmv and better monitoring than the little bmv screen
You do not need to buy a 712, you can get the headless shunt that has Bluetooth made by Victron. Just means you have to use an app rather than looking at a screen. I found you can do more on the app anyway
 

st3v3

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You do not need to buy a 712, you can get the headless shunt that has Bluetooth made by Victron. Just means you have to use an app rather than looking at a screen. I found you can do more on the app anyway

Yea, good bit cheaper too.
 

Derekoak

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You do not need to buy a 712, you can get the headless shunt that has Bluetooth made by Victron. Just means you have to use an app rather than looking at a screen. I found you can do more on the app anyway
Hi I would love to buy cheaper, but I want the device to act on the information. The daly app gives information but no one knows how to use the information to switch a relay. The 712 has a programmable relay. I think the shunt has not? If there was a cheap way to add a programmable relay then I do not need the little 712 screen. As you say the app is better.
 
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Geeky Philip

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Looking more I will have monitoring with the daly app. what I am short of is as you say " getting the BMS info out into the wider world." Until someone hacks the Daly BMS!
Despite its cost the only way to get automatic action seems to be the victron bmv 712 with its programmable relay, with added Ve direct to usb. Is the RPi just for setup of the bmv and better monitoring than the little bmv screen
The Daly BMS does come with a USB cable and I have connected mine to a PC to test it. It also has a programmable I/O port but I have no idea how to control that.
 

wildebus

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That sounds like it could be handy? Maybe someone on the Will Prowse solar forum will be looking at this and posting something?
 

Derekoak

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The Daly BMS does come with a USB cable and I have connected mine to a PC to test it. It also has a programmable I/O port but I have no idea how to control that.
That is the Uart port I mentioned I think?. I was searching on solar forums for that. I could not find anyone who has succeeded in linking it to an RPi yet I am not registered with that forum though so maybe I have restricted search.
 

Derekoak

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Yea, good bit cheaper too.
Even if a Bmv is the way to go spending £250 ish to get an uncertain increase in life for a battery pack and accessories that only cost £550. Some of the accessories almost certainly able to be reused if the batteries need replacing. The economics need justifying
 

wildebus

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Hi I would love to buy cheaper, but I want the device to act on the information. The daly app gives information but no one knows how to use the information to switch a relay. The 712 has a programmable relay. I think the shunt has not? If there was a cheap way to add a programmable relay then I do not need the little 712 screen. As you say the app is better.
The SmartShunt has two inputs - Battery +ve and secondry for either another voltage sense or a temp sensor. The only SOC Monitor in the victron range with a relay is the BMV-712 unfortunately.
Ref 712 vs SmartShunt ... I can see a big attraction of the SmartShunt for unattended installations and to save money. I have the 712 in my van (Got it before the SmartShunt was released) and even though I use a computer to check the info, I still like dropping the little flap in the motorhome to quickly look at the voltage. If I had a CCGX with the built-in screen or the optional display on the Cerbo then the Smartshunt does the trick IF the relay is not needed.

What could be very nice and a good value solution IF it were possible is .....
Have a SmartShunt and a Victron MPPT Solar Controller with a load terminal (100/20 or smaller).
Share the SOC information via the Bluetooth 'Smart Networking' in the same way that the voltage, temperature and current can be shared.
Add an option to the MPPT Config where you can enable the LOAD output based on SOC as well as on voltage parameters.
That would allow the Load terminal to work in the same way as a relay does and give you a programmable SOC setup for under £200 as well as a world-class battery monitor and excellent solar controller.
But it isn't possible :(
 

Petes

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I wonder what defines a cycle as far as lithium is concerned, maintaining lithium at 50% say in storage is fine but I think any charge that is applied is a cycle so this approach is unlikely to prolong the life. Quite happy to be shot down in flames on this but my ebike battery considers any charge a cycle as does my iphone.(I think)
I believe a better approach is to charge it to 100% then turn charger off until it reaches say 30% and then repeat charge. Havent figured out how to do that yet but I reckon the BMV relay output may do that.
 

Derekoak

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What stops that being possible? I guess the Soc data will not share?
It is a shame that after Victron has allowed Its OS to go on an RPi it also cannot receive SOC data from a smartshunt and then operate several relays
 

Derekoak

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I wonder what defines a cycle as far as lithium is concerned, maintaining lithium at 50% say in storage is fine but I think any charge that is applied is a cycle so this approach is unlikely to prolong the life. Quite happy to be shot down in flames on this but my ebike battery considers any charge a cycle as does my iphone.(I think)
I believe a better approach is to charge it to 100% then turn charger off until it reaches say 30% and then repeat charge. Havent figured out how to do that yet but I reckon the BMV relay output may do that.
There are several lithium chemistries lifepo4 is only one. I think your i phone is not lifepo4.
What I have read is lifepo4 can cycle for an indeterminately long period between random high and low points between about 25% and 75%. I read there is a memory effect although it can be erased, by absorbtion at a significantly higher charge. If that is true any fixed charge points are not very good. I am almost certain that it is bad to charge to near 100% and leave it there at all. I also do not know more than what I have read . No first hand experience at all!
 
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wildebus

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What stops that being possible? I guess the Soc data will not share?
It is a shame that after Victron has allowed Its OS to go on an RPi it also cannot receive SOC data from a smartshunt and then operate several relays
Victron do have a programme of continuous improvement so maybe some time in the future.
The Victron mains charger I bought a few years ago had new features added a few months ago and I could access them after doing the free firmware upgrade. I don't know any other company that provides that type of service other than Ablemail - and this is why TBH I seem such a Victron fanboy :)
 

Nabsim

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Dave I have the 700 with a Bluetooth dongle. I thought that has a relay built in? I know if has low and high alarm points that will output, that’s why I thought relay
 

wildebus

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Dave I have the 700 with a Bluetooth dongle. I thought that has a relay built in? I know if has low and high alarm points that will output, that’s why I thought relay
nah - it has all the alarm features, but not the actual programmable relay that operates on certain parameters

If you go into Victron Connect and click on settings, you will see a menu like this:
1618390752863.png

This is the SmartShunt. Yours will be the same I think except you will also have a "Display" menu listed

This is the BMV-712 settings ....
1618390845692.png

As well as the "Display" (missing from the headless SmartShunt), there is the "Relay" menu added.

This is what you see in the relay. A pretty flexible set of options there based on SOC and voltages of both main battery and aux (starter) battery (or temperature instead if you have a temp probe rather than the 2nd battery connection that I do)
You also have the ability to invert the action of the relay (depends what you are doing to what mode you want).
1618390913522.png
 

Nabsim

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Yes mine is like the smart shunt. You can use the alarm settings to trigger relays though can’t you? I seem to think it mentioned something about relays in the manual which is why I wasn’t sure if the alarm functions were the relay. It’s a long time since I looked at the manual though so I may be getting confused lol
 

wildebus

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Yes mine is like the smart shunt. You can use the alarm settings to trigger relays though can’t you? I seem to think it mentioned something about relays in the manual which is why I wasn’t sure if the alarm functions were the relay. It’s a long time since I looked at the manual though so I may be getting confused lol
maybe it is a generic BMV manual covering all the models, so talks about the relay in general terms?
Yup - just had a look ... one manual covers 700, 700H, 702 & 712 in 8 different languages.
(702 is like 700 but has the 2nd input for 2nd battery or temp. 700H is a high Voltage model (above 48V?) )
 

wildebus

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Going the DIY cable route can be a dead-end though. I found a device would randomly disconnect without warning. remove and reconnect and it would be ok for a while and inbetween another device would disconnect.
great if your idea of fun is frustration :( The geniune Victron VE.Direct-USB cables never have an issue (and there must be "something" in the big lump in the Victron cable which makes a difference?)
 
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