Battery Monitoring -- How I Done It --

[Dellmassive]

Battery Monitoring -- How I Done It --

Part #1

Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends are not cut short from lack of power.

Battery monitoring is even more important with Lithium Lifepo4 batteries as the voltage stays fairly constant for 90% of the capacity.

first off lets look at a few basic 12v meters.

here a great little unit that I've been using for ages....

you can plug it into your 12v socket and it will you you a basic voltage reading. . . .

Dual USB Car Charger - Jebsens Top Rated Car Charger with Two USB Ports, 4.8A/24W,


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But what do those numbers mean?

well, when the engine is not running it will show you the Voltage of the battery . . . from this we can get a rough idea of SOC "state of charge" or the DOD depth of discharge.


this chart is an idea for a SLA "Sealed Lead Acid" battery.

we can see that with a voltage of 12.4v the battery could be 80%.


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here is the same chart for an AGM battery, the type of battery on a T6 and stop/start car






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anf just for reference, here is a Lifepo4 leisure battery chart.








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One thing to note is that when you are drawing a load from the battery these numbers and readings will go a bit squiffy, this is due to something called volt drop. . . . its similar to water pressure in a pipe dropping when you open a tap. . . . . . . so these numbers are best observed when all your kit is switched off . . . .


here are another couple of examples of volt meters that can be hard wired . . . though it may be best to wire them through a switch so that they are not on 24/7

#1
LED small round Volt Gauge - XCSOURCE Car Motorcycle Waterproof Blue LED Digital Panel Display Voltmeter Voltage Volt Meter Gauge Black DC 12V MA1028: Amazon.co.uk: Electronics



#2

LED Slim Volt Meter - EEEKit Car Motorcycle Digital Voltmeter, White LED: Amazon.co.uk: Electronics



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So you get the idea of the voltage means at rest . . . but what about charging?

well you can you the voltmeter to monitor the charge voltage from your alternator, EHU, solar or DC-DC charger .. . . as a rough guide we have this for the smart chargers:

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What are the smart charger stages?

Adaptive three step charging, are configured for a three-step (or more) charging process: Bulk – Absorption – Float. (these values depend on the battery type, temperature, current - so are variable)

Bulk (14.6v - 15.3v) During this stage the controller delivers as much charge current as possible to rapidly recharge the batteries.

Absorption (14.6v - 15.3v) When the battery voltage reaches the absorption voltage setting, the controller switches to constant voltage mode. For lead acid batteries it is important that during shallow discharges the absorption time is kept short in order to prevent overcharging of the battery.

Float (13.2v - 13.6v) During this stage, float voltage is applied to the battery to maintain it in a fully charged state. When the battery voltage drops substantially below this level, due to a high load for example, during at least 1 minute, a new charge cycle will be triggered.

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Redarc BCDC1250D spec - https://www.redarc.com.au/Content/Images/uploaded/BCDC1250D Instruction Manual.pdf


REDARC BCDC1240 40A 12 V DC-DC -
REDARC 8065 40 A 12 V DC Battery Charger: Amazon.co.uk: Car & Motorbike

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If you have both the starter and leisure battery setup them it may be worth looking at two separate 12v monitors or look at some of the available dual voltage monitors, like this :




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Now these are all very nice, but what about bluetooth and your smartphone?

well these have been around a while now,

the first version i had was the CTEK CTX Battery Sense:

a nice small device that attaches to the battery and has a nice APP for your smartphone, when you are in range (10meters ish) it will update the phone and give you live readings of SOC and voltage/temp.

CTX BATTERY SENSE

CTEK Vehicle Battery Monitor - CTEK 40-149 Vehicle Battery Monitor: Amazon.co.uk: Car & Motorbike

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another option that i now favor is the Quicklynx BM2

Bm2 Battery Monitor: - QUICKLYNKS Battery Monitor BM2 Bluetooth 4.0 Device Car 12V Battery Tester Diagnostic Tool for Android iOS iPhone Digital Analyzer Battery Measurement Units: Amazon.co.uk: DIY & Tools



its a similar device, but gives more more data and a brilliant history readout so you can monitor voltage trends over night or then whole weekend . . . . similar to the CTEK but a bit better IMHO.

You can see the effects of the DC-DC charger above and its different stages and how that effects the battery voltage.


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Bm2 Battery Monitor: - QUICKLYNKS Battery Monitor BM2 Bluetooth 4.0 Device Car 12V Battery Tester Diagnostic Tool for Android iOS iPhone Digital Analyzer Battery Measurement Units: Amazon.co.uk: DIY & Tools


Part#2 to follow.


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Kit List And Stuff -- How I Done It & What I Use --
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Dellmassive`s -- "how I Done It" -- Thread
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• Charging:
• Battery Chargers - How I Did It -
• Battery Charging - Main Battery Earth Point -
• Battery Monitoring -- How I Done It --
• [Guide] Battery Maintainer (for Starter battery) -- How I Done It --
• Which Jump Starter?
• Seat Base Electrics, EHU+Charger+solar+install - How We Done It -

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[Dellmassive]

Battery Monitoring -- How I Done It --
Part #2

In part#1 we looked at basic volt meters.

now its time to look at power meters, these generally have a "current shunt" or "induction coil" inline with the circuit to monitor the power coming into and out off a circuit.

when connected to a battery you can use one to monitor the power that is being drained from . . . . . . and

also recharged too the battery. . . .

In fact this is exactly what VW use on the T6 EU6 Bluemotion/stop/start. . .

the shunt is connected to the negative pole of the starter battery and monitors all of the power coming and leaving the battery, from this the van "energy management system" can determine the SOC and DOD of the starter battery, it does this to keep the starter battery at approx 80% SOC for the stop/start/regen and also is what will disable the stop/start when have you heated seats/heated windscreen on.

the vans battery monitor is under the tab - here on the left:

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So what the difference compared to a voltmeter?

well these devices will give you a better under standing of the battery capacity and the used percentage...... once full/calibrated the battery monitor will read 100% . . . .

as you use your battery over time the monitor will track the % so its easy to follow your usage . .

The best part is this works in reverse too . . . so as you start charging you battery bank the meter will also show the charged percentage going back into the battery.

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My personal favorite battery monitor is the Victron BMV712 smart.

its bluetooth, and has a screen, and links up to other Victron kit.

BMV-712 Smart - Victron Energy

Victron Energy BMV-712 Smart Battery Monitor - https://amzn.to/2tGunE8



with the in-line version current shunt monitors you need to select one that is within your power usage, as an example the Victron comes with a 100A shunt, but a 500A shunt is available.

This device will show you many metrics for the battery SOC,DOD,voltage,temp,%,Time left to run, time left to charge. etc etc.

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other options are available:

heres one i got for testing the Lithium battery packs . . .

Induction loop battery monitor - https://amzn.to/394Q5Sx

DollaTek DC Ammeter,Digital DC Multimeter 0-90V 100A Voltmeter Ammeter Current Amp Power Watt Capacity Time Meter Battery Tester Monitor with LCD Screen Hall Sensor 12v 24v 30v 48v 60v 80v Voltage




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here is another great bit of kit . . . . I use these in-line with battery chargers and solar kit to monitor battery charge currents and watts . . . or just the power solar panels are generating in the summer.

you can also run 2 on a solar system to work out the efficiency, use one to monitor the solar coming from the panel and a second one to monitor the power being delivered to the loads or your battery bank.

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200A High Precision Power Analyzer Watt Meter Battery Consumption Performance Monitor with LCD Backlight for RC, Battery, Solar, Wind Power

Power Analyzer/Watt?Amp Meter -
https://amzn.to/2Qk6IBk



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Here is an option from Votronic that comes with a remote display:

100A 12V/24V SMART BATTERY SHUNT WITH LCD BATTERY MONITOR AND 5M CABLE

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine





So we can see that the power monitor is a great improvement over a basic volt meter.

you can use it to actively monitor your power drain and recharge rate.

This is especially effective when camping or in the wild when the meter will show you how long you have left running you fridge, LED lights and USB chargers over the weekend.


And on the flip side . . . . how long it will take to charge back to 100% via your EHU or solar etc.

More in Part#3


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Kit List And Stuff -- How I Done It & What I Use --
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Dellmassive`s -- "how I Done It" -- Thread
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[Dellmassive]

Battery Monitoring -- How I Done It --
Part #3

This part we look at Lithium LIFPO4 batteries and battery monitors.

in the most part people are using SLA batteries, ie AGM, EFB or even good old standard Lead ACid.





As we know you can only use 50% of the available capacity: Dc-dc Charger (for Leisure Battery) -- How I Done It --

The issue being is that in a leisure situation on a SLA (sealed lead acid) battery, you can only use the the top 50% of the battery power, its referred to a 50% DOD (depth of discharge) . . . it means on a 100Ah battery you can only use 50ah . . . beyond this the voltage drops too low to be usable and battery damage can occur... that means that if your leisure battery is only 80% charged in the first place . . . . and you can only use 50% . . . then you end up with 30% or less of your battery for your leisure applications . . . . . (this is not good and why your battery wont run your fridge and LED lights for a 3day camping trip =[ )




One of the reasons for moving to Lithium is the increased usable capacity to up-to 100%, as seen over here: Lithium Lifepo4 12v Batteries - - - Time For An Upgrade ? - - -


what we can see from the research and testing is that the Lifepo4 batteries have very little volt sag and very little voltage drop off . . . . . what that means is that the voltage drop cannot be used to determine the SOC or DOD like we can with a SLA battery . . . . . That means that with a lithium battery this chart is useless:




The lifepo4 battery will hold its voltage from 100% down to 5% . . . . and then drop of the cliff...

this was witnessed here: Lithium Lifepo4 12v Batteries - - - Time For An Upgrade ? - - -


and here:

Bm2 Battery Monitor: - https://amzn.to/2sMgRhP

That means that we NEED a power meter/monitor to quantify the SOC/DOD . . . .

With a lithium this is done by fully charging the battery and "resetting the meter SOC to 100%"

from this point on the voltage will basically stay constant, but the SOC will vary . . . so the only way to tell what power you have left is with the percent monitor or the Ah readout from your monitor . . .

Again this is where the Victrcon BMV712smart comes into play.

Victron Energy BMV-712 Smart Battery Monitor - https://amzn.to/372VibB





another interesting thing with lithium lifpo4 is the rest voltage is much higher than SLA. . .

they are very happy sitting at 13.5v or even 14.20v when fully charged . . .

which caused an odd situation when connecting up the BM2 battery monitors to them . . .

the BM2 readout for both Lifpo4s showed that they were charging . . .! even though they were just sitting there doing nothing . . .






. . . after a few emails to Quickinks the BM2 guys about the options for changing the charge float point in the BM2 they said it was not possible . . . but they had just released a new BM2 for Lithium . . . . (so a quick import from Legend in China later we have this . . . . .)




This as actually worked out to be the very same BM2 unit but with different firmware so that the battery charge/full/low settings are adjusted to suit.

Bm2 Battery Monitor: - https://amzn.to/398ILp6

Apparently these are the first 2 Lithium BM2 units in the UK !!

You can see the standard SLA version is loaded with V5 and the Lithium has V6 firmware.







SO thats why you need a battery monitor . . . . especially if you have or plan to run a Lifepo4 battery bank.

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Kit List And Stuff -- How I Done It & What I Use --
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Dellmassive`s -- "how I Done It" -- Thread
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[Dellmassive]

Battery Monitoring -- How I Done It --
Part #4

here are some readouts from the various monitors . . .

this is the 12v socket version . . . showing a normal 14.7v alternator charge during driving before the start/stop kicks in.



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This is a BM2 readout showing the 13.2v float charge from a Redarc DC-DC charger, the dips are the charger sampling the battery voltage every 100sec to keep an eye on things.



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This is a BM2 history readout - it shows the 24hr slot for 21/10/19, you can see the high peaks are charging phases from the Dc-DC charger.



next up is the CTEK monitor, showing the main starter battery.



and the next pic shows the AUX battery . . .





this is the front screen showing all available monitors,



Next we move onto the Victron BMV . . . again same van, and the AUX battery again.

Its showing a 100% SOC and a charging float voltage of 13.28v fromo the DC-DC.



this is a history view, the next tab over . . . . .



and the third tab - graph, This is showing a 1min slice of live data, its showing the float charge of 13.28v @ 0.4A from the DC-DC being disconnected while the DC-DC samples the battery voltage . . . . then re-applies the charge voltage causing a slight current spike that quickly settles.




Next up we have the BM3 APP, its a different version of the BM2 APP that allows multiple BM2 units to be monitored on the same page/timeline . . . .

you can see the live graphs for the battery's and current voltages.



this is the next tab . . . the history view . . . .



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This next pic shows a BMV monitor detailing a battery discharging . . . we can see the battery is at 12.35v and draining -0.8A (thats 800mA that my phone was using while charging)

we can see that its quantified as 11W, the battery SOC is 100% and we have an estimated 5days 10hours of run time before the battery is depleted . . .



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trhe next shot shows lower down the screen, which includes the temperature and Relay state (which can be used as LTD for lithium batteries)



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Kit List And Stuff -- How I Done It & What I Use --
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Dellmassive`s -- "how I Done It" -- Thread
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[Dellmassive]

Installed some more battery monitoring...

we have 2x slim white Voltage monitors , , - https://amzn.to/38nvDeU

One for the starter and one for the Aux . . . . and a switch on the common neg to disable them.





with this switch (will be installed in the roof panel blank piece ) : https://amzn.to/3bnNcNM





below - https://amzn.to/3buBxNj





I've stuck them to the rear view mirror so they are easy to see . . .




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they have a nice crisp white display,

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and dont get in the way when driving . . .,




this is a random pic of this mornings sunrise . . . shortly after the above pics were taken . . .,




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here is this mornings readouts , , , the starter battery first:

(From the BM2 units : https://amzn.to/2tSkhRc )



and yesterdays 24hr view . . .



and the AUX battery : ( Connected via the Renogy DCC50S DC-DC charger (no solar))



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and again the previous 24hr readout . . .



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edit, more picks . . .



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[mmi]

and yesterdays 24hr view . . .

So smart alternator was doing 3 hours straight at 14.8 Volts? What was the temperature outdoors?

 

[Dellmassive]

So smart alternator was doing 3 hours straight at 14.8 Volts? What was the temperature outdoors?

yep, 100mile trip to work . . . 6-9am

temp @ 6degC . . .

Temp data:


my observations . . .


if starter battery is fully charged then smart alternator will just keep battery at static voltage with no charge @ 12.4V

when some accessories are switched on (like Radio/Nav, blowers on low) smart alternator will raise voltage to compensate to around 13.3v.

Regens will still raise voltage to 14.9V under breaking, then settle down again on acceleration.

only when larger loads are switched on (heated seats, heated mirrors, heated windscreen etc) will cause a steady 14.9v constant charge. . . . . - the LED headlights also cause this raise

If that starter battery is low you will get a constant 14.9v too.

so cold dark morning = 14.9v for the 3hr drive due to heated seats/heated mirrors, then LED lights.


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[Dellmassive]

in the interest of science and Data Analysis . . . . . here is the last 11 days of data logging for the starter battery. (Via BM2)

from 1st Feb 2020 to 11th Feb 2020:

@mmi this is for you . . . . And everyone else that likes this kind of stuff.

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[Dellmassive]

in the interest of science and Data Analysis . . . . . here is the last 11 days of data logging for the starter battery. (Via BM2)
from 1st Feb 2020 to 11th Feb 2020:

Here is the same timeline . . . . . but now with the Aux battery (again a BM2)

The Aux battery is the other-side of the Renogy DCC50S 50A DC-DC charger and has had minimal loads running. (USB chargers + LED lights etc)


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[Dellmassive]

some new monitoring data over here on the DC-DC thread . . .


Dc-dc Charger (for Leisure Battery) -- How I Done It --

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[goldeneye243]

I has some problems with my battery monitors - They disappeared from BM3.

So I removed BM3 from my phone but it appears to have gone from the play store too! Shame as I liked some of the features of BM3...

 

[mmi]

I has some problems with my battery monitors - They disappeared from BM3.

So I removed BM3 from my phone but it appears to have gone from the play store too! Shame as I liked some of the features of BM3...

Seems to be still available at ► BM3 for Android - APK Download

 

[Dellmassive]

** NEW PRODUCT **

Victron does it again . . . . . . https://amzn.to/3azIA5R

This time with the "Smart Shunt" Bluetooth battery monitor . . . . Yes Please . . .

I need one, and i need it now !!!

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Note that a difference between the SmartShunt and the BMV712 is that the SmartShunt has no visual or audible alarm; neither does it have a programmable relay.

All other comparisons with the BMV hold true: the SmartShunt operates in the 6.5VDC to 70VDC range; draws less than a milliamp; and monitors a battery capacity of up to 9999Ah.

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SmartShunt – new product launch
...the battery status monitor you view on your phone.



SmartShunt has been launched and is available in three models: 500; 1000; and 2000 Amps.

The SmartShunt is a powerful battery monitor with Bluetooth on board. It can be installed out of sight, behind the scenes – whilst live data from the device is relayed to your mobile phone or laptop via the VictronConnect App, which is free to use.

All the usual features are there – such as battery state-of-charge, voltage, current load, time-to-go – and all user-programmable settings …together with extensive historical information which allows you to analyse your system’s performance.

SmartShunt can be hard-wired to any ‘GX’ device
The SmartShunt can also be connected to any device in the GX family including the Colour Control GX and the new Cerbo GX using an optional VE.Direct cable. This provides the GX device with battery data for system control – and there’s no need to find room for a BMV display.

The SmartShunt can do more than comprehensively monitor your main battery bank – additionally you can choose to either:

• monitor the voltage of a second battery – the starter battery for example
• or you can connect a temperature sensor (optional accessory) for temperature compensated charging
• or you can monitor the midpoint voltage of your battery bank (cable included) to keep an eye on battery health.

Note that a difference between the SmartShunt and the BMV712 is that the SmartShunt has no visual or audible alarm; neither does it have a programmable relay.

All other comparisons with the BMV hold true: the SmartShunt operates in the 6.5VDC to 70VDC range; draws less than a milliamp; and monitors a battery capacity of up to 9999Ah.



Included in the box are two fused-cables for +I've connection; and for second battery – or midpoint – monitoring.

Prices start at €133 / £114 / $148 for the 500A model.

Dimensions: H x W x D:

500A: 46 x 120 x 54 mm

1000A: 68 x 120 x 54 mm

2000A: 68 x 120 x 76 mm

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SmartShunt - new product launch | Victron Energy

SmartShunt - Victron Energy


I've just grabbed one from Amazon . . . . get yours here > https://amzn.to/38rdk7C



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[hoggle]

@Dellmassive. If i was to buy another BM2 and use it on my leisure battery, can the app read both the starter and leisure batteries at the same time? Or do you need to download a 2nd app?

 

[Dellmassive]

The same APP will pickup multiple BM2 units....

I've got 6 or so running on the one app.....

You can look at each one at a time..... the is another app that will let you see both on the same screen......

But I prefer the standard app.

 

[Higgidav]

You can use the same app - just need to select which battery you wish to connect to. As far as I am aware you cannot view both batteries simultaneously.

 

[hoggle]

Iv'e just downloaded the App, and I'm hoping to fit the BM2 this weekend. So, i will just order another monitor for the leiasure battery. And what you doing with 6?

 

[Dellmassive]

Lol..... 6x BM2 units are...

T6 starter
T6 leisure.

Lifepo4#1
Lifepo4#2

Solar shed SLA battery bank.
Camping AGM.

And a couple of spares...

 

[goldeneye243]

I think that the BM3 app is what went wrong for me. It isnt available any more, which is a shame as it has some extra features...

 

[St4n99]

Am sure @mmi posted the link to the APK file further up the post and it works on Android