SmartShunt with Blue tooth monitoring.

[terry2]

Hi all, hope your all keeping safe and well.

I have always been after a blue tooth item that can monitor the cells using Bluetooth.

And I've found it well not me, by watch this video

[YouTube]https://www.youtube.com/watch?v=_GjcGZsK4fI&ab_channel=DIYSolarPowerwithWillProwse[/YouTube]

https://www.youtube.com/watch?v=0HG4GiH ... tronEnergy

It's the The Smart Battery Shunt by Victron in the Netherlands.

https://www.victronenergy.com/battery-m ... tery-shunt

It has a very good app Android and apple and PC

Is it way over spec? Oh yes
Does it cost two arms and a kidney? 100% yes

It's what I always wanted so I bought one from amazon.

I am just waiting for some 10mm lugs to before I can fit the bad boy

[Burgerman]

Can I ask you what you think it will achieve for you? And is it for lithium or lead you plan to use it for?

[terry2]

Can I ask you what you think it will achieve for you? And is it for lithium or lead you plan to use it for?

If you read the manual it tells you it's for lead or lifepo4

As I've said many times. I need to know the state of charge.
Remember I use my chair for everything. I can't drive a vehicle.

So all the functions it can do can be seen on my phone or tablet.

No more lifting the body up and getting at the cells.

[Burgerman]

You realise that a 100Ah lead battery can be a 30Ah one too? Just depends on how you use the chair. So knowing the state of charge by measuring Ah will be no better than the battery guage on the chair.

So for lead its pretty useless.

For lithium, if it tells you the range based on Ah used and you stick to say 80% max discharge it can be reasonably safe. But if you use a bms rather than a hobby charger its posible to have one cell go below 2.5V while the rest are still at 3.1xxV and kill those cells. So for lithium monitoring you want to see cell voltages. Not overall voltage and Ah.

The Ah remaining in a lead battery depends on discharge current.
An 8mph chair will give you say 35 Ah from a full 100Ah lead battery if you do 16 miles in 2 hours first thing non stop.
The same 8mph chair used for 1 mile here, another their, all day long will give you maybe 80Ah as you are discharging over 10 hours or so.
And if you do a mix of both as most of us do its anyones guess.

So do you consider 30A as a full battery or 90? 100% point is 20 hours = 100Ah.

1C means 1 hour. 0.5C means 2 hours.

[terry2]

You realise that a 100Ah lead battery can be a 30Ah one too? Just depends on how you use the chair. So knowing the state of charge by measuring Ah will be no better than the battery guage on the chair.

So for lead its pretty useless.

For lithium, if it tells you the range based on Ah used and you stick to say 80% max discharge it can be reasonably safe. But if you use a bms rather than a hobby charger its posible to have one cell go below 2.5V while the rest are still at 3.1xxV and kill those cells. So for lithium monitoring you want to see cell voltages. Not overall voltage and Ah.

The Ah remaining in a lead battery depends on discharge current.
An 8mph chair will give you say 35 Ah from a full 100Ah lead battery if you do 16 miles in 2 hours first thing non stop.
The same 8mph chair used for 1 mile here, another their, all day long will give you maybe 80Ah as you are discharging over 10 hours or so.
And if you do a mix of both as most of us do its anyones guess.

So do you consider 30A as a full battery or 90? 100% point is 20 hours = 100Ah.

1C means 1 hour. 0.5C means 2 hours.

What are you going on about? You're going off on one again.
I'm amazed you didn't post pictures of things like you normally do

I never mentioned a bms,

Once more for you.
If you read the manual it will tell you what the app can do. Remember the word "APP"
That's what I want it for.

[Burgerman]

Yes the APP will display lovely figures. I have read the manual. At least about half of it. But on lead they are meaningless. And on lithium they dont show cell voltages which is all you really need.

What are you going on about? You're going off on one again.

No I am trying to explain that it wont tell you much of any use on lead over the wheelchair display. It cannot tell you how many Ah you have left to use. That varies with how you use the chair hugely AFTER your reading, hence the chart you cant understand. So its almost as useless as the usual wheelchair battery meter for lead. That also reads amps and applies a peukert calculation.

I mentioned the BMS because with no PL8 currently available the cells can be miles out of balance on lithium and you cant know. So while the Ah reading will be reasonably reliable on lithium (practically no peukert) it doesent prevent 1 cell going below a safe voltage while the pack as a whole has 50% left... For lithium you must see all cells on your display individually.

I cant dumb it down any more I have tried. You dont want to know the important details. So I give up.

[Burgerman]

At very least get one of these and check periodically towards the last quarter of the charge as you turn in place or climb a ramp. https://www.banggood.com/ISDT-BattGo-BG ... rehouse=CN

[woodygb]

The Smart Shunt appears to at least make an attempt to involve Peukert in it's capacity / usage calculation.

Page 8

https://www.victronenergy.com/upload/do ... -IT-PT.pdf

[Burgerman]

Yes. The issue is this.

I set off in a fully charged 100Ah wheelchair at max speed for 1 hour headed to the bank and back. 1 hour at 8mph is about half the range, (8 miles) and around the 2 hour rate so its peukert correction thinks I am going to get only say 40Ah to 50Ah. So it thinks that you used 20Ah and are at 50% discharged...

Then when home I watch TV for a couple of hours. The battery then recovers much of its charge as the charged inner lead paste recharges the surface/acid face. Reversing the peukert corrction that it has applied. So now I have an 70/80Ah battery again and it thinks theres only 20 left. It recovers more the less its used during the day. So nowhere near the 50% point at 25Ah used it thought was correct. So I may have tons left indoors or outdoors at a later time after some time in recovery.

In other words it would be reasonably accurate if you didnt stop for a natter or to eat. OR go fast for half an hour hen slow or go back home downhill. It isnt accurate unless the discharge rate is reasonably constant.

I just think its a lot to spend on something that basically does the same thing as a wheelchar controller does now. And for lithium, it will be accurate in Ah, but has no cell monitor and thats really the only thing that does need watching if you travel long distances. For lithium there must be better monitors.

[terry2]

Yes the APP will display lovely figures. I have read the manual. At least about half of it. But on lead they are meaningless. And on lithium they dont show cell voltages which is all you really need.

What are you going on about? You're going off on one again.

No I am trying to explain that it wont tell you much of any use on lead over the wheelchair display. It cannot tell you how many Ah you have left to use. That varies with how you use the chair hugely AFTER your reading, hence the chart you cant understand. So its almost as useless as the usual wheelchair battery meter for lead. That also reads amps and applies a peukert calculation.

I mentioned the BMS because with no PL8 currently available the cells can be miles out of balance on lithium and you cant know. So while the Ah reading will be reasonably reliable on lithium (practically no peukert) it doesent prevent 1 cell going below a safe voltage while the pack as a whole has 50% left... For lithium you must see all cells on your display individually.

I cant dumb it down any more I have tried. You dont want to know the important details. So I give up.

Please do

[terry2]

The Smart Shunt appears to at least make an attempt to involve Peukert in it's capacity / usage calculation.

Page 8

https://www.victronenergy.com/upload/do ... -IT-PT.pdf

I will have to find the right settings for the shunt.
But it's a step in the right direction for what I want.

[terry2]

Yes. The issue is this.

I set off in a fully charged 100Ah wheelchair at max speed for 1 hour headed to the bank and back. 1 hour at 8mph is about half the range, (8 miles) and around the 2 hour rate so its peukert correction thinks I am going to get only say 40Ah to 50Ah. So it thinks that you used 20Ah and are at 50% discharged...

Then when home I watch TV for a couple of hours. The battery then recovers much of its charge as the charged inner lead paste recharges the surface/acid face. Reversing the peukert corrction that it has applied. So now I have an 70/80Ah battery again and it thinks theres only 20 left. It recovers more the less its used during the day. So nowhere near the 50% point at 25Ah used it thought was correct. So I may have tons left indoors or outdoors at a later time after some time in recovery.

In other words it would be reasonably accurate if you didnt stop for a natter or to eat. OR go fast for half an hour hen slow or go back home downhill. It isnt accurate unless the discharge rate is reasonably constant.

I just think its a lot to spend on something that basically does the same thing as a wheelchar controller does now. And for lithium, it will be accurate in Ah, but has no cell monitor and thats really the only thing that does need watching if you travel long distances. For lithium there must be better monitors.

It has settings for the Peukert
But you would of known that when you read the PDF

[Burgerman]

Yes I realise that it does even before reading that pdf file. I have looked at lots of their stuff over the years. Your wheelchair controller also takes that into account or they would be worse than they already are. They also take cable resistance etc into account nd use a rolling average. There is no way to have an accurate lead acid battery guage. Unless its at a constant rate discharge. But thats not what anyone in a powerchair. It would be better on a boat/solar system for a house etc. Also a 500A system is too high. It will reduce resolution. You really want something around 200A. Most of the time it will be drawing 10 to 20A. With occasional jumps to higher levels.

[terry2]

These are the options I get in the android app.

Now I will have to go through the manual for each option for Lifepo4, Then I can fit it.

But I don't have to calibrate the shunt and cells till I have the options sorted.

[Burgerman]

If thats the only settings then you need to click advanced or something?

What settings will you choose?

[Burgerman]

Burgerman: I cant dumb it down any more I have tried. You dont want to know the important details. So I give up.

Terry: Please do

And comments such as:
"You are going off on one again, what are you on about?"
Just shows your ignorance.

Any charger, can charge any battery badly. Most do exactly this. And thats why theres a saying "batteries dont die, they are killed". By ignorance such as you display above.

Why is it so complicated? Because IT IS. You might not like that, but thats the truth. You emailed tesla! Even if they had replied the answer would be way more complex than my replys! And you would just delete it because it was complicated... Batteries are NOT SIMPLE.

Tiny differences in settings, and currents and voltages is the difference between big problems sooner or later and a HEALTHY, reliable system that lasts many years.

Batteries and charging ARE complicated if you want to do it right. If you dont give a crap, then just carry on doing as you do. Details matter.

[terry2]

If thats the only settings then you need to click advanced or something?

What settings will you choose?

I'll let you know when I have read the manual.

[terry2]

Burgerman: I cant dumb it down any more I have tried. You dont want to know the important details. So I give up.

Terry: Please do

And comments such as:
"You are going off on one again, what are you on about?"
Just shows your ignorance.

Any charger, can charge any battery badly. Most do exactly this. And thats why theres a saying "batteries dont die, they are killed". By ignorance such as you display above.

Why is it so complicated? Because IT IS. You might not like that, but thats the truth. You emailed tesla! Even if they had replied the answer would be way more complex than my replys! And you would just delete it because it was complicated... Batteries are NOT SIMPLE.

Tiny differences in settings, and currents and voltages is the difference between big problems sooner or later and a HEALTHY, reliable system that lasts many years.

Batteries and charging ARE complicated if you want to do it right. If you dont give a crap, then just carry on doing as you do. Details matter.

It's just you making sure you do your 2-4 page answer.
You always do it. With the same things.

Other people answer people correctly. And not with a lot of numbers only you seam to use.
Others here have told you how you go on, and your all about the numbers.


This shunt is just to let me know what the cells are doing.
Not trying to do this, that, and the other.
If you don't like what I am doing. Don't post in it.
Oh by the way. When did you last have your calibrating stuff calibrated at the factory?

Just had my yearly calibration of my heart and breathing things.

Back on topic.

I haven't fitted yet as I am waiting for a friend in my bubble to come and make up new leads with 10mm lugs.

[Burgerman]

This shunt is just to let me know what the cells are doing.

Thats the one important thing. So you can see the NUMBERS for each cell. You know the numbers you dont want! And it cannot do that.
It cannot monitor cells at all only the complete pack. So its useless for lithium. That cell group level, is all that matters and it doesent measure that!
Thats why I commeted and tried to explain to you why. But obvioulsly you are on a different level.

Also, the numbers are the thing that matters. You dont get that. Thats not my problem but it will be yours though. You cant help some people.

When did you last have your calibrating stuff calibrated at the factory?

My fluke 289 gets factory calibrated every 2 years as recommended by fluke. And I have a resistance, current, and voltage reference too. Not that it matters to you you dont want to know anything.

[Burgerman]

I'll let you know when I have read the manual.

I already have. It wont help you one bit because it need the numbers that you dont know or want to know!
And even then, you need the knowledge you are not interested in learning. And it still cant tell you the cell voltages which is the single thing actually needed.

[terry2]

I have got the shunt installed and charge the cells to 100%
I picked these settings. Hope I have got them right

[Burgerman]

That depends on what you are expecting this to tell you. But right now it looks to be set to lithium ion so it wont tell you anything useful. It will tell you your battery isnt full when it is.

[terry2]

That depends on what you are expecting this to tell you. But right now it looks to be set to lithium ion so it wont tell you anything useful. It will tell you your battery isnt full when it is.

What makes you think that?

[Burgerman]

Those settings are not correct. It wont work for Lifepo4.

In fact its difficult to get that right on this chemistry anyway.

7 cell lithium ion would give you 29.4V since they are charged to (and then remain at) 29.4V. So going just .2V past that choosen voltage of 29.2V.

So provided that this setting is there to 'reset" the gadget to zero, and tell it its had a full charge, then its what you would choose for lithium ion 7S packs such as I use on my hobby stuff. And thats just the 2nd setting. On a low impedance lithium ion pack a 3 minutes at or above 29.2V would be OK to tell the device that its fully recharged and to reset to zero Ah and fully charged.

Is discharge floor of 20% basd on Ah claimed (setting 1) or voltage? Or some combination of both? Becaue if it uses voltage that will be wrong too as every cell has different chemistry and vastly different discharge curves. And so you need to be able to tell it the lowest voltage you want to go to. If based on Ah used, then it needs to be set to a lower figure. Or you will see an "empty" battery when you still have 36Ah remaining, the same as a full set of lead bricks.

Tail current? No idea what that does. Does it say?
Charged detection time of 3 mins is OK on lithium ion. But on lithium ion phosphate you need it to sit at full voltage on CV stage for at least 15 mins to show a full charge. And this depends on charge rate. So needs to be set to around 10 mins minimum. But that depends on the charge termination mA point you set on the PL8. This should be 15 to 20 mins at CV for a proper charge.

On current threshhold, I have no idea what this refers to. Does it say?

Isnt there a advanced button or anything?
When discharging how will you know when say cell 5 has gone too low? The problem is you dont. Its only a whole pack battery meter. Like the one in the joystick.

[steves1977uk]

I don't see the point in a SmartShunt when a cheap 8S cell voltage checker can be more useful.

Steve

[Burgerman]

I agree. But hes bought this now.

Tail current - Some lithium battery chargers stop charging when the current drops below a set threshold. The tail current must be set higher in this case.

So if you set say 250mA as the termination current on a PL8 then this should be set to say 500mA or even 1A or 1% of a 100Ah battery or .5% of a 200Ah battery? So that it can tell the difference between it ending the CC stage and the balance, and CV stage and determine if its really full or not? So what you set this to depends of what you set the termination current to in the PL8 settings. And must be greater. But not too much greater. Maybe double?

Discharge floor This setting is used in “the time to go” calculation and is set at 50% by default. But lithium batteries usually can be discharge significantly deeper than 50%. The discharge floor can be set to a value between 10 and 20%,unless the battery supplier advises otherwise.Important warning. Lithium batteries are expensive and can be irreparably damaged due to very deep discharge or overcharge. Damage due to deep discharge can occur if small loads slowly discharge the battery when the system is not in use. Some examples of these loads are alarm systems, standby currents of DC loads and back current drain of battery chargers or charge regulators. A residual discharge current is especially dangerous if the system has been discharged all the way until a low cell voltage shutdown has occurred. At this moment the state of charge can be as low as 1%.

But it doesent know the cell levels. So this setting is pretty much a guess. I would set to 10% and that leaves a 10% margin for individual cells discharging below that figure. Without wasting 36Ah of his battery!

The lithium battery will get damaged if any remaining current is drawn from the battery. This damage can be irreversible.A residual current of 1mA for example can damage a 100Ah battery if the battery has been left in discharged state during more than 40 days (1mA x 24h x 40 days = 0.96Ah).The SmartShunt draws <1mA from a 12V battery. The positive supply must therefore be interrupted if a system with Li-ion batteries is left unattended during a period long enough for the current draw by the SmartShunt to completely discharge the battery.

So fit a BATTERY switch as the chairs system also takes out power. An anderson loop, or a accessible battery plug etc or whatever is easiest.

As for the correct voltage at setting 2, then you want to choos a figure that shows its fully charged. So a safe figure is 3.5V per cell, or 28.4V.
Why? Because the current 29.2V setting is or should be way above the charge voltage of 3.6v x 8 = 28.8V And we charge at 28.8V and so this must be set at a little less like 28.4 to 28.6V to be sure we exceed this. In use a FULLY charged battery can be between 28.80V straight after charge, and within a hundred yards that will fall to 3.4V or below. Typically 3.38Volts or similar. The rate of voltage drop is far flom linear!

You might want to buy a cell log and check when the chair is near empty, to be sure you are not damaging a weaker cell already. With 10% in reserve that should not be an issue. But best to know.

[terry2]

I agree. But hes bought this now.

Tail current - Some lithium battery chargers stop charging when the current drops below a set threshold. The tail current must be set higher in this case.

So if you set say 250mA as the termination current on a PL8 then this should be set to say 500mA or even 1A or 1% of a 100Ah battery or .5% of a 200Ah battery? So that it can tell the difference between it ending the CC stage and the balance, and CV stage and determine if its really full or not? So what you set this to depends of what you set the termination current to in the PL8 settings. And must be greater. But not too much greater. Maybe double?

Discharge floor This setting is used in “the time to go” calculation and is set at 50% by default. But lithium batteries usually can be discharge significantly deeper than 50%. The discharge floor can be set to a value between 10 and 20%,unless the battery supplier advises otherwise.Important warning. Lithium batteries are expensive and can be irreparably damaged due to very deep discharge or overcharge. Damage due to deep discharge can occur if small loads slowly discharge the battery when the system is not in use. Some examples of these loads are alarm systems, standby currents of DC loads and back current drain of battery chargers or charge regulators. A residual discharge current is especially dangerous if the system has been discharged all the way until a low cell voltage shutdown has occurred. At this moment the state of charge can be as low as 1%.

But it doesent know the cell levels. So this setting is pretty much a guess. I would set to 10% and that leaves a 10% margin for individual cells discharging below that figure. Without wasting 36Ah of his battery!

The lithium battery will get damaged if any remaining current is drawn from the battery. This damage can be irreversible.A residual current of 1mA for example can damage a 100Ah battery if the battery has been left in discharged state during more than 40 days (1mA x 24h x 40 days = 0.96Ah).The SmartShunt draws <1mA from a 12V battery. The positive supply must therefore be interrupted if a system with Li-ion batteries is left unattended during a period long enough for the current draw by the SmartShunt to completely discharge the battery.

So fit a BATTERY switch as the chairs system also takes out power. An anderson loop, or a accessible battery plug etc or whatever is easiest.

As for the correct voltage at setting 2, then you want to choos a figure that shows its fully charged. So a safe figure is 3.5V per cell, or 28.4V.
Why? Because the current 29.2V setting is or should be way above the charge voltage of 3.6v x 8 = 28.8V And we charge at 28.8V and so this must be set at a little less like 28.4 to 28.6V to be sure we exceed this. In use a FULLY charged battery can be between 28.80V straight after charge, and within a hundred yards that will fall to 3.4V or below. Typically 3.38Volts or similar. The rate of voltage drop is far flom linear!

You might want to buy a cell log and check when the chair is near empty, to be sure you are not damaging a weaker cell already. With 10% in reserve that should not be an issue. But best to know.

Thanks BM for your help.

As soon as my lockdown is over(March 31st) and I can go out.
I will do runs to the NEC by me and back till the volts drop to 3.V using a ISDT BattGo to check.
Then using the info above I should get the shunt near enough.

Then in the summer I can go to the beach using just my chair, with a stop half way there
I already have a spare 6.8" phone and a phone holder. I will be able to keep an eye on things
as I will be going 11 MPH most of the time.

That is all I want it for

[terry2]

I don't see the point in a SmartShunt when a cheap 8S cell voltage checker can be more useful.

Steve

I will be traveling over 200 miles in my chair.
The last thing I want is to pull over and lift my seat\undo the cover and check the cells.
It could be pissing it down that day

So having the info with in eye sight is good.

[Burgerman]

Your chair will take very little current from the battery compared to a typical rear drive powerchair. Its a myra isnt it? If memory still works. So it doesent do tank steer and drives in the same way as a scooter. So instead of seeing peaks of up to hundreds of amps, you will see 10, 20, mostly with a few peaks a bit higher. As such you will get much more range than a typical powerchair. But because that current sensor can do 300 or 400? Amps its accuracy will be less than expected. You will only be using a small amount of its scale. So dont count on huge accuracy.

You dont need lift the seat if you just get a long 8s balance lead extention. Leave it hanging somewhere accssible. Tape it under the arm top.

Also as you will see speed makes little difference to how fast the battery gets used up. Because traveling in straight lines uses the lowest current. And traveling at say 5mph takes half the Amps that traveling at 10mph does. But it takes twice the time. So the net result is the same Ah per mile results.

That doesent apply to lead. Where taking higher currents for shorter time (going 10 mph) takes the same Ah per mile. But the battery has less Ah to give the quicker you discharge it. So going 5mph with lead takes you further.

[terry2]

After using the smart shunt for a bit I find it very helpful.

I can see the amps my chair draws on the fly.
No more full power from the off anymore.

I take it slow and build up to 11 mph.

Just got to run down the cells nd see if it matches the PL8. If not I can adjust things in the settings.