JuncTek Battery Monitor vs Victron SmartShunt

Horsefly

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This isn't really a BMS topic, but I couldn't figure out what would be the right forum to post it in.

Back in November I purchased one of the JuncTek 400A battery monitors as discussed in this thread;

https://diysolarforum.com/threads/bluetooth-battery-monitor-0-120v-0-600a.28564/post-342574

I was too busy with other stuff, and am now getting ready to take a look at it. I've searched the board, and can't find too much about how accurate the Coulomb counting and SoC calculations are. Has anyone compared it with the Victron SmartShunt? The JuncTek clearly has lots more functionality, having a temp sensor, Bluetooth Interface, display module, relay control etc. But if it doesn't give an accurate reading of SoC, it may not be worth it.

Has anyone done a side-by-side comparison of the JuncTek and the Victron monitor devices? I'm thinking if you just put both shunts in series it would be pretty easy to compare them as a battery is put through charge and discharge cycles.

Edit to tag @kang lee here, as I think the JuncTek is his product.
 

sunshine_eggo

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I was too busy with other stuff, and am now getting ready to take a look at it. I've searched the board, and can't find too much about how accurate the Coulomb counting and SoC calculations are. Has anyone compared it with the Victron SmartShunt? The JuncTek clearly has lots more functionality,

This is laughable. Victron makes among the best battery monitors on the planet. Does the JuncTek offer the following:

Peukert exponent?
Temperature influence on capacity?
Accuracy?

having a temp sensor, Bluetooth Interface, display module, relay control etc. But if it doesn't give an accurate reading of SoC, it may not be worth it.

Smartshunt can be used with the same temp sensor as the BMV, so the only things it doesn't have are a display module and a relay.

Has anyone done a side-by-side comparison of the JuncTek and the Victron monitor devices? I'm thinking if you just put both shunts in series it would be pretty easy to compare them as a battery is put through charge and discharge cycles.

No comparison, but when I upgraded to the BMV, I haven't looked back. Ultimately, the Junktek was $50 I didn't get to put towards the BMV.
 

Horsefly

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This is laughable. Victron makes among the best battery monitors on the planet.
Easy there cowboy. I'm not here to say your girlfriend Victron is ugly. ;) I think I saw one of your posts where you said you have inappropriate dreams about Victron equipment. (I loved that comment! 🤣) I in fact already have a Victron SmartShunt and am happy with it, and I really like everything I see from Victron.

I'm just willing to consider the JuncTek if it does an almost Victron-like job, and adds the nice color display. The other people who use this system are not in the least bit interested in looking at an app on their phone to see what the SoC is. More importantly, I'm just experimenting to see how it does. I was just hoping someone has done a face-off of the two. I purchased the JuncTek with one of the discounts that were offered to forum members, and just opened the box for the first time.

I think I read somewhere else here that there is no way to enter a peurket coefficient or charge efficiency multiplier, which doesn't bode well for how it would do with SoC. It may be hard to do in my battery box, but I may try to put the JuncKet in series with the Victron and do a few cycles.

Now @sunshine_eggo I know you are going to say I should have just got the BV712 since it has a display, but that isn't where I'm at. The JuncTek was cheap, and if it doesn't do the job I'll just stay with the SmartShunt.
 

sunshine_eggo

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Easy there cowboy. I'm not here to say your girlfriend Victron is ugly. ;) I think I saw one of your posts where you said you have inappropriate dreams about Victron equipment. (I loved that comment! 🤣) I in fact already have a Victron SmartShunt and am happy with it, and I really like everything I see from Victron.

Sorry. I'm a little touchy. She's so sexy, but she has a Blunibrow.

Now @sunshine_eggo I know you are going to say I should have just got the BV712 since it has a display, but that isn't where I'm at. The JuncTek was cheap, and if it doesn't do the job I'll just stay with the SmartShunt.

I don't even have the BMV-712... just the 702. I don't need the bluetooth, and I sometimes forget there's a display at all.

Sounds like you're perfectly positioned to conduct your own testing and sharing with the group. :p
 

Horsefly

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A quick update. I have the JuncTek battery monitor hooked up in series with my Victron SmartShunt. I've done one full charge and then set the SoC (manually) on the JuncTek to 100%. I'm now doing a discharge for a bit.

This makes the 4th item that I have on one battery that should report SoC. Besides the JuncTek and the SmartShunt, I also have a Thornwave Labs PowerMon-5S shunt, and a JBD 8S 100A BMS.

One thing that I've noticed on the JuncTek and the Thornwave devices is that I can't tell how they calibrate themselves for SoC. The SmartShunt has three items that allow it to synchronize each time the battery is charged: Charge Voltage, Tail Current, and Charge Detection Time. During charging, once the charge voltage has been achieved and the current drops to the Tail Current and both stay there for the detection time, the battery is considered completely full and the SoC is set to 100%. In the case of these other two items, it seems as though they will eventually get out of sync and have to have the SoC set manually, which somewhat defeats the idea of using them as SoC monitors.

I'll try and do a couple of partial discharges and charge cycles to see how they all do.
 

sunshine_eggo

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I think they purely count Ah in/out and ignore anything over 100%. Since charging is less than 100% efficient, they eventually get mostly accurate when batteries are regularly charged to full.
 

Horsefly

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I think they purely count Ah in/out and ignore anything over 100%. Since charging is less than 100% efficient, they eventually get mostly accurate when batteries are regularly charged to full.
Yeah, I suppose if they just count the charge coulombs and stop at 100%, it will probably probably be pretty accurate at SoC during discharge, as long as the battery gets charged back to full fairly often.

That reminds me: The JuncTek and the PowerMon-5S also don't allow any user input for charge efficiency or peukert exponent like the Victron does. More reason why I'm not too sure how accurate these will be.
 

eabyrd

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Smartshunt can be used with the same temp sensor as the BMV, so the only things it doesn't have are a display module and a relay.
Smartshunt also lacks mid-point voltage monitoring that her big sister does ohhh soo wellll, but I do admit she is a cute petite little package and spot on as far as I can tell accuracy wise so I'm happy having both of them hanging around
 

Horsefly

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So I've done several somewhat shallow discharges (60-70% SoC) and full charges, and the BMS, Victron SmartShunt, and the JuncTek all track within 1% on the SoC percentage. For some reason the Thornwave Shunt (PowerMon-5S) goes down faster than the others, even though I've done a zero reset on the current a couple of times.

Anyway, I think I'll call an end to the test. The JuncTek has lots of pretty nice features, and as long as the battery gets a full charge now and then I think it will display SoC pretty well. I like the look of it. I'm going to leave the Victron SmartShunt in place, but I've got an idea for another place I can use the JuncTek.
 

Horsefly

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Yeah, I think I heard about something we had that we in the US thought we had named cleverly, and when we tried to sell it somewhere else (maybe China) it turned out the name translated into something not so pleasant. I can forgive them for the naming.
 

newbostonconst

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Thanks for the info....I have 2 Victrons....BVM-712 with dongle and Smartshunt. I never look at the display and only use the app. The smartshunt is only good for like 10 feet but the dongle works for like 100 feet in my house.

Love the idea of putting them in series....
 

Rickey

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This isn't really a BMS topic, but I couldn't figure out what would be the right forum to post it in.

Back in November I purchased one of the JuncTek 400A battery monitors as discussed in this thread;

https://diysolarforum.com/threads/bluetooth-battery-monitor-0-120v-0-600a.28564/post-342574

I was too busy with other stuff, and am now getting ready to take a look at it. I've searched the board, and can't find too much about how accurate the Coulomb counting and SoC calculations are. Has anyone compared it with the Victron SmartShunt? The JuncTek clearly has lots more functionality, having a temp sensor, Bluetooth Interface, display module, relay control etc. But if it doesn't give an accurate reading of SoC, it may not be worth it.

Has anyone done a side-by-side comparison of the JuncTek and the Victron monitor devices? I'm thinking if you just put both shunts in series it would be pretty easy to compare them as a battery is put through charge and discharge cycles.

Edit to tag @kang lee here, as I think the JuncTek is his product.
Junctek's KG-F firmware and mobile phone app have updated:
1, first update the firmware, then update the mobile phone app, you can set the full voltage, full current and detection time in the mobile phone app extension; the above three conditions reach the set value and the capacity percentage will be automatically completed by 100%;
3. Cumulative power only calculates electricity consumed during charging;
4. The cumulative capacity only calculates the capacity released when discharge;
5, the voltage in the mobile app, the scale range of the current instrument panel can be freely set, and the scale value of the voltage current curve also changes.
6, the temperature can switch to set Fahrenheit or Celsius;
 

Bigtruckin85

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Junctek's KG-F firmware and mobile phone app have updated:
1, first update the firmware, then update the mobile phone app, you can set the full voltage, full current and detection time in the mobile phone app extension; the above three conditions reach the set value and the capacity percentage will be automatically completed by 100%;
3. Cumulative power only calculates electricity consumed during charging;
4. The cumulative capacity only calculates the capacity released when discharge;
5, the voltage in the mobile app, the scale range of the current instrument panel can be freely set, and the scale value of the voltage current curve also changes.
6, the temperature can switch to set Fahrenheit or Celsius;
Upgrading the firmware is not very intuitive at least on my unit.
A problem I was having is the electricity consumption and elapsed Ah moved together and I didn't really understand what it was trying to tell me. After speaking with Kang lee (lee@junteks.com), he told me about a firmware and app update. The electricity consumption now work independently showing Kw into batteries, and Ah out from batts.
Initially on the app, I'd select upgrade firmware and the app would freeze. I found a video online that showed removing the temp sensor wire and shorting the 2 pins together. The green light on the box will be solid. You should then be able to go back to the firmware upgrade in the app and use code 000.
The updated app also is not super intuitive. They have added an "extended services" button in settings, which you enter code 0000. This will allow you to adjust the full and empty voltages. So the soc will reset when it reaches those points and stays there for an adjustable period of time with adjustable tail current.
There is also a new "after sales" button, which is where you can update the firmware using code 8610.
I'm really happy with the unit now that it's been updated. If I didn't have Kang's contact, I would have never known and probably given up on it.
 

Horsefly

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Upgrading the firmware is not very intuitive at least on my unit.
A problem I was having is the electricity consumption and elapsed Ah moved together and I didn't really understand what it was trying to tell me. After speaking with Kang lee (lee@junteks.com), he told me about a firmware and app update. The electricity consumption now work independently showing Kw into batteries, and Ah out from batts.
Initially on the app, I'd select upgrade firmware and the app would freeze. I found a video online that showed removing the temp sensor wire and shorting the 2 pins together. The green light on the box will be solid. You should then be able to go back to the firmware upgrade in the app and use code 000.
The updated app also is not super intuitive. They have added an "extended services" button in settings, which you enter code 0000. This will allow you to adjust the full and empty voltages. So the soc will reset when it reaches those points and stays there for an adjustable period of time with adjustable tail current.
There is also a new "after sales" button, which is where you can update the firmware using code 8610.
I'm really happy with the unit now that it's been updated. If I didn't have Kang's contact, I would have never known and probably given up on it.
Thanks for that @Bigtruckin85 - I'm sure I would have gotten pretty frustrated when I got around to trying to upgrade the firmware. You've bore the pain for the rest of us!

I was impressed that after I posted my thoughts about the synchronization factors that it was missing, the guys at Junkek reached out and we exchanged a couple of emails. They wanted my input, which is not real common these days. Anyway, it sounds like they implemented what I was suggesting, so I'm happy.
 

Bigtruckin85

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Thanks for that @Bigtruckin85 - I'm sure I would have gotten pretty frustrated when I got around to trying to upgrade the firmware. You've bore the pain for the rest of us!

I was impressed that after I posted my thoughts about the synchronization factors that it was missing, the guys at Junkek reached out and we exchanged a couple of emails. They wanted my input, which is not real common these days. Anyway, it sounds like they implemented what I was suggesting, so I'm happy.
They do seem really responsive to suggestions. I haven't had time to talk to Kang about it yet, but one thing I'd like to see is a way to save the daily in and out, or reset in and out independently of each other. I've tried to export the historical graph and it didn't really do anything. As it is, each night I write down the watts that went in and in the morning I write down what went out overnight. The trouble is you can't seem to reset those individually. In not sure what "current clearing" does, but data clearing resets both the in and out at the same time. So that creates a little inconsitancy unless you time things exactly right or just use a running total and do the math each day. Or I could just not worry about keeping track. Lol
 

Browneye

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Upgrading the firmware is not very intuitive at least on my unit.
A problem I was having is the electricity consumption and elapsed Ah moved together and I didn't really understand what it was trying to tell me. After speaking with Kang lee (lee@junteks.com), he told me about a firmware and app update. The electricity consumption now work independently showing Kw into batteries, and Ah out from batts.
Initially on the app, I'd select upgrade firmware and the app would freeze. I found a video online that showed removing the temp sensor wire and shorting the 2 pins together. The green light on the box will be solid. You should then be able to go back to the firmware upgrade in the app and use code 000.
The updated app also is not super intuitive. They have added an "extended services" button in settings, which you enter code 0000. This will allow you to adjust the full and empty voltages. So the soc will reset when it reaches those points and stays there for an adjustable period of time with adjustable tail current.
There is also a new "after sales" button, which is where you can update the firmware using code 8610.
I'm really happy with the unit now that it's been updated. If I didn't have Kang's contact, I would have never known and probably given up on it.

My unit is slightly different, a KG110F. I was able to upgrade the firmware to ver 1.1.12, which according to the app store is the latest update in the history summary.

The temp probe pin short doesn't light up the indicator solid green until you connect to it with the app.
I do not have a button in settings for 'firmware update', only 'after sale'. Selecting this required the 8610 input, then a firmware update code input of 000, and then it downloads and updates the unit.
Entering 0000 in the 'after-sale' does nothing. I don't find any other resets for amps out or watts in.

I also do not have an 'extended services' button in settings.

I was most disappointed in not being able to change the temp sensor to F. Clicking on the temp area only allows for calibration from 95-105%, nothing for changing the reading output.

I sent an inquiry to Kang Lee.

Otherwise it's been a really nice meter and seems to work very well.
 

Bigtruckin85

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My unit is slightly different, a KG110F. I was able to upgrade the firmware to ver 1.1.12, which according to the app store is the latest update in the history summary.

The temp probe pin short doesn't light up the indicator solid green until you connect to it with the app.
I do not have a button in settings for 'firmware update', only 'after sale'. Selecting this required the 8610 input, then a firmware update code input of 000, and then it downloads and updates the unit.
Entering 0000 in the 'after-sale' does nothing. I don't find any other resets for amps out or watts in.

I also do not have an 'extended services' button in settings.

I was most disappointed in not being able to change the temp sensor to F. Clicking on the temp area only allows for calibration from 95-105%, nothing for changing the reading output.

I sent an inquiry to Kang Lee.

Otherwise it's been a really nice meter and seems to work very well.

My unit is the KG140F. My app version is 1.4.25 with android. I had to delete the old one and rescan the code on the little box. It wasn't available in the app store and I had no way of knowing there was an update until I asked Kang about changing things in the app. It sounds like you might be on an iPhone though, so that might be why some things are different. This version did allow the switch to Farenheit which was awesome.
 
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