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Old 26-02-2019, 06:07   #1
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Question SG200 State of Health calculation Help

Hi everyone. I recently installed a Balmar SG200 with the hope that it would give me an idea of how screwed up my batteries are. Unfortunately, after a few weeks of use, the battery monitor is still telling me that my 3+ year old bank of 5, 125AH Lifelines have a State Of Health of 100%. I am 100% sure that this is incorrect. I am fairly positive that I programed the correct initial battery bank capacity (625AH) and the correct chemistry (AGM), and that I wired everything correctly. I concurrently installed a 60 amp Sterling Pro Battery Charger (purchased form mainesail) and upon completion of this install, intentionally discharged the batteries to 11.7 V. When I unsuccessfully tried to start my motor at this voltage, the bank went to 10.5 V while the starter was turning the engine over. I immediately recharged with the charger and noticed that while the Sterling Pro was telling me that it was putting out 14.4 V during the latter part of the absorption phase, the SG200 and my other voltmeters were only showing 14.2 V at the battery with 5 amps still going in before the charger switched to float. I assume this is due to voltage drop and intend on replacing my battery switch and thickening up some battery cables. I am wondering if this possible voltage drop is causing the SG200 to not reset to a bank full state and making it unable to calculate SOH. Any Ideas?

I am living and cruising on the boat, at anchor in Pohnpei at the moment. I have about 400 watts of solar which when sunny puts the MPPT chargers into float. I know that I have been operating at a partial state of charge on these Lifelines for much of the time that I have had them. I have never equalized them but with this new charger intend to try that out soon. Between the Sterling charger and the battery there is about 5’ of 4 AWG to the buss bar and then another 4 feet of 01 AWG to reach the battery.

So my main question is how I get the SG200 to tell me the SOH of these batteries. I am wondering if it makes sense to bump the output voltage of the Sterling charger up to 14.6 theorizing that with the 0.2 V drop this will get the batteries to their 14.4 V and tell the SG200 that the taper charge / full battery voltage has been met.

Thanks for any input you electrical gurus might impart.

Grant Gardner,
S/v Viandante
Pohnpei, FSM
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Old 26-02-2019, 14:39   #2
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Re: SG200 State of Health calculation Help

Grant,

For the SG200 to calculate a SoH, it needs to see and identify a couple of events. The first is charge termination. I think it is a good possibility that the SG200 is not recording the fact that this has occurred. The difference you mentioned on the voltage readings could certainly play a role - have you checked/verified the voltage with a good handheld meter at the battery when the charge is finishing??

We can help you get this working, but it is a bit of question and answer, and best done over the phone, or through email.

Can you go to Balmar.net and open a case with us here: Contact Technical Support | Balmar

Thanks,
Chris


Quote:
Originally Posted by granche1 View Post
Hi everyone. I recently installed a Balmar SG200 with the hope that it would give me an idea of how screwed up my batteries are. Unfortunately, after a few weeks of use, the battery monitor is still telling me that my 3+ year old bank of 5, 125AH Lifelines have a State Of Health of 100%. I am 100% sure that this is incorrect. I am fairly positive that I programed the correct initial battery bank capacity (625AH) and the correct chemistry (AGM), and that I wired everything correctly. I concurrently installed a 60 amp Sterling Pro Battery Charger (purchased form mainesail) and upon completion of this install, intentionally discharged the batteries to 11.7 V. When I unsuccessfully tried to start my motor at this voltage, the bank went to 10.5 V while the starter was turning the engine over. I immediately recharged with the charger and noticed that while the Sterling Pro was telling me that it was putting out 14.4 V during the latter part of the absorption phase, the SG200 and my other voltmeters were only showing 14.2 V at the battery with 5 amps still going in before the charger switched to float. I assume this is due to voltage drop and intend on replacing my battery switch and thickening up some battery cables. I am wondering if this possible voltage drop is causing the SG200 to not reset to a bank full state and making it unable to calculate SOH. Any Ideas?

I am living and cruising on the boat, at anchor in Pohnpei at the moment. I have about 400 watts of solar which when sunny puts the MPPT chargers into float. I know that I have been operating at a partial state of charge on these Lifelines for much of the time that I have had them. I have never equalized them but with this new charger intend to try that out soon. Between the Sterling charger and the battery there is about 5’ of 4 AWG to the buss bar and then another 4 feet of 01 AWG to reach the battery.

So my main question is how I get the SG200 to tell me the SOH of these batteries. I am wondering if it makes sense to bump the output voltage of the Sterling charger up to 14.6 theorizing that with the 0.2 V drop this will get the batteries to their 14.4 V and tell the SG200 that the taper charge / full battery voltage has been met.

Thanks for any input you electrical gurus might impart.

Grant Gardner,
S/v Viandante
Pohnpei, FSM
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Old 27-02-2019, 02:43   #3
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Re: SG200 State of Health calculation Help

I'm sorry I can't help. Did you read this thread on the Balmar in 2018?


Balmar SG-200 Battery Monitor
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Old 27-02-2019, 03:12   #4
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Re: SG200 State of Health calculation Help

Quote:
Originally Posted by witzgall View Post
...We can help you get this working, but it is a bit of question and answer, and best done over the phone, or through email.

Thanks,
Chris
I've been waiting for your response as nobody else had chipped in - so thanks for responding.

Yes more information is needed to get to the problem - but I would suggest that the error could come from your Installation manuals SUP-0250 REV A and REV B where the installation diagram is incorrect. The common terminals from the auxiliary batteries (probably starter batteries) are going to the batt (-) terminal on the shunt and not to the 'cable' common neg bus side. This means that any charging coming from the auxiliary engines will not show on the SG200 and any discharge from the starter motor will also not show because these are not connected to the common-ground bus.

Most installers will not move the alternator negative on the engine block to the common negative bus. Also any other charging or discharge sources must go to the common negative bus or the SOH will never be accurate. This has always been a major problem with shunt based battery monitors and is why my original Smartgauge has always been accurate. I also recommend every one with a Smargauge has a charge discharge ammeter.

On your website (SG200 Battery Monitor | Balmar) the installation diagram is correct but when you click 'download manual' you get REV B where the diagram for the aux battery negative cables is incorrect.

This possible installation error can be checked by reading the current on the SG 200 from the engine alternator when charging and from the starter motor when starting from the main battery bank.

This is a major error and will have caused all installations to be reading incorrectly. Even with the correct installation diagram many installers of shunt based systems forget to move the common negative from starter batteries to the shunt common negative as they assume this would mean that the starter battery drain will show up as a discharge on the main battery bank monitor.

All shunt based battery monitors will also read incorrectly if new load or charging sources are installed by connecting directly to the main house bank and not going via the common-ground. This should be highlighted in the installation manual.
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Old 27-02-2019, 05:58   #5
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Re: SG200 State of Health calculation Help

We are aware of the issue with the drawing, which is why it has been changed on the website, and will be soon in the manual. The majority of installations will not run those extra negative cables, they are only needed in isolated ground systems. You are correct, in those instances the current measurements could be quite off. In the corrected drawing, only a small percentage of the current will be mis-read. There would be parallel paths to ground in those cases, but of course the majority of the current would be carried in the heavy battery cables, and not in the presumably small gauge extra wires.
We never intended the current from starter batteries to be measured, as you seem to imply. The aux leads are for voltage only. The lesson is don't run those extra wires unless you connect the voltage leads and get no readings. Then, use small gauge wires back to the shunt as the corrected drawing shows. Don't forget the fuse at the battery end!



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Old 27-02-2019, 07:50   #6
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Re: SG200 State of Health calculation Help

Chris
Thanks for your quick response, but I think you have misunderstood my post. I shall send you a PM.

The incorrect REV A&B diagrams will not show any charging current from the alternator. Just to clarify the common large negative charge/discharge cables don't go through the shunt. The new diagram on the website shows these correctly, but it doesn't show the extra negative voltage monitoring cable that you talked about, this needs to go from the battery (-) to the shunt voltage connection. You point this out in the manual:

Note: Negative Leads to Aux. Batteries are Only Needed on Isolated Ground Systems.

I'm afraid most users won't understand what an Isolated Ground System is!

I was also pointing out that using the old installation diagram that the current from the starter motor would not show up when the OP was trying to use the house battery to start his engine. This would give errors on the SoH, and of course the SoC. The SoC would soon correct itself.

When using the auxiliary (starter) battery of course you don't want the current to show on the battery monitor which is measuring only the House battery current. I was also pointing out that many installers think that your new wiring diagram might suggest that this would happen. The discharge current only goes back through the battery that is supplying the positive current to the starter battery. Likewise when charging the house battery the current only goes back through the negative cable of battery that is connected to the alternator - that is the engine block. This is why the starter battery and the house battery must have a common negative cable connecting the banks together - and this must go through the shunt.

I hope this clarifies my post.
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Old 27-02-2019, 22:36   #7
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Re: SG200 State of Health calculation Help

Thanks guys.



On my boat i just use the house bank to start my motor and do not have any auxiliary batteries. I am confident that all loads are on the correct side of the shunt. I basically just swapped out my old Link Pro and wired this puppy in its place so it was a pretty simple install.





Chris,

I have checked the voltage with my hand held units but unfortunately I cant say how accurate they are. They do seem to mostly agree with the voltmeters that are part of my solar chargers which are wired directly to the battery terminal. I have sent in a request to Balmar so hopefully someone there can walk me through this over email.



Right now I am mostly using the sg200 exactly as i did the Link Pro, as a simple amp meter. Would really like to get this SOH feature figured out since I am trying to decide if I am going to ship a set of Firefly halfway back across the Pacific.



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Old 27-02-2019, 23:12   #8
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Re: SG200 State of Health calculation Help

Do a 20h discharge test and you will know for sure
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