Balmar SmartGauge and Solar panel

[Val V]

My type 27 deep cycle battery recently died. I didnt know it was coming because only indication I had at the time was the boat voltmeter on the panel. During the day it would always show over 13+ volts which is the output from the solar panel. The solar is connected to the single house battery through ViewStar charge controller.
I went for a sail in the bay and the only thing running was my plotter. After the sun had gone down, the solar went off and the plotter turned off. Battery charge was about 11.4. So I gathered the battery must have not taking the charge anymore or not holding the charge and I was being fooled that all is good by the misleading voltage reading.

Now I replaced the battery with another exact type deepcycle and also purchased SmartGauge controller hoping to not be caught off guard. Installed the SmartGauge but the meter is now also getting fooled because during the day it reads the voltage from the battery which is again over 13 volts because of the panel. I called Balmar and asked the question about accuracy and they said the meter will get its reading at night when the solar is off but at night the boat isnt being used. Except for when I am sailing, everything is off while it's on its mooring ball.

@Maine Sail did extensive review of this meter. Even Balmar is using the review in their advertising, but there is no mention of how the meter would perform is the battery is continuously being charged (by solar panel in this case). Is there is any way to really know if the battery is not holding the charge and must be replaced?

Much appreciate anyone who would take the time to reply. Thank You!

 

[dlochner]

The Smartguage sensing wires need to be attached directly to the battery (fused of course) so the gauge is never turned off, unless it is disconnected from the battery. If you have it wired to the on/off switch, it will not read the state of charge correctly.

 

[Val V]

The Smartguage sensing wires need to be attached directly to the battery (fused of course) so the gauge is never turned off, unless it is disconnected from the battery. If you have it wired to the on/off switch, it will not read the state of charge correctly.

Thanks, this is already how it is wired.

 

[dlochner]

Thanks, this is already how it is wired.

Good, it wasn't clear in the original post, sounded like it was wired to a switch.

It takes the Smart Guage a few cycles to to accurately gauge the State of Charge. The algorithm that calculates it measures charge and discharge rates and voltage.

Until the battery is fully charged it will accept a voltage in the 13+v range. Once it has reached 100% SOC the battery voltage will remain high for about a day until it settles in to its resting state. On the Smartguage, the SOC reading is a better indicator of battery condition than the voltage.

 

[Val V]

The battery voltage remains over 13+ volts because this is the trickling charge coming from the solar panel. It stays like this all the time not just the first day. This is normal behaviour for the solar panel and the controller.
The problem is that SmartGauge all it sees during the day is that voltage and low amps and I dont understand how it can ever produce accurate results if the reading of the battery is tainted by voltage coming from the panel.

 

[Maine Sail]

The SmartGauge is an SOC gauge not a SOH (state of health) meter... You can learn to predict SOH by how fast SOC drops compared to how fast it used to... It is most accurate when not charging but even when charging the SOC can be as accurate as 10% once it learns the banks behavior.

For SOH you need to run a physical capacity test such as a 20 hour test or an RC test (20 hour more accurate with used batteries) or conduct a conductance test. Conductance testing is only really reliable for predicting cranking health not house bank health..

 

[dlochner]

The Smartgauge only reads voltage, it does not read amps. Here's one of the original technical articles that describes the difference between SOC based on amp counting and the SOC that comes from the Smartguage.
http://www.smartgauge.co.uk/sgvahrs.html

It is most accurate when not charging but even when charging the SOC can be as accurate as 10% once it learns the bank.

The key statement here is "once it learns the bank." When the SG is first connected to the battery bank it guesses at the SOC and starts at 75% (? could be 80%, can't remember) and then begins estimating SOC based on the charge and discharge cycles. With each cycle it becomes more accurate.

 

[walt]

I dont know if this is related to the OP problem or not..

A while back, there was a post here where someone was using an ACR (battery combiner) that would switch in a second battery when the battery voltage got over 13 volts (or so.. maybe depends on the particular ACR).

The switching in and out of the second battery apparently confused the Balmar gauge. I dont remember what the resolution on this was or if there was one and this configuration is of course fairly common for keeping a backup battery charged.

Is the Balmar meter accurate if you have an ACR in your battery setup?

 

[dlochner]

The Smartguage can monitor 2 battery banks, but can only calculate SOC on one bank. The other bank is voltage only.

I have an ACR and a SG and the ACR doesn't seem to bother the SG.

 

[Val V]

Wanted to update everyone on my further findings. Today I spoke with SmartGauge in UK since Balmar said they didnt actually invent it and just rebrand the one made in UK I figured I'd call the source. The guy there was incredibly helpful and in addition to speaking with me also replied with an email explaining few things. Email from him is below but the key for me the part about getting the reading from SG with either solar off or after dark.

"Many thanks for your call and your explanation of your sailboat electrical system and the installation of the Smartguage Battery Monitor.

I understand that you are concerned that the inclusion of a 100w solar panel into your electrical system will, by virtue of continually supplying your new battery with charge, ‘trick’ the smartguage into thinking that the battery is in good health when in fact the battery maybe declining in health.

Given that you have experienced this ‘collapse’ in battery health previously, I can understand your question.

The Smarguage Battery Monitor operates by watching the battery through it’s cyclical life and calculates the health of the battery based on those readings taken. You would have seen that the monitor reading would have started at a lower % State of Charge and over time it would have reached 100%, assuming that there is no problem with the battery.

If the battery was damaged, then you may see a high voltage very quickly displayed under charging conditions. Alternatively, if health of the battery is depleted, the SoC % will not reach 100% despite charging.

As your solar panel is 100w, and you have a single battery system, it maybe (depending on light conditions etc) that the panel will provide a sufficient charge voltage to keep the battery voltage as you would expect to see and potentially mask a battery problem. This is simply due to the fact that your battery is not cycling. If this is a concern of yours, you can perform a routine check by disconnecting the solar panel (if you have a switch arrangement) or alternatively, by covering up your solar panel. Alternatively, you can check your Smartgauge SoC readings after last light."