All About Boat Batteries

[NiceAft]

Russ said: "A bit pricey" I waited to purchase it until I was at the Annapolis Sailboat Show, all of the purveyors have show pricing.

Jimmy,

I took the photo in the dark, using a flash. I don't believe there were any open circuits.

[Jimmyt]

Jimmy,

I took the photo in the dark, using a flash. I don't believe there were any open circuits.

The plot thickens...

[Neo]

The plot thickens...

It sure does

[Jimmyt]

I would suggest you turn the charger on and check the battery voltage while charging. That will tell us if the charger is putting out. Should be over 13volts, likely over 14 at that state of charge.

[Neo]

This is intriguing ... I can't find a single 12v Battery monitor that doesn't use a shunt resistor .... My curiosity (of the SmartGauge) is killing me

News Flash! ... I just found this .. https://marinehowto.com/smartgauge-batt ... ring-unit/

And a technical explanation is pretty much all here ... https://www.navitron.org.uk/forum/index ... ic=13169.0

[NiceAft]

I have to tell you that what I just read is so far over my head, that the only thing I got out of it is that the Smartgauge is a quality piece of equipment that outshines others.

[Inquisitor]

This is intriguing ... I can't find a single 12v Battery monitor that doesn't use a shunt resistor .... My curiosity (of the SmartGauge) is killing me

News Flash! ... I just found this .. https://marinehowto.com/smartgauge-batt ... ring-unit/

And a technical explanation is pretty much all here ... https://www.navitron.org.uk/forum/index ... ic=13169.0

Was a great read, especially the methodology of how it works. Very interesting about how its using a database of capacity curves of lead-acid to determine where it is in the capacity range, even accounting for different discharge rates and resting. No wonder its so expensive. But also noted - "It falls flat on its face with LiFePO4 batteries, but this was to be expected because LiFePO4 has such a flat voltage curve as to be apparently unlearn-able." So, it doesn't help me.

Fortunately, the BMS that is needed anyway for monitoring and protecting the LiFePO4 cells ($110) also does the same sort of thing, but monitors individual cell voltages and uses an integrated shunt to track currents. The Bluetooth app permits human monitoring.

[Jimmyt]

Jimmy,
I don't believe there were any open circuits.

Ray,
I'm assuming that you meant all of the boat electrical stuff was "off". An open circuit is off. So, you basically said everything was on, which seemed out of context...

The gauge is doing so much thinking, it's hard to know what voltage is being shown. Instantaneous, resting? I would probably have gone with instantaneous voltage and use all of the thinking to display state of charge. But, who knows? Just don't like the 12.3v reading for a battery that's been on the charger.

[NiceAft]

Jimmy said:

Ray,
I'm assuming that you meant all of the boat electrical stuff was "off". An open circuit is off. So, you basically said everything was on, which seemed out of context...

See, over my head

[Neo]

It's worth investing in a cheap $25 battery load tester to see what happening with your battery. ....https://tinyurl.com/yyepz7k3

These dead easy to use .... and all the instructions are on the back. Monitoring is one thing ... but testing is "Something Else"
https://tinyurl.com/y3xd48bh

[NiceAft]

Today I got into the cabin and turned on the VHF, and cabin lights (LED). I also turned off the charger:.

The % charged showed 72%.

The batteries showed 13.05 V & 13.10 V

[Neo]

Today I got into the cabin and turned on the VHF, and cabin lights (LED). I also turned off the charger:.
The % charged showed 72%.
The batteries showed 13.05 V & 13.10 V

Without turning the charger again do the same thing again tomorrow as it may provide a bit more insight

[NiceAft]

You are asking to leave the charger off for another day. That will have to wait. 6:30 PM here, and too cool 39c and dark to start trying to climb through the tarp to get into the cabin.

Will have to wait to do it again.

Please come up with something other than “stuffed”

[Be Free]

I have to tell you that what I just read is so far over my head, that the only thing I got out of it is that the Smartgauge is a quality piece of equipment that outshines others.

If Rod at Marine How To can't understand how it works none of us are likely to figure it out. I wish I could justify the cost of one; they look very interesting. I had to settle for following his advice on properly installing an amp hour counter.

[Jimmyt]

You are asking to leave the charger off for another day. That will have to wait. 6:30 PM here, and too cool 39c and dark to start trying to climb through the tarp to get into the cabin.

Will have to wait to do it again.

Please come up with something other than “stuffed”

To be frank (tired of being me, anyway), I'm hesitant to say anything based on that meter. If it truly is in continuous learning mode, it is in the process of adapting (or has already adapted to) your new usage strategy of sitting in the driveway on the charger. So, the state of charge may be meaningless to judge actual usage. Now, if the meter occasionally imposes its own load test to take readings, that might explain some things.

My daughter and son-in-law have a learning thermostat. They both fiddle with the set point rather whimsically. Consequently, you might wake up at 2:00am, marinating in your own juices, to find the heating setpoint has mysteriously jumped up to 75 deg F because someone got up to feed a baby, and got cold a week ago. A learning device can be a great thing as long as you are teaching it correctly. Reminds me of idiot parents who have the baby in the shopping cart, watching the parent pick up stuff from the shelves and either put it in the basket or back on the shelves. The child watches this behavior, and upon getting it dialed-in, mimicks the behavior. Then, the "genius" parent slaps the kid around for having learned the behavior they just taught it... But, I digress.

Based on your latest numbers, the charger is putting out. However, the no-load sag to 12.3 volts is alarming. Also, after being on the charger for over 24 hours, I'm a little flummoxed by the 72% state of charge reading. So, short of performing the tried and true load test (as Neo suggests), and lacking access to other data from test instruments, I guess we'll have to go with the "Ray" method. As long as it cranks the engine, it's good to go...