MacGregorSailors.com

The meter doesn't base SOC on the voltage. It bases it on the known amp/hr capacity of the battery and then calculates the SOC on following the amps that have gone out of the battery and into the battery and a few other parameters.

And that is the only way to do it with any degree of accuracy.

But that meter is definitely showing 8 AMPs going into the battery at 92% SOC -> A quick look at the M2 manual show it has a separate screen page for load <-

At 92% soc the internal resistance of the battery would prevent such a high AMP flow.

13.4-13.7 is a float voltage absorb is normally 14.4 plus and 8 AMPs is not an absorb current.

kadet wrote:

...But that meter is definitely showing 8 AMPs going into the battery at 92% SOC ...

I guess we still don't know if it is one battery or two or three?

Sumner

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1300 miles to the Bahamas and back -- 2015

The MacGregor 26-S

The Endeavour 37

Trips to Utah, Wyoming, Idaho, Canada, Florida

Mac-Venture Links

Batteries, geeze - we never worried about such things in the past - this is not stuff I am accustomed to worrying about. ALL the motors were pull start in my day and they were all very small and we rarely used them.

I'm in a different world now.

I am looking at some "Blue Sea Systems" meters for voltage and I need a place to put them, so I guess I need to make a dashboard for the meters to go on (there is not enough room where the panels are) so I guess I need to make a dash board over the dinette in that area where John put all those instruments and buttons and switches an stuff that he has. I guess I need to make a "dashboard" too.

I will start on the dashboard this morning - I anyone want pictures of the build as I do it? Or would you rather just see it when done?

I guess we still don't know if it is one battery or two or three?

Not sure what you mean by that as it makes no difference to the SOC and Resistance. Any 12v lead acid battery is more than one battery technically. 6volt is 3 in 1 and a 12volt is 6 in 1. By banking multiple batteries all you are doing is increasing the volts or AH capacity.

I suppose if they were wired poorly I would expect greater resistance but that would mean the AMPs should be lower.

But it would be nice to know what the actual setup is.

As I said in my first post on this Blue Sea make some of the best battery monitors but they are $$$

Many units around that do the same as the Bluesea, Bluesea may be slightly better quality but they are around 5 times the price of equivalent units.

around 5 times the price of equivalent units.

That's a bit harsh Mike, more like 3

I would think that 3 batteries @92 could accept more current than a single one,

Sumner

Sumner wrote:I would think that 3 batteries @92 could accept more current than a single one,

Sumner

Sorry Sumner I must not be conveying what I mean clearly, I am always criticised by my family and friends for being too technical

Batteries enter absorb state with a smart charger between 80-90% SOC as this is the percentage of SOC where the resistance begins to spike and the battery will not accept higher amperage. It does not matter if the battery is a single battery or multiple batteries. As the percentage is on the whole sum of the total. So whether it is a single 12v 125AH battery or 2 12v batteries in parallel or 2 6v batteries in series it is the SOC that leads
to internal resistance of the total that is the trigger for Bulk, Absorb or Float.

This is one reason in multiple battery banks it is recommended to re-charge each battery individually from time to time to equalise the SOC across the whole bank as if they get out of sync a single battery in the bank may reach full charge before the others, this will cause it's resistance to spike creating a false state and the charger will switch to absorb or float before the rest of the bank is up to charge.

And even though the Blue Sea does a good job of of calculating Volts AMPS and AH used and or returned there are so many other factors that determine the true SOC like resistance, temperature, health of the batteries, efficiency of the charging and type of loads applied that ultimately the SOC is still just an estimation and cannot be fully relied on. It is a better estimation than just taking a volt reading while the battery is under load or charge like most $20 battery fuel gauges do but it is no more reliable that an at rest voltage reading or doing your own calculation with a couple of $15 watt meters measuring charge and load.

And for the price of a Blue Sea M2 I would rather have a DC to DC MPPT solar charger for load balancing and maintenance of my house battery, but that is a whole other story I will try and document after I get my new motor fitted.

Mark
Here is a pic of my bulkhead dash board
http://i844.photobucket.com/albums/ab1/ ... smn962.jpg

I will b installing my Victron batt. monitor just below my sniffer alarm detector on the bulkhead
https://www.victronenergy.com/battery-monitors/bmv-700

http://i844.photobucket.com/albums/ab1/ ... kxugxu.jpg

Here is a full pic of the bulkhead dash board the Brass anchor bell has been removed since this pic was taken to make room for more instruments & will b reinstalled in another location at a later date
http://i844.photobucket.com/albums/ab1/ ... 428e30.jpg

Hope this gives u some idea,s , the reason I like to mount monitors in that location is because they can b seen from the cockpit without havin to go into the cabin to read them , just my preference

J
PS notice the grab handle installed there also makes a nice safety feature

kadet wrote:

around 5 times the price of equivalent units.

That's a bit harsh Mike, more like 3

With a MSRP: of $304.79USD and most places charging more I recon it is ore like 5 times.

When you can get a nice unit like this DC 8-80V 50A High Precision LiFePO / Lithium / Lead Acid Battery Tester Coulomb Counter for less than $25USD.
https://www.banggood.com/DC-8-80V-50A-H ... mds=search

Electronics are dirt cheap,its just the Marine electronics market that feel they can gouge you pockets.

Would someone help with a definition of a term? What is SOC? What do the letters stand for?

Herschel wrote:Would someone help with a definition of a term? What is SOC? What do the letters stand for?

system on a chip or system on chip (SoC or SOC) https://en.wikipedia.org/wiki/System_on_a_chip

Im pretty sure it refers to "state of charge" in this instance.

Lee Ward wrote:Im pretty sure it refers to "state of charge" in this instance.

That would be the correct answer

When you can get a nice unit like this DC 8-80V 50A High Precision LiFePO / Lithium / Lead Acid Battery Tester Coulomb Counter for less than $25USD.

Apples with apples not apples with oranges.

That is a dumb meter with no memory or learning of load/charge it is not a battery monitor just a meter like the watt meters I was talking about.

I was thinking more along the line of something like a NASA BM-1 compact