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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329179 is a reply to message #329071] Thu, 15 February 2018 17:30 Go to previous message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
Senior Member
I am going to jump in here again now that the subject has changed to batteries and the charging there of.....

What I learned most of what I know about batteries, I learned sailing long passages with two men that survived as submariners in the Pacific during WWII. As they survived in a service that had huge losses, one must allow that these men were both knowledgeable and lucky.

They had all the instruments technology could provide. This included bank volt and current meters with 5 significant digit displays. Both conceded that there measurements were indicative, but not very effective for determining actual state of charge (herein referred to as SOC). Batteries are subject to many idiosyncrasies. They were so advanced, that they later in the war, they even had charge current integrators that reported to sum of ampere hours into an out of the Sargo (a BIG flooded cell) batteries. (How's that for a early version of a Trimetric or Victron?)

Both stated at that the only real way to evaluate SOC is by the electrolyte density.

I now have a Trimetric. The SOC it reports is very much in line with the electrolyte density as I measure it with a refractometer. Refractometers are not temperature sensitive. Mine was quite expensive when I purchased it, but there are now CCVs available at reasonable cost if you do not like the idea of a modern current integrator.

Other interesting things:
No two banks will ever be identical.
Even upon departing Electric Boat (in Groton CT where many were built) the engineers would be identifying differences.
Never could any two banks be charged in parallel and be brought to the same SOC. They had to be charged independently.
Discharging in parallel was less problematic, but still, one would go down faster.
Some things never change.

What prompted both of these discussion (that I actually managed to listen to all of - amazing for a lad of my age) was difficulties had with the house bank of three different vessels all in the process of traversing great distances without any support and having to count on the house bank to supply so much essential power. These discussions are why I have rerigged so many vessels with separate house and engine banks. (Kind of like how GMCs were shipped.)

Little aside for amusement. They had an evaporators onboard to distill sea water. Their first job was to make battery quality water. If they had running time left or the unit came out of spec for battery water, then they use that as potable water for the crew. Let's just say it was a tough life. Washing was not a big priority.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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