Re: (ET) Multi-bank 12V chargers

[Ken Olum <kdo cosmos phy tufts edu>]

   From: "David Roden" <etpost drmm net>
   Date: Thu, 18 May 2017 15:45:27 -0400

   > they will not disclose the exact algorithm used in their charger. 

   Are they trying to sell to OEMs?  I don't know an engineer who would 
choose 
   a charger for his product if he couldn't get its profile details.

You would think so.  Minn-Kota mostly makes electric boat motors, so I
suppose boatbuilders would be likely to integrate motors, batteries, and
charging systems into their boats.

I found my conversations with Minn-Kota surreal.  I started with what I
thought was an innocuous question, "I bought your charger; could you
please tell me the profile so I can verify it is working as designed",
and eventually degenerated into them saying "We don't make all the info
on our items available to any and everyone so they don't try to steal
them."  I escalated and got a phone conversation with some manager
there, but he took the same line.

   > and the transition from absorption to float seems to me to be at a
   > rather low current. 

   If the battery is really fully charged, float current should start at 
zero.

   That said, IMO there's no reason to use a float charger with an ET.  It 
   might be different with your Ox, if it presents parasitic loads on the 
   battery when it's not operating.

Sorry.  I wasn't very clear.  In the absorption phase, the charger (on
the AGM setting) holds a constant voltage of 14.4V and the current
slowly drops as the battery finishes charging.  Then at some point it
decides it is done, goes to 13.2V float for 24 hours, and then shuts
off.  Presumably it decides the absorption phase is done because the
current has dropped to some level, and this level seems to be somewhat
below 1A.  I'm a little concerned that there might be some circumstances
in which this low current might not be reached, and batteries would be
overcharged.

I would not leave this charger connected indefinitely.  Even in the off
phase it watches the battery voltage and restarts the charging processes
if it falls below 12.6 (I think).  I understand the point, but I think
it is more likely to repeatedly go through the charging cycle
unnecessarily.  But even if it not completely "charge and forget", I
think it is at least "charge and forget until morning".

                                        Ken