You have it right if you are talking about an echo charger. The simplest 
explanation is that the echo charger is a relay that closes based on the 
differential of voltage between the two battery banks. It allows a controlled 
amount of current (Max 15A in the case of the one I use to charge the battery 
under the v-berth) to flow in only one direction. So you wire it with charging 
source on the house bank, and when the start battery is low and the house is 
charging the relay closes and delivers part of the charging current to the 
start battery. Start bank high and house bank low, the relay remains open.

 

An ACR is a bi directional device that also closes based on voltage 
differential between the two banks. If house is high and start low, the current 
flows to the start battery. If start is high and house low, the relay still 
closes and current flows from start to house. The Blue Seas ACR I did not use 
in my system will pass up to 120A between the batteries based on the voltage 
differential, so I really would not characterize it as a “controlled current” 
device. If the voltage differential is too great, the Blue Seas ACR will not 
close, which prevents current flow if one of the batteries or cables is shorted.

 

I think of a battery combiner as a temporary switch that puts the two banks in 
parallel regardless of the voltage differential. In effect it is an electronic 
alternative to the ALL position on the traditional 1-ALL-2 battery switch.

 

And in answer to another question about the impact of an ACR or echo charger on 
a two bank charger: since the relay closes on voltage differential, and both 
legs of the charger start out at essentially the same voltage, there shouldn’t 
be a great differential and the relay shouldn’t close while the charger is 
running. YMMV, since the software that controls the output current and voltage 
of each leg of the charger can vary by manufacturer.

 

Rick Brass

Washington, NC

 

 

 

From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of John Pennie 
via CnC-List
Sent: Wednesday, April 06, 2016 8:14 PM
To: cnc-list@cnc-list.com
Cc: John Pennie <j...@svpaws.net>
Subject: Re: Stus-List Automatic Charging Relay

 

So if I understand this correctly it isn’t a 2-way street.  When a charging 
source is connected to the house bank the rise in voltage will close the 
solenoid and the two bank are now joined.  The voltage “sensor” is only on the 
house bank side.  So if the starting bank is at 14 volts and the house bank is 
at 12v the circuit will remain open and the banks will remain isolated.  Do I 
have this right?

 

John

 

 

 

 

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