Alternator to VSR!

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RJD393

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I am in the process of replacing a multi battery isolator with a DVSR. The alternator is a Valeo unit on a Volvo D2-55. At present the B+ is connected to the isolator which will be moved to a connection for the engine battery. There is also a wire from the D+ terminal to the service battery connection on the isolator. I am guessing that this is a sense wire - is it still needed? If so connected to where? Thank you for any advice.
Richard
 
RJD393 said:
I am in the process of replacing a multi battery isolator with a DVSR. The alternator is a Valeo unit on a Volvo D2-55. At present the B+ is connected to the isolator which will be moved to a connection for the engine battery. There is also a wire from the D+ terminal to the service battery connection on the isolator. I am guessing that this is a sense wire - is it still needed? If so connected to where? Thank you for any advice.
Richard
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its not a sense wire if it is connected to a battery which might itself not always be connected to the alternator output. The voltage sensing must be from a battery or other point which is always connected to the alternator output. It must sense what the alternator is deivering
 
RJD393 said:
Sailorman - have been looking at this but struggling to work out what is needed when the Adverc is not included.
Click to expand...

The Adverc is an advanced alternator controller. Ignore it if you do not have an Adverc or other (eg Sterling) advanced regulator

Without it all you ned is a means of distributing the power generated to the two batteries.

Commonly this can be by manual switching, diode splitting or VSR. When diode splitting is used in order to compensate for volts drop across the diodes battery sensing for the alternator is desirable otherwise not normally necessary.
 
I would have expected the D+ terminal to be connected to the battery +ve via a small bulb, (the battery warning light), and the "ignition" switch. That would provide excitation to enablr the alternator to start charging.
I'm puzzled by the connection to the service battery. That would excite the alternator, but at the cost of a permanent drain on the battery unless it's switched off when the boat is left.
Has that wiring been done by a previous owner?
 
Like Earybird I would have expected the D+ terminal to have been the warning light connection


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Sorry Earlybird I didn't explain that too well- the connection from the D+ to the service battery is not the only connection to the D+ terminal. There is also a connection to the alternator/main engine electric harness. Those connections make sense - it is this other one which seems un-necessary.
 
In that case, I'd be tempted to disconnect it when you fit a VSR. If the alternator charges, ie the light goes out and you get 14+ volts, then things should be OK IMHO.
 
RJD393 said:
Sorry Earlybird I didn't explain that too well- the connection from the D+ to the service battery is not the only connection to the D+ terminal. There is also a connection to the alternator/main engine electric harness. Those connections make sense - it is this other one which seems un-necessary.
Click to expand...

Get rid of wire from D+ to "service bat".Keep wire from D+ that goes into dash panel harness.It goes to 12V thru the charging indicator bulb.This 12v is picked up from starter solenoid,which is conn to Start bat,thereby sensing the Start bat voltage,for charging purposes-as it should do.
The beauty of using a VSR instead of a diode or any other splitter,is that you don't have to worry about sensing different battery banks.
When the engine starts,it charges the start bat. & when start bat.reaches 13.5V or so,the VSR parallels the other bat. bank to the start bat.,& both banks get charged until BOTH reach 14.2 or so.Simple.
For those that want to use a more sophisticated step charge regulator,it makes no sense to use a VSR.The VSR just parallels the banks & both banks will end up same voltage anyway.In this step charge case,it would only make sense to have a manual,heavy duty 'Emerg.Start switch to use only in case Start Bat was low.(Any 1 both 2 or on/off bat sw would work,if used only as an on/off sw.)
 
Thanks all for your replies. I am going to wire up without the D+ link wire as it doesn't seem to have any purpose. Will post back afterwards to update.
 
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