Increase voltage of a remote sense alternator

D

darylat8750ft

.
Sep 26, 2013
6
ocean alexander 44 where ever we happen to be
Hello,
First thanks MaineSail for your time and expertise on these forums..

I picked up a Delcoremy 28SI 160 amp alternator with remote sense for my trawler. I'm using double v belts (would have loved a multi groove belt but that would have tripled the cost of this install) . I built the pivot mount bracket and a threaded belt tension device.
My battery bank is about 800 amps . Eight 6 volt golf cart batteries.

The voltage is factory set at 14.0 volts. Would it work and make sense to put a switchable circuit with a resister into the remote sense line to make the alt. see low enough voltage to put at least 14.4 or maybe as high as 14.8 volts to the battery?
If I limited the voltage to 14.4 could I not bother with a switch?
Thanks,
Daryl
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,709
Canadian Sailcraft 36T Casco Bay, ME
darylat8750ft said:
Hello,
First thanks MaineSail for your time and expertise on these forums..

I picked up a Delcoremy 28SI 160 amp alternator with remote sense for my trawler. I'm using double v belts (would have loved a multi groove belt but that would have tripled the cost of this install) . I built the pivot mount bracket and a threaded belt tension device.
My battery bank is about 800 amps . Eight 6 volt golf cart batteries.

The voltage is factory set at 14.0 volts. Would it work and make sense to put a switchable circuit with a resister into the remote sense line to make the alt. see low enough voltage to put at least 14.4 or maybe as high as 14.8 volts to the battery?
If I limited the voltage to 14.4 could I not bother with a switch?
Thanks,
Daryl
Click to expand
This can be done and has been done, some just use a diode to trick the alt into seeing a lower voltage so it compensates up. Alternatively a replacement regulator can be fitted to that alt and they come in numerous differing voltages. It is a pretty easy swap out for a competent shop...
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,264
Hunter 310 West Vancouver, B.C.
Maine Sail said:
Alternatively a replacement regulator can be fitted to that alt and they come in numerous differing voltages. It is a pretty easy swap out for a competent shop...
Click to expand
Given that one could be motoring as much as ~ 8-10 hrs. in a single day, what is the maximum safe fixed regulator voltage to apply to the batteries ? Let's go one step further and say, very likely, one comes away from the dock with fully charged batteries on the first day of a cruise ?
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
Ralph, depends on the battery manufacturer's recommendations and type of battery. MS has answered this one numerous times.
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,264
Hunter 310 West Vancouver, B.C.
Stu Jackson said:
Ralph, depends on the battery manufacturer's recommendations and type of battery. MS has answered this one numerous times.
Click to expand
Stu, going back to the OP here, he (she ?) has said the batteries are golf carts which I'm assuming are flooded.

Smart chargers have program selections for lead-acid, AGM, gel, or lead-calcium, all requiring different voltages for different types. They pound it in during the bulk charge and then back off so as not to ultimately overcharge the battery. Maine has suggested a replacement (fixed) regulator which come in numerous differing voltages.

For a flooded battery, what is the FIXED voltage recommended for a flooded battery ? ? ? ?

Technically speaking, my Hitachi internal regulator was dumber than a pound of beetle poop :D (I like that analogy) at 14.2V so I replaced it with a Balmar ARS-5. I also carry a fixed regulator (mounted beside the Balmar) set at 14.5V and ready to plug in should the Balmar have problems.

Also, the OP mentioned going to 14.4V or as high as 14.8V. What fixed voltage does he want ? This is getting as difficult as nailing jello to a wall.

IMHO with batteries that size and cost, he wants an external regulator and nothing else.
 
D

darylat8750ft

.
Sep 26, 2013
6
ocean alexander 44 where ever we happen to be
I apologize. I should have more explicit in my first post.
The batteries are a bank of 8 Duracell GC2. Factory recommended charge voltage is 14.4. I have read (somewhere �� Not on the decca east penn site) that for the first stage of charging that up to 14.8 is ok and may even be desired. It appears that diodes with a .3 voltage drop are available and some with .7 voltage drop are also. Choosing the appropriate diode is outside of my area of expertise. And designing anything fancier than a basic power circut is also something I should avoid.

I would really like an external regulator but it is not in the budget this year. This is a trawler so when charging from the main engine it is usually run several hours any time it is started so just bumping up the voltage to 14.4 should do the job. I do have a good inverter/charger that has adjustable 3 stage charging and the ability to condition.
 
J

jackever

.
Aug 28, 2013
12
Columbia Challenger-24 Redwood City
Maine Sail said:
This can be done and has been done, some just use a diode to trick the alt into seeing a lower voltage so it compensates up. Alternatively a replacement regulator can be fitted to that alt and they come in numerous differing voltages. It is a pretty easy swap out for a competent shop...
Click to expand
Diodes are polarity dependent, one way will appear as an open circuit to the regulator, which hopefully will shut it down.
It will not need to be a high current one since it is just going into a measurement circuit. 1N914 or 1N4148 or equal should work, but if you want a little more ruggedness, 1N400X series.

Bat+ ____|\|____ Reg
.................|/|
Anode............. Cathode
dots just for spaceing
This will give about 14.6 V

Using resistors you would need 2 to make a voltage divider, unless you know the input resistance of the regulator.

Best of luck
Jack
 
Daveinet

Daveinet

.
Sep 20, 2014
1,329
Rob Legg RL24 Chain O'Lakes
I would recommend using a diode to drop the voltage. Its just simple math. Either you are adding .3 volts or .7 volts to what ever voltage it is sensing. The stripe on the diode goes toward the alternator. You can also install a switch to bypass the diode when you don't want the drop. I did this in my motorhome several years ago, as there were many losses between the alternator and the batteries. While technically I could have gone directly to the battery, that would have been more trouble than it was worth. The idea worked very well. (several years later, I did finally fix the poor wiring issues and got rid of the diode)
 
J

jackever

.
Aug 28, 2013
12
Columbia Challenger-24 Redwood City
Rob, Are you dropping the charging voltage, or the voltage read by the remote sense input.?
 
D

darylat8750ft

.
Sep 26, 2013
6
ocean alexander 44 where ever we happen to be
Thanks Jackever,

Just the information I was looking for. 14.6 should be fine for short runs. I will put a switch in the circut so I can reduce the voltage back to 14.0 after the battery is topped up on a passage.
 
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