Hi Again DandJ
The Sterling AVR 12 has three programmable battery settings and the type is indicated by the LED colour.
Open Lead Acid LED yellow. 14.8V @ 20oC
Gel Exide Specs LED green. 14.4V@ 20oC
Sealed AGM LED red. 14.1V@ 20oC
If you undo the four screw and remove the cover you will find some dip switches that allows you to set the relevent battery type charging parameters.
For the top volt dipswitch (1) awayfrom 1 (2) to 2.
For the next volt down dipswitch (1)to 1 (2) away from 2.
For the low setting dipswitch (1)away from 1 (2) away from 2.
Regards
Ian

Hi Ian,

I agree the Sterling unit is working correctly.

When we are drawing over 15 amps from our battery for long periods (for our navigation computers, fridge etc), and the battery temperature exceeds 40º (which can be due to the ambient temperature, not just the high charge rate), the Sterling unit shuts down and reverts to the built-in in regulator. The built-in regulator will also reduce the charging rate after a time to a trickle charge. This might maintain the battery voltage level, but does not replenish the charge.

So effectively we can actually loose battery charge, which is not good and I don't know the answer, except resetting the Sterling unit (by switching it off and on again - not recommended), or driving only when cooler (not practical).

As far as I know the charging voltage of the Sterling DAR12 (AR12VD) is not adjustable.

Dandj

We've had a Sterling DAR12 Alternator Regulator in our Oka for the past couple of years with a 120 amp alternator charging 3 batteries. It works fine with the following reservations:

1) The regulator allows the 120 amp alternator to produce it's full output continuously. This means that the engine pulley/belt /tensioner system needs to be very robust to transfer around 2 HP to the alternator. If it's not, the belt will slip and burn out. A serpentine belt or dual pulleys and belts would be preferable.

2) The regulator has a temperature sensor which attaches to a battery terminal and reduces the charge rate if the battery temperature exceeds 40ºC. This is in accordance with battery manufacturers recommendations to protect the battery. However, in our climate in the outback, this temperature can be reached quite easily and quite often, and may mean the battery will not be charged completely. I wrote to Charles Sterling about that and his rely was less than helpful. Basically he said I could remove the sensor or not, it was my decision. Nothing about how to resolve the problem.

3) Don't overfill batteries with electrolyte (acid). Since a smart regulator can charge batteries at a high rate for long periods they can vent a lot of fumes and express acid while doing so if the level is too high. Use bicarb soda solution to neutralise any acid spills.

Nevertheless, the concept of a smart alternator regulator is good and the DAR12 works well. It only requires a small mod to the alternator and should it ever fail, the original alternator regulator (which is not removed) takes over again.

Just be aware that during the heat of the day, batteries may not be charged adequately. This probably applies to all good smart regulators, not just Sterling.

Reply: Hi Dandj
The unit is working correctly and when it shut down with over temp on the batteries it is only the Sterling that shuts down and the alternator is producing power as per a normal alternator.

Aterling has this feature whereas most other smart regs like Balmar for instance is fitted with the standard reg removed so any problems you have nothing.

The voltage drop in modern alternators appears to have been first introduced in Africa where batteries were only lasting 12 months.

I do not know what batteries you are using but to get continuous charging drop the voltage of the Sterling down to the next setting if you are continuously in hot areas and the battery temp will not get to cut off as quick.
Regards
Ian