Smart Alternator Question

[Arbee]

Take a device like this: the Renogy Rego.

It features the ability to hook up an optional Smart Alternator cable if the vehcile into which you are installing this product has just such an altenator.

And on page 54 of the linked manual, the logic the device will use to have the house battery charge the starter battery differs based upon whether you have this Smart alternator cable (i.e. you have a Smart Alternator) connected or not.

Here's my question. With the vehicle's engine off how does the device, even with the Smart Alternator cable connected, know you that you have a smart alternator if (I presume) no current is being carried on this cable with the engine off?

Is there something about merely plugging in this Smart Alternator cable into the device that tells it you have a Smart Alternator, independent of whether that cable has current in it, or do I misunderstand where that cable gets attached at its end nearest the vehicle's engine?

It is my presumption that you hook this cable into some 12V outlet that is energized only when the engine is cranked, no?

TIA

 

[mikefitz]

Take a device like this:

No thanks, that's one of the worst manuals ( and perhaps product) that Renogy have produced.

, know you that you have a smart alternator if (I presume) no current is being carried on this cable with the engine off?

What Renogy are trying to say.
Because a smart alternator voltage output has varying voltage its unable to use the 'on' and 'off' voltages seen on a normal alternator (on over 13.5 volts, off below 12.7 volts)
So to ensure the smart alternator system will still work, ( its voltage of often below 13.5 volts when the engine is running) the unit has a control input, 12v charger on, 0v charger off. To confuse the installer the instructions discuss 'ignition on, key on' and 'D+' alternator charging signal . Either of these could be used, ignition on is easy to find on the vehicle, D+ , not so easy.

And on page 54 of the linked manual, the logic the device will use to have the house battery charge the starter battery

The stuff on page 53 and 54 does not make sense. The unit is claimed to be bidirectional but with the engine off there in no power input.
I suspect where other chargers, solar or AC, are connected up a part of the 'family' then this bidirectional feature is possible.
The Renogy units that have DC to DC and MPPT combined could charge the starter battery. Renogy have a history of producing manuals that are lacking in clarity.

The alternator connection diagram shown on page 21 is wrong and misleading, D+ signal, alternator running , is not the same as ignition on, the picture on page 35 is no help.

I can see what Renogy are trying to do, creating a family on units using Anderson connections, a kind of plug and play.

I can see this product causing yet more grief for folk buying Renogy devices.

 

[Arbee]

So Mike--and BTW thanks--the notion of two different charging algorithms from the house to starter battery, as per the manual, based on whether you do or don't have a smart alternator and corresponding smart alternator cable hookup is complete B.S. when the engine is not cranked, as any time the engine is not running, to this Renogy device's way of seeing the world, it is the same as if the engine were not running and this smart alternator cable were not hooked up.

I guess that I'm trying to say that for the unit to detect a smart alternator the smart alternator cable not only needs to be installed but the dang vehicle engine and alternator has to be running. Stated yet another way, with no current on the smart alternator cable, such as when the engine is off, it might as well be as if the smart alternator cable weren't connect at all.

Agreed?

 

[mikefitz]

Agreed

Yes