Alternator v. no alternator - 10% gain @ 70 km/h

[rh77]

Great Experiment as always!

I wonder if you could hook up a switch that's tied into the alternator's draw to switch the load on and off...

For example, on decel with engine on, you could flip the heavy-duty switch to begin charging (kinda like TangoJetta's fuse, but with a switch). This may extend battery life.

RH77

[JanGeo]

Another thing to consider is the injector response is changed slightly when the battery voltage is reduced - think about it - it gets a pulse of a certain voltage which may be the full battery voltage through the ECU. Lower that voltage and the valve may open a little slower and end up leaning the air/fuel mixture - anyone ever trim the supply voltage to extend the mixture range? If anything it could affect performance at higher RPM.

[onegammyleg]

Originally Posted by rh77

Great Experiment as always!

I wonder if you could hook up a switch that's tied into the alternator's draw to switch the load on and off...

For example, on decel with engine on, you could flip the heavy-duty switch to begin charging (kinda like TangoJetta's fuse, but with a switch). This may extend battery life.

RH77

Perhaps it wasnt noticed last time I said it , so Ill say it again ,, it wouldnt be hard to make up a switching arrangement so that the alt only charges when neutral is selected and the brake light is on.
This likely would mean you are stopped at the lights idling or rolling down a hill.

Alternatively it could be switched by a vacuum switch.

Of course keeping an eye on an ammeter and voltmeter gauge set would be handy just to make sure your not leaving the battery discharged.

[cfg83]

Brock -

Originally Posted by Brock

Oh, one thing I use a lot is a Deltran water proof battery tender. It charges at a lowly 800 mA up to 14.6v and then drops back to 13.2v float. I would strongly recommend one of these (or a larger version) if your messing with a disconnected alt. The battery will die a quick death cycling it without a good true full charge. I use this charger on our van, I suspect the alternator is a bit off in the van and never full charges the battery.

On the wagon the Deltran will show a full charge in 30 minutes and the van takes 4-6 hours.

Even running the alternator as normal the cars starts much quicker in winter and I figure it doesn't have to run the alternator as hard to get the battery charged back up after sitting a while since it starts “full”.

Even a solar charger would likely work in most cases for this "topping off" of the battery

I looked up the "Deltran water proof battery tender". Could some circuitry go between that and say a Uni-Solar flexible solar panel (FLX-11) with these specs :

Rated Power (Wp) = 10
Max Power Point VMPP (V) = 16.5
Max Power Point IMPP (A) = 0.6
Short Circuit Current ISC (V) = 0.8
Length/Widht = 21" x 17"

The max Amp of 0.6 may be too wimpy, yes?

If no, then would a smaller Deltran charger be more appropriate?

Or maybe skip the charger alltogether and attach the solar panel directly to the car via some simple cicuitry, yes?

Thanks,

CarloSW2

[onegammyleg]

Quote:
Originally Posted by Brock
The battery will die a quick death cycling it without a good true full charge. I use this charger on our van, I suspect the alternator is a bit off in the van and never full charges the battery.

On the wagon the Deltran will show a full charge in 30 minutes and the van takes 4-6 hours.

Even running the alternator as normal the cars starts much quicker in winter and I figure it doesn't have to run the alternator as hard to get the battery charged back up after sitting a while since it starts ?full?.

Even a solar charger would likely work in most cases for this "topping off" of the battery

I dont fully agree with the statement ?The battery will die a quick death cycling it without a good true full charge.?
Lead acid batteries die most often from water loss from overcharging , being left disharged or undercharged for long periods of time and to a lesser extent overheating from external sources.

If a switchable ALT was employed and the battery returned to full before switching the engine off (or charging of AC at home up to full) then I really doubt any significant life reduction of a battery.

In fact , it may even extend the life if the car is always overcharging it.

I think it would need some experimentation to bust or umm ,unbust? this one , unfortunately the results would take years to obtain and even then , there are many variables that can affect battery life even in normal service.

[onegammyleg]

Originally Posted by onegammyleg

,, it wouldnt be hard to make up a switching arrangement so that the alt only charges when neutral is selected and the brake light is on.
This likely would mean you are stopped at the lights idling or rolling down a hill.

Alternatively it could be switched by a vacuum switch.

I have revised my idea , , just have it switched when the brake pedal is pushed.
The now charging ALT will also give a braking effect as well.

This could save on brake pad/disc wear + with the FE savings from effectively no ALT it must come out on top against the possible life reduction of the battery.

i think its worth a try

[onegammyleg]

What poo-poo's that idea is that ime normally coasting in N by the time I touch the brake pedal.

[MetroMPG]

Originally Posted by onegammyleg

What poo-poo's that idea is that ime normally coasting in N by the time I touch the brake pedal.

Me too. An alternator that only charges during braking, idling or engine over-run would rarely get used in my car. I hardly do much of those things - the battery would be dead pretty quickly.

Besides, what about those massive losses to belt friction and the pulley fan while the alt isn't being used? So wasteful...

[Silveredwings]

Originally Posted by MetroMPG

Me too. An alternator that only charges during braking, idling or engine over-run would rarely get used in my car. I hardly do much of those things - the battery would be dead pretty quickly.

Besides, what about those massive losses to belt friction and the pulley fan while the alt isn't being used? So wasteful...

From the sounds of it, you'd be running a loss just for energizing the alternator field windings.

[MetroMPG]

OT - Silveredwings: You sold the BMW too? Did I miss a thread? Are you bicycling everywhere now?