Automatic alternator cut out/regen braking

[NiHaoMike]

If the voltage regulator module could be opened and the datasheet found for the control chip, couldn't the datasheet be studied to understand how to modify how it works?
I'm not sure if the diodes are Schottky but if they aren't, change them to Schottkys. That should halve the rectification losses. (Forward voltage of a Schottky is about half that of a regular diode.)

[stryker16]

Originally Posted by tjts1

I still think you are better off just running a deep cycle battery charged at home every night and completely eliminate the alternator. 100 miles range is good enough for me 99% of the time.

Can anyone tell me if there is a difference between physically removing the alternator belt and just disconnecting the field windings. Obviously the latter has the advantage of being easier to turn on/off. I would think that it would still cause some parasitic drag on the engine though.

My intention is to make my truck run like tjts recommends, charging it each night. But I would rather not remove the belt as you never know when you will need the alternator to recharge the batts. Maybe the answer is as obvious as it seems I just wanted confirmation and couldn't find it.

[COMP]

just put a cut-out switch to shut it off

[modmonster]

Originally Posted by diesel_john

if i put a 140 amp alternator on the drive shaft, that's over 2 HP, i will feel that baby when i hit the regen button.

you will also vapourize your battery! unless it is the size of an EV pack.

[whitevette]

Originally Posted by tjts1

I still think you are better off just running a deep cycle battery charged at home every night and completely eliminate the alternator. 100 miles range is good enough for me 99% of the time.

Hmmm.... Come out early in the morning, set the choke, check it is in neutral
( or "Park") and yank the starter rope! This will save those precious amps....

Seriously, have you followed GM's reasoning behind the "Volt"? It's the same thing...except the Volt's battery is far better than a deep-cycle K-mart!
The Volt even has a charger in it...driven by gasoline ( diesel later?).
And...check out those side mirrors! Slick! I want one!!!

[NiHaoMike]

Originally Posted by modmonster

you will also vapourize your battery! unless it is the size of an EV pack.

Use a high current battery pack like the kind they use for power tools. There are some NiCds about D-size or so that are rated to a good 200A! You'll need 10 in series for a 12v pack since a single NiCd cell is 1.2v.

140A is a lot to switch, though. Commonly available contactors top out at 60A and that's for AC. You'll have to use an industrial-grade contactor before the rectifiers as they're only rated for AC. Have you thought about using a 120/240v alternator (like the kind used for backup generators) along with a high voltage battery pack and a switching power supply? Or just feed the 120v into some modified microwave oven transformers and rectify it, with the contactor on the 120v side.

[extragoode]

Your 140A alternator could be chosen to have a field switch which means you wouldn't have to switch the whole 140A. I can't imagine the field being more than a couple dozen amps.

[NiHaoMike]

One approach is to find the sense point of the voltage regulator circuit and add a resistor (value calculated based on existing resistors) to it. Connect it to 12v to turn it off (the regulator will sense higher voltage and reduce the duty cycle of the pass transistors) and connect it to ground to force it on (the regulator will sense lower voltage and increase the duty cycle of the pass transistors). A small relay can ground the line when the brake lights are on for a little regenerative braking. A switch with a resistor or pilot light bulb in series (to prevent a shoot-through short circuit) can connect the line to 12v to disable the alternator, but not disable regenerative braking. (Alternatively, the common of the regenerative braking relay can connect to the line, with the normally open to ground and the normally closed directly to the alternator disable switch.) I'm not sure if the regulator would become unstable from this, but a datasheet can be checked for information on design.

[andylaurence]

Originally Posted by AXMonster

I think I know what I need to do now

Ideally the feed to the regulator should be 0v whan I want the alternator ro be producing no output.

I think it may be gatting some excitition from elsewhere i.e. picking up RF and then this voltage/current acts as the power to get the coils energised.

I need to ground the input to the regulator when not in use i.e. ground the yellow wire.

I think a relay that is grounded on the NC side and then fed the field voltage/idiot light voltage when activated should do the trick. So when not in use the alternator field windings are not fed any voltage and cannot 'pick up' any voltage!!

Did you manage to get it working? This sounds like a great mod to use wasted energy to keep the battery charge.

Cheers,
Andy

[Piwoslaw]

Not sure if this hasn't already been proposed, but instead of using sensors to see when the car is in gear, and when the gas/brake/clutch is pressed, etc., why not look at the engine's rpm? If we want to engage the alternator only when accelerating or enginebraking, then it's enough to have it switch on when rpm's get above idle. For example, if idle is 800rpm, then have the alt kick in above 1200, or maybe 1500 to have more low-end torque. There could also be a switch for charging only during enginebraking (battery above 90% full), or enginebraking plus acceleration (batt below 90% + gas pedal pressed). And, of course, a manual override ON-OFF-AUTO switch.