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-   -   Automatic alternator cut out/regen braking (

AXMonster 03-13-2008 01:21 PM

Automatic alternator cut out/regen braking
If the alternator produces parasitic drag when the field windings are powered up, but its not really needed to charge the battery, how about this for an idea?

A smart controller that cuts the power to the alternator's field windings in normal cruise or accel conditions, thus removing the electrical load on the engine caused by the alternator.
When decelerating (0% pedal and no fuel injected so 0% duty cycle) the alternator is switched back on and charges the battery at a high current, thus providing more braking effect.

If the battery voltage gets too low the controller can switch the alternator back in until its within a reasonable range again.

Any thoughts?

tjts1 03-13-2008 01:24 PM

All new BMWs have this.
Pair it with a deep cycle battery and you have yourself a winner.

Daox 03-13-2008 01:25 PM

This would be a real problem for us P&Gers haha.

AXMonster 03-13-2008 01:37 PM


Originally Posted by Daox (Post 14038)
This would be a real problem for us P&Gers haha.

Shouldn't be as the charging wouldn't occur without the engine turning :) :cool:

I'm sure even the most hardcore P&Ger has to brake sometime??? LOL

Daox 03-13-2008 01:43 PM

I read the whole thing now. It seems the system monitors battery charge, so if you get low enough it should just kick in no matter what. But, normally its not charging during acceleration. When your P&Ging, your engine is only on when your accelerating. :)

H4MM3R 03-13-2008 01:55 PM

These are links for switches that might work for you.

AXMonster 03-13-2008 01:57 PM

It would have to charge during accel if the battery got too low, well that's what I'd set my system to do :)

H4MM3R 03-13-2008 02:12 PM

On board battery charger. Keeps the battery fully charged. Link>>>

Use only one deep cycle "AMG" battery for everything including starting.

I used this set up in 2003 Suburban worked great.

AXMonster 03-13-2008 02:19 PM

Ok, I have it sorted. Two systems required. First is the duty cycle switch system which will switch an output if a duty cycle goes above a set value. This would be set to 1% and then the output reversed (so 1 is 0 and 0 is 1). Therefore when the duty cycle drops below 1% then the alternator is energised. The reversing of the output could be simply done with a small relay.

Secondly there would be a voltage controller switch that cuts the alternator back in at a set voltage (say 11.5v) and then switches it off again at another value (say 12.5v).

These circuits are available here

Item numbers KC5375 & KC5377

H4MM3R 03-13-2008 02:24 PM

Nice link. Can't wait to hear how it works for you.

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