Alternator Regulation Revisited

[Stu Jackson]

Originally Posted by Sternwake

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Not being able to walk away, I use a ~25$ transpo540HD ford Voltage regulator(not all 540 hds are adjustable voltage, look for screws rather than rivets). It had an adjustable voltage trimpot inside the casing(2k ohm), which I removed, soldered wires to the legs, and ran to a remote bourns 10 turn 2K ohm potentiometer, mounted next to my ammeter/voltmeter and alternator and battery temperature gauges.>>>>>>>>>>>>>>>>>>>>>>>>>>>
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I know manual Voltage regulation is not for everybody, but perhaps some are thinking they absolutely have to have a balmar 614 regulator, or similar, to achieve good battery charging while the engine is running, or just accept the voltage regulation of alternators with internal regulators which slow battery charging greatly, and kill battery banks prematurely.

I think the adjustable transpo540HD, even if one does not find manual voltage control to be desirable, should be a good economical spare to carry.

Sounds a lot like the old SPA CREEK AUTOMAC unit.

[Fuss]

My multiplus is set to 29.6 and every chance running the engine I hit my batteries hard...but I’m not motoring for 12 hours, but if I did then I would not care as how can you fry batteries well watered that sometimes need an equalisation at over 32 volts

[Sternwake]

Originally Posted by Fuss

....................................... modern 12v cars charge all day at 14.4 and the batteries don’t fry,.............................................. ........

A lot of modern vehicles for the North American market, perhaps others, intentionally keep the battery only around 75 to 80% charged in an attempt to get slightly better MPG / fuel economy. When braking, they will crank voltage upto 15+ from ~12.6v. If they kept the battery more charged then raising the voltage so much would not allow battery to accept much amperage from alternator when voltage is raised to 14.7v+.

A lot of people on Automotive forums will take a voltage reading right after engine start up, and assume that is the voltage the regulator always allows, when the 14.4v might last only 10 minutes or less before dropping to mid 13's. My vehicle was 14.9v for a few minutes after engine start up, then 13.7v, with the occassional brief spike back to 14.9v for no particular reason I could ever determine. I tricked the original VR inside engine computer with a 10 ohm 50 watt resistor into thinking it is still connected to the alternator, and use external regulation. if I just disconnect the engine computer VR the check engine light comes on, it reverts to not taking sensor readings, and I can't pass smog tests.

I get 50 to 66% more amperage into the battery at 14.7v vs 13.7v, it depends on the battery and its health where within that range where it falls..

Trojan, a few years back raised their recommended EQ voltage to 16.2v from 15.5v.

https://www.trojanbattery.com/tech-s...y-maintenance/

I was about to type that this brought them up in line with Rolls Surrette, but just checked and it appears R/S has lowered their recommended EQ voltage to 15.6v to 15.9v at 77f.

https://rollsbattery.com/public/docs...ery_Manual.pdf

Back when i still cycled flooded batteries I found with my particular battery what took 4 hours at 15.5v, took 45 minutes at 16.2v.