well some people are mad over authenticity when it comes to older cars
Controlling the field coil will not decrease the power
the dynamo needs regulating at all times or you can end up with 40 volts (I managed 18 before pulling the plug on it and it looked eager to keep rising)
I can set the current limit in the software and it will run to that, so if I have a temp sensor and related algorithm to increse the amperage figure when the weather is cold I can allow more power to be generated in winter but keep it to normal levels in the summer so as to not burn anything out.
I suppose I could just replicate the "burst fire" control of the original and run at a high clock speed, at the end of the day it still results in a crude PWM but with a drift in frequency, in his case this was 70-150 Hz hence my choice of frequency. in any case once built I can use both versions of control, thats the beauty of the uC method I get to play with variables without unsoldering stuff all the time, or redesigning the whole project.
as it happens i got a more steady regulation than the original reg, so I did something right
I think you'll find that that's how it works, both originally, and as you're doing it.
How?, the battery will stop the voltage rising that far, just as it does on the original regulator, and just as it does for an alternator.
You seem a bit confused about what you're doing? - as I said you can't increase the output, only decrease it - and that's what the original regulator did. No need, and no point, in monitoring ambient temperature - you charge the battery until it's full, then drop charging current to a low level to keep it topped up - same winter or summer.
Why did you want a more steady regulation?, what advantage does it give?.
When your battery is being subjected to 18 volts (I got it that high using a test bed made up of an underpowered motor rigged to a dynamo) the battery will soon dry up and you will have some "interesting" results
if the engine speed is high enough you will get more than the rated current from it, I was able to set how much current I wanted at will and easily got 20 amps out of the 20 amp alternator, I'd easily get more in fact when i blew the prototype (pcb track fell apart due to my poor build of a first PCB) it peacked at 30 amps at which point the voltage became so high on the mosfet gate it blew, the regulators are set for 13.5ish volts so no harm in taking it to 14-14.5 volts more current would easily flow
wasn't particularly after a steady regulation it just occured that way, probably due to the lack of (or insignificant) hysteresis in my circuit that the original reg will have, the only time mine was not pretty steady and much like the original was when it was taking too long in playing catchup with the engine speed
well I got my battery to hit 18 volts ! I think it was fully chrged so just could not take it anymore
if the battery is flat I do need all the current I can get and can get it but a flat battery can go down quit low like 7 volts (we did it on my friends car with all the testing we did) so with a voltage difference of 6.5 volts the charge current can be very high and high enough to burn the dynamo out so current regulation is also implemented to prevent a literal meltdown, in cold weaher i can allow that to be a bit more current but must stop things overheating
I think the hysteresis in the old reg was due to the voltage being sampled off the battery so there was a delay in rise and fall of voltage, I am taking the measurements from the dynamo itself
Going from what he's told me before in another thread, the dynamo is poorly designed and other car owners have had problems with them burning out. One of the reasons for designing this circuit is to fix the problem of the dynamos burning out.
I agree 18V on a lead acid battery isn't going to do it any good but it shouldn't be fatal on a flooded lead acid battery.
My experiences were 40's and 50's, I don't think they were used after that?.
I used to have a 1954 350cc Velocette that had a dynamo
Previous to that we had a lot of old bikes and cars we used to run in the fields and on the moors.
I beleive that they were used up until the late 70's, even the VW beatle camper vans use them, I checked my neihgbours one out.
That would be the exception, presumably because they still used 6V system years after everyone else switched to 12V.
didn't know that, but I thought I heard of someone making a semiconductor reg for a ford car of the 70's but might be wrong. I think mechanical regs may have held out for a long time until powerful semiconductors became viable and affordable
ah yes but the regulator in an alternator is not far off what the semiconductor regulator for a dynamo is, I would guess it was thought convenient to switch both generator type and regulator type. If I stuck a full wave rectifier on my regulator cicuit I'm sure it would run an alternator as well, I'm carrying 20 amps in my reg, with modern alternators putting out 60+ amps I'm sure any time before the 70's it would have been a feat to find diodes capable of that capacity without getting rather hot, or being huge exspensive but I might be wrong
Your thinking on rectifiers is also incorrect, large rectifiers go back MUCH longer than that, don't limit your imagination to silicon!.
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