Redoing my electrical installation (it had never impressed me) I need to install a largish elco (10000 uF, 25V) in an installation all done with crimp-on "Flachschieber" and fork or eye connectors.
How to attach such connectors to my elco? Or what is an alternative of wiring it? Trying to avoid soldering, but not fanatically.
I already realised that, however I do it, I must make sure the electrical connections do not carry any weight as they do on pcb's - the part will be tie-wrapped to the firewall.
Use a capacitor with screw terminals and then use ring crimps.
A bit like this
Hm. I could have thought of that myself - but I thought only the largest elco's are available in that "screw terminal" style? Then again, one day I may well have the same issue for a LED or a power resistor.
BTW you can install a larger value capacitor, and certainly a larger voltage rating capacitor, in this position.
The capacitor probably just sits across the battery bus and the value is not critical. Anyway, electrolytics have a crap tolerance - say +80% -20%. Going for a higher voltage rating (to get the desired can style) improves reliability dramatically.
Going for a higher voltage rating (to get the desired can style) improves reliability dramatically.
You seem to disagree here with most others.
There seem to be two schools:
any voltage below the rated voltage has no effect on aging
voltages much lower than rated increase aging
It's probably more important that you make sure ripple currents are within the rated limit.
That may be true for wet electrolyte caps i.e. they need the voltage to maintain the oxide layer in a good condition, but would you use one of those in a high reliability application? I would use a solid aluminium cap.
But you may be right that all the ones big enough for this application (the large screw terminal style) are wet electrolyte - example. I did only a quick google.
The solid ones are in smaller cases. All the ones we use at work are solid aluminium, or tantalum.
With tantalum caps, there is a dramatic life increase by going for a higher rated voltage.
In this particular case, the elco is there so that the rectifier/regulator sees something that behaves slightly like a battery even when the battery isn't there, for instance when the charge fuse is blown.
So in normal circumstances there are no ripple currents at all, except for the elco's impedance being lower than the battery's, or so I should think. Come to think of it, I could do worse things than to parallel it with a faster smaller capacitor.
It's an interesting question, what the ripple current might become should the battery become disconnected, or dry, etc.
One could probably have a good stab at the value, knowing the amplitude of a 3 phase rectified 24V alternator output, and taking max engine RPM as the worst case.
I will leave it to Tom here to interpret the maths
You really believe we sport three-phase alternators in a microlight? Ever wondered the weight? Can't find the exact details now, but certainly the Rotax delivers a single phase AC, of up to 22 volts if memory serves.