Hi Adey,
Obvs the two are different...
Any insight re comparison appreciated?
Aha… now, educated myself to how a "series" rr works compared to a "shunt" rr and SCR v Mosfet (old tech v new tech) works.
The SH847 is a series rr so only draws the current needed so the stator isn't working at 100% output all the time. So there is limited excess power needing to be disposed of. Therefore this unit doesn't need to be Mosfet to dispose of that without excessive max temp. It is SCR. Both it and the stator run cooler as a consequence of being "series" and hence are more robust/ reliable/ stable.
NB Read a thread postulating that since the stator isn't at 100% output all the time under a "series" rr it is less of a load/ drag on the engine so a modicum of hp is no longer taken up in power generation. So in theory more hp to ride with and/ or better fuel consumption. Hmmm…
Now the FH020AA is still a "shunt" rr (so stator always at 100% power gen) but uses Mosfet tech to manage and disipate excess power (shunt) more efficiently so runs cooler than an SCR shunt rr dealing with the same situation. Because of Mosfet's ability to quickly and gradually manage voltage changes (and heat dissipation) it sounds as if it is therefore more suited to LiFePo4 charging.
So it sounds to me that a series rr with Mosfet tech is the utopia for a BB using a LiFePo4 bat i.e. cooler temps, matched battery charging profile, protecting LiFePo4 from damaging voktages and arguably a modicum of better fuel consumption as some isn't burnt generating surplus electricity which only gets dumped as wasted heat… the heat being a danger to stator, rr and bike general electronics re burn out/ shorter life spans).
That utopia doesn't seem to be found by me yet but in the meantime the SH847 sounds defo the way to go though the cheaper FH020 would suffice!
There are of course other specs which make either of these units a great improvement over stock or suitable for an engine capable of high revs (sports bike v lower reving cruising style bikes) re max amp capacity (50A max) and stable voltage management and Li battery usage but limited interest bumping my gums further here.
Have I got any of this wrong?