Rectifier/regulator question

[Mikekitts81]

I often see regulators/rectifiers in the open on a motorcycle and not under the seat with the fuse box etc bikes like the Harley some have then at the front between the frame under the radiator and most bikes seem to have them at the side of the frame or in the open were wind can hit them and I notice the regulators have the fins on like the old air cooled engines so do they need the fresh air supply to be air cooled or would you say iam fine putting one under the seat with everything else as iam really thinking off hiding everything out the way ...

[bowber]

They need to be in air flow to cool them as they get rid of excess power as heat, they also get warm just flowing the current. I think there are some newer designs or R/R that work by disconnecting the charge circuit rather than dumping the excess but I can't tell you which ones to look for.

Steve

[Craig-SM]

The majority of bikes still have the series type rectifiers which run hot and as Bowber said need the airflow to remove the heat.
More recent bikes are coming with MOSFET rectifiers which are much more efficient at handling the power from the generator so don’t run as hot and last longer too.

[HedgeHopper]

If you are after reliability, changing to a mosfet reg/rec is a worthwhile upgrade, they come up on evilbay regularly

[Hugh]

Greetings,

As colleagues have said rectifier regulators require large heat sinks to prevent their overheating hence the need for plenty of cooling airflow and heat sink, possibly into the frame. When electricity flows through a conductor it naturally produces heat as a byproduct. Zener diodes as fitted to Norton, BSA and Triumphs also need large heat sinks hence fitting them to the large alloy footrest plates and/or finned units situated under the headlamp. The newer MOSFET systems run much cooler and so last longer.

We had problems with my son's Daytona and the recommendations were to change to a MOSFET, (Metal Oxide Semiconductor Field-Effect Transistor), regulator rectifier which we duly imported from the USA at a cost of about £165. We later found that his bike although outside of the normal warranty was subject to a recall for a change of unit so we were given the new item back, soon after he sold the bike. If anybody wants a virtually unused unit then I still have the unit on a shelf, would sell at £55.00 ono.

TTFN

Hugh.

[Craig-SM]

I've had one fail and fry my battery whilst doing RTTW in 2016, once i got the bike started on the way out which is more of a slow shuffle than riding, a bike not far in front caught fire and went up very quickly. Heard later it was one the Blood riders and it was the rectifier that had caused it. The rider was OK and the bike could be replaced.

Biggest problem with going from a series to a MOSFET rectifier is the wiring isn't plug and play so you need to create the wiring to suit which isn't that difficult, just be sure to use a sufficient gauge wire in doing so.

[catcitrus]

I do two things--firstly I fit a charge indicator (small LED which changes colour) to all my bikes including trail bikes--this tells me that the charging system is functioning ok and not failing to charge OR OVERCHARGING. Secondly, on a longish trip, I carry a spare regulator/ rectifier to suit the particular bike. The aftermarket ones are serviceable enough in an emergency and not that expensive. I have also been out with people where it fails and the battery fries and the bike is dead--new battery and regulator /rectifier required in the middle of nowhere.!! Goodness knows why they don't fit any charge indicator to modern vehicles--it was very necessary when Joseph, Prince of Darkness was fitted.

[Oop North John]

Goodness knows why they don't fit any charge indicator to modern vehicles--it was very necessary when Joseph, Prince of Darkness was fitted.

Because they never go wrong

[Peirre]

Some of the cheaper mosfet rr’s on eBay are of dubious quality and sometimes difficult to distinguish between the the good ones