Load relief relay rating
- Thread starter Green Boy
- Start date
It's not easy working out the rating of BMW relays, the colour doesn't seam to mean anything.
But the relay needs to be of a higher rating than the fuses down stream.
Heated grips 4amps
High beam 7.5amps
Low beam 7.5amps
Horn 7.5amps
Indicators ?
That totals in excess of 26.5amps plus whatever the indicators draw.
Therefore I recon to be safe the relay needs to be a minimum of 30amps.
Does that help.
Ian
But the relay needs to be of a higher rating than the fuses down stream.
Heated grips 4amps
High beam 7.5amps
Low beam 7.5amps
Horn 7.5amps
Indicators ?
That totals in excess of 26.5amps plus whatever the indicators draw.
Therefore I recon to be safe the relay needs to be a minimum of 30amps.
Does that help.
Ian
sledgegreen
Registered user
I think you might need a little bit more than 30 Amps.
Indicator bulbs are 21W each, so if you use the hazard lights that makes 84W total. 84W/12V = 7Amps. Add that to Ian's total of 26.5 = 33.5. Plus, the flasher unit will draw a bit and I have no idea how much.
You might get away with 30W if the head and dipped lights don't work together, but I suspect that they at least overlap when switching from one to the other. However, I would leave a bit more of a safety margin.
If you have LED indicators, the indicators themselves will draw less current. But if they use resistors to make them flash at the right rate, I suspect that the resistors will use some power.
Indicator bulbs are 21W each, so if you use the hazard lights that makes 84W total. 84W/12V = 7Amps. Add that to Ian's total of 26.5 = 33.5. Plus, the flasher unit will draw a bit and I have no idea how much.
You might get away with 30W if the head and dipped lights don't work together, but I suspect that they at least overlap when switching from one to the other. However, I would leave a bit more of a safety margin.
If you have LED indicators, the indicators themselves will draw less current. But if they use resistors to make them flash at the right rate, I suspect that the resistors will use some power.
Maybe I should have clarified my post. The indicators are not powered via the load relief relay, they get power direct from the battery. (hence hazard flashers). However, there is a control for the indicators which comes off the load relief relay to the flasher module. Probably just powers the flasher unit (low current).
Ian
Fanum
Toubab
The load relief relay (relay 5) is exactly the same as the horn relay next to it.....(6), and they are interchangeable.
(the numbers vary according to which diagram you look at, but they're the two on the same side as the big chunky starter relay...opn the other side of the plastic partition on that side of the box, there are 3 relays and a spare slot.)
I don't know what rating it is, but I doubt it's very high at all......it doesn't carry the power for all of the items mentioned above, it just switches off the trigger feeds for the relays to them, IYSWIM.
Anyhoo, I do know that the horn relay next to it and the load relief relay itself are interchangeable.......
(the numbers vary according to which diagram you look at, but they're the two on the same side as the big chunky starter relay...opn the other side of the plastic partition on that side of the box, there are 3 relays and a spare slot.)
I don't know what rating it is, but I doubt it's very high at all......it doesn't carry the power for all of the items mentioned above, it just switches off the trigger feeds for the relays to them, IYSWIM.
Anyhoo, I do know that the horn relay next to it and the load relief relay itself are interchangeable.......
They are not the same. They carry different part numbers, and the load relief relay is yellow, and the horn relay black. The only reason they are interchangeable is because they carry the same contact arrangement.
No it doesn't, Down stream of the load relief relay are all the fuses for the circuits mentioned and downstream of those are the relays. (depending on which model and year of bike)
The horn relay only carries a max load of 7.5amps, but is probably rated at 20 to 25amps as the motronic and fuel relay are the same and are 15amp protected. The load relief relay needs to be a lot higher rating than 25amps.
OK using a horn relay in the load relay slot might not make any difference in the short term, but having experienced a lower rating relay welding it's contacts together, I would not advise it.
I always go for the highest rating relay possible. The contacts are beefier, and stand up to arcing better, and there is less chance of the contacts welding together.
Anyway, this is all arbitrary, the OP never stated why he needed to know.
Ian
Fanum
Toubab
Fair point.....my knowledge of them extends only to the fact that they can be swapped out in a 'get me home' situation
Keep them
They're not worth much on their own, but could save a trip if you really need one.....My little bag of spares always includes a decent 30A ISO relay, just in case, and enough spare wire/connectors to re-route and wire it in if necessary
