TR Fuse box relay bypass

well done
on the photo I can not see exactly:
the 6 red wires from the fuse box are 1.5 or 2.5 mm²? 1.5 seems me to small
the 1 red wire from orignal to your fuses is 4mm² or 6mm², last would be better
the blue wires are going to the fans/pumps and so on? so also 2.5 mm²
the white wires have plus for switching on/off the relais? then 1.5 mm is ok

 

what you understand under: the wires are 16 gage 1,5 mm? what means gage here? I know a pressure gage

bosch says for continious working:
1,5 mm² 16 A
2,5 mm² 25 A
your wires are very short, but I would use more mm²

 

"gage" (for wire) = AWG = American Wire Gauge - see: https://en.wikipedia.org/wiki/American_wire_gauge

 

thank you steve
this is complicated for me, because I have to count from US size to euro size, but I understand now what is gage but why not gauge?

so gage 16 is then 1,31 mm² and gage 15 then 1,65 mm², so only good for 16 A and not for 25A? or do I have a couting mistake?

 

It can be spelled either way in English (gage or gauge or just ga for shorthand). Yes, comparing the cross-sectional area is the right way to convert between AWG and the metric gauges (although they don't match up exactly). While 15ga exists in the AWG standards, trying to get that would be very difficult as usually only the even wire gauges are readily available in that range (...20, 18, 16, 14, 12...). As far as the current capacity, that's a bit of a black art dependent on wire length and the heat transfer situation. As this reference suggests:

https://www.powerstream.com/Wire_Size.htm

typical ratings are very conservative. On the plus side, those runs are very short and not in a bundle, but I might have opted for 14 ga for maybe the AC stuff (my recollection is that is the AC is highest current fuse, but I may be wrong about that). Things like the fuel pumps and cooling fans really only draw ~10A even though their fuses are much larger (i.e., the fuse really only protects against a dead short situation - otherwise they would blow on motor start-up).

 

in europe ( don´t know in great britain? ) for automotive and also for house installation it is usual:
1 mm², 1,5 mm², 2,5 mm², 4 mm², 6 mm², 10 mm², then of course bigger and smaller sizes.
the AWG sizes are hardly to get here

https://www.powerstream.com/Wire_Size.htm shoes only conductor diameter, not the cross sectional area as we are used here.

nevertheless I would replace on this very well done fusebox then the 1 red main wire where there comes all the power for all fans and pumps by a 6 mm² or AWG 10, just now it looks like only AWG 12 ( 3,31 mm² ) and that is definitely to small for all

 

Hi David, good example of creativity imo !

Well done; saves you a lot of thouble later.

More ownesr should either get the "Helms" version or do so as you did.

Please show us when you are (really) fitting the board

 

Owwww ... yes I remember ....

Any idea wher to get one; when you will have the set (I hope you get a pair/set) ?

 

I hope so for you David.

Please make some photo's from old and new ones, wear etc ... the reason why you exchanged them ...

We all can learn from this

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Dave, this looks wonderful and you're really inspiring me to do something very similar with my car! My one question about your construction technique is, do you know the melting point of the ABS that everything is being mounted to? I know my fuel pump relays (and maybe the other relays, too) tend to get very hot.

 

OK, that seems fairly high. What is the highest temp the heatsink around a relay will get to -- or maybe more importantly, what is the highest temp the heatsink around an IMPROPERLY FUNCTIONING relay can get to?

 

It is wear ... and nothing else imo .... guess what happens if one teath breaks ....

 

Well, my relays, at least fuel pump relays get pretty hot. Even when the cars is just idling for 5 - 10 minutes, touching them for 2 full seconds is hard to do because they're so hot. Maybe that's because my relays are (going) bad. They could be almost literally "burning up". I'm ordering new relays to put on a board like you (Dave) created above, but maybe before I put them on the new board, I'll just replace the existing (original factory-installed) relays and see how they do temperature-wise.

On another note, I'm no electrical engineer, but I would contend that the metal casings on the relays act as heatsinks, so that's what I'm referring to instead of a traditional heatsink like we find on the ignition coil modules.

 

you may try an other relais for the fuel pums with the same parts number and check if those also will get so warm. if so then th eproblem is not the relais ( or this relais also in not ok ), and if this relais has normal temperature then you know the other is going wrong

 

Many problems with the relais were published her since a long time.

Try "Search" function to find these valuable threads ...

 

Almost a year ago David ... can I find a thread anywhere with your gearbox (gb) story ?