I think you are right
The worry I have is about the big cable from the battery to the starter being live all of the time once the master is on.
Cars are even worse, the starter cable is hot all the time! I don't see a big problem and if making a forced off field landing turning the master off, which would de-energize the starter wire, if I understand your design. Turning the master off is one part of the non-normal check-list for forced landings, in every factory plane I remember, along with turning the fuel off and some times opening the door a crack.
My thought concurrs with yours that I will put a 300amp ANL in beside the battery. If it blows when I hit the starter I will increase it, but very much doubt I will have to.
It depends on the starter but you are probably right, 300 amps is max, wire wound are less, PM starters higher.
Under the engine, almost between the starter and alternator there are some tappings in the block. (I think these were used for old fashioned starters.) I was going to mount a smaller ANL there in case the alternator ran away. Your idea to put a maxi blade fuse there is interesting, though I havnt really mulled it over properly. I only have a 40 amp alternator so I guess a 40 amp fuse is plenty. The link is VERY short from the alternator output to the starter cable. Since I dont have 40 amps of load it is hard to see how 40 would flow unless the battery was empty....but then I could not start the engine.
I think you are good either way. The only comment I have is a fuse will not help with an OV, Over Voltage, just over current, ie short. BTW they make in-line fuse and fuse holders up to 60 amps in the MAXI ATC blade style.
Inadvertent starter activation appears to me no different than it was before surely? In the 'normal' situation you have to cause the starter relay to function which will then cause the second starter relay to function. Here you will just have to cause the second relay to function. There seem about the same number of ways to do this with either setup. The main message is don't work on the plane with the master on. Situation normal! Have I missed something?
I agree. I think about poor Stein & his hand, ouch! Be careful around props. I agree, but with master-off, mixture cutoff and ignition off, you are pretty safe. However there's no fail safe to keep us from doing something absent minded. May be a big sticker on the starter or somewhere under the cowl to remind you to "CHECK MIXTURE/MASTER/OFF OFF BEFORE MAINTENANCE".
I struggle to see how the Skytec solenoid would inadvertently operate while the engine is running. Why should it get jolted into action any more than the conventional one. Is this a real worry? I cant see it. What is a real worry is that I operate the starter in error once the engine is cooking, but my thought here is that with a double pole switch I will ensure that once the alternator is on I can not put power on the relay that pulls the solenoid in.
Again I agree with your logic. The old saying s**t happens, but short of pushing the start button, the starter is very unlikely to activate. Actually the typical secondary firewall starter contactor most use is a weak point. If you don't mount it properly, so positive G's keeps it open, it can make the starter engage. Van did not know this years ago and many RV's ended up doing acro and finding their starter engaging, than acting like a generator in-flight. Actually before Van's recommended mounting contactors the way they do now, for an interim period they suggested horizontal mounting, but they don't work well horizontal. They are not designed for that orientation and fail.
Right now my biggest problem is sourcing the part cole hersee part no : 46211, hole dia 1-17/64 or the other part you quoted the other day. Do you have a model / make numbers for the second pair of parts?
Van sells the #24115 continuous duty 12v contactor. Its cole hersees basic part. I'm not sure what a #46211 is.
For a while I looked at the #24200 Latching Solenoid, SPST 12V. It's brilliant and basically like the #24115, but it latches either closed or open. You activated it with momentary switch, which does makes it a little weird. Hit the momentary switch once, it latches open, hit it again it latches closed. Once in either position, it stays there with no power to the actuation coil through the switch, which is the nice part. It does take 3/4 amp to keep the #24115 closed while the #24200 takes nothing (once latched). I gave up on the #24200 latching solenoid for two reasons: one, weird switch operation with a momentary switch; two, it stays latched closed if you lose power to activate it. The basic #24115 is normally in the open position; without the 3/4 amps to stay closed, it's fail-safe or normal position is open. I like the idea of not wasting an amp holding a relay closed, but its part of doing business with remote contactors with high current capacity.
You may want to check with boat suppliers, heavy truck and equipment suppliers like forklift and gate lift dealers. They all use these cole hersee relays.
and the sum is? If its less than 50 amps you can use a 50 amp CB. You really don't want to run your 60 amp alterantor at 60 amps. I am not suggesting you undersize the CB, but if you total load is say 45 amps (including 5-7 amp dead battery charge) a 50 amp CB (or what ever size your load indicates) is good enough. There seems to be jump in CB case size (and cost as well) with CB's over 50 amps. +50 amp range means more heat & the need for a bigger case.
