That wouldn't be too difficult to do with a couple of cables and a manual switch I don't think. Couldn't you just bridge the batteries with the manual switch for emergency situations? It wouldn't hurt the isolator would it?
Indeed you could - I'm not sure how would be the best way to do - I know it would be easy with two manual switches and one automatic. However, with just one manual and one automatic might be a little more difficult (but a hell of a lot fun to think about!). Not sure what the impact on an automatic switch would be if the 'main' was not there to switch back to...? Hummm, this might a case where a SP 1315 which is bi-directional might come into play - the typically used SP 1314 is only one-directional.
I don't think you would want to actually bridge the batteries - in an emergency situation, you have to get the patient out of there so the functionality/integrity of the main has to be maintained. However, the winch, lights, etc., could all be attached to the largest practical aux battery (to not exceed the limitations of the stator - which, BTW, I'm not all that sure there are any, if you don't consider 'time' - if the engine is turning at optimum RPMs the stator is outputting 14.4V...) . But really, with well maintained batteries, the main will probably be at full charge long before you get to the scene anyway, so in effect, all the charge would be passing through the main to the aux anyway - about the same as having a manual switch set on 'Batt 2'.
When I find a spot to mount a car battery I think I am going to use a manual switch I have a 2013 800 and I haven't found a write up yet on those.
In my past experience with isolators in an automotive and marine environment it doesn't seem to pour in as much juice. May not be true but it seemed that way. I burned up a relatively new isolator and it was my fault, i ran the battery too low and recharged it with the alternator. Major electrical law violation... Dumb ass! Never burned up a switch though. Didn't learn the first time, officially a dumb ass. Can't do that with a stator though, those are a PITA and expensive.
I also like the idea of being parked and running the radio or whatever and can drain the battery dead without fear. When I get home I can charge it. It should also make auxiliary component wiring a little easier, maybe a connection or two less. One less connection, one less thing to keep clean and dry! I am accustom to the switches so it is not a big deal to remember. After a few hours of plowing the neighbor hood I put it on the trickle charger and leave it there most of the time.
Thanks again for the insight guys.
DU, sounds like you are golden! You bring up a couple of points, that for the sake of others that may be reading this thread, may be good to cover. First is the wiring of accessories - a fuse block off your aux is a good idea and can save you from having a messy pile of wires attached directly to your aux (2nd) battery - easier to fuse them properly also. Also, as you said, a manual switch is more forgiving than an automatic switch if you experience a dead short - pretty easy to fry an automatic - probably one reason why manual switches are so popular in marine environments.
Like I said in my last post, it is pretty important that when using a manual switch, you still have to either ensure there is some sort of isolation between the two batteries (like a diode, which is hopefully built into the switch), or the two batteries have to be exactly the same or as close to it as possible. The reason for this is that if two batteries are hooked up in parallel, the weaker battery will drag down or limit the stronger battery to the weaker battery's level. So, for example, if you have a lawn mower battery paralleled to a truck battery, after a very short time, you will have the equivalent of two lawn mower batteries wasting a bunch of the potential of the truck battery.
One other thing you mentioned that could be handy to know is there is (usually) some overhead in using an automatic switch - usually around 1V (to power the unit itself). So if you measure the voltage coming into switch at 14.4V and coming out of the switch around 13.4V, that's why. Normally, it is inconsequential but knowing it can save your from trying to find where that missing volt went! I would guess there is probably some drop in a manual switch also, but I have no idea what it would be (if anything).
Sorry for the long posts - some day I will get a life and not have so much time to ramble on here :ambivalence:
