A) if you use a suitable controller there should be no reason to have a flat starting battery as nothing should be run off of this when the car is off.
B) if you choose to run heavy cable through the car unprotected IMHO is plain stupid, if the battery is capable of supplying enough amps to run a starter then the short circuit current will be enough to set fire to your car in case of a crash....
My aux battery is just that, an aux battery for use with fridges etc, I don't have or want the option to try and start from it, if I was desperate and needed to do this out bush I'd remove the reat battery and jump start off it with it out of the car.
IMHO if you want dual starting battery options put them both under the bonnet...
X2 on what JJ said. I had an 80ah/650cca crank/deep cycle aux and a stock main under my bonnet and it worked a treat once I finally had the job done right, only took me three years and a knowledgeable auto electrician to finally get me sorted. I installed a HD override switch instead of trying to run through the solenoid. I actually had a need for an under bonnet dual battery set up because I had a 12T winch I needed to drive.
__________________
Lay down with dogs and you will wake up with fleas; scratching the surface not treating the disease. Over 5'000 Club
we go by "b&s" at work for all our heavy cable sizes
even our suppliers use b&s as their main sizing
i guess it all depends on the industry you are in...
Every auto electrician I have used or spoken to calls anything 8bs or thicker cable BS. I used to buy cable from Autopro and they too called it BS as did my old local Autobarn..... I really have only have ever heard it called BS, when speaking about auto cable. On some of the thinner gear like 6mm twin I have heard it called 6mm..... But I agree with RB depends on the trade. Compared to 240v and higher the way it is measured is not the same, but in my experience if you tried to talk in real terms of the amount of copper in an auto cable auto electricians would probably be thinking you mean something in a higher rating.
Regards A
__________________
Lay down with dogs and you will wake up with fleas; scratching the surface not treating the disease. Over 5'000 Club
My Dana 44 rear axle was fitted today. All went well as it was an XJ one. the brakes are bigger, 10 inch instead of nine. The slave cylinder is smaller to compensate. The braking on my 31s has been vastly improved. No more standing on the pedal. My drums seem out of round though. I will suss that issue out tomorrow.
__________________
Go hard. You can rest when you die
"98 XJ. RE 3.5 inch lift. Dana 44. 4.11's. 32's
Have you got a braided rear line Rusty? If not get one and I can tell you the brakes will improve even more, even though they are only rears.. I was surprised how much better brakes I had by just swapping the line on my 8.25 axle.
Regards A
__________________
Lay down with dogs and you will wake up with fleas; scratching the surface not treating the disease. Over 5'000 Club
Have you got a braided rear line Rusty? If not get one and I can tell you the brakes will improve even more, even though they are only rears.. I was surprised how much better brakes I had by just swapping the line on my 8.25 axle.
Regards A
A new longer braided rear brake line was fitted with the diff change. The pedal firmness has improved a lot.
__________________
Go hard. You can rest when you die
"98 XJ. RE 3.5 inch lift. Dana 44. 4.11's. 32's
Well I replaced out all 4 shockies, as two had started to leak months ago, scored a near new set of another member, they came off his KJ. And fitted a bar with winch, also found on this site.
Next is the rear brakes. Lucky I only have 4 weeks off or I will end up broke....
__________________
96, OBDII, and Black....
255,000
Just repair what needs repairing.
Well I replaced out all 4 shockies, as two had started to leak months ago, scored a near new set of another member, they came off his KJ. And fitted a bar with winch, also found on this site.
Next is the rear brakes. Lucky I only have 4 weeks off or I will end up broke....
AJOR does not vouch for or warrant the accuracy, completeness
or usefulness of any message, and are not responsible for the contents of any
message. The messages express the views of the author of the message, not necessarily
the views of AJOR or any entity associated with AJOR, nor should any advice
be substituted as technical advice replacing that of a mechanic. You agree,
through your use of this service, that you will not use AJOR to post any material
which is knowingly false and/or defamatory, inaccurate, abusive, vulgar, hateful,
harassing, obscene, profane, sexually oriented, threatening, invasive of a person's
privacy, religious, political or otherwise violative of any law. You agree not to post any copyrighted
material unless the copyright is owned by you or by AJOR. The owner, administrators
and moderators of AJOR reserve the right to delete any message or members for
any or no reason whatsoever. You remain solely responsible for the content of
your messages, and you agree to indemnify and hold harmless AJOR, the administrators,
moderators, and their agents with respect to any claim based upon transmission
of your message(s). The use of profile signatures to intentionally mislead or misdirect any member on this forum is not acceptable and may result in your account being suspended. Any trip that is organised through the AJOR forum is participated
at your own risk. If you or your vehicle is damaged it is your responsibility,
not that of the person that posted the thread, message or topic initiating the
trip, nor the organisers of AJOR or moderators of any specific forum. This forum
and associated website is the property of AJOR. No user data is harvested and no information supplied in your registration will be sold for profit.
I really have only have ever heard it called BS, when speaking about auto cable. On some of the thinner gear like 6mm twin I have heard it called 6mm..... But I agree with RB depends on the trade. 
Compared to 240v and higher the way it is measured is not the same, but in my experience if you tried to talk in real terms of the amount of copper in an auto cable auto electricians would probably be thinking you mean something in a higher rating. 
