One should only parallel two batteries if they are of the same type and age
otherwise the poor battery will drain the good battery until they both put
out the same voltage and you could end up without the ability to start your
truck. Furthermore, if both batteries are low your alternator may not be
able to charge them both at the same time and could overload the alternator
(though with a '68 you could probably put in a big enough alternator to
compensate since you don't have all the electrical draw that modern trucks
have). If you just put in some kind of switch (i.e. a solinoid) then when
you cross connect the batteries the poor battery can drain the good battery
very rapidly which can cause all kinds of problems, even a fire.
I recently added a dual battery setup to my Dodge and went with a
Hellroaring BIC-95300B isolator/combiner which is designed to provide a
backup starting battery. It cost about $250 for the unit, remote switch and
shipping, but I think its worth it. Under normal operation, the truck runs
from the main battery. Once the main battery reaches a full charge the
backup starting battery gets charged. When I shut off the engine and there
is no charge going to the batteries then only the main battery is connected
to run the radio, lights, camper, etc. If the main battery doesn't have
enough amperage to crank the motor, I throw a switch in the cab and the
backup battery is combined through a regulating circuit so as not to
overload the battery cables and I have enough current to crank the engine.
You can also combine the batteries if you are using high current devices
like a winch. I have used it after camping for over a week, using the
lights, fan, stereo and water pump in the camper. The battery monitor will
indicate a poor or weak battery (I don't know what voltage the indicator is
measuring for it's various levels), yet I throw the switch and viola, the
engire cranks without a problem. Before then, if the monitor got down to
poor, I would barely have enough current to start the engine on a warm day.
"SnoMan" <admin@snoman.com> wrote in message
news:eo0qc253d3sgejk9q55q0bbicci06gd5el@4ax.com...
> On Sun, 30 Jul 2006 17:31:39 GMT, "ihcnut via CarKB.com" <u19951@uwe>
> wrote:
>
>>It is a 68 IH 4x4 p/u and I would like to have confidence that the engine
>>will crank. If I could switch from one battery to another, it would be
>>nice.
>>I have been in the situation where the battery went dead while on the
>>trail
>>and it is more than just aggravating.
>
>
> I would just parrallel two of them because you will get more than
> twice the power that way. More than running each one down seperately
> because battery efficency drops as load increases due to interan
> resistance and gassing and spliting the load between two batteries
> reduces load per battery and will also give you a lot more starting
> power too, even when they are nearly dead.
> -----------------
> The SnoMan
> www.thesnoman.com
