NO battery isolator?

[Gary - K7GLD]

It appears our '02's don't use any means of battery isolation between the 2 batteries, and merely run them straight parallel from the alternator?



Not usually considered good practice due to potential internal differences in battery internal resistance or similar imbalances...



Probably not really a big deal, but curious - or am I missing something?

 

[tgbol]

Most diesel trucks (pick up and big rigs) do not use an isolator. Most of the trucks at work have four six volt batteries two groups of series then paralleled. 12 volts and lots of amps.

 

[DieselDoghouse]

No isolator probably since the batteries always function tandem in their charge/discharge roles. After alll, there is no isolator between the cells on a single battery either. You have a good point though as far as connection. 2 years ago I lost all power: the near Mopar battery failed, the far Mopar was not connected due to loosening cable lug bolt - check your lugs!!

 

[BK]

it's a standard common practice and not an issue of the both batteries are in the same state of health and the connections are kept in good shape.



If you loose one battery for what ever reason and the other is in fine shape and don't replace the bad battery, you will be over stressing the other battery and will loose it too.



It's done to gain the capacity needed to deal with the heaters and cranking over all those big cylinders with lots of compression.

 

[TowPro]

Hi Gary, My 98 don't have a isolator either, it would have to handle a "boat load" of current if there was one though



See your getting ready to retire the 1st Generation? Good luck with the new truck! Guess you don't listen to Will Sill go on about diesels either! (inside joke from another news group)

 

[redneckdr]

batteries

also a good idea to replace both batteries at the same time. if not, the old battery may go bad, and take out the newer one.

 

[BK]

redneckdr, as a purist I agree and I would spend the extra bucks if I had it at the time.

But if there was some reason for an early demise of one of the batteries and the remaining "good" one can be tested and shown it's completely up to snuff... it would be fine not to replace it.

 

[SnoKing]

BK, if you put a new battery with a old one. The new one very shortly will be the same as the old one. Always replace both at the same time. Call a battery shop and verify. Also it is best to get two batteries from the same manufactoring run. (That is same make, model, capacity and manufactoring date) SNOKING

 

[BK]

Snow King,

The things that make a battery share are capacity, temp coefficient, conductance, esr and wiring.



If the battery can be tested and shown to be at capacity, then all other internal characteristics will be fine. better yet the use of a conductance "bridge". but I doubt any battery shop could even tell you what one is.



Again I only mentioned that if one of the two found an early demise some how. . it happens, whether it's from manufacturing problem, broken stud, bad wiring in the system, a wrench through the case... what ever. . and the other battery is in fine shape.



If it's just due to age... . and one goes... ya the other isn't far behind and I would change both.



And when you do have one "old tired" battery... . it's not that there is magic that the "new one will become like the old one" ... I've hear the comment that the old battery will pull down the new one... that just doesnt happen when the old one is at capacity and in good shape (different when there is a shorted cell - but then the battery wouldnt be at capacity!-hence my comment)... it's purely the fact that if the original battery in the pair is not at capacity and can't do it's share of work, the other battery will be overstressed to some degree and cause an earlier death.







-BK

 

[SnoKing]

What ever! At least we have engines that start with minim cranking. This would be a much bigger deal with some of the PSD that are hard starting. SNOKING

 

[Gary - K7GLD]

HMMMmm - well, I suppose this is sorta moot anyways, since the function of an isolator is more to *isolate* one battery from another in a manner that allows ONE battery to be discharged under load SEPARATE from the other, rather than BALANCING the charge level or rate to the pair - there's STILL only a SINGLE voltage regulator supplying BOTH batteries - regardless of their individual condition... SO, even WITH an isolator, problems will arise if a POOR battery is paired with a good/new one...

 

[BK]

Originally posted by Gary - KJ6Q

HMMMmm - well, I suppose this is sorta moot anyways, since the function of an isolator is more to *isolate* one battery from another in a manner that allows ONE battery to be discharged under load SEPARATE from the other



more so the point was that in our CTD rams, you cant isolate the batteries, both are needed to create the total capacity required to start the truck in all conditions.





, rather than BALANCING the charge level or rate to the pair - there's STILL only a SINGLE voltage regulator supplying BOTH batteries - regardless of their individual condition... SO, even WITH an isolator, problems will arise if a POOR battery is paired with a good/new one...

Not totally true, very much depends on the point of regulation and fault with the battery. With the most common failure (battery turns into a bucket of water)... the good battery will not be effected at all.