2nd Gen Non-Engine/Transmission Using battery isolator/combiner to use different batteries

[EBurmeister]

Has anybody tried this? I have used Hellroaring Technologies isolators/combiners in the past, with pretty good luck. My thought is that I can use different batteries, and not have to replace 2 at a time. Plus, based on past experiences, no matter how close in resistance batteries are, they are always different, so when the truck sits they are constantly swapping current back and forth and causes them to go dead in a few days(along with the slight draw from ECU). The isolator would allow them to be separated while the truck is off and always keep at least 1 battery at a full charge. What are your thoughts on this?

 

[WestTN]

Using unequal batteries is really not a great idea. The strongest battery is always overstressed when starting. Batteries really don't like this kind of operation.



This looks like a soluion lookingh for a problem.

 

[EBurmeister]

I should have better explained how isolators/combiner combo's work. Different batteries shouldn't matter a bit, the point of the thread, because when the truck isn't running they are not connected.

 

[Road Dog]

If your batteries are going dead in a few days then you have a bad battery or an abnormal current draw in the truck. A vehicle battery should lose 1 - 2% per month. I leave my truck parked for months at a time without issue. I try and charge it at least once a month (lead acid batteries last longest when kept fully charged) but it doesn't always happen.

 

[AH64ID]

My dad used one of these a few years back on his suburban when he did a dual battery setup. It worked good for a few years, but then failed; we think from the head.

The fix was a HD CD solenoid, and a oil psi switch. The solenoid also got closed when the starter relay was energized. So you had dual batteries for crank, and when the engine was running. . but were isolated when it was shut off.

I plan to do this to my 05 one of these days, but a HD CD solenoid isn't cheap

In addition, this wont cause your batteries to stop dying, you have another issue.

Fisheries - Product Detail

 

[PC12Driver]

+1 on WestTN's reply. In a multi-battery setup, if one battery goes bad both should be replaced. The older battery will have a different internal resistance than the newer battery, which will result in a lower voltage for a given load. So like he said above, the stronger battery is not only carrying most of the starter load, but it is also trying to put some juice back into the lower-voltage battery at the same time. That'll accelerate wear on the new battery.



Then when the batteries charge after the start and during the normal truck-running state, the stronger battery will boil as the system continues to try to bring up the weaker battery. Same effect as leaving a battery on a trickle charger (not a maintainer). Again, more wear on the "good" battery.



An isolator works great for things like winching or other high draw applications, because you'll always have a backup battery available. Like Road Dog says, if your batteries are dead after a couple of days there is something else wrong with your truck. They don't "swap current back and forth" as they sit; the batteries will reach an equal voltage (again, why two same-aged batteries are needed) and then stabilize. Mine sat for about two months at one point and the truck started just fine.



Save your money on the isolator and fix the problem.

 

[DMcLeod]

I have used the Hellroaring Tech. unit on a plow truck for years with not one single problem. There's a number of different wiring configurations, and doing what you say is likely possible. On the plow truck (Not a CTD) I run a redtop starter battery and a bluetop for the plow. Work's great. For the cummins, however, I would keep it simple with two of the same batteries. Your second battery will likely cost less than the combiner unit. As stated, if your batteries are going dead in a few days, you have other issues.