I plan to add a second battery to my ls swap. I have seen people run a cable off the starter to the second battery and then a ground for the battery. is this a safe way to do it or would a different way be better? I'm open to any suggestions.
CK5
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Adding a second battery Ls swap
- Thread starter Cucv_M1008
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If you want to isolate the starting battery from accessory loads you should use an Automatic closing relay(ACR) as an isolator. This will keep your main battery separate from auxiliary, and allow for ea battery to be charged, when the engine is running
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I use a hellroaring isolator and it's worked well for 7-8 years. They have a newer version.
batterys should if tied together be of the same brand / size / closest production dates possible from what i have heard over the years .
Here's how I did mine 25 years ago or whatever. I replaced the big relay once in that time.
+/- are reversed on battery 2 in the pic. The switch chooses which battery runs accessories when off, the relay attaches them together when running. Toggle switch is manual fail safe in case one battery is super dead. Big switch allows entire system to be manual if needed, or keep batteries together when on a trickle charger.
+/- are reversed on battery 2 in the pic. The switch chooses which battery runs accessories when off, the relay attaches them together when running. Toggle switch is manual fail safe in case one battery is super dead. Big switch allows entire system to be manual if needed, or keep batteries together when on a trickle charger.
my dad back in the day use to do a semi battery under the cab on the frame .........
i have been doing a 850-1,000 cca battery for years with a BIG alt and zero problems . and mine is in the cold winters of the north east and on a plow truck with lots of lights .
I
I run two group 31 stud type semi truck batteries in modified factory trays in my diesel K5.
My K5 had the mounting points for a driver's side battery tray. Presumably for the diesel option or something. I think I got a tray from the dealer, but LMC probably has them too. Mirror image to passenger side.
Can’t you just run them in parallel like a 6.2l diesel?
For me the point was to have an isolated backup to avoid getting stranded. Extra cranking power is a bonus.
Is that a real concern? I ask because I see alot of people do complicated wiring for what if situations, in turn inducing failures. If you have two good batteries you shouldn’t have problems for 3-5 years. If there is a drain, then isolate and fix that instead of adding components.
Redundancy is good but what is the driving factor that it is needed?
Redundancy is good but what is the driving factor that it is needed?
Rock auto has them, way less than LMC for same imported repops. Yes the diesels need the extra cranking power to heat glow plugs and crank. Idolator is keep cranking battery from dying, while your ARB fridge and power inverter suck the aux battery dry.
So my rig has 2 electric fans. a/c condenser, trans cooler, electric fuel pump, front and rear a/c blowers. 12v center console cooler, winch extra lights, no electric cooling fans and a 2k watt inverter in it's future. I do run dual group 34 agm AC delcos, iirc 750ahr with a ACR to separate them. 105 alt did ok keeping batteries up, at highway speeds. When I was moving I would start the 12v cooler 1/2 day before traveling 250 miles, this would drian the aux bat down to @ 9v. Leaving in the early evening as the desert was cooling down, still running a/c, my head lamps would dim and brighten as the acr closed the low battery would draw down the charging voltage below the acr and it would open, this would go on for @ 50 miles. The next summer I discovered that 2 days of driving around 25-35 mph with ac and no cooler the main batt would die. Charging voltage at those speed just wasn't enough to keep the main bat up. When the fuel pump quit I was able to lock the aux bat to main to get home, only a mile or two. I up sized to a 140amp modified cs130, so far no issues.
Guess if your truck is stock or close to it, a higher ahr or cca would give added service, but not for slow speed rig with added loads.
Guess if your truck is stock or close to it, a higher ahr or cca would give added service, but not for slow speed rig with added loads.
Only reason really is if you are camping and needing to run electrical items with the engine off and don't want to risk killing your battery.
I have 1 down to the starter to a distribution block on the firewall then to the alternator, 2nd battery is connected to the alternator as well.
it'll work like that. As long as both batteries are equal and good shape. One bad cell and neither bat may charge.
Both were put in at the same time
