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By Ejgunth87
Supporting Member
I'm at the point with my Ecto build where I'm ready to purchase a new primary battery for the car, and the secondary battery for the roof equipment.

I've been looking around for batteries, and I'm hoping someone can point me in the right direction. I plan to purchase a gold or platinum battery from CarQuest that has about 800-1000 cranking amps (an upgrade from my current 500-650 cranking amps), to ensure a clean start every time. I'm looking at Marine batteries for the secondary battery, but I'm not sure what to look for in terms of specs. The best I've found so far was a 750-900 cranking amps with a 160 minute reserve. If anyone has figured out how many amps the roof needs to run, that'd be helpful too.

I plan to have my Ecto at day long cons and events with the lights on, so I'm looking to be able to run stuff for 8-10 hours at a time. Some of them are indoors, so starting the car to recharge won't always be an option.

Any suggestions or recommendations would be greatly appreciated.
By Ecto96
My new Ecto build has two batteries (like the last one did) and the best cure I found for the double dead drawback is to have some form of disconnect between the two. I preferred a manual one so if I killed the secondary, the primary could still run the car (and also not overwork the alternator). Plus, it really is hard to determine run time (I've found) as there are other variables. Age on the batteries and whatnot.

So far as in amperage, there's a lot of variables there. What is wired to what in the roof rack? What lights are you using? Their draw? Mine is wired so everything stock about the car relies on the front, while everything from the radio to the lights works on the spare. My two lightbars are rotators with halogens, and pull about 30 amps combined. Not including sound.

I got the biggest dual-purpose I could. They're meant to charge/discharge but also give that strong oomph when starting. Basically with the two connected the starter spins the hell out of my engine.

Finally, mine also has a built in permanent charger. It's under one of the seats and I can plug her in (so if you're indoors or have a place to run an electric cord from, it's a good idea) now downside is it's an older charger I had, and I'm not sure how many amps it supplies, and it isn't telling me lol it's a digital one. I know the older analogue ones usually run 1-12 amps, with a 50 amp start, but that wouldn't work for my 30 amp draw, unless I wanted to sit on 50 amps all the time and I don't.

Oh, one more thing, you may want to invest in a better alternator to supply all that power. I'm planning to wait until my stock one dies, then I'll replace it with a bolt on that does 120 amps at idle (stock's top power output) and at 1200rpm (cruising speed) over 200 amps. When my spare's down in the 60% range, the stock alternator tends to whine when I connect the two, so I just drive her home and plug her in inside the garage.

Hope all this has helped.
By D1gger
RV's and emergency vehicles frequently run a dual-battery setup with what's called an isolator. This allows both batteries to charge with the engine running, but isolates one battery to run the electrical load with the engine off, keeping the other fully charged to be able to start the engine, even if the one is dead.
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By Ecto96
Isolators capable of handling a large amp output are pretty pricey though, at least at batteries plus bulbs they are.

Like I said, I used a cutoff switch because I like the manual operation ^-^
By D1gger
My setup has lots of LED's, lowering the amp draw to around 25 amps total with everything running including the siren. The single biggest load is the 3-pod mini vector which pulls around 13 amps and the siren only pulls about 10 amps. The strobes are less then 2 amps total. The stock alternator and battery system has been handling it just fine, but I also don't run the siren or lightbar without the engine running.

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