90' Bronco 2 System Amperage?

[Calloway]

I've been doing some research trying to find out exactly how much amperage the entire stock electrical system pulls on my B2. The reason I'm asking is because I'd like to install a dual battery setup to better handle the situation I'm dealing with. I'm running a set of KC Highlites (4 lights total) and each one has a 100 watt bulb. So if my did the conversions right that's almost 35 amps total? I have a stock 75 amp alternator as well. Electrical Isn't my strong point so any help is more than welcome. At some point in the future I'm looking to put an 8 or 10 thousand lb winch on the front... My current system looks like this:

75 amp alternator (stock)
Interstate Workaholic "Die Hard" Battery powering:
-Custom roof bar with KC Highlites
-rest of the vehicle

When I go out on the trail at night and stall the engine the vehicle wont start if all the lights are on thus forcing me to cut the lights off and start the vehicle. I know that running them for extended periods of time will kill the battery life. I was thinking about installing a second battery (true "deep cell") and switching the lights to it. Does this sound like a good idea? Or is there a better way to accomplish this? Any future winch setup would also be powered by this battery... Thanks in advance guys!

 

[bfiakas]

Since you can't restart at a full electrial load you're at peak ampage and plus some! You have to calculate your full electrical load of your system and verifi what the stock altenator is putting out the rated output . I run an 80 amp Alt. on my 88 EB which is what's called for.Do you use relays on your lights?

 

[Calloway]

They are run in pairs, both of which have relays that were included from KC. They came stock with 55 watt bulbs but I knew I was gonna put 100 watt bulbs in so I wired them with higher gauge wiring than what came with them. I also put new fuses in to handle the load. As far as the alternator goes I haven't tested it but its fairly new as the actual stock alternator failed about two years ago, but I only bought a replacement for it.

 

[lil_Blue_Ford]

Most vehicles have a cut-out switch on the stock lighting so when you crank the engine over to start, it cuts out the lights until the engine fires, so I'm not really surprised that you have to cut the lights to start the truck.

That said, I would look into swapping in a larger alternator to handle the electrical load. A dual battery setup will help at first, but if you're draining the battery faster than the alternator can charge it, adding another battery to the system will not help, once it drains down, you just have yet another load on the alternator. IIRC, there is some info in the tech archives about putting a bigger alternator in.

 

[PetesPonies]

If you ran a 100A alternator I believe you will have more than enough power to run your extra lights.

 

[Calloway]

Most vehicles have a cut-out switch on the stock lighting so when you crank the engine over to start, it cuts out the lights until the engine fires, so I'm not really surprised that you have to cut the lights to start the truck.

The stock headlights and Bosch lower fogs aren't bothering the starter as I am able to start it with them on, so I dont think I have a cut-out switch on those. The aftermarket KC roof rack is whats drawing my amperage. I'm worried about this b/c I'd rather not kill my $200 battery with it only being 2 years old. I see what your'e saying about the Alt not being able to handle both Batteries after running them. But here's another question: Could I run my current (starting) battery and still add a second true "deep cell" with maybe a 100 Amp Alt? Is that combination of different types of batteries possible? Iv'e heard that once both are under load then one could pull more current than the other shortening the life of both batteries... *Keep in mind* I'm planning on adding a winch in the future, powered by the deep cell, with that said would a 100 Amp Alt still be efficient for that much load? Thanks again

 

[PetesPonies]

First of all, what kills a battery is sulfation, not using it hard. People not in the know think you hurt a battery from using it. The only thing you can doto hurt a battery is over heating it. trying to start a car engine is not usually going to over heat the battery.
The charging system works by supply amperage, as it is needed, to the batteries to keep them charged. Your charging system should be able to supply the electricity needed to run everything in the vehicle. Otherwise, you will be running off the batteries, but that is not how the system is supposed to work.

 

[Calloway]

I agree with what your'e saying, but "deep cycling" a starting battery won't hurt it?

Your charging system should be able to supply the electricity needed to run everything in the vehicle. Otherwise, you will be running off the batteries, but that is not how the system is supposed to work.

That's exactly my problem, my charging system can handle the entire stock system, it's the light bar that it wont keep up with. And it definitely wouldn't handle a winch on top of all that! My B2 is my DD so I'm not running around with these things on all the time (as it is illegal here), just on occasion when I'm on the trail... but that circles back around to the question at the top of this post. I guess I should ask this: What is the best setup to properly handle the entire stock system PLUS the light bar and an 8 thousand lb winch?

 

[wildbill23c]

Your best bet is to purchase your dual battery setup, along with a battery isolator which will allow you to keep your vehicle's stock battery for running the vehicle's stock electrical system to include the original lights and such, then run your second battery to the other side of the battery isolator. What this will do is keep your vehicle's main battery charged at all times so you aren't left with a dead starting battery. Once your vehicle's main battery is within a certain voltage tolerance the isolator will switch over and charge your other battery. In your case running all those lights be sure you get a higher amp alternator and a higher amp battery isolator. You need the isolator, if you don't you'll drain both batteries and unless someone can give you a jump you'll be sitting there dead as the battery drain from your lights will draw off of your starting battery without the isolator and will just drain both batteries. You need the higher amp alternator to help charge both batteries quicker to keep from running your auxiliary battery down.

In this setup, keep your vehicle's wiring as is, just take all of your wiring for lights, winch, etc and connect to the 2nd battery once you get it installed and you will be good to go. You aren't going to be using the winch all the time, and if you do, you can kill the KC lights, or at least half of them until your done with the winch. This will also all depend on what battery you chose as your second battery, get one with lots of amp hours as that will help you if you need your lights and winch all running at the same time. The more amp hours the battery will give the more you'll be able to use the battery before it needs recharged.

 

[RajunCajun]

It couldnt hurt to run a bigger alt and parallel two batteries of the same would it? That was my plan for my B2.

 

[wildbill23c]

It couldnt hurt to run a bigger alt and parallel two batteries of the same would it? That was my plan for my B2.

Running both batteries together without a battery isolator will leave both batteries dead at the same time so you wouldn't be able to start the vehicle. Having the battery isolator gives you the ability to run a 2nd battery separately from your vehicle's stock battery that will not cause the stock battery to be drained allowing you to still be able to start your vehicle even if the 2nd battery has been completely drained. This also allows you to use the stock alternator to charge both batteries, as it charges one battery at a time, always the main battery first, then the 2nd battery. The isolator automatically switches the charging between the batteries as they reach a set voltage it switches to charge the other battery.

Battery isolators range from about $30-thousands of dollars depending on how expensive you want to get LOL. But that's the best way to protect your vehicle's main battery from being depleted and leaving you stranded. Another nice thing with the battery isolator is if your vehicle's battery fails at some point you can always swap the wires around and run your 2nd battery as your primary to get home.

Here's a diagram of the simple isolator wiring installation:

 

[Calloway]

wildbill, looks like you answered most of my questions! Much appreciated. I see what your'e saying about the isolator, I was curious about that. So get a high amp hour battery as the second then. Would you recommend a "deep cell?" I read something once about how batteries with a low Cold Cranking Amperage last longer over a prolonged usage, is that true?

 

[RajunCajun]

I'll go poke around few websites today for one. It would only be a problem for someone that has an automatic trans truthfully. When mine dies out I just dump the clutch from a roll! lol

 

[PetesPonies]

What I am saying is, that what you do will not effect it's ability to recharge itself. You have not damaged it.

 

[wildbill23c]

wildbill, looks like you answered most of my questions! Much appreciated. I see what your'e saying about the isolator, I was curious about that. So get a high amp hour battery as the second then. Would you recommend a "deep cell?" I read something once about how batteries with a low Cold Cranking Amperage last longer over a prolonged usage, is that true?

For your second battery a deep cycle battery is your best bet, they are designed to be continually drained and recharged. A true deep cycle battery doesn't have cranking amp ratings as they aren't designed for starting (however in an emergency can be used as a starting battery).

You definitely want a high amp hour output battery, they're pretty expensive but with proper installation and maintenance they'll last many years.

As for low cold cranking amp battery lasting longer, not necessarily, it more depends on the condition of the battery overall than it does the cranking amps.

 

[Calloway]

What I am saying is, that what you do will not effect it's ability to recharge itself. You have not damaged it.

Thats good, here I was thinking that I was killing my battery life running that many amps... thanks

For your second battery a deep cycle battery is your best bet, they are designed to be continually drained and recharged. A true deep cycle battery doesn't have cranking amp ratings as they aren't designed for starting (however in an emergency can be used as a starting battery).

Could you point me toward a good brand that makes a battery for this? I appreciate it...

 

[PetesPonies]

As for low cold cranking amp battery lasting longer, not necessarily, it more depends on the condition of the battery overall than it does the cranking amps.

Exactly, it is strictly controlled by the condition of the plates.

 

[wildbill23c]

Thats good, here I was thinking that I was killing my battery life running that many amps... thanks



Could you point me toward a good brand that makes a battery for this? I appreciate it...

Optima, Diehard are 2 right off the top of my head. $240 for the Optima, and the Diehard is around $110.