Hey fellas, I know this subject has been discussed before but I'm not having much luck finding any info using the FTE search thingy.

Basically I'd like to add a second battery to my 86 F150 to aid with starting in the frigid temps we're having here.

Currently the truck has a 1000 cranking amp/800 cold cranking amp battery, the battery is only about 6 months old, I've tested it and its fine. The truck also has a 130 amp alternator, it's also about 6 months old, I had it tested too and it checks out fine as well. My battery cables are all new, my connections are tight and clean as well. The starter and solenoid are also new.

According to my voltmeter she holds a solid 14.5 volts at idle, She has no problem maintaining 14+ volts with the heater blowing, head lights on, and cd player cranked up.

Based on what I mentioned above I'm sure my charging system is fine. The truck starts just fine at 0 degrees and up, but the last week or so we've had an average low temp in the -20F range, with wind chills pushing the negative 30 to 40 degree range. To make matters worse I work 3rd shift, so I get out between 3 and 4AM when the temps are at their worse. The truck will turn over on those bitterly cold mornings but it turns over really really slow, it hasn't left me stranded yet but I think its only a matter of time.

So what I was thinking of doing was adding the identical 800 cold cranking amp battery that I currently have in my 96 F150. Both batteries are exactly the same, I purchased them together and as I said before they're about 6 months old.

What exactly is involved with adding a second battery? If I just ran a new cable from the positive on one battery to the positive of the other, and negative to negative, would that work?

Thanks in advance to anyone who takes the time to respond, any advice to keep me from burning the truck down would be greatly appreciated.

 

YES, But I'm not sure that will help all that much. In temps like that OIL is real thick causing the condition. You might want to look into a block heater or leave a trouble light on under the oil pan. Of course that requires an electrical plug. Or run a 5-30 synthetic oil during the winter.

 

What gauge wire are you using for you starter and ground?

 

Pretty much everything turns over slower in these kinds of temps. If you have been able to keep cranking, and it never really slowed down, then you are ok. Heavier cables like Stosh likely is hinting at won't hurt, and if you were to go to a second battery, you would want them anyway because the little ones will melt down if cranked on for too long with that much battery power.
Oil is thicker, tolerances become tighter in cold like that. Hopefully we are largely done with that, but it is too early to say for sure. Another possibility is the starter is getting weak, but if it has been cranking and firing fine, you really don't have anything much to worry about. If you were slowing down cranking and barely getting by I would be more concerned.

 

To answer your question, yes; bat + to bat +, bat - to bat -.

 

I second this opinion. Doing this would be easier and likely more effective at getting your engine started in bitterly cold weather. Block heaters work well. A small light bulb will put out enough heat to keep the oil from turning into glue too. Lots of folks in Alaska use block heaters with good success. Now if the darned batteries would just not freeze.

Ed

 

Here is how the factory dual batteries are hooked up if you are interested,

 

If it is something you really want to do, get the battery tray and cables from a diesel of about the same age, up til 94, and swap them in.

 

Thanks for the responses everyone, and Merry Christmas.

I installed a electronic block heater when I rebuilt the engine over the summer, unfortunately there's no place to plug her in at work. I'm currently running 10-30 synthetic blended oil. Once I get a few more miles on her, and get her broke in a little more, I may try 5-30 and see how she does.

I believe my cables are zero gauge, anyways they're about three times as thick as the factory ones were. I made them using the same cable and terminal ends that my buddy uses on his tractors and other heavy equipment. Some of his machines have 5 or 6 industrial sized batteries, so I'm sure my cables could easily handle the additional juice of a second battery.

One thing I didn't really consider earlier is that this engine is still a pretty fresh rebuild, I've only got about 2500 miles on it. Perhaps its still a little tight, not completely broke in yet.

I had the starter tested and its fine.

Its been cranking and starting alright, but like I said there was them few really cold days here where it hardly turned at all. I'm responsible for locking up shop after hours so I'm the last person to leave by at least a half hour or so. Figured it would really suck if the truck crapped out on me there since no one is around to bum a jump start off of. The Mrs. gave me a jump box for a early christmas present so I've been keeping that charged and in the truck. If all else fails I've also got my battery charger tucked behind the seat, but it would suck having to sit around and wait a few hours for it to charge.


I've got a couple days off here so I'm gonna try and rig something up with the second battery just for the hell of it.

Oh before I forget, I've heard people mention battery isolators being used on dual battery vehicles. I did a quick search and couldn't really find much online. What would be the advantages or disadvantages in using an isolator?

 

Please, do yourself a favor. You are doing fine by running synthetic. But there's no point in running a synthetic without using the best thing about it.. it's cold flow properties. Use a 0W-xx or 5W-xx. Just so you know, a 0W-30 would be much thinner in the cold temperatures than a 10W-30, BUT when warmed up, they would be the same.

Now, there is a range in each of the weight scales that they can vary. Example, 5W-30 Pennzoil Platinum is thinner than 0W-30 Castrol Syntec (aka German Castrol) at 212F. Castrol Syntec 0W-30 is almost a 40 weight type of oil. It is highly shear stable and would probably be what I'd use in an engine like yours. Another good oil is 0W-40 Mobil 1. I'm not a fan of the other Mobil 1 weights, but this one returns GREAT used oil analysis results. Thing about it is, it starts out in the 40 weight range, and typically shears down to the weight of German Castrol. BUT, that's just how it does, it still is a good oil. I use the 0W-30 Castrol Syntec myself. But, I wouldn't mind to use the 0W-40 M1, but with what I'm using, my truck uses NO oil.

 

You do know that synthetic is NOT recommended for new engines don't you?

It will not allow the rings to properly seat.

I've been working on racing engines my whole life and it is pretty well known that you should not introduce full synthetic until after the 3rd to 4th oil change.

 

Setups like The factory diagram in the previous post, and a 2nd battery using a isolator, are used when the power drain for the 2nd battery is different than the main battery. That's why it's called a "isolator". It isolates the 2nd battery drain from the main battery drain.

For your purposes, the diesel setup will be the best, both batteries hooked together. I know you said in an earlier post the 2nd battery will be the same age and the same type of battery. For anyone else reading this thread, this point is very important. By hooking both batteries together, you are really just creating one large battery. They have to work together. If one battery is down on strength, then both batteries will only be as good as the weakest.

 

I have heard people SAY not to use synthetic in a new engine, but with no backings. LS1's came with synthetic from the factory, along with many others. There's really nothing wrong with it. It just costs more to get your first few quick oil changes in.

 

Believe what you want. I'm telling you from experience that rebuilt or new motors have much better ring sealing and break in with conventional oil.

 

I have also heard that synthetic is too slick, and prolongs ring break in. The rings seating in the bores is a little touchy, with the ring material, the finish on the bores, and the break in procedure being critical to hurry up the process. A engine can use a lot of oil and have a lot of blowby till the rings break in, so a rebuilder is going to want this to happen as soon as possible to keep the customer happy. Nobody likes a newly rebuilt engine that burns oil.