dual battery hookups for dummies

[Capt Jack]

ok, let me start off by saying, I HATE WIRING and electrical sh!t.  I suck at it and dont know jack about it.  hence my question:

Im looking to run 2 batteries in my ride with the idea of having some serious cranking power available for when the starter is heat soaked while waiting in the staging line.  theres nothing so thrilling as being next to run and having the car not crank over.   

with that, how should these be hooked together to make this happen?

str
+  <----------------|   +    |-----------|   +    |
                      |          |           |         |
                      |          |           |         |
-   <----------------|   -      |-----------|   -     |
gnd

-or-

other?



in addition, what does that do to the charging of said batteries?  anything else that I should be concerned with/considering before doing this?
bad idea in general?  better solutions?

CJ

[NYrr496]

I don't think you need to run two batteries. Why haul the extra weight around? Here's what I did before. Use a mini starter, jump the solenoid and use a remote ford style solenoid energized by the key. This way, when you energize the remote solenoid, the solenoid on the starter gets full battery voltage and no more starting problem. Keep the cables as short as possible, make the ground cable the same size as the positive. Use 1/0 0r 2/0 cable. For a battery, use a group 24 1000 cranking amp. Group 24 is nice and compact. If you don't understand exactly what I'm saying, I'll try to send diagrams of some sort. Also, when it's set up this way, the segment of cable going to the starter is only energized during cranking. A great feature when running headers.

[Evan]

I've never heard of anybody doing this before, but it sounds like a great idea. I had an old ford truck and i liked the way the starter wiring worked. how did you jump the solenoid? i guess you could use a short piece of wire, or a piece of steel with two holes in it? thanks,    -Evan

[mopar stu]

why did  you're battery die at the track?as said before why add the extra weight? i would just address whatever  problem you had with the charging system.

[NYrr496]

You can use a short piece of wire to jump the solenoid out on the starter. I was talking to my buddy before about this post. He owns a battery store. He said they don't make 1000 amp group 24's anymore. He said a group 31 has more reserve capacity. Group 31 is a pretty big battery. A group 24 can still be had with 900 amps. That should be plenty to start a big block. I believe the formula is 1 cranking amp per cubic inch. I believe 99% of starting problems are from poor cabling and cheesy connections. Use a piece of ten guage to jump the solenoid. A piece of copper would work too.  Capt. Jack, you say you hate wiring, when I was younger and didn't understand it like I do now, I taught myself a few valuable lessons. Get excellent quality wiring tools and supplies, be VERY neat and clean, and keep it simple. Make every part of the system one piece at a time and test it as you make it. Believe me, you'll pick it up quickly and get very good. You'll amaze your friends. Also- get a good digital multimeter like a Fluke. They're a little pricey, but once you learn to use it , there will be no problem you can't cure.

[ski]

I don't think you need to run two batteries. Why haul the extra weight around? Here's what I did before. Use a mini starter, jump the solenoid and use a remote ford style solenoid energized by the key. This way, when you energize the remote solenoid, the solenoid on the starter gets full battery voltage and no more starting problem. Keep the cables as short as possible, make the ground cable the same size as the positive. Use 1/0 0r 2/0 cable. For a battery, use a group 24 1000 cranking amp. Group 24 is nice and compact. If you don't understand exactly what I'm saying, I'll try to send diagrams of some sort. Also, when it's set up this way, the segment of cable going to the starter is only energized during cranking. A great feature when running headers.

My buddy did this on his BB Cheb that would never crank when hot.  Never had a problem after that.

[NYrr496]

The only car I haven't done this to is my wife's Saturn. I just looked at a mini starter. Once you remove that plastic doo hickey that the cables connect to, it would be very easy to fabricate a small solid jumper. Just make sure it doesn't ground on the housing.

[jamesdart]

when i get my 67 ready to hit the track, its getting 2 batteries. my 69 has a huge truck and tractor battery in the trunk, it is huge, probably 80lbs, 1100cca  i think. it works great, but id rather run 2 smaller batteries, one one each side. nothing wrong with extra weight when its over the rear tires. my buddies and i found that when you start running a weak betatery it takes its toll on a starter.

[mopar stu]

I'm still not gettin it.a good workinig alternater and 1 good battery won't get you through 1 day at the track?It seems to me you may have other issues.a proper charging system will last months.

[Capt Jack]

I believe the big problem is heat soak in the starter.  once it cools it starts like a champ.  the main body of the problem that I can see is cooling in general. 

on any cold start, no racing, just running around day, it starts n stops with zero issue.  it can be 100F outside...and so long as I havent been idling at a light for an hour, everythings fine.   its when the heat starts to really build up that things start getting sticky.

scenario:  if I idle in line, its easily reaching 280 or more by the time I reach the tree, even if I get in line stone cold...especially on a 300+ car night like last night.  this is a parking lot drag setup, (ie amateur night) so alot of the time its not 'rack n fire' getting people through.  if I start and stop as I roll up, it tends to not have enough grunt to turn over sufficiently until it chills for a few minutes, at which point it starts fine.  a thing everyone behind you in line just loves!   . 

added to that, I'm usually there alone and while I can usually enlist folks to help push me forward in line, thats not what Id call a reliable solution and I have been there when you suddenly realize that hmm....none of these idjuts speak engrish aparrently and end up grunting the thing forward by myself.   .  however from what Im hearing, it sounds more like an issue of getting all the power to the starter vs the starter or power itself. 

history:  I just moved the battery to the trunk with a big brand new mutha humper of a battery.  1000 ca.  I used the cable and ends supplied with the kit, proper tools for attaching, blah blah.  it was a good clean install and the routing keeps the cable as short as Im able to do so from point A to point B.  I might be able to shorten the route a little, but that would probably only eliminate a foot or two from the overall cable length.  hence, my aparrently ill advised solution of a second battery.  I honestly dont mind the thought of the additional weight.  Im still carrying around a full interior, carpets, all steel etc.  in concept and practice, its not actually a race car, just a car that I get to race on occasion.

I believe if I can solve the cooling problem in general (probably thru the addition of a good high CFM electric fan) then all this wouldnt be an issue at all.  I just need to be able to idle this thing long enough to get to the front of the line (more often than not, a considerable amount of time) without it barfing every oz of coolant out on the track doing a burnout (like it did last night  .  boiled so bad it overflowed the overflow).  another thing the folks behind you just love.

so truly, its a compound problem....with my solution being perhaps not so hot (pun intended) 

so....did that help?

[mopar stu]

280 degrees? ,i think that is the source of your problem

[NYrr496]

Yeah. You have to sort out that temperature issue. But I'm tellin' you, jump the pull in connector to the positive terminal on the starter and add a slave solenoid. I think Painless sells a kit called Hotstart or something like that. You don't need to buy that, though. If you see how to set it up, you'll be able to build your own for much less. With the starter set up this way, you aren't trying to energize the starter solenoid through the small pull in wire. I promise, it works really well.

[Capt Jack]

if you have a diagram for that, I'd be most appreciative as I'm not sure I'm understanding what you mean.

but yes, Im looking at fixing that heat issue post haste.

[W2-408]

I run dual batteries in my car for the main reason that in the later rounds of the day, after running the electric fule pump, water pump, and cooling fan, as well as msd ignition, a single battery starts to weaken, even with a good alternator, and I don't have a generator.  Never had a problem since setting up the dual battery system, plus it is weight where I want it. I also went way overkill on cable sizes too, but wanted minimal voltage drop.

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[NYrr496]

if you have a diagram for that, I'd be most appreciative as I'm not sure I'm understanding what you mean.

but yes, Im looking at fixing that heat issue post haste.

I'll figure out a way to post a diagram. I'll speak to someone at work in the print shop. They can scan what I draw and then I can try to get it on here. It won't be until Monday.

[Capt Jack]

thank you.  thats fine and greatly appreciated.   

same goes for everyone else.   

...plus it is weight where I want it.

sort of my thinking as well.  I stuck a bit of weight in the trunk for the runs I made on friday.  just 50lbs seemed to knock a bit off my 60' and just felt better as far as hooking up.  if the weight helps, it might as well be doing something while its there.

pretty much Im realizing I have a number of issues that need addressing on this car...but then, thats what we do.  right?   

[Evan]

is it this one?

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRF%2D30203&N=700+400012+4294925143+4294839066+115&autoview=sku

[NYrr496]

Yeah, that would do it.

[Capt Jack]

ohhhh.....ok.  now I get it.  a ford starter solenoid. 

why didnt ya just say so? 

    (kidding.  thanks for the info.)

CJ

[NYrr496]

In Mopar lingo, that's a slave solenoid. You don't want to have Ford parts on your car now, do you?

Do you get the part about jumping the starter solenoid and putting that in line?

[Capt Jack]

in plain lingo...no

[brickman]

I have a battery in the rear of my 48 and the new stock starter went to hell fast at first.  It was because of 180 lbs of compression and poor ground on the frame in the rear.  I bought a real good gear reduction starter and made a good clean ground and the car starts right up no matter how hot with one battery.

[norwaycharger]

This guy knows his things.
http://www.madelectrical.com/catalog/st-1.shtml

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[NYrr496]

Capt. Jack, I've been very busy at work. I got the diagram scanned and the print shop e mailed it to me. I can't figure out how to get it on the site. If you send me an e mail, I'll send it directly to you. clark.dexter@timewarner.com

[Capt Jack]

sent.  I'll post it for everyone when it gets here.

thanks

CJ

[ski]

Good info Drummerboy.