2/0 vs. 1/0 cable vs. ????

[Portland Suburban]

Alright, so I am planning for new batteries for the lead sled AKA 1982 Suburban 6.2L. In thinking about new batteries, I am thinking it might be good to do the cable conversion along with Dr. Lees battery update. Alright...

So there seems to be two popular cable conversions. 1/0 and 2/0. 1/0 is used by the local electrical updater here in town. In reading mcmaster.com the amperage ratings for both are:

1/0

[CleviteKid]

As you probably know, those "amperage ratings" are based on continuous useage, with a low enough temperature rise that the insulation is not compromised. Our engines will draw on the order of 600 amps, with the 27MT starter (less with the 28MT), but for at most a few seconds.

The issue then is the voltage drop in the cable. 10 feet of 1/0 cable will have a resistance of just under 0.001 ohm, and 10 feet of the 2/0 cable will be just under 0.0008 ohms. At a 600 amp draw, there will be just over 1/10th of a volt more voltage at the starter with the larger cable. Only you can decide if that 0.1 volt is important or not.

If your Portland Suburban is in Portland, Oregon, I would say don't bother. If it is in Portland, Maine, go with the bigger cable. Here in Miami I could use 18 gauge zip cord . . . . . . .

Dr. Lee :cool:

[Portland Suburban]

18 guage zip cord. Now that is funny! Well, yes, I am here in Portland, Oregon .Now while it does not get that cold, it does dip down into the 20's for a few days. smile.gif

In reading, it is not the cost of the 2/0 gauge that is the issue, but rather the non flexiness of the cord. So...maybe 1/0 will be fine.

[NH2112]

Try welding cable, the stuff is so flexible you can tie it in knots at -40. The covering does tend to get soft and sticky if oil gets on it, though, and its flexibility means it's not the best at abrasion resistance, but split loom can help. The most important thing to look for to handle high current is the Circular Mil Area, which is basically the surface area of the wire strands in the cable. A high CMA means a lot of surface area, which means a large number of very small strands. It should be imprinted on the covering itself, at least on good cable.

[bmiszuk]

I bought my Suburban last winter. It came with one battery and that simply wasn't enough to turn the engine over fast enough when it got cold. (The Suburban was from a warmer climate.) So I replaced them with two Autozone 875cca batteries thinking I'd solve my starting problems. It helped, but wasn't enough. $160+ spent.

Then I had new battery cables made to replace the old crummy ones. I wanted 2/0 cables, but the guys who made the cables told me I didn't need them and 2/0 was hard to handle. I reluctantly went along and got 2 guage cables made. Even with the new cables the engine cranked slow and was hard to start and I was disappointed. $60 spent.

Then one day my starter died, after extended long periods of too-slow cranking when I was trying to get it started. I went to the local parts store and dropped $150 for a rebuilt. Not a gear drive, the 'old fashioned' kind. The result? The truck turns over incredibly fast even in cold weather and starts very well.

I wonder why I'm telling all this! :rolleyes: I suppose it's to say that every time I thought I was fixing my starting problem, I was wrong. I am now convinced that there are many things that must all work properly for a 6.2 to start well in cold temps. Need good batteries, good cables and connections, a fresh starter, a good glowplug system, and fuel lines that don't suck air. It's worth the trouble to check everything. As I've worked on the truck and made mistakes (ie. fuel lines sucking air, one battery disconnected, etc) I've noticed how so many different things can really cause hard starting problems.

Sorry for the lengthy reply. I know it's not really what you asked about. But as cold weather approaches maybe the mistakes I made will help others. My 6.5 never started as well as this 6.2. I wish I knew then what I know now.

[Portland Suburban]

Thanks for the reply. I am fairly confident that my batteries are a serious weakpoint. I did a test to confirm my fears. On one cold day (35 degrees here with wind) to check for control, I turned her over after running the glows. Very slow almost dead. After jumping the sub with my truck AND car both running, it turned over like it was a balmy day after running for a few hours. Boom. Started right up.

Verdict: Underpowered batteries.

On a side note, my suburban WANTS to run. It always starts warm. There may be some air getting in there or water-but I have not drained the water/fuel seperator in a while. Need to do that.

Chris

[bmiszuk]

I have to agree with Phil about welding cable. That's what I have now. It's really flexible. I use split plastic loom to protect the cable in areas where it might rub on something.

Sounds like your batteries are bad. Do you know how old they are, and are they a matched pair?

[CareyWeber]

Originally posted by bmiszuk:
I have to agree with Phil about welding cable. That's what I have now. It's really flexible. I use split plastic loom to protect the cable in areas where it might rub on something.

Sounds like your batteries are bad. Do you know how old they are, and are they a matched pair? I built my own battery cables using 1 gauge welding cable and it was the one of the best mods I have done. :cool: ;)

Protect them and they'll last! ;)

Carey

[Portland Suburban]

Well, today at work I did a little figuring. I really have two ultimate choices.
1)Run welding cable all around the engine bay with 1/0 or 2/0 cable. Hopefully in the process, reduce the clutter and ground points in the rig.

2)Move the batteries into the rear and run 4/0 cable from front to back which will reduce the number of ground points. Of course, I could go with smaller cable given that the interior will be warmer than the outside.

So....choices choices.

[NH2112]

Actually, conductivity is better at cold temps than hot. That's why they're trying to develop room-temperature superconductors, to eliminate both impedance AND liquid nitrogen tongue.gif

[mhagie]

Unless the Suburban is now a Drag car leave batteries in stock location and go with the smaller welding cable, 2/0 is a waste for your location 4/0 is not even worth considering.
Read NH2112 post and follow it you will be better off.
Do the Dr. Lee battery bolt mod while you are at it.
chances are you will have to replace the batteries as the pair is no better than the weakest one,
2 new batteries around 800cca will fix you up. :D
Merle

[Portland Suburban]

I have heard that comment before about not moving the batteries. While I respect your opinion, I whole heartedly disagree. If the batteries can be moved, move em. There are a few reasons why they are better off in the back. The least of not which being....ahem...extreme weather.

I am not starting a fight here, but there are credible reasons why they could be moved, and I highly doubt anything is a true "waste"-even large cables. One never knows when one might need to move to wisonsin...

[NH2112]

Originally posted by Portland Suburban:
I have heard that comment before about not moving the batteries. While I respect your opinion, I whole heartedly disagree. If the batteries can be moved, move em. There are a few reasons why they are better off in the back. The least of not which being....ahem...extreme weather.

I am not starting a fight here, but there are credible reasons why they could be moved, and I highly doubt anything is a true "waste"-even large cables. One never knows when one might need to move to wisonsin... I do just fine in NH with a single Wal-Mart 875CCA EverStart mounted under the hood, and stock-sized battery cables. At least the truck doesn't start any harder in the cold than my K10 w/dual 800CCA & 2/0 Thomas & Betts battery cable. (No fuel heater, either, and no gelling problems.) I run the block heater for about 2 hours before I leave for work, and it starts within a couple seconds even at -30F.

Where are you referring to when you mention putting them "inside?" It's not going to be much warmer, if any, inside the truck than outside, and the distance from batteries to starter will most likely be farther, unless you're talking about putting them in the passenger footwell or under the passenger seat.

A fully-charged battery will still deliver more than enough current to start the engine at -40F. If the battery isn't getting a full charge, none of the other mods you mention will make a difference - you'll just have bigger cables with lower resistance to handle a still-inadequate amount of current. Hooking a fire hose up to your garden-hose sized water faucet won't fill your pool up any faster smile.gif

If you move to WI, just put a battery warmer on each battery and splice the cords into your block heater cord, they'll consume maybe 150W and help more than relocating the batteries or high-perf cables.

[Portland Suburban]

I think I mentioned a few times that the cables would be done in conjunction with the new batteries. In other words...of course I am changing out the batteries.

[bmiszuk]

Phil, what do you do when you can't plug in the truck? Does it still start well on one battery if the outside temps are cold and the engine is cold also?

In my experience, one battery is good for a warm engine (ie block heater) or warm outside temps, but not enough when everything is really cold. But I also had a weak starter so that probably affected things too.

[NH2112]

I've left the truck running before when I had no access to electricity, but that hasn't happened very often. I've stayed at hotels before that had no problem with me plugging in to an outside outlet, or running my 100' cord into an entrance (not the lobby.)

[jcomp]

I went with 4/0 cable and top post connectors. I had a crimper for that size and made all of the cables myself. I'm sure it is overkill but I know that the weak link in my starting system is not the cables or connectors.

While I was at it, I also went with a remote mounted solenoid and relocated all of the primary power taps from the starter solenoid to the hot side of the glow plug relay, which is connected to the batteries by a 0ga cable. All that goes to my starter now is a big battery cable.

[Portland Suburban]

Thanks...I wondered where all the accessories went into...

[NH2112]

Since my glow plugs are manually-operated through a toggle switch, I'm thinking of installing an ether system for cold starts when I don't have the luxury of electricity for my block heater. Most likely I'll have to set it to deliver a smaller shot than normal, due to the high compression. The last thing I want to do is shatter some rings!