New Batteries and Cables

[Dave Box]

Sonic is on the money. I used to work in an environment where we transmitted 100 kHz at about 25 kV. Research showed that due to the skin effect the best conductor was copper plumbing pipe. Solid copper was a waste of time and money as the power was just transmitted along the skin.

I also wonder at the accuracy of the hostile atmosphere of the battery bay. Gassing batteries give of hydrogen which is lighter than air and dissipates readily. As long as your cables are thick enough and well made and as long as you protect your battery terminals and connections with sealant or Vaseline I would bet that your auto store cables are going to be fine.

Dave

[sonicj]

I would at some point like to build a rig for measuring and comparing different cables & constructions techniques. Unfortunately, due to the high currents involved, quantifying the performance of one battery cable vs another is rather difficult (aka: expensive) task with off-the-shelf instruments. It would certainly be interesting to see the difference "Auto Store Cables" vs "Welding Cable" or Crimp vs Solder actually makes in real quantifiable numbers!
-sj

[rabbitreborn]

Originally Posted by sonicj

This is only true for AC. skin effect
-sj

Thank you for the correction. I was unaware that this applied ONLY to AC. Always nice to learn something new every day.... I do have one question regarding this though if I may? ARC welders are for the most part DC welders. If Skin Effect only effects AC, why then does every ARC welder manufacturer use fine strand welding wire for their machines? I would assume that with the higher cost or Welding cable, in these economicly troubling times that they would gladly switch to automotive grade cable since it would save them signifigantly on the cost of production of the units.

Originally Posted by Dave Box

I also wonder at the accuracy of the hostile atmosphere of the battery bay. Gassing batteries give of hydrogen which is lighter than air and dissipates readily. As long as your cables are thick enough and well made and as long as you protect your battery terminals and connections with sealant or Vaseline I would bet that your auto store cables are going to be fine.

Dave

If the battery compartment isn't a hostile environment, why would you need to coat the terminals? Not trying to start an arguement, but I work on at least 20-30 carts a week, and with little exception, most of them have lousey maintenence on the batteries/cables/battery trays. While the gas is lighter than air, for some reason, it still manages to reform as a liquid once it hits the outside of the batteries and run down the sides causing all manner of havoc with every bit of metal it comes into contact with...... including the terminals and cables...

Maybe I am off my rocker, but as a mechanic that works on these things daily, I much prefer to work with something that is highly flexible and has the best protection I can provide.

[yurtle]

Originally Posted by sonicj

I would at some point like to build a rig for measuring and comparing different cables & constructions techniques. Unfortunately, due to the high currents involved, quantifying the performance of one battery cable vs another is rather difficult (aka: expensive) task with off-the-shelf instruments. It would certainly be interesting to see the difference "Auto Store Cables" vs "Welding Cable" or Crimp vs Solder actually makes in real quantifiable numbers!
-sj

I'd think any firm that can do current injection for testing medium voltage breakers could do this. Definitely not off-the-shelf, but easily in reach for anyone that maintains switchgear, and I'll bet they would do it for free. Just schedule your testing and have the cables handy.

[yurtle]

Originally Posted by rabbitreborn

Thank you for the correction. I was unaware that this applied ONLY to AC. Always nice to learn something new every day.... I do have one question regarding this though if I may? ARC welders are for the most part DC welders. If Skin Effect only effects AC, why then does every ARC welder manufacturer use fine strand welding wire for their machines? I would assume that with the higher cost or Welding cable, in these economicly troubling times that they would gladly switch to automotive grade cable since it would save them signifigantly on the cost of production of the units.

Welders use relatively low voltage and high currents. My Lincoln Amp buzz-box is 225 amps. The wire has to be flexible. That's all. The ampacity of a solid copper conductor of the same gauge is about the same, but far less functional.

[JohnnieB]

Originally Posted by Dave Box

..............I also wonder at the accuracy of the hostile atmosphere of the battery bay. Gassing batteries give of hydrogen which is lighter than air and dissipates readily. As long as your cables are thick enough and well made and as long as you protect your battery terminals and connections with sealant or Vaseline I would bet that your auto store cables are going to be fine.

Dave

Gassing cart batteries give off more than just hydrogen.

I know electrolysis of water produces both hydrogen and oxygen in gaseous form, and I suspect hydrogen sulfide is also out-gassed since free sulfate ions and free hydrogen ions are present on the negative plates while a battery is being charged. I don't remember enough about chemistry to spell out the exact formulas for the subsequent actions and reactions, but the trapped air in the battery compartment must be both explosive and corrosive as evidenced by reports of battery explosions and the need to apply a protectorate to exposed copper and lead to keep them from turning green and yellow.

Granted, the battery compartment in most carts is fairly well ventilated, but during the gassing phase, I'm pretty sure the atmosphere above the batteries is a pretty wicked brew.

-------------------

Other than flexibility, I don't believe it makes much difference on carts what the strand count is as long as the jacket material is impervious to oil, water and acid and the lugs are hermetically sealed. The same is true about whether solder or crimp is better for the lugs. If done properly with lugs that can be hermetically sealed, both ways will work.

Of course, the 2Ga cables on my cart are the welding type with a 600+ strand count and silver soldered lugs.

[Dave Box]

If the battery compartment isn't a hostile environment, why would you need to coat the terminals?

It's a valid question and the answer is that every time you connect two dissimilar metals one will become an anode and the other a cathode. When you pass a current through them, the anode will corrode. Corrosion needs oxygen so if you coat the anode with lithium grease or Vaseline or a propriety spray you will eliminate the oxygen and ergo the corrosion.

As a slight aside this is why in the 50's auto manufacturers switched to a negative ground system to stop the car body and chassis being one large anode.

Dave

[JohnnieB]

Originally Posted by Dave Box

If the battery compartment isn't a hostile environment, why would you need to coat the terminals?

It's a valid question and the answer is that every time you connect two dissimilar metals one will become an anode and the other a cathode. When you pass a current through them, the anode will corrode. Corrosion needs oxygen so if you coat the anode with lithium grease or Vaseline or a propriety spray you will eliminate the oxygen and ergo the corrosion.

As a slight aside this is why in the 50's auto manufacturers switched to a negative ground system to stop the car body and chassis being one large anode.

Dave

What you say is correct, but I believe there is some acid in the air also.
Otherwise, why do both the lead battery posts and the copper lugs corrode on both positive and negative battery terminals
(The copper would be anodes of the dissimilar metal junction on the negative battery posts and the lead would be the anodes on the positive battery posts.)

Also, cart battery trays are eaten away by something and there is no current flowing through them. (Unless somebody is using a grounded frame for accessories. )

[Dave Box]

First two caveats.

I am here just for the academic distraction. If proved wrong then that's great because I have learned something new. I am not about to argue, but I might disagree.
Secondly, sometimes I troll through the sparky section just for fun during an otherwise boring moment. Whenever I see an answer from JohnnieB I always stop and take notice for here I have discovered well written and intelligent replies, so once again no arguments here.

I think the answer to
Otherwise, why do both the lead battery posts and the copper lugs corrode on both positive and negative battery terminals
is that there is dissimilar metal in each terminal i.e. the lead post, whatever the lug is made from and the bolt holding it together so each terminal has its own little anode and cathode.

I scoured the four corners of the internet (ok the first three pages of Google) but could find no reference to batteries giving off anything other than H and O. Here is a typical quote from an RV article.

In the worst case (ie. a seriously overcharging battery beyond 70% of full charge) produces about 0.2 litre of hydrogen and 0.1 litre of oxygen for every watt/hour of charge. Keeping to a safe 2% concentration requires about 10 litres of air per watt/hour - or 2.5 litres per watt/hour to stay below a borderline 4%.

A 12 volt 100 amp/hr battery charging at a runaway 35 amps accepts about 14.4 volts X 35 amps/hour - approximately 500 watt/hr. It will produce about 100 litres of hydrogen/hour - requiring 5,000 litres of air/hour to dilute to 2%- or 1250 litres of air/hour to dilute to 4%.

I would respectfully suggest that corroded battery bays are most likely due to sloppy maintenance. If a battery is overfilled the electrolyte will expand during charging and it will overflow. I suspect that this 35% solution of sulfuric acid will do two things.
It will mix with the dirt and dust on the top of the battery, providing a current leak path between the terminals thus shortening the battery life.
It will dribble down into the battery tray where it will do what acids do best.

Keeping oxygen away from your battery terminals and washing your batteries (and consequently you battery bay) with baking soda will make a world of difference.

Dave

[JohnnieB]

Dave,

First of all, thanks for the kind words.
I do try to be clear, concise and factual in my statements and answers and I also try to differentiate between what I know to be true and what I think may be true.
Of course, what I think to be true is sometimes proven wrong, and I learn something new.

The color of the corrosion I get on my cable lugs and battery posts tells me it is sulfates and/or sulfides of copper and lead, so the lugs and posts are being exposed to sulfur ions. The most likely source for these ions is the sulfuric acid in the electrolyte and the lead sulfate on the plates, but how exactly the sulfur ions get from point A to point B is unknown to me.

I'm fairly conscientious about not overfilling my batteries, but the baking soda mixture I use to clean them always foams when I spray it on, so there is an acid present. Source unknown.

However it gets there, baking soda and a scrub brush, a good rinsing followed by a protectorate of some kind is definitely the way to go.

John