6V Battery Cables

[mmcdowel]

Got good info off this site about making sure the 6V systems use the large battery cables.  Went home and double checked my Meadowbrook and noticed the cable to the negative terminal was quite large, but the cable off the positive terminal to ground is about 1/2 that size.  Should both cables be the of the thicker variety? My pic of the smaller cable didn't come out well or I would have attached.  The thicker cable is pictured.

It seems to start fine, but maybe doesn't spin as its supposed to.  

Thanks in advance.

 

[knuckleharley]

Yes,you need both cables to be that size,or even bigger.

 

If you have trouble finding cables long enough,you can usually get them made at a tractor dealer for a reasonable price.

 

6v systems draw a lot of amps,and lots of amps heat up small battery cables and crystallizes them,which limits the amount of amps they will pass.

[mmcdowel]

Thanks!  Andy Bernbaum  offers "factory diameter" cables with the cloth covers, etc, etc. for a reasonable price.  I've got them on order.  If they aren't as advertised I'll send them back and go to the tractor supply.  Usually Bernbaums is pretty good though.  Will advise!

 

[Don Coatney]

1 hour ago, knuckleharley said:

 

 

6v systems draw a lot of amps,and lots of amps heat up small battery cables and crystallizes them,which limits the amount of amps they will pass.

 

Never heard of crystalized battery cables. Can you further explain? 

[Plymouthy Adams]

the greenish and white fluff on the cables and post of a battery is the 'crystalizing' of the acid on the surface exposed to air.   I believe this is what he is referring to......a cable built without a lead wicking effect on the end strands would be subject to hide this crystalizing inside the strands of a cable that has been subject to a bit of bird caging and or growth inside the terminal.    Usually this is just referred to as a corroded condition

 

Edited August 31, 2018 by Plymouthy Adams

[Dodgeb4ya]

Battery cable wire strand count is important when buying cables... cheap cables...less copper less fine copper wire strand count meaning less current carrying capability causing slower starter cranking power.

Buy good quality battery cables like fabbed up welding cable with commercial quality terminal ends.

Some replacement cables look big but that's because of the thick outer rubber/plastic covering.

[sser2]

Positive cable is short, so it can be of lower gauge compared to negative one. The important issue is voltage drop in the cable, which increases with cable length and decreases with cable diameter.

 

Making your own cables to your own taste out of scrap copper wire is a very easy task - all you need is propane burner, solder, and electric flux. Home Depot sells 0 and 00 gauges multi-strand by the foot at very reasonable prices. Lead battery clamps are also inexpensive.

[mmcdowel]

Stopping by Home Depot and Napa on my way home.  Thanks again for all the support.  She always seems to start fine, but I bet she will be a little perkier with the proper wires.  I'll let you all know how it goes.  MMc

[knuckleharley]

7 hours ago, Don Coatney said:

 

Never heard of crystalized battery cables. Can you further explain? 

Sure. They get so hot they turn colors and get stiff. When they do that they are resistant to passing current.

 

I call that crystallizing. If that's not the right word,I apologize.

[maok]

MoThe idea that you need a much larger gauge battery cable for a 6v in comparison to a12v is incorrect.

The torque required to turn a given engine is the same regardless of battery voltage. the torque is directly proportional to the amps from the battery.

If someone has a DC amp clamp meter and 6 and 12 volt batteries, they can verify.

 

if the engine takes some time to start, yes larger cables are of benefit.

[knuckleharley]

15 minutes ago, maok said:

MoThe idea that you need a much larger gauge battery cable for a 6v in comparison to a12v is incorrect.

The torque required to turn a given engine is the same regardless of battery voltage. the torque is directly proportional to the amps from the battery.

If someone has a DC amp clamp meter and 6 and 12 volt batteries, they can verify.

 

if the engine takes some time to start, yes larger cables are of benefit.

Did you ever try to explain this to the engineers that designed all the cars made before 12 volt systems became universal?

[maok]

I wasn't invented until 12volts...?

[Dodgeb4ya]

This National Data Book showing both 6 and 12 volt starting motor stall torque amp draws on a 1953 Chrysler V-8.... 6 volt starter draws more amps... heavier cables required for the 6 volt.

1953 Chrysler's used both 6 and 12 volt systems... The Crown Imperial was 12 volt.

 I would assume someday you will appreciate heavy duty high strand count battery cables and a good battery ? when the engine seems to balk at starting quickly.

Edited September 1, 2018 by Dodgeb4ya

[maok]

The below is from this site - https://electronics.stackexchange.com/questions/39387/how-are-current-and-voltage-related-to-torque-and-speed-of-a-brushless-motor

 
In any motor, the basic principle is very simple:

rotational speed is proportional to voltage applied
torque is proportional to current pulled
A 100 volt motor is a motor that can take a maximum of 100 volts, and a 50 volt motor a maximum of 50 volts. Since the 100 volt motor can take more volts, if all else is equal, it can give you a higher maximum speed.

But the difference in voltage does not affect the torque. To get more torque to go up a hill, you need to supply your motor with more current. A motor that can take more current (and a battery and motor controller that can supply more current) will give you more torque to help you up the hill.

 

Here are screen dumps from another site of someone doing the experiment;

 

 

What is interesting is that the 12volt battery is actually slight more current draw because of the extra friction created at the higher turn speed that the 12volts produces.

[rallyace]

Power is measured in watts. Your starter motor delivers a specific amount of power that can be measured in watts. One watt = 1 volt x 1 amp.  The amperage for any specific wattage is directly proportional to the voltage. For example,  600 watts at 6 volts = 100 amps and  600 watts at 12 volts = 50 amps.  Wire size determines its current, or amperage, capacity.  The wire size for 6 volts needs to have twice the current carrying capacity of wire that is intended for 12 volts.  The wire sold at just about every auto parts house is sized for 12 volts. You should use a minimum of a 0 gauge wire (that is zero gauge) from the battery to the solenoid, from the solenoid to the starter and from the block to the battery for a 6 volt system.  Yes, I am an electrical engineer.

 

[maok]

2 hours ago, rallyace said:

Power is measured in watts. Your starter motor delivers a specific amount of power that can be measured in watts. One watt = 1 volt x 1 amp.  The amperage for any specific wattage is directly proportional to the voltage. For example,  600 watts at 6 volts = 100 amps and  600 watts at 12 volts = 50 amps.  Wire size determines its current, or amperage, capacity.  The wire size for 6 volts needs to have twice the current carrying capacity of wire that is intended for 12 volts.  The wire sold at just about every auto parts house is sized for 12 volts. You should use a minimum of a 0 gauge wire (that is zero gauge) from the battery to the solenoid, from the solenoid to the starter and from the block to the battery for a 6 volt system.  Yes, I am an electrical engineer.

 

 

As an electrical engineer, you would know that a DC motor (starter motor) spins twice as fast when 12 volts is applied than 6 volts, so the power applied is twice the amount with the same load on the motor.

What do you think the current drawn will be with twice the power?

 

[Dodgeb4ya]

Just install commercial  heavy duty cables to make sure you have covered your current draws!

You can look at charts all day long and just go to sleep..................

[classiccarjack]

I hope someday the bickering stops amoungst one another...  Sigh

 

One other solution is to buy welding cable, it's fine strand design works excellent for replacement battery cables.  Make sure you get a good crush on the terminal then solder it.  If you heat shrink over the ends, it will help prevent corrosion.  I own several Diesel trucks, and noticed a improvement on starting them on really cold days in Kansas, after I made my own cables out of welding cable....

 

Please let us know how the cables you ordered turned out.

[mmcdowel]

Will do.  They should arrive later this week.  I'll send pics.

[classiccarjack]

15 hours ago, mmcdowel said:

Will do.  They should arrive later this week.  I'll send pics.

Awesome!  I look forward to see how they look. 

[mmcdowel]

Cables arrived!  Not quite as thick as what I had anticipated, but they are sturdy....will barely bend.  Feels like a solid rod of copper.  Can't see the ends as they are neatly soldered across to tell if its multiple strands or not.  I really like the original looking covering.  Oddly they are different part numbers, but have had a chance to look closely enough to find the difference.  What do you all think?  These are definitely thicker than what I have on there now.

[Plymouthy Adams]

with the length, cable and bolt eye terminal being the same, if you ordered a positive and a negative cable the different number will reflect the size of the battery clamp....the positive post on a battery is just a tad larger than that of the negative....

[mmcdowel]

AH!  I understand.  Do these look OK?

 

[Plymouthy Adams]

look is one quality in a build.....the ability to conduct the current without voltage drop or heat generation that will lead to thermal runaway...well that is a dynamic test...

 

will they look right at home in your engine compartment, you betcha..!!

[rallyace]

On 9/2/2018 at 1:25 AM, maok said:

 

As an electrical engineer, you would know that a DC motor (starter motor) spins twice as fast when 12 volts is applied than 6 volts, so the power applied is twice the amount with the same load on the motor.

What do you think the current drawn will be with twice the power?

 

When I made my post I suspected I would see this as a comment. Here is the technical reply. The torque (and associated power) produced by an electric motor is a direct function of the flux density created by the coils in the motor. The flux density is a function of the construction of the motor.  Motor speed and torque produced are inversely proportional. Maximum torque occurs at what is known as Locked Rotor conditions (zero RPM). As the speed increases, the torque decreases. and the resultant power created will decrease. The motor will attempt to spin faster under load on 12 volts but will be limited by the torque it can produce and the loads created by the internal friction of the moving parts in the engine.

Edited September 10, 2018 by rallyace