2ga vs. 4ga

bigpoppi

Don't know if there is or has been a thread concerning the two... Have read responses from the masses, that 4ga wires have been used by many in applications up to 500amp controllers, and others that have said 500 amp and up 'should' use 2ga wires... first question, are stock wires 6ga.?... second, will only going to 4 ga. be a weak link (besides the stock motor), when I add the 500amp Alltrax controller (pkg #909 from Scottyb)? third, what's an SOC? read it and drew a blank on what it is, someone had mentioned they needed to increase theirs..... forth, will or should there be a difference between 2 and 4ga wires with a 500amp controller? and Fifth, and this is just me taking a shot... if scotch taste so bad why drink it!!! just kidding couldn't be serious the whole thread....

BGW

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scottyb

Stock cables are 6g, that's good enough for golf with 2 passengers in the cart on a moderate course. Even carts used for golf benefit from the increase in cable size to 4g.
Years ago 4g was all we ever used. Recent recommendations from controller manufactures state 2g is needed at 500 amps and above. Certainly at 36v this is true but, at 48v you are actually drawing less amperage so a case could be made to raise the bar at higher voltages. Aftermarket or high torque motors will also demand more amperage = bigger cables.
The important thing is that you have fresh welding cables of 4 or 6g throughout the cart.(to the motor, controller, F&R, solenoid, & the batteries .
If you have small or bad cables they will present resistance which will create heat. This resistance and heat can result in a component melt down at the F&R, cable end, or battery connection. Big fresh cables provide the conduit for the motor to draw whatever amperage is needed without unwanted resistance.

JohnnieB

1. Older carts had all 6Ga cables, newer carts have all 4Ga and some in the middle had a mix of the two.

2. I went with 2Ga with a stock PDS controller.

Safety (Heat issues)and efficiency (Performance loss) are the two main reason for using larger cables.

The length of the high current cables varies with body style and drive type, so I'll use 20', which I believe is about the minimum length for comparison.
500A through 20' of 6Ga cable drops 8.125V and generates 4.1kW of heat.
500A through 20' of 4Ga cable drops 5.108V and generates 2.6kW of heat.
500A through 20' of 2Ga cable drops 3.213V and generates 1.6kW of heat.

3. SoC = State of Charge. In a nutshell, the higher average SoC maintained, the longer it is before you have to replace your batteries.
Basically, if I am not actually diving my cart, my batteries are 100% SoC. (If have a DPI 36V charger the goes into float charge when normal charge cycle is complete. )

4. Yes. See voltage drops listed in answer 2 above. Don't know how much difference 2V will make with a Sepex motor, but it will definitely make a difference with a Series motor.

My original cables didn't even look bad, but i noticed a gain in low end torque and acceleration when I went to all 2Ga cables. My stock PDS controller limits motor RPM, so no difference in top speed was noted, but with an aftermarket controller that doesn't limit RPM, there might be an increase in speed.

5.

bigpoppi

So, all questions answered, new questions arise.........JohnnieB, SoC, state of charge, the point at which you keep your batteries charged..... so, how will I know if my charger has the 'float mode', guess I can google the model #. And, if it has a float mode, can I leave the cart on the charger for lengths of time, like 2 or 4 days....?? now looking at Scottyb's sight, $250 2ga. cables, brings the other question, is there a difference between cables made for 6v batteries vs. 8v batteries.. just thinking I can put 6 under the seat and a 12v for accesories opposite the controller, and store the charger under the rear seat...... never ending, why, what, how come, but what if?....

yurtle

Your question on SOC might have been related to a SOC meter. There are several different ones available, but a digital meter is the best. You spend a ton on your batteries, and a "small" investment on a good meter like ScottyB sells is cheap insurance for long battery life.

JohnnieB

1. Not exactly. State of Charge is the percentage of energy left in the battery, but you never want to use more than half the energy stored in a deep cycle battery because you drastically reduce the life expectancy if you do.
Here are a couple charts:
The first is Soc vs voltage. (Voltage is measure 12 hours after battery comes off charge)
The second is Projected charge cycles (life expectancy) vs average SoC maintained.

2. Just post the make and model or pictures of it.

3. You can float charge a battery forever. It is a constant voltage charge, held below the gassing stage, so the current flow is basically equal to self discharge rate, plus any parasitic drain.

On the other hand, a Trickle charge is constant current or current limited to low value type charge and the voltage can climb up into the gassing stage and use water.

4. Get the complete set (10 cables) - looks like he has them on sale for $199.

5. They are the same. The cables don't know what the voltage is, only the amps. 36V system draw more amps for the same performance as a 48V system, so they typically need bigger cables.
(Actually it is the other way around, 48V systems draw fewer amps for same performance, so some people skimp on the cables. )

6. Sounds like you are planing on 6 x 8V for a 48V battery pack. That will give you about the same run time as a 6 x 6V 36V system.
Accessory battery under the driver seat is where they are usually placed.

7. If it is weather proof. if you go with an On-Board charger, stear clear of the QE line. They seem to have a high failure rate and aren't repairable.

8. Getting into metaphysics I see.

Attached Images

	StateofChargeChart.jpg (53.8 KB, 0 views)
	SoC vs Theoretical Charge cycles with Voltages.JPG (119.3 KB, 0 views)

bigpoppi

Textron 915-3610 36v charger.... and yes/kinda/sorta leaning towards the 6-8v's, adding a battery tender, but am open to other idea's and advise.. as far as the draining of the batteries, I've tried not going below 37... my trips are usually just to daughters house and back, with lights on, on the way back. speakers soon to be added with a small amp, at the camp ground, it's just little jaunts, adding the DVM will be easier to keep track...

JohnnieB

Ouch!!! That is one of the QE chargers.
When it fails (or you upgrade to 48V), get one that is reliable and repairable.

For the portable type charger with float, the 48V DPI shown here is a good one. http://www.cartsunlimited.net/48v_Battery_Charger.html
For an on-board type charger with float, there is one out there, but I can't remember the make and model. Hopefully, someone that has one will chime in.

If your typical usage isn't taking you much below 37V on your 36V system, and you don't change your driving style too much, you should be fine with a 6 x 8V 48V system.
Adding a 12V accessory battery while help cart run-time also.

When using a DVM battery meter, let batteries rest a few minutes after stopping cart to get a good SoC reading.

bigpoppi

Well, knock on wood, hope the charger lasts til I convert to 48 volts... I talked to a friend at work, asked him on how often he charges his (48v) cart... he said every few weekends, he waits til the lights dim when he hits the 'juice'. Figuring he's waiting too long, tried to direct him to the forum, but he said 'it's ok, it's been working so far, If I have to change the batteries, so be it!'.... I guess ignorense is bliss?.

Again, thanx for the advise and input, I await the onboard charger info. one question, what is involved in reprogramming the controller if first set to 36v and later to 48v.... can it be set to 48v settings and run by a 36v system???

scottyb

The controller can be set up initially so that you can run 36v now and 48v later. You can get a solenoid that can handle both voltages or you can wire your activation circuit to remain on 36v for the solenoid......