36v vs 48v performance

[mrphilf]

Just ran the cart for about an hour and a half thru the woods.

It's definitely stronger than it's was before the charger. I still dropped to the low 42s and even the high 41s to pull some hills that are pretty steep but far from flip over steep, and it was just me on the cart.

Immediately on parking the cart:

Ambient air temp 61.4
Motor 131.7
Controller top 78.6
Controller side 74.8
FNR switch backing plate 81.6
Battery terminals on FNR switch all between 100-102
Top of each battery all around 67-68
Solenoid 101.8

So everything except the batteries is over 10 degrees above ambient air temp

[JohnnieB]

Check the battery pack voltage while the charger's green light is on (Float charge mode) It should be about 52.5V.

The technology the DPI charger uses to determine when the battery is fully charged is better than most, so they are being fully charge, or will be after a few charge cycles.

An imbalanced battery pack reduces the life expectancy of the batteries. They ought to be within about 0.1V of each other.

The problem with 8V batteries, you have to have an 8V charger to charge them separately. However, running back-to-back charges will eventually equalize them, or at least get them closer.

When you want to restart the charger, leave it unplugged several minutes. (5-10)

The Pot-Box sound like it is in the ballpark. I was looking for it being way out or only about 1/2 the value it ought to be. The 1/2 speed reverse puts a 5K resistor in parallel with the 0-5K pot, so it only goes from 0 to 2.5k and sometimes the motor direction, f/r switch and the direction selection lever gets out of sync when they are changed.

Low pressure tire will reduce the top speed, but I'm no sure how much power they steal at low speed.

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It would be best to have a separate battery for the winch unless you have an 8V charger and can give the batteries you use some extra charging after using the winch.

[JohnnieB]

Originally Posted by mrphilf

Just ran the cart for about an hour and a half thru the woods.

It's definitely stronger than it's was before the charger. I still dropped to the low 42s and even the high 41s to pull some hills that are pretty steep but far from flip over steep, and it was just me on the cart.

Immediately on parking the cart:

Ambient air temp 61.4
Motor 131.7
Controller top 78.6
Controller side 74.8
FNR switch backing plate 81.6
Battery terminals on FNR switch all between 100-102
Top of each battery all around 67-68
Solenoid 101.8

So everything except the batteries is over 10 degrees above ambient air temp

Solenoid and F/R getting a bit warm, but not hot. Motor is running cool. Heat gain in the Solenoid and F/R is power not getting to the motor.

Sounds like there is not enough Amps getting to motor for some reason.

The batteries are not broken in yet, so the are at less than their rated storage capacity, Plus the 61° temperature knocks that down by another 15% or so.

Maybe it will improve when the batteries are broken in and the weather is warmer.

[mrphilf]

Should I be looking for weak connections somewhere? If I'm running warmer than normal there should be a reason...and if it's more than one component I would think more than just one bad wire or bad crimp

[JohnnieB]

Originally Posted by mrphilf

Should I be looking for weak connections somewhere? If I'm running warmer than normal there should be a reason...and if it's more than one component I would think more than just one bad wire or bad crimp

Just make sure every connection is clean and tight. Be careful with the battery studs, they are just hex head bolts embedded in lead, so don't tighten them too much or they will turn in the lead and cause a hot spot. The tightening spec is only about 10 ft/lb.

Ideally, there would be no heat gain anywhere except the motor, batteries and controller, but in reality there is some resistance in all the cables, connections and contacts, so the goal is to minimize it.

You've replaced the stock 6Ga cables with 2Ga cables, the stock 85A solenoid with a 200A solenoid and the stock F/R switch with a HD F/R switch, and nothing is getting hot, so the amp delivery system doesn't appear to have any major bottlenecks.

The motor is capable of producing a lot of torque, but isn't getting very hot, so I suspect it isn't getting all the amps it needs to produce the torque it is capable of generating. That means the battery pack is not producing the amps, or the controller isn't allowing the motor to draw the amps it needs.

It will take two voltmeters to do it, but by comparing the battery pack voltage to the voltage between the M- and B+ terminals on the controller will show if the controller is going to 100% duty cycle when the cart is slowing down on a hill. The pack voltage will drop under load, but the two voltmeters should read very close to the same voltage if the controller is wide open.