expected run and charge time on new batteries

[duurmeehr]

First test drive today on resurrected cart with new batteries and all new cables. Not sure what to expect.

36V resistor drive system. That resistor assembly sure gets hot also.

Never had a cart before. Fully charged new batteries before starting. I estimate I may have went about 2 miles with some hills before voltage dropped to 37.5 volts and I figured I better stop and recharge following break in procedures?

Connected up charger and was surprised when it knocked itself off after about an hour. I grabbed my meter and the pack said 39.8 volts after about 30 minutes off charge.

Full charge according to the SOC chart???

How much range should I expect to get out of that resistor system?

This cart is going to be used for hunting only, good roads but some hills.

Could there be some issues with the operating system limiting range or is this just inherent of the resistor system wasting energy?

[Yamahaman]

I read some where new batteries will get better after light usage and freguent charging after about 15 or so recharges.

[Sir Nuke]

Originally Posted by Yamahaman

I read some where new batteries will get better after light usage and freguent charging after about 15 or so recharges.

This is very true.....after about 20 or so cycles they should reach their max potential. after that, ALWAYS remember.....keep it plugged it! if you use is....CHARGE IT! and of you don't regularly use your cart, and don't have a charger that has a "float" feature.....do yourself AND your cart's batteries a favor and unplug and re-plug in your cart about every week or so to maintain your pack fully charged.

[JohnnieB]

duurmeehr, sounds like you are taking the voltage measurements too soon after charging, or discharging the battery pack to make an accurate SoC estimate.

To get a good SoC estimate, you have to wait about 12 hours after the charger shuts off to take the voltage reading. Waiting just 30 minutes will give you an artificially high because you still reading the surface charge voltage. When a 36V battery pack is charged, the pack voltage is about 45V when the charger shuts off and it takes about 12 hours for the chemistry equalize throughout (equilibrate) and when it does, the voltage should be about 38.2V for a fully charged 36V battery pack. (New batteries will be slightly higher)

When amps are drawn from a battery, the voltage drops. The more amps drawn, the more the voltage drop. For a typical 36V battery pack, the voltage drop is about 1.0V per 100A of current flow. The voltage drop is almost instantaneous, but the recovery is slow. The voltage recovery time is actually more than an hour, but most of it occurs in the first few minutes, so waiting just 5 to 15 minutes after the cart stops moving is sufficient to get an SoC estimate to see if it is tine to head back to the house and charge the batteries.

When I do battery testing and range estimating, I let my batteries rest at least half an hour after the end of the measured test drive.

-----------
A resistor drive cart is most efficient when the pedal is on the floor.
The heat being generated by the resistors is wasted electrical energy and all the resistors are bypass when the pedal is on the floor.

To estimate your cart's maximum range, charge batteries overnight.
Measure the distance traveled with a GPS or GPS phone app.
Let batteries rest 30 minutes at end of GPS measured trip.
Subtract the SoC for the chart for that voltage from 100%
Divide the percent of SoC used on trip by the miles of the trip to get the %Soc used per mile.

Multiply that number by 50 and you have an estimate how far your cart will go without taking the battery pack below 50% SoC.

[JohnnieB]

Originally Posted by Yamahaman

I read some where new batteries will get better after light usage and freguent charging after about 15 or so recharges.

New batteries only store about 75% of their rated storage capacity and it takes anywhere from a dozen or two, up to a hundred or so, charge cycles before they'll store their rated storage capacity. New batteries should not be discharged too deeply for the first 20 or so charge cycles. Discharging no more than to 75% SoC is typically recommended for the first 20 cycles.

In the Trojan Tech tip video linked to below, at about 1:58 in, it states it takes 75 to 150 charge cycles, but I believe most of the gain occurs in the first two dozen cycles.
http://www.trojanbattery.com/floatbox/trojantips78.html

[duurmeehr]

Originally Posted by JohnnieB

duurmeehr, sounds like you are taking the voltage measurements too soon after charging, or discharging the battery pack to make an accurate SoC estimate.

To get a good SoC estimate, you have to wait about 12 hours after the charger shuts off to take the voltage reading. Waiting just 30 minutes will give you an artificially high because you still reading the surface charge voltage. When a 36V battery pack is charged, the pack voltage is about 45V when the charger shuts off and it takes about 12 hours for the chemistry equalize throughout (equilibrate) and when it does, the voltage should be about 38.2V for a fully charged 36V battery pack. (New batteries will be slightly higher)

When amps are drawn from a battery, the voltage drops. The more amps drawn, the more the voltage drop. For a typical 36V battery pack, the voltage drop is about 1.0V per 100A of current flow. The voltage drop is almost instantaneous, but the recovery is slow. The voltage recovery time is actually more than an hour, but most of it occurs in the first few minutes, so waiting just 5 to 15 minutes after the cart stops moving is sufficient to get an SoC estimate to see if it is tine to head back to the house and charge the batteries.

When I do battery testing and range estimating, I let my batteries rest at least half an hour after the end of the measured test drive.

-----------
A resistor drive cart is most efficient when the pedal is on the floor.
The heat being generated by the resistors is wasted electrical energy and all the resistors are bypass when the pedal is on the floor.

To estimate your cart's maximum range, charge batteries overnight.
Measure the distance traveled with a GPS or GPS phone app.
Let batteries rest 30 minutes at end of GPS measured trip.
Subtract the SoC for the chart for that voltage from 100%
Divide the percent of SoC used on trip by the miles of the trip to get the %Soc used per mile.

Multiply that number by 50 and you have an estimate how far your cart will go without taking the battery pack below 50% SoC.

Good information. I will try that tomorrow.

I can already see another addiction coming on. This is as bad as when I started reloading my own duck and turkey shells 30 years ago!

It sounds like the resistor drive is not conducive to creeping along up and down the hills at the hunting property turkey hunting. Any idea what percentage of loss the heat wasted in the resistors make up?

I may need to start a new thread with this but I am gonna ask advice anyhow. I don't mind spending money on this old cart but would like what I do to be forward compatible if I decide to update 20 years newer or so.

My tires are rotten so I have to buy new anyhow. I could gain 2 inches ground clearance if I go from 18 to 22 but need to make sure I still have enough torque to climb the hills in the road albeit slowly. Speed is not important torque and range are. I am guessing I will have to lift the body a pinch to give some room to keep from scrubbing.

Would it be worth it to go to a controller type drive system to gain extra distance? What size would I need to be sufficient but not go overboard? Does someone make a kit with pedal sensor, drive etc? Can I buy one slightly to large for this stock motor in case this stock motor is anemic or a newer cart needs a bigger motor later? Who would be the person to call with such questions???

[JohnnieB]

Originally Posted by duurmeehr

Good information. I will try that tomorrow.

I can already see another addiction coming on. This is as bad as when I started reloading my own duck and turkey shells 30 years ago!

1. It sounds like the resistor drive is not conducive to creeping along up and down the hills at the hunting property turkey hunting. Any idea what percentage of loss the heat wasted in the resistors make up?

I may need to start a new thread with this but I am gonna ask advice anyhow. I don't mind spending money on this old cart but would like what I do to be forward compatible if I decide to update 20 years newer or so.

2. My tires are rotten so I have to buy new anyhow. I could gain 2 inches ground clearance if I go from 18 to 22 but need to make sure I still have enough torque to climb the hills in the road albeit slowly. Speed is not important torque and range are. I am guessing I will have to lift the body a pinch to give some room to keep from scrubbing.

3. Would it be worth it to go to a controller type drive system to gain extra distance? What size would I need to be sufficient but not go overboard?

4. Does someone make a kit with pedal sensor, drive etc? Can I buy one slightly to large for this stock motor in case this stock motor is anemic or a newer cart needs a bigger motor later? Who would be the person to call with such questions???

1. Not unless you like starting grass fires. I don't know what the % loss is. but the resistors do get hot enough to set grass on fire.

2. Going to a 22" will decrease the torque by 18%.

3. A controller would be a lot more efficient. I don't know what all can be done to upgrade a resistor drive cart, but there are quite a few guys on this forum that have upgraded them.

4. http://www.cartsunlimited.net/conversion-kits.html

[cgtech]

The resistor system draws roughly the same amps where ever the pedal is. If you are traveling at 20% of top speed, the resistors are "burning-off" that other 80%. The exception is when at full throttle, the resistors are bypassed, allowing full power to reach the motor.