Upgraded to 48v, charging dilemna

[imaeyeguy]

Originally Posted by cgtech

Also keep in mind the minimum amp capacity of the charger to satisfy the battery charging requirements. This is an example from Trojan batteries. A T-105 has a 225ah rating at 20 hour discharge rate. And they want a charge rate of no less than C/20. This means any charge rate lower than 11.25a for the bulk phase is unsuitable. A big reason is the battery needs to circulate the electrolyte to prevent stratification of electrolyte, and a lower rate won't achieve this.

Does the bubbling that occurs relate to the charger providing sufficient amperage? At the end of charging cycle, my batteries gurgle and bubble pretty vigorously. Water levels never seem to go down though each time I check.

[mutant]

water loss is erratic and unpredictable from what i have observed on here-bubbling is normal but there is no way,to my knowledge,to use it as an indicator of amp sufficiency or proper charging stage profile....

[JohnnieB]

Originally Posted by imaeyeguy

Ran first test. After charging all the batteries and letting them sit overnight, I took the cart for a quick 1 mile ride. Here are the voltages afterwards starting with the battery connected to Plus (+) terminal first:

1. 6.44V —— 1st 36V group
2. 6.45V
3. 6.45V
4. 6.45V
5. 6.44V
6. 6.44V —— Last 36V group
7. 6.45V —— First 12V group
8. 6.44V —— 2nd 12V group

Total Pack voltage 51.7V

Should be noted that #5 and #6 are connected as 12V by manufacturer to run lights and turn signals.

Did I give enough stabilization time? Voltages seem high since I’ve been reading that 6.37V was 100% charged.

The 1 mile trip was more than enough discharging to eliminate the surface charge. 500 yards is usually far enough.

The Voltage vs SoC charts are the averages from a statistically significant number of mature batteries discharged under controlled conditions. New batteries will have higher than average voltage and older batteries will have lower than average voltage. The at-rest voltage will also vary by battery manufacturer, Trojan being the lowest voltage and US Battery being the highest voltage.

What make/model are the batteries you are using?


Tapping two 6V batteries for the 12V accessories will kill those two batteries and harm the rest. Use a voltage reducer fed by the entire pack or use a separate 12V battery for 12V accessories.

[JohnnieB]

Originally Posted by imaeyeguy

Does the bubbling that occurs relate to the charger providing sufficient amperage? At the end of charging cycle, my batteries gurgle and bubble pretty vigorously. Water levels never seem to go down though each time I check.

The bubbling (gassing) is caused by the electrolysis of the water in the electrolyte. Technically, water decomposes into Hydrogen and Oxygen gasses whenever an electric current passes through it, but in a lead-acid battery the lead sulfate that forms on the plates during discharge is also being converted back into lead and sulfuric acid at the same time, so very little gassing occurs until the on-charge voltage reaches about 2.35VPC (Volts per Cell), which is about 56V for a 48V pack.

Temperature, atmospheric pressure and several other factors influence how vigorously the batteries gas, so it cannot be used to estimate quality or quantity of charge and water usage is unpredictable.

[gornoman]

JohnnieB is my hero.

[imaeyeguy]

Originally Posted by JohnnieB

The 1 mile trip was more than enough discharging to eliminate the surface charge. 500 yards is usually far enough.

The Voltage vs SoC charts are the averages from a statistically significant number of mature batteries discharged under controlled conditions. New batteries will have higher than average voltage and older batteries will have lower than average voltage. The at-rest voltage will also vary by battery manufacturer, Trojan being the lowest voltage and US Battery being the highest voltage.

What make/model are the batteries you are using?


Tapping two 6V batteries for the 12V accessories will kill those two batteries and harm the rest. Use a voltage reducer fed by the entire pack or use a separate 12V battery for 12V accessories.

Batteries are made by Interstate. Got them from Costco.

RC 105, Amp Hr @ 20hr: 205.

The 12V setup by manufacturer is only for lights and turn signals, I tried to disconnnect but it seems the ground does other things besides just the signals and lights so I left them alone. I seldom use either.

I have a separate small 12V AGM Deep cycle size U1 battery that has 45 reserve capacity for accessories.

[cgtech]

Electric golf carts generally Never use a "ground" like a car does. The TXT electric falls into the category of "never uses a Ground".

[imaeyeguy]

Originally Posted by cgtech

Electric golf carts generally Never use a "ground" like a car does. The TXT electric falls into the category of "never uses a Ground".

What I meant by that was when I disconnected the negative black wire from battery that corresponded to the lights and blinkers, other things on the cart stopped working. So that led me to believe that there were more than a few items that used that same wire as the “ground”. It would be a lot of rewiring to resolve so I left it alone.