DPI charger and interstate batteries

[meangreenmachine72]

Ok, thats great. Thank you very much for the information. This site is so helpful and interesting.

[branson]

the new batteries are working out great. I'm just curious why the state of charge is reading so high. the last time the batteries were charged it finished at about noon on Monday Using charge mode 1. I checked the state of charge this morning before I left for work. I get a reading of 51.43. should I be adjusting my state of charge chart to reflect that and not discharge the pack to the voltages on the existing chart?

[JohnnieB]

Originally Posted by branson

the new batteries are working out great. I'm just curious why the state of charge is reading so high. the last time the batteries were charged it finished at about noon on Monday Using charge mode 1. I checked the state of charge this morning before I left for work. I get a reading of 51.43. should I be adjusting my state of charge chart to reflect that and not discharge the pack to the voltages on the existing chart?

You should probably be using a US Battery SoC chart. Notice that there are Two versions attached.
The first one uses 2.133V for a fully charged 2V cell, while the other uses 2.137V. Both values came from US Battery.
Also, the At-Rest voltage of new batteries tends to run a bit higher when fully charged.

An At-Rest voltage of 51.43V is a ballpark figure for a new 48V battery pack, but how did you get there?
Did you disconnect the charger at about noon Monday when the charger completed its regular charge cycle?

The reason I ask is because the DPI goes into float charge after the regular cycle finishes and if the charger is left plugged into the cart (and AC power), so the voltage ought to have been about 53.1V this morning.

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As for correcting the charts due to the higher voltage at 100% SoC, don't bother. Once below about 90% SoC all the Voltage vs SoC charts track about the same.

[branson]

yes the DPI charger has been disconnected since about noon on Monday. I did not have time to get individual battery voltage reading this morning but I'm on my way to stop by at lunch time and I will get those measurements. if nothing else just for my own curiosity
P.S thank you for the new battery chart

[branson]

I just did a quick check on the battery
pack 51.40
#1. 8.60
#2. 8.56
#3. 8.54
#4. 8.56
#5. 8.57
#6. 8.60

[JohnnieB]

The float charging does make getting an At-Rest voltage a royal pain , but the way I track my battery health is by burning off the surface charge and then letting the batteries rest for half an hour.

Basically, I unplug the cart, drive to the end of the road I live on and back, then let the cart sit for about 30 minutes and take the voltage readings. That is a 1.7 mile round-trip and I get the about same reading in half an hour that it would have taken 12 hours to get if I had just let the pack self-discharge.

I have a 245AH-42V pack, so you may not have to travel quite as far to burn off the surface charge.

It doesn't matter too much if the numbers between the two methods don't match exactly, just as long as you do it the same way every time.

[JohnnieB]

Originally Posted by branson

I just did a quick check on the battery
pack 51.40
#1. 8.60
#2. 8.56
#3. 8.54
#4. 8.56
#5. 8.57
#6. 8.60

Looking good.
Only a 0.06 variance between batteries.

[branson]

thanks Johnny. I guess I was just overthinking it. when I see that my batteries have such a higher state of charge then the other charts I don't know why. it makes sense if you use a different battery than trojanyou would have to use a different chart

[JohnnieB]

Originally Posted by branson

thanks Johnny. I guess I was just overthinking it. when I see that my batteries have such a higher state of charge then the other charts I don't know why. it makes sense if you use a different battery than trojanyou would have to use a different chart

What it boils down to is that different manufacturers use different acid concentrations for the electrolyte and the cell voltage is tied to the Specific Gravity of the electrolyte. The more concentrated the acid, the higher the voltage, but only at, or approaching, fully charged.