hight Voltage readings

[lawnripper]

I posted a couple times regarding high voltage readings... 2000 PDS 36v.

Even after 7-8 miles of hilly terrain etc... where as b4 my reading would have been more like 37. 4 or somethan I am getting readings of 38.9 / 39.0
I have a brand new DVM and have tried another DMV from my electrician friend and still the same reading. I also notice my run time is not what it was.. not bad but definitely shorter runs. Also this morning after charging I did my normal 2 week check and clean.. and more than half of the cells where dry. One more thing.. I have noticed that when the charger starts up it used to go up to almost 20 amps.. as of about 1 month it has been starting on the 15 amp mark. Anybody have a clue as to what could be going on? Sulification?
Any help much appreciated...

[lawnripper]

Does anyone have any idea on what could cause high readings off the battery pack and individual batteries? Have tried 3 different DMV with same results.

Thanks

[simple man]

I have one thought here, did you replace any of the batteries and maybe got an 8V one by mistake?

[JohnnieB]

What are the individual battery voltages? (They should be 6.37V 12 hours after the charger shuts off automatically.)

Do you have an auxiliary battery for accessories?
If so, how is it connected. Entirely separate or does it share a common B- with the main pack?


Dry cells and sulfated plates produce high internal resistance in the batteries and would explain dropping from 20A down to 15A when charger starts up.

Also, if the batteries weren't discharged very much, the starting amps will be low with some chargers.

[lawnripper]

Johnnie B, Do I let the cart sit for 12hrs. after charge or use it like normal (which is about 1-2 miles per day)?
I have been getting high reading 38.9 even after 10 hrs since full charge and driving around 2-4 miles.


This sounds interesting...."Dry cells and sulfated plates produce high internal resistance in the batteries and would explain dropping from 20A down to 15A when charger starts up." If this is the case what do I do?


All batteries are 6v. there are no voltage reducers or extra battery.
The cart has the same perk and the run time is shorter but still not bad.

[JohnnieB]

Originally Posted by lawnripper

1. Johnnie B, Do I let the cart sit for 12hrs. after charge or use it like normal (which is about 1-2 miles per day)?
I have been getting high reading 38.9 even after 10 hrs since full charge and driving around 2-4 miles.


2. This sounds interesting...."Dry cells and sulfated plates produce high internal resistance in the batteries and would explain dropping from 20A down to 15A when charger starts up." If this is the case what do I do?


3. All batteries are 6v. there are no voltage reducers or extra battery.
The cart has the same perk and the run time is shorter but still not bad.

1. After the charger shuts off automatically, either let it set for 6 hours or more (12 preferred) or drive it around for about 10-15 minutes. This get rid of the surface charge and will give you a meaningful SoC reading.

2. Keep the fluid level in the batteries above the plates at all times and keep the batteries as fully charged as possible and practical. Other than that, it is pretty much an irreversible part of the natural aging process.

3. That eliminates one possibility of where the extra voltage was coming from.
What is the temperature where you live. If it is above 80°F (27°C) it might be a factor.

[JohnnieB]

I just remembered, you have a PDS cart.
Are you running in Steep Hill or Mild Hill modes? (the ones with regen braking)
If so, the motor is charging the batteries when you lift you foot of the pedal or coast down hills.

That may be why the voltage is higher than normal.

[lawnripper]

got it! I will check the readings again and write them down.
The other day while the cart was reading 38.9 I tested the pack while driving up a hill and it went down to about 35.7 on the steep parts.

a few days agao I checked water levels after a all night charge and a lot of the cells in various batteries had no water covering them... I was so bummed. I check the levels at least 2-3 times a month.

We are in our dry/hot season and these hight v radings and 15amp on start do seem to have consided with our climate change.. we are averaging about 90-100 degrees since November. (the rainy season is a lot cooler).

[lawnripper]

I have had the Freedom chip going since I got it in August.

[JohnnieB]

Originally Posted by lawnripper

I have had the Freedom chip going since I got it in August.

Do you have hills that you coast down and the cart seems not to go much fast the about 18MPH (or whatever if the max speed is on level ground) ?
That will also turn on the regen braking.