Friday, March 9, 2012

Zivan Overcharging

I'm doing my 7th charge right now and have learned that I have to watch the Zivan 120V DC charger very carefully.

The first couple of charges went as expected.  There's a display LED on the unit that tells you what charging phase you're in.  When first plugged in, a red LED comes on, it beeps twice and two stages of fans come on.  When it reaches the 80% charge point, a yellow LED comes on.  When it reaches the 100% charge point, a green LED comes on and the charger shuts off.  This should allow fo unattended charging overnight.  The first 3 charges put in about 8.0 KWH to 8.5 KWH, ran through to the green LED and shut off around 6:45 hours to 7:00 hours.

This matches what I was expecting, given the characteristics of the battery pack:

242 AH * 6V = 1452 WH per battery.
1452 WH * 20 = 29,040 WH = 29 KW per pack.
Charge range goes from 70% to 100% of pack capacity = 30% of pack capacity
29 KW * 0.3 = 8.712 KWH.

On charge #4, I noticed that it was still yellow but was up to 9.0 KWH at 7:00 hours and the pack voltage was 157V!  The PakTrakr was reporting overcharge on several of the batteries.  I pulled the plug and let it stand until the next day.  The pack had dropped down to 128V or so and PakTrakr said all batteries were now good.  I decided to check the water level and found that every cell, 60 of them, was about 1/2" down from full, but not anywhere close to the top of the metal plates.  This may be natural, but I certainly wasn't expecting to water the batteries every 4 charges.

Charge #5 was a partial, interrupted by a popped breaker as I was charging it from a different plug on a different side of the house.

Charge #6 hit 157V again, at 7:16 hours and 8.68 KWH.  Now I'm worried and I just can't trust the charger.

Here's the whole charger and the two stickers on the charger:

I do have T125 type batteries with 240AH capacity (actually rated at 242AH) , so hopefully the factory settings were done correctly.

This F5 sub-model isn't even listed on the Zivan web site, only ones starting with F7.  Also, there's no explanation of the U1, U1E, U2 and U2E voltage values and how the charging phases work in the NG3 manual.  The charging curve page is blank!  You can see that my physical model doesn't even look like the one in the manual.  Mine doesn't have the long bar of LEDs showing the charging state, just the circular 0-80%, 80%-100% and 100% charging LED display.

I just spoke with the staff at Zivan / Elcon in Sacramento and described the symptoms.  He had me check the small rotary switch and it's set to "4" which is correct.  He said given the model and switch setting, it was correct for my batteries and shouldn't go up to 157V and said I should send it in for testing.  When I asked if he would be able to look at it within a couple of days of arrival, he said "Jesus, no way", as he has about 150 chargers already in line for repair.  He gets about 3 more every week.  Even though I just got it into the car, it's out of warranty and if I pay a $35 rush fee he'll look at it soon after arrival.  I need to include a note stating what I'm seeing happening, the make and model of my batteries and my contact details.

Wow, I'm not thrilled that this is happening so soon after getting the car rolling.  I have to decide when the time is right to send it in, as I have a couple of week-long out-of-town trips coming up.  I get to pay for shipping two ways, repair and possibly rush fee.

I'm 4 hours into the charge now and it's at 134.6V and 5.35 KWH.  I use a Kill-A-Watt unit to watch voltage, current, AH and time of power delivery.  I'll watch it closely through the rest of the charge.  Next charge I'll log 15 minute data on volts, amps and KWH so I can see what's going on, and report it accurately to Zivan repair if necessary.  If the repair is prohibitively expensive, I may just go right for a 240V AC charger.