Do I have Enginer PHEV battery problems?

I have recently purchased and installed the 2KWh kit from Enginer. It started out by being able to take about 1.9 KWh from the house power to get fully charged according to the watt meter. This value has declined over the past 3 weeks to where I can only get the Kill A Watt meter to indicate that only about 1.1 kwh can be put into the batteries. Needless to say I'm buring through the PHEV batteries faster and faster. Plus the charge times are getting shorted and shorter.

Tonight I lifted up the cover on the pack and read the battery voltages from the BMS system after I got the red discharged light on the switch inside the car. Batteries 1-4 all have voltages in the range of 2.7 to 2.9 volts and the others, batteries 5-16, have voltages between 3.2 and 3.4 volts. I decided to start keeping track of everything that I can by recording the battery information. I plan to record them after the charger shuts down as well to see how much voltage is on each of the cells at full charge. However, this wide spread in voltages seems to be out of the ordinary.

From some of the posts I've seen about the Enginer batteries, 2.7 volts seems very low. But, how is it that I have 4 batteries that are low. I can understand 1 low battery when discharged, but 4??? Plus they are side by side???

Well, so much for my first post. I hope someone can tell me if this is out of specification for bettery voltages. What steps can I take to remedy this situation?

Paul

 

I have the latest model (I think). It has the 16 cell BMS and the 5KW inverter.

 

Great idea. I have an adjustable 20 volt/5 amp power supply and I can try it. I will go slowly (2-3 amps) and try to get the 4 low cells up to 3.3 to 3.4 vollts. Good to hear that this fixed your problem. I'll let you know how it works out.

 

Well your suggestion seems to work in terms of getting all the batteries up to 3.3 to 3.4 volts. I left the charger on for about 3 hours at 3.5 amps and 13.8 volts. After that I let the batteries sit overnight to balance. This morning I found them all up to 3.3 to 3.4 volts. I still plan to monitor the batteris with the BMS to see if they stay up to that level. I will also see how many KWh I can put into them with the watt meter. With luck the problem will be solved or if it happens again I will have a solution.

 

Dan -

Thanks for the information. The results from depleting the charge today led to the voltages being about 3.1 volts on cells 1-4. So I put my charger back on those 4 tonight to try and get them closer to the other cells which are about 3.3 to 3.4 volts. I have a pretty good power supply that lets me limit both the current and voltage at the same time. This should be a safe way to add charge without going over the safe limit of voltage.

From what you said above and Jeff said in his earlier post I may need to do this more than once. So I redid cells 1-4 at the low voltage. Is it better to inject current at the bottom when the cells are depleted or is it better to charge all the cells up and inject charge with my power supply at the high end?

After the balance charge, I plugged in the wall power and was able to charge with 1.8 Kwh, which is the best I've seen go into the pack in at least a couple of weeks. I'm still experimenting with the cells and will see if I can get more Kwh into the cells if I keep balancing at the cell tops.

I was wondering what would happen if I take the plugs on the BMS which sense the battery voltages and switch them around. Have you ever done that? Would it take the lower banks (1 & 2) and charge them higher than the two higher ones (3 & 4)? That would be a lot easier than having to haul out the power supply and plug it into the bank of four I want to charge independently.

Paul

 

Hi Mad –
Thanks for the information about the Enginer supplied BMS. I certainly hope that I have a BMS which is good enough to properly control my batteries. I have the newest system from Enginer which is designed to balance 16 cells rather than the old system which required 2 BMS devices each having an 8 cell capacity. Good luck with your new system. My system works OK, but I am certain that it will get better after I get the cell balancing corrected. The current system was only taking 1.3 KWH from the house AC power. With improved balance I hope to bring that up to about 2KWH which is the number quoted in the sales brochure.
Paul

 

Hi Flan -
I think you are probably correct with your assessment. I was reporting the reading on my Kill-A-Watt meter that is plugged into the house receptacle. After the receptacle comes about 60 feet of 16/3 wire which goes out to the car battery charger. That sounds like a lot of I2R heat loss in the wires plus there is a lot of heat generated by the charger. Anyway, my problem was that I saw the amount of power indicated by my watt meter and consumed by the charging process with a depleted pack was steadily going down. Plus, the length of time the car would use the auxiliary battery was decreasing as well. That was the reason for my post. All the responses have started me on a quest to use my 20 VDC power supply to either charge separate cells or banks of 4 cells that seem out of balance. When I looked at Dan’s charts in his post, there is an indication that these LiFePO4 cells will self balance with the provided BMS given enough time (weeks). My cells didn’t seem to be going in the right direction. They apparently needed a little help.
Paul

 

V8 -
Well I guess that is what this has turned into. However, when I started this thread I had no idea of what was wrong with my pack. I've had lots of help from other folks' responses. But it looks like this is a long term problem and the balancing could take quite some time. If you look at Dan's post in this thread, his charts indicate it could take several weeks before this works itself out. I will just have to monitor my cell voltages and ensure that they are within specification. I have already seen some improvement using the ideas from other PC members.
Paul