Battery settling voltages. What is acceptable?

[Repro]

I have four Lion Energy UT1300's connected in parallel. I recently disconnected them to do a capacity test.

After fully charging individually, then sitting 2 days individually, here are the voltages:

13.68V
13.66V
13.42V
13.12V

The batteries were all charged to 14.6V within an hour of each other. Lion Energy says it is acceptable. However, the battery with the lowest voltage will more than likely continue to discharge. I think it is going bad. Just wanted some opinions on the varying voltages. Thanks in advance!

 

[snoobler]

There is some variability between manufacturers and sizes, but I tentatively disagree with Lion based on the raw numbers.

I have some Calb cells that sat fully charged for a year and were at 3.30-3.31 and retained > 90% of their charge.

Without knowing your charge method, I see some room for uncertainty:

1. Were they all at exactly the same voltage before you charged?
2. Were they each on the charger for exactly the same amount of time?
3. Did the batteries measure 14.6V AT the battery terminals with a separate meter?

If any of the answers are "No" or "I don't know", then confidence of proper/full charging is low.

I would place all of the batteries in parallel and charge with leads attached to opposite ends of the bank, e.g., (-) to (-) of #1 and (+) to (+) of #4. Charge until each BATTERY voltage measures 14.6V @ the battery.

 

[John Frum]

I have four Lion Energy UT1300's connected in parallel. I recently disconnected them to do a capacity test.

After fully charging individually, then sitting 2 days individually, here are the voltages:

13.68V
13.66V
13.42V
13.12V

The batteries were all charged to 14.6V within an hour of each other. Lion Energy says it is acceptable. However, the battery with the lowest voltage will more than likely continue to discharge. I think it is going bad. Just wanted some opinions on the varying voltages. Thanks in advance!

What were the battery voltages 1 minute after charging?

 

[Repro]

I charged the batteries fully in parallel last week and kept and eye on the voltage of all four and independently. Connected, they settled to13.47V after two days as well as independently. I put them under a load to discharge them a little, then disconnected them, and charged two each at the same time with two IOTA DLS-45 (with LiFePO4 modules) for approximately 1 hour. The other two were charged with two Bioenno Power 20A chargers for about 1 hr 45min. All batteries were charged at the same time to 14.6 V. The 20A chargers needed 45 min longer.

The voltages immediately after charging dropped to 14.2V except one that dropped to 13.8V. My biggest concern is that the differing voltages of that amount is slowly causing damage to the stronger batteries. Am I wrong?

 

[snoobler]

I don't trust the IOTA algorithm.

No idea about the Bioenno units.

I see a lot of variables, and I'm not seeing that you indicated the 14.6V was AT the battery terminals. Cabling/connection resistance particularly in temporary setups can completely jack with the charge.

I would repeat the four-in-parallel charging as I described above (cables to opposite ends), immediately disconnect the batteries from each other and take voltages at 5, 30, 60 minute, 12 hr, 24 hr and 48 hr marks as individual batteries.

Then run a discharge test of each.

 

[Repro]

Will do! I will be using the IOTA charger again as they are best chargers I have. Heck, even Lion Energy told me to buy them as their engineers use them as well. Looks like I tossed out some money if the algorithms can't be trusted. I will have to babysit them till the charging process is completed if I am to disconnect them when done. I will let you know. Thanks!!!!

By the way. What AC charger do you recommend specifically for LiFePO4?

 

[snoobler]

I generally recommend Powermaxx PM3. They follow a traditional FLA/AGM RV 3 stage profile, 14.4, 13.6, 13.2V, which can work very nicely for low-stress LFP charging.

Where they fail is in the RV wiring. If the gauge is thin, the wiring can cause so much voltage drop, the battery will never see anything close to 14.4; however, 13.6V can get a LFP charged to about 95% in about 6 hours. Sucks if you're on genny, great if your on shore. Good wiring makes genny charging more feasible.

The IOTA suffer from the same issue, and they have no float, which means if you hit 14.6V prematurely due to wiring losses, there is no follow-on charging at lower voltages.

It's a mixed bag.

If the wiring is beefy with negligible voltage drop between charger and battery, the IOTA will outperform the Powermax to quickly charge to something north of 80-90%, but with no follow-on charging.

Most RV wiring between the converter and the battery results in significant voltage drop. For that reason, I recommend PM3 over IOTA.

 

[HRTKD]

For your test, as long as you get all four batteries charged to as high as the charger will go (while still less than or equal to 14.60v), that's good enough. Use the same charger for all four batteries in parallel.

Then disconnect and take individual measurements. All you really care about for this test is that all four batteries rest at the same voltage. If one goes a lot lower than the others, that battery is the problem child.

 

[Repro]

Thanks! Big help. I will post the results.

 

[Repro]

I just ordered the PowerMax PM3-45. I will use it exclusively with the Lion Energy batteries. Thanks for the tip.

 

[HRTKD]

It seems to me that many of the mainline AC-DC converter vendors that are making them for RV units aren't producing a converter that is optimal for LiFePO4. Yes, many of them have a LiFePO4 charge profile. But given the larger Ah capacities of the LiFePO4 batteries, especially the DIY variety, the charging amps could be much higher. Since a LiFePO4 battery can accept a much higher charge rate, there should be a plethora of converters with charge rates in excess of 60 amps.

The limiting factor may be that most RV 120v AC systems aren't built to provide the amps that are required. For example, the IOTA Engineering 75 amp converter uses a NEMA 5-20 plug for connection to a 20A receptacle. On my trailer, the plug doesn't matter because I have to cut it off and wire the cord directly into the circuit breaker panel. But I would need to replace the existing 15 amp breaker with a 20 amp breaker. That's a fuzzy area. Not every breaker panel can handle that.

If my generator has the capacity, I would want my converter to get the charging done ASAP so I could minimize the time the generator has to be on.

 

[snoobler]

The nice thing about the current LK model of the PM3 is that it's adjustable for voltage, and it can also operate as a constant voltage supply.

PM3 12V LK series. Sometimes, you'll run across old stock that doesn't have those features.

 

[Repro]

Wow, thanks for that. I just cancelled my order as it was not the LK series, and placed an order for the 45A LK version at the same price.

 

[Repro]

The PowerMax charger was sent per UPS ground and I have a tracking number, but still no status. I am going to wait till it arrives, and use it for charging these batteries. I am going to connect the 4 batteries again in parallel to balance 24 hours before the charger gets here. It may take a week till it gets here. Thanks snoobler for the tip on the charger. Can't wait till it arrives.

 

[Repro]

OK, my PowerMax converter arrived early today. It was the LK version that is switchable for fixed and adjustable voltage. Looks just like my IOTA's without the COMM port for the LiFePO4 dongle. The batteries were at least 24 hours in parallel to balance, I then applied a 30A load for two hours, and connected the PowerMax. Charging the batteries in parallel was completed in about 4 hours.

I just disconnected the batteries, leaving them stand individually, I measured the voltages of each battery, and all were at 13.79V. I will measure again at the intervals you gave me, and I will post them when done. Thanks!

 

[Repro]

So, here are the results for the four Lion Energy batteries.

Three of the batteries surprisingly showed the exact same values during the monitoring, and only one was different at the 5 minute measurement with a voltage of 13.78V, but was still at 13.78V 30 minutes later. After that, all three measured the same as shown below.

5 Min = 13.79V for two batteries, one was 13.78V
30 Min = 13.78V for all three
60 Min = 13.78V
12 hours = 13.76V
24 hours = 13.74V
36 hours = 13.72V

This was the battery that I had identified and suspected of having issues. I am going to continue to monitor and document the voltages.

5 Min = 13.68V
30 Min = 13.66V
60 Min = 13.61V
12 hours = 13.52V
24 hours = 13.31V
36 hours = 12.99V

I did the same for a set of new 200Ah batteries just to see the difference between year old batteries, and batteries I below that bought in January. Here are the measurements. These were charged in exactly the same manner as the batteries above, with one exception. I used the IOTA DLS-45 with LiFePO4 dongle to charge them. Both batteries exhibited the identical measurements throughout the measurement period.

5 Min = 13.81V
30 Min = 13.81V
60 Min = 13.80V
12 hours = 13.78V
24 hours = 13.77V
36 hours = 13.76V

 

[snoobler]

IMHO, you have a bad battery based on the outlier behavior.

 

[Repro]

After another 24 hours, the battery has continued to discharge and was at 12.34V this morning. Going to initiate a warranty claim. Thanks!

 

[snoobler]

Yuck. I would expect it has a dead cell.

 

[Bob142]

After another 24 hours, the battery has continued to discharge and was at 12.34V this morning. Going to initiate a warranty claim. Thanks!

Please let us know how Lion Energy handles the claim. Several of us have Safari UT batteries and the warranty is one of the reasons for choosing them over DIY (it was for me at the time). Thanks.