Help with uneven charging and discharging of Lithionics batteries

[SolitaryPine]

Hi, about 3 weeks ago I purchased a used 2022 LE2 with the Lithium Pro package. I've searched for the answer to this question here and in other places, and have a suspicion, but I thought I'd ask the experts here before I start making expirimental changes just in case someone can tell me for sure what is wrong.

The issue I'm having is that the three lithium batteries, which appear to be in good condition, do not charge and discharge together simultaneously. So, if I'm using a load, one battery might report that it is dispensing 20 amps, and the other 5A and the third might be 1A. Eventually they will all become discharged. The same is true in reverse, when they are charging, one will receive more amps than the others and reach full charge first.

My suspicion is that the wiring of the batteries is not correct, from what I've learned from watching YouTube videos about RV lithium battery set ups. My understanding is that the batteries are supposed to be wiried in parallel, with diagonal take offs. There appear to be four different take offs in my setup (I haven't figured out what each one is yet, but I'm guessing one is for connection to the Xantrex Inverter/Charger and one is for the battery pad heater, but I'm haven't figured out what the third and fourth are). It looks like the pad heater is the one that is not connected properly. However, I find it odd that the problem exists whether the heater is on or off.

Note that I don't believe the previous owner changed anything (the marks on the cables and terminals would indicate that also), so it was almost certainly set up this way at the factory. I've attached a photo of the cable connections to the batteries, and I would be happy to make another post with photos of the Xantrex settings or the Lithionics battery app information if anyone would like to see that.

Thanks in advance for any help you can provide!

Paul

 

Edited January 22 by SolitaryPine

[Roger]

Paul, your battery wiring looks identical to mine.  I have not paid attention to the discharge / recharge rate of my batteries so I cannot comment on that. I have noticed that the charge state of my batteries is generally not the same all the time and one battery in particular sometimes will show a lower charge state (by 5 to 10%) than the other batteries when I am boondocking.  

The wiring of the batteries is parallel which means that the voltage stays at 12 volts while increasing the capacity in this case to 390 Ah.

I am keeping a better eye on my batteries that in the past and will chart their discharge rate and status during my next trip to see what they are doing.   You have me curious. 

[SolitaryPine]

Thanks Roger. Mine are off by well over 10%. Here's screenshots I took of the SOC of all three batteries yesterday. They were much closer together a few days ago.

 

 

 

 

Edited January 22 by SolitaryPine

[Roger]

Paul,

You can also look at the the technical bulletin located here and try that. 

Roger

[rich.dev]

@SolitaryPine looks like your batteries are wired correctly. I have 2 x 320ah batteries in our 2023 Oliver and have seen the same thing you have on the phone app. 

I read following on the Lihtionics website:

The SoC is a ‘metered reading’ from an electronic Hall Effect Shunt and is a count-down meter that is most accurate on its first cycle after calibration* but becomes less accurate over time. It simply counts amps-in and amps-out but some losses will occur. Being a metered value, it does not actually measure state of charge “real time” but instead “calculates” or estimates state of charge.
-Explanation: *every two weeks, a full charge cycle in which the battery reaches 14.4 volts is required to trigger a recalibration of the internal Hall Effect Sensor shunt. When the battery exceeds 14.2 volts during charging, the SoC re-sets to 100%. (In order to fully charge a lithium ion battery, the DC loads may need to be reduced so the charge current exceeds the discharge current to allow a full battery charge.)
-Why does the meter “drift” and lose accuracy over time? When a consumer is micro-cycling a battery via a series of multiple discharge cycles and has partial charge cycles from solar or alternator charging, the SoC meter loses accuracy, called “sensor drift” over a two week time period. This is also called ‘short charging’ as the battery never fills and the SoC meter does not reach recalibration voltages of 14.2(12 Volt Battery, 28.4 (24V), 53.25 (48.0) or 56.8 (51V) batteriesrespectively.

I think as long as the voltages are the same your batteries are fine. 

[SolitaryPine]

2 hours ago, Roger said:

Paul,

You can also look at the the technical bulletin located here and try that. 

Roger

Thank you. I saw that and I suppose it's possible that the previous owner damaged the BMS of one or more of the batteries by not doing that reboot sequence correctly. Unfortunately, the TSB doesn't really tell me what the symptoms of that damage would be, and the batteries otherwise appear to be functioning normally.

[SolitaryPine]

@rich.dev Yeah the voltage is pretty far off also. 12.90 vs 13.62, so I don't think it's that issue.

Edited January 23 by SolitaryPine

[jd1923]

7 hours ago, SolitaryPine said:

My suspicion is that the wiring of the batteries is not correct

Wiring is fine, but who knows why OTT has three (3) runs to the batteries directly, no need for that. It's odd that on the B- side there are 2 heavy gauge wires, likely two 4/0 (not sure given the picture) and one 6 AWG and on the B- side there are one (1) heavy 4/0 and two (2) of the lighter 6 AWG cables. I would correct this. One 4/0 +/- connection goes to the inverter, another connects your MPPT SC and the 3rd my be your heater pad.

On our hull we had one 4/0 cable on both +/- cables and two (2) 6 AWG cables. I removed all of the 6 AWG connections to the batteries and connected them directly to the Inverter and internal buses. Yes given the pen markings, this is OEM and correct given this fact.

I tested mine today in my installation (NOT Lithionics)! Watching TV, running about 3A with the A/V system on inverter and a few cabin lights on the draw was 3A and pretty even between the two 300AH batteries at 97% SOC. I fired up our Emeril Air Fryer, requiring about 124A and the closest battery was drawing 6-8A more than the next battery. This is normal. You showed a picture at 35% SOC. In this case the difference between the two batteries should be more than when total SOC is fuller, near 90% SOC.

Question is, when done, say at night not connected to the SC or shore power, do the 3 batteries read near the same SOC. If so, you're over-thinking the details, not to worry, the batteries will balance out soon enough!

[Cameron]

call or email Dimitri at Lithionics. He was a great help in answering all my questions. One of the things he shared is that the batteries sometimes need to be synched so they all charge equally. He suggested that I go onto the Xantex phone app, find Custom Absorption Voltage, and change the setting from 14.4 to 14.6. He said that it would be ok to up to 14.9 if needed to push the SOC to 100% for all three, but then I should leave the setting at 14.6. It's worked so far.

[Doug S]

Hi, The SOC is calculated, but the voltage should be measured. At no load there shouldn't be any measurable difference between the batteries that are all wired in parallel. I think something is likely wrong with the electronics in the battery with the 12.9 V. The other 2 are pretty close together (.02V). That's quite a bit different than .7 volts. Odd too that this is the battery with much lower charge. Just a guess, but .7V is close to one diode drop, which could mean that this battery has a blown protection diode in it and is therefore the primary soldier and the others are along for the ride until he is discharged.....

[jd1923]

7 hours ago, SolitaryPine said:

Thanks Roger. Mine are off by well over 10%. Here's screenshots I took of the SOC of all three batteries yesterday. They were much closer together a few days ago.

 

I should have looked closer the first time at your pics. Your battery #1 could be going bad. That’s a very large SOC and voltage difference. How can such a voltage diff be possible, with 3 batteries wired in parallel?

Ask the manufacturer about a testing procedure for warranty claim. Do not upset the cabling, in case of warranty claim, but I would love to know voltage readings of the three batteries individually, and with a reliable multimeter vs. an app reading.

[SolitaryPine]

Thanks guys. Because a couple of you suggested possible issues with the battery itself, I've submitted everything I know to the support email at Lithionics and will let you know their response once I get it.

[Rivernerd]

19 hours ago, Roger said:

your battery wiring looks identical to mine.

Our 2022 Hull #1291 also has the 390 Ah Lithionics package.  Your wiring is the same as ours.  Our discharge and charge rates for our 3 batteries are not identical either (per the Lithionics app), but are closer than yours.   But, DC voltages, as measured with a multimeter, are the same among the three, which satisfies me that "all is well."

I presume you have done a full discharge down to reserve capacity, then a full recharge cycle charging for a couple of days until the all batteries show 100%?  This is the recommended method for recalibration. 

I am interested in the response to your queries from Lithionics.  Please post.

Edited January 23 by Rivernerd