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Old 12-26-2018, 10:31 AM   #1
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What happened + how to prevent in the future??

I've got a puzzling problem and I'm hoping the sage knowledge of the IRV2 group can help.

I’m trying to figure out what happened and why so that I can prevent in the future.
My environment is Magnum hybrid 3012 inverter + Magnum BMK + Magnum MPPT 100 + (3) 200a LifeBlue Lithium batteries (the new high amp “fixed model”)from Starlight + 1300w solar array on the roof.

I live in NH and the RV is stored for the winter(sadly). This was my first ‘season” with the new Solar/Lithium install and I am certainly not an expert or even close. Everything has been working great since I completed the install earlier this year, with the help and support of Larry @ Starlight and this great community. We had several trips in the spring and summer with the completed install and everything worked flawlessly.

I put the RV into storage in OCT, made sure all the batteries were not fully charged (were approx. 70%) tripped the breakers to the solar so no charging, no 120v from street into house batt., but I did have a small trickle charger to the Engine battery. I flipped the "Salesman Switch " to kill all 12v batt usage, locked her up and went home.

In NOV, went to check.. all good... batteries fine.. exercised the genny with a load for about an hour, but made sure it wasn’t charging, as I didn’t want to raise the charge levels in the lithium. Then I checked all switches, batt levels, etc, flipped the salesman switch again and left.

Came back in DEC, and 2 of the LifeBlue couldn’t even connect via BT so I couldn’t even get a connection on the BT or reading on my iPhone app. There were No house lights, no 12v anything. Checked all breakers, all good.
Even the Magnum BMK was blank. I did get a reading of ONE of the lithium @ 79%. the battery that the Magnum BMK was wired to.

So I plugged in street 120v.. still nothing.. let it sit while I booted the laptop and MiFi to research what went wrong.. and after about 10 min, the BMK came to life, and 2 of the LifeBlue that I couldn’t get a reading, came back to life with 0% SOC. Magnum BMK came back to life to.
all the Magnum BMK settings were still there except for date/time. I started charging, Bulk mode. ODD as it only ‘bulk charged” @ 13.6-13.8 (it fluctuated), and not at the 14.6 that it is set for. Unless I am misunderstanding this.
I am guessing that the ONE battery @ 79% prevented it from going to 14.6?

here is what I am puzzled at:

1. Why did they drain at all? All switches were off/tripped, should have been zero drain I would think?. Could I have potentially a bad “Salesman Switch” and the phantom drains were really still there?

2. Why did they drain to zero, and why only two of them drain and not all three? I didn’t note it, but I thought I saw the two @ 0% still had 11 volts. I believe that this is what the built in BMS stopped it at, to prevent completely draining the battery. Is this correct?

3. Did I do any damage to the batteries?

4. Why not all three drain/charge the same rate? I did properly bring them to full independently before connecting them together during the initial installation.

5. Why does one maintain @ higher SOC?

6. What happens if the storage charge is over 50%?? Should I have brought them ALL to 50% before I shut them down for storage? Did keeping that @ over 50% cause impact?

7. Magnum BMK when set to equalize mode, it is only bulk charging at 13.8 vs 14.6 which is set for absorb mode. Why is that?

8. Again this 2 dead + one good is bothering me. I have no idea why this is.

Ideas?
Thanks everyone in advance 
-mike
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Old 12-26-2018, 10:47 AM   #2
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If Lifeblues bms did what is suppose to do your batteries should be fine. What you need to find out is why 3 batteries wired in parallel only drained 2 and one is still charged. Email/ call to lifeblue?

O% is SoC, it seems those 2 batteries DoD was 100% within what lifeblue calls a full cycle and the bms shut those batteries down. The spec sheet shows lvd at 11.0v but doesn't actually say that the bms cuts them off at that volt. But does show discharge cutoff at 2.0v on any cell, that is still pretty low though. Another reason why being able to view individual cell voltages can be helpful.
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Old 12-26-2018, 11:10 AM   #3
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Was it real cold, like 0°F ?
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Old 12-26-2018, 11:12 AM   #4
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Thanks..
well between NOV and DEC.. it did get down into the teens and single digits.. but i dont think to 0 deg .
the days that i was @ the RV, it was in the high 30's to low 40s
-mike
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Old 12-26-2018, 11:15 AM   #5
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Thanks!!
I thought about emailing Larry @ Starlight directly, but I also wanted to hear the advise/thoughts from here too and Larry usually reads and replies to these. He's fantastic at that.
-mike
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Old 12-26-2018, 11:27 AM   #6
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I forgot to add that even though lifeblue recommends 50% dod for extended storage 70% should not have an effect for the issues your seeing. Even if it was below freezing that shouldn't prevent anything other than being able to charge the batteries and once again does the bms prevent this? Error on the side of caution and warm batteries before charging?
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Old 12-26-2018, 03:03 PM   #7
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With two of the three batteries draining a picture of your install would very beneficial to troubleshooting. If two of them drained then all three of them should have drained. Lithium has a very slow self discharge. Perhaps the two batteries have some sort of parasitic draw on them. The internal BMS saved the two that discharged but now you need to figure out the why and once you do you need to start all over again and bring them all up to 100% SOC individually prior to connecting them in parallel. Then drain them down to roughly the 50% level prior to continued storage. BTW of the two batteries that are discharged what are the individual cell voltages for each battery showing?
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Old 12-27-2018, 11:58 PM   #8
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The typical LiFe battery (regardless of mfg) has a min and max temperature for:
- charging
- discharging

Typically the min discharge temperature is lower than the min charge temperature - but - this may or may not matter.

Typically the BMS is designed to internally shut off an electronic relay so that if the (battery) temperature drops below about 30 - 35F, it cannot be accidentally charged.

Even if this relay / mosfet is "off", it can still leak a tiny bit of current and give a voltage reading (of some kind) at the terminals. My guess is that you are seeing this false reading of various voltage levels and thinking that it represents the internal voltage. Most likely it doesn't.

If you want to actually charge these batteries, they need to be warmed up until the entire battery is again above ~ 35 - 40 F.

If you are actually charge them when they are cold, they will be ruined. The BMS is there to help you avoid this problem, but think of it as a "back up / failure avoidance device", not not "a controller".

Avoiding the issue in the future would ideally include a heating blanket of some kind to help keep the entire battery above 40F - all of the time, including in storage.

This is the main pro / con of modern Li vs AGM batteries - AGMs have very good low temperature tolerance but Li is more tolerant of partial charging. Obviously weight is a substantial factor as well.
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