Magnum MS2812 LBCO values

[Smitty77_7]

We've had two occurrences while boon docking the last few weeks, where our LBCO has done it's thing while brewing coffee in the AM.

800AH battery bank, Lifeline X's 4 L16's. Both the Magnum BMK Meter and the MidNite Classic 150 Controller indicated SOC in the 71/72% range. (BMK Meter was 71% and Classic was 72% - always glad to see two different measuring methods being close to each other:)!). 

I had the LBCO value set to 10.2V. 

Question:

1) BMK Meter and MidNite use the battery bank size, and track In/Out AH's to basically calculate a SOC percentage level. (Sure, both have different logic programed to cover things like battery efficiency - but basically just a bathtub flow in/out way of measuring.)

2) As a battery bank starts to age and the under load voltage levels drop faster. The above SOC measurements don't really see this(?). So a 70%+ SOC level, may not accurately represent the level of your batters charge?

3) Taking all loads, and charging, off of the battery bank and letting it set for say 30 minutes to 'rest' - would then allow a multi meter reading of the voltage, and provide the most accurate assessment of the batters level of charge? (AGM, so no turkey baser sucking of water to test:)!).

Gang, kind of a check to see if my thinking is sound. Unless I have a battery problem, I'm thinking I'm going to lower the LBCO down to 10.0V - to avoid shutting down too early. (Note: We usually wake up in the AM with a 75-78% SOC level indicted. We ran the fan for a few hours the nights when we wok up to the 71/72% indicated SOC level. 

Am I thinking this thru correctly, that the SOC indicated may not accurately represent the actual level of charge of a battery bank that could be having a problem? 

Any opinions on LBCO value settings? Does Lifeline AGM vs say GC2 Wet make a difference  on LBCO values? (I know the Lifeline AGM charging logic is different then say wet, and even other AGM's. But I would think LBCO values would be the same for Wet/GEL/AGM?)

TIA, and best to all,

Smitty

 

 

 

[Yarome]

The BMK is fairly clever and employs several different methods in determining SOC... not just the AH capacity entered. It accounts for voltage variances, amps in/out, effeciency values, temps, etc. The SOC is only displayed once ALL of the three following are met: The charging voltage has stablized (not to be confused with a residual charge dissipating), the current has dropped to a percentage of the AH capacity and the AH used is within 1% of being fully returned.

So, yes. Your BMK does see the variances as your batteries age and, based on the above, can accurately calculate the immediate SOC without the need to let the residual charge dissipate. So... the SOC value is likely an accurate reading of the current capacity, but doesn't in any way represent the overal health of your bank in terms of what that capacity currently is.

As you know... high loads will pull down your "apparent" voltage even though that may not necessarily represent the absolute SOC. As your batteries age, that "draw down" value will increase, and is very likely the reason why your LBCO is kicking in and giving you such a low voltage reading.. at THAT particular moment. Your batteries may no longer have the capacity to back those heavier loads or there is another issue at play... like a failing cell. If that makes sense.

LBCO values between AGM and GC2's? In a sense, yes. AGM's are going to be able to maintain higher loads with less draw down than a wet cell. So... if you were running an AGM bank next to a wet cell bank, the wet cells will trip the LBCO sooner than the AGM, but once the AGM reaches LBCO levels then the remaining SOC will be lower than the wet cell. Did I say that right?

Knowing that... you "could" use a bit lower LBCO value on wet cells than you would with AGM's... IF it didn't adversely affect any of your electronics.

All of that aside... from the numbers and usage that you're stating... I would be highly suspicious of the possibility that one of your individual cells in one of your 6v's is starting to go out on you. It doesn't sound like a full on shorted cell... although hard to really say with just the information to date... but "something" isn't right. I also don't know exactly how long you've been running the bank or the actual usage and such to date. It MAY just be aging out, but if it seems premature then I would be load testing them individually to try and determine if you have a likely suspect playing havoc on your bank.

Dunnaknow if I help or confused you more, but such as it is... 

[Smitty77_7]

Hi Yarome - Thanks! And yes, Magnum and MidNite both have some 'Computer Kung Fu' stuff that does ore then my simple In/Out... And glad that you pointed out it is more sophisticated then I knew, so SOC% levels should be closer then I thought. 

4 1/2 year battery bank. With most of it's life in the above 75% SOC range, with an occasional dip down to low 70's SOC. We had one occurrence with a combo of a power outage, and an electric heater still on, that drew us down overnight to our first LBCO event. And I believe we were down to ~50% SOC + or - 10% SOC on that occurrence. (Power was restored about 90 mins before I got up, and SOC level was back up to ~65% at that time. This was 14 months or so ago.)

As I have never equalized the bank, and now that we're back on shore power, I've gone ahead and set the bank to equalize. As mentioned, I've set the LBCO to 10.0V. I'll turn of Shore Power tonight at the pole, and suspect we'll be at 75-77% SOC in the AM when I get up. I'll then run the power down with a lighter load, until I see 71% SOC (Repeating the same condition.), let things rest for a bit, then fire up the coffee pot and see if the LBCO value of 10.0V allows things to cruise along. 

We'll be off of this trip in early September. If everything cruises along fine until then, I'll wait to back at the homestead... Then I'll un-connect cables, and do some individual battery voltage readings. See if one of the four is not behaving well... 

 

[Smitty77_7]

Just wanted to confirm I think I was the root cause of our LBCO kicking in, having it set too high.

-I did equalize for the first time with this set of Lifeline's

-Set LBCO to 10V

-Boon docking at the Tillamook Elk's, and waking up to pre coffee pot usage SOC of 75-77%, depending upon if they were at 100% SOC at start of the night. Two out of Three it's been between 96% & 98% after the sun goes down. 95% and above I'm always happy with.

-Post pot of coffee brewing, 74-75% SOC

I still will when we're home in mid September, unhook the batteries and test each battery to see what values I measure at the posts, and how much deviation I see. 

Follow up post in case someone else does a 'Duh!' setting of their LBCO values:)!

Best to all,

Smitty

[Smitty77_7]

I'm having a jolly good time responding to my own thread:)!

Today is our last day of boon docking for sometime ahead. SOC was lower today at 72% when I turned on the coffee (Started the evening TV/Direct DVR around 6:00PM at 96% SOC, after a full day of clouds (Surprise.) here in Tillamook.). 

I decided before starting the coffee pot, I'd bump the LBCO down a bit more on this cycle, so set it to 9.8. As the coffee was brewing, I heard the Samsung RF18 start up. Two seconds later the LBCO cut in with Low Battery message. 

It was too early to fire off the generator due to fellow Elk's boon docking relatively close to me in the field, so decided to wait until 8:00AM to start it up. About 7:45AM the MS2812 came  back on by itself. MidNite Classic 150 controller reflected a little over 11A being generated in the misty drizzle. 

Went ahead and fired up the generator at 8:00AM, and recharging until we had off to our next destination today, and suspect the combo of the solar and 200A Alternator will top us off before we arrive. 

Now it may have just been luck that the refrigerator did not 'start up' while brewing the pot the last two days, or the higher SOC/Voltage on the first two days was enough to not kick in the LBCO with the 10V setting. Or, it could have been self preservation of the Magnum, as the combo of coffee draw (This pot draws 1450W, into a Thermos only, so once it's done brewing it's shut off. About 5-7 minutes.) and the start to the RF18 was too much amps on the inverter(?).

For the balance of this trip, anytime we boon dock and are not able to start the generator before brewing due to camping noise etiquette - we'll just use the percolator. 

Will test the batteries when home in September, and see what that shows... as mentioned, could be a bad cell, or heck - maybe the 4 1/2 year old non abused bank of X's 4 Lifeline L16's are getting weak... Hope not, as they're a pretty penny:)! (Lived on the top side of ~ 75% + or = 3% of their lives while boon docking, otherwise in maintenance charge mode while on shore power. I'd say going back the last 4 1/2 years, we've boon docked less then 10 maybe max 15% of the time. (Mostly on our 2014 Alaska trip.) And only one time has something caused the batteries to draw down for the LBCO to cut in, before this series - so sure not abused by usage:)!).

Mostly info sharing here, as until I test the battery and MS2812 - no reason to speculate too much:)! 

Interestingly, when the MS2812 kicked back on, the LBCO was back at the default value of 10V. So will need to check all of the other settings over the next few days, to be sure no other settings have changed. (Like charging logic to use Lifeline AGM default settings by Magnum, as an example.) 

Welcome any thoughts that my series of posts may have prompted, that I should consider.

Best to all,

Smitty

 

[fly2low]

Smitty

Nothing to add.  Just thank you for posting, as I always learn somethong,

[Al F]

A suggestion for testing your batteries.

There is no reason why 2 of your batteries would not support the 130-160 amps of 12V DC required by the inverter to power your coffee maker.  So rewire your battery bank to one pair of batteries and then test.  Keep swapping in the batteries until you have check to see if any one of the batteries may be causing the problem.  Be sure to change your charging controllers to 400AH instead of 800AH. 

With a residential fridge you probably don't want to do this while on the road. 

With 800AH of batteries at 70% SOC, I would not expect that the fridge starting the compressor with the coffee maker on would cause the LBCO to kick in, if the batteries are good.  Even with just 2 batteries (400AH) they should handle the load.