Help: Lithium newbie wants to camp!

[medora]

Hi all - we have delayed a trip to Killarney Provincial Park three times now, and pretty much have to leave tomorrow or it’s not gonna happen. Here’s the problem:

I (with the help of an electrical-savvy pal, who himself if away camping right now), installed a Victron smart shunt, charge controller, and two new 100ah LIpo4 batteries recently - and I also added two 100W panels up top, which brings me to 300w of solar. The idea was to upgrade our 2012 17b to power two Dometic CFX coolers on long boondocks. Seems like we should be good, right? Well … over the last two sunny days here in SW MI things have gone south, and my smartshunt shows a charge of 17% currently. It was hot here yesterday and I cranked up the MaxxFan while prepping to pack - and that seemed to zap a whole lot of juice without me realizing it. When I realized yesterday evening that our system couldn’t keep up I turned it to low and kept my fingers crossed … but this morning came out to one of the Dometics off (probably low voltage?)

It’s sunny out now - but I’m stalled at 17%.

I am very new to this and reach out to you all for help today figuring this out, as if this happens again we are toast. Shouldn’t this setup be able to handle this?

Warning that I am a newbie - if possible, please explain in non techie terms. I can use a multimeter and am familiar with the wiring so … what can I do to salvage this trip? Is it possible one of the batteries is offline? Am I so discharged now that the system would not be able to catch-up? (I can plug in but I also want to monitor what’s happening today so …)

[Vermilye]

I'd take a careful look at the wiring, connectors, fuses, etc, (including polarity of the panels & connectors) - 300 watts of solar should be producing far more than 1.6 amps when the controller is in Bulk & the lithium batteries are at 17% unless you are in deep shade or very low light conditions.

[medora]

Thanks. If a fuse was blown wouldn’t something not be functioning in the system - resulting in me not getting any readings? We’ve checked polarity repeatedly due some other issues so I know that’s not it. And wiring should be solid tho I will pull out the mattress again (oye) to confirm. Anything you’d look for via multimeter?

Plenty sunny here today (photo was abt 10 ET)

[medora]

Btw - my electrical guru who is in Utah right with a new grandbaby ♥️ - is flagging the 165 ah used yesterday, would the bulk of that that be the MaxxFan on high? Still seems like this should be able to handle the load but yikes!

[medora]

Another question - what does “discharge floor” refer to and will my batteries no longer charge on solar if we fall below that percentage?

[Keith3]

If the coolers were warm they may have taken a lot of juice to cool off. I don’t know what they normally draw, but I imagine they draw a lot more if trying to get cool.

That may explain your usage, at least.

I’d try to pre-cool those at home before putting them on the batteries.

[medora]

Originally Posted by Keith3

I’d try to pre-cool those at home before putting them on the batteries.

Sadly, they were cool - and full of frozen and refrigerated stuff. So it’s not that.

[rubicon327]

Originally Posted by medora

Btw - my electrical guru who is in Utah right with a new grandbaby ♥️ - is flagging the 165 ah used yesterday, would the bulk of that that be the MaxxFan on high? Still seems like this should be able to handle the load but yikes!

I just measured our Maxxfan on high with amp reading of 3A on Victron BMV-712 monitor. So if you ran for 24 hours that would be ~72 amp-hrs.

[medora]

Originally Posted by rubicon327

I just measured our Maxxfan on high with amp reading of 3A on Victron BMV-712 monitor. So if you ran for 24 hours that would be ~72 amp-hrs.

That’s kind of you to measure!
And that suggests my readings are high. I wonder if there’s something up with my fan. I’ll try to see if I can isolate the fan energy usage from the coolers over the next few days. STILL tho - shouldn’t a 300w array be able to keep up with this, esp given I had no issues with my old lead acid 100w panel setup?

[John in Santa Cruz]

my setup is a Norcold N2175 DC compressor fridge, 2 x 206AH LiFePO4 batts totalling 5260 watt*hours, and a 360W LGE single solar panel, using a Victron 100/30 MPPT solar controller, and a SmartShunt on the batts.

I don't often kick that MaxxFan deluxe up to high, more often its on around 2-4 out of 10, but it really doesn't draw that much power. The fridge is, of course, on 24/7. On cool nights the furnace might be run at 68F until we go to bed, then 63F all night, and a bit of 70F in the AM til the chill is gone.

I can run a full week on this setup with NO solar and still have 40% battery capacity, and my solar panel will charge about 2000WH per full sunny day if the batteries are deeply discharged (so two days to fully charge a deeply discharged batt). my normal average when things are happy is around 700WH solar per day, and about 30% of that is just topping the already charged batts.

so yeah, it sounds like something isn't working right ofr you, but hard to guess what.

[BobG]

Try adjusting the battery settings for the shunt:
Charged voltage to 14.3 or 14.4
Discharge floor to 5%
Tail current - I don't know. I use 4% but not sure.

[rubicon327]

Originally Posted by BobG

Try adjusting the battery settings for the shunt:
Charged voltage to 14.3 or 14.4
Discharge floor to 5%
Tail current - I don't know. I use 4% but not sure.

FWIW Battleborn recommends the following settings if using a Victron BMV. Should be the same or similar for most LiFePo lithium batteries.
Battery Capacity: Total Ah of your bank of batteries
Charged voltage: 14.4V but note that this number should be about .1 or .2 volts below the charging voltage set in your charging device
Discharge Floor: 0%
Tail Current: 2-4% is good
Charged Detection Time: 3m
Peukert Exponent: 1.05
Charge Efficiency Factor: 99%
Current threshold: 0.10A
Time to go averaging period 3m
Battery Starts Synchronized: blue button should be to the right
State of Charge: leave alone
Synchronize SOC to 100%: Leave alone, this device will sync itself at the top of the charge
Zero Current Calibration: Leave alone

Full article:
https://battlebornbatteries.com/faq-all-about-bmvs/