Upgrade off grid cabin in cold climate

[HarryN]

In response to the comments about temperature, it is usually above 0 degrees Celcius. But, in cold winters with little snow, we have experienced that the water we store in the same cellar have frozen. However, if we place the containers with as much surface area as possible in contact with the ground, the water does not freeze.

Thanks for that info. It is an "indication" that if you have the batteries in direct contact with the floor, and a cover over them - such as a drink cooler to insulate them from the air - it might just work.

Any easy test would be to put some water jugs in the basement in a drink cooler - with the bottom cut out.

If possible a thermometer to look at actual temperatures once in a while and see if it stays at 5 - 10 C.

 

[OffGridIdaho]

I share a cabin in a cold climate with my siblings and now it is time to upgrade the batteries as we have had 2 low voltage disconnects. The last one after charging with a generator. I then did a load test with all consumers, and it triggered disconnect after 3.5 hours and 260Whrs.
An energy audit results in 900 Whrs a day in worst case, but more likely closer to 600 Whrs. Mostly lights, the big consumers are TV, WIfi and PC a couple of hours each day.

How do I upgrade this system in steps starting with the batteries?
The decision i struggle the most with is AGM or LifePo4? I have been reading a lot about LifePo4 and the more I read, the more sceptical I become.
It has to be low maintenance. I have to do all the maintenance and there is a 3 hour drive.
It has to be easy to operate for my siblings.
I would like to be able to extend the capacity if necessary.


This is the third iteration of the system and it is now 7 years old:

Solar panels	2x140W	Should have been 611W according to energy audit
Solar regulator	EP Solar Tracer MPPT 2215BN 20A (12/24V, 260/520W)
Charger	60A, Automatic 1260
Inverter	Inverter 400W, EP Solar NP400-12	Only used to charge PC
Batteries	2 x AGM Solar 290 100 hour in parallell	The batteries are stored in the cellar, usually 2 degrees Celcius in winter.

Thanks!

So you will see why I say just run a generator below. Its cheaper and a lot less work to make power.

If you dont want to just run a gen while you are there then you could upgrade to Lifepo4. Put the batteries inside a 10cu ft chest freezer with 2 60w old school light bulbs that ONLY kick on when temps drop below 40f and shut off at 45f. Run 2 or three bulbs as redundancy in case one burns out. You could also insulate the inside of the chest with Vacuum Sip panels which are R60 per --->1<---- inch. Yeah!
I would then buy 8 280ah EVE cells and run in series 24v or 2s-2p for 12v. Also buy a Samlex Inverter/Charger 12-24 or 12-12 either hard wire or 120v socket. I prefer HW as you can rig up a 4 plex 120v socket next to a breaker box. Get a victron MMPT SCC and a smart shunt (30 days activity) and link them with bluetooth. The samlex has a sleep mode that only draws 7w. Buy a JKBMS and have the battery low shutoff set to 34f as a fourth redundancy. Lastly I would buy 4 x 400w panels to cover the cloudy days. Lastly add a victon Lynx as a fancy busbar. For cells get the half cell mono perc bi-facials. The jkbms heater prefs could be set to run the light bulbs.

I use 2kw per day and can go 3 days without sun. If we get a little sun it can drag out to 5 or 6 days. I get about 6.5kw from the pack.

https://www.donrowe.com/v/vspfiles/pdf/evo-f-series-spec-sheet.pdf

Samlex EVO-1224F-HW 1200W, 24V Pure Sine Inverter/Charger | DonRowe.com

The Samlex America EVO-1224F-HW, 1200 Watt, 24 Volt Pure Sine Wave Inverter/Charger is a rugged inverter/charger designed for mobile and off-grid applications

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Victron SmartSolar MPPT 150/70-Tr

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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Victron SmartShunt 1000A/50mV

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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Victron Energy Lynx Distributor | 1000A

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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Boviet 370W Bifacial Solar Panels (Black) | Up to 444W with Bifacial Gain | BVM6610-370-HC-BF

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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EVE LF280K V3 Grade A Cells - 3.2V LiFePO4 280Ah Battery

Brand new Grade A EVE LF280K LiFePO4 cells with 280Ah capacity. 10+ years design life, 6,000 cycles. Get unmatched power and performance for your energy storage needs.

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JK BMS 8-24S - 200A Continuous - 350A Peak - 2A Active Balancing - JK-B2A24S20P

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[Baard]

Thanks for all the input.
I will continue with AGM as it will be easier to install and maintain. As we only use the cabin occasionally and do not cycle daily, it is not necessary to add the complexity and pay for the advantages of Lithium.

There is however one thing I really do not look forward to, and that is carrying the heavy AGM batteries into the cellar.
The choice is now between 2x200Ah at 60kg each or 4 batteries of a smaller size. The shop I am talking to have 4 150Ah at 45kg each which I can get for a really god price as it was ordered by a mistake. Smaller sizes are not in stock and I will not get the same discount for those.
Are 4 batteries in parallel going to be a problem with AGM if I connect diagonally, to posts or halfway?

 

[OffGridIdaho]

You dont have to cycle Lifepo4. You could just set the MPPT scc to charge to 65% and stop, leaving it in a safe charged soc.

 

[sunshine_eggo]

Thanks for all the input.
I will continue with AGM as it will be easier to install and maintain. As we only use the cabin occasionally and do not cycle daily, it is not necessary to add the complexity and pay for the advantages of Lithium.

There is however one thing I really do not look forward to, and that is carrying the heavy AGM batteries into the cellar.
The choice is now between 2x200Ah at 60kg each or 4 batteries of a smaller size. The shop I am talking to have 4 150Ah at 45kg each which I can get for a really god price as it was ordered by a mistake. Smaller sizes are not in stock and I will not get the same discount for those.

Yeah, I have some beastly FLA/AGM batteries... always worried the straps will break.

Are 4 batteries in parallel going to be a problem with AGM if I connect diagonally, to posts or halfway?

No. The center two will not share the load as much as the outer two, but it's generally acceptable.

 

[HarryN]

Thanks for all the input.
I will continue with AGM as it will be easier to install and maintain. As we only use the cabin occasionally and do not cycle daily, it is not necessary to add the complexity and pay for the advantages of Lithium.

There is however one thing I really do not look forward to, and that is carrying the heavy AGM batteries into the cellar.
The choice is now between 2x200Ah at 60kg each or 4 batteries of a smaller size. The shop I am talking to have 4 150Ah at 45kg each which I can get for a really god price as it was ordered by a mistake. Smaller sizes are not in stock and I will not get the same discount for those.
Are 4 batteries in parallel going to be a problem with AGM if I connect diagonally, to posts or halfway?

Not sure how strong you are, but the mass of large batteries is one of the reasons that I use batteries that weigh about 25 Kg.

Honestly carrying 45 and 60 Kg batteries is kind of dangerous. It takes almost nothing to make that concept go downhill fast.

If you decide to do that, try to rig up some kind of sled and rope system. Maybe some wood planks over the steps to make a slide.

There are wiring diagrams for balancing the charge / discharge of batteries in parallel - and they work very well.