100AH Lithium cant handle start up draw

[shade]

I have installed many FF banks over the years, start a new thread

Do tell.

Firefly Oasis carbon foam AGM battery

https://oceanplanetenergy.com/advanced-energy-storage-systems/firefly-energys-oasis-group-31/ Given the performance for the price, the Firefly seems ideal for a house battery, but I didn't find much mention of it on ExPo. Are there some downsides to carbon foam AGM technology? Compared to other...

www.expeditionportal.com

 

[john61ct]

done told

 

[spressomon]

Ok, maybe the OP has answered this question here or the cross post on 'MUD, and I just missed it; but what was the response from RELiON? It appears, to this layman anyway, the published specifications for the OP's battery should power the ARB compressor without issue. And, I also wonder, how they are increasing the cell temps for charging below freezing (per the specs on this battery)?

FWIW, I've been super happy with my LiFePO4 drop in battery I purchased from ElectricCarPartsCo (3-years). Granted its a 200Ah battery but it powers my ARB dual compressor without issue. Ditto a 2000w sine wave inverter, etc., etc. Ditto for a friend of mine I recommended to them. And I just purchased another system for an off-grid RV trailer project I'm building.

 

[john61ct]

Some LFP vendors claim their chemistry tweaking alone allows for charging at lower temps compared to most other LFP.

Color me skeptical.

But note, the "freezing" point of water is not **that** cold, so maybe at very low trickle current rates. . .

But get it wrong and the whole bank is scrap.

Personally I'd put them in a well insulated box, with heat pads starting 12-24 hours before charging required.

Or just keep inside the living space.

 

[luthj]

The charge rate at low temps is limited by ion mobility in the electrolyte. If you exceed that limit, you will start plating the anode. Each cell design is different. There are many different electrolyte formulas, porosity of the anode, etc.

From the trillium manual.

Maximum Charging Current @ Temperature
>73°F (>23°C) 110A
41° to 73°F (5° to 23°C) 56A
32° to 41°F (0° to 5°C) 15A
14° to 32°F (-10° to 0°C) 6A
-4° to 14°F (-20° to -10°C) DISCHARGE ONLY

 

[shade]

The charge rate at low temps is limited by ion mobility in the electrolyte. If you exceed that limit, you will start plating the anode. Each cell design is different. There are many different electrolyte formulas, porosity of the anode, etc.

From the trillium manual.

Maximum Charging Current @ Temperature
>73°F (>23°C) 110A
41° to 73°F (5° to 23°C) 56A
32° to 41°F (0° to 5°C) 15A
14° to 32°F (-10° to 0°C) 6A
-4° to 14°F (-20° to -10°C) DISCHARGE ONLY

What's a good DC-DC charger that allows manual input of those values?

 

[luthj]

What's a good DC-DC charger that allows manual input of those values?

I have not seen any with the ability to cover the whole range. But I have not done a deep dive on the recent DC-DC offerings. Though much of Victron gear has fully programmable options, often quite advanced. I would guess several models offer the minimum charge voltage setting, but little else.

There is one drop-in company (very expensive sadly) which has a BMS with internal heaters and a solid state control. In low temps it sends most of the charging current to a heating film around the cells, until they are warm enough to accept a full charge rate. I can't remember the brand right now.

 

[luthj]

Here it is.

Lithium Battery for Low Temperature Charging | RELiON

The new Low Temperature series feature a heating element allowing the battery to be safely charged in cold temperature climates.

relionbattery.com

 

[john61ct]

A lab style power supply with adjustable voltage and current works just fine.

From top notch Sorensen or TDK Lambda costing thousands, to cheap chinese at $60.

You just need to stop-charge via an HVC or manually, depending how close to 100% Full you want to get.

Holding CV / Absorb for the sake of your BMS getting its agonizingly slow balance-bleeding routine done, can dial current right down to 1A or less as needed.