Building 24V Li-ion battery from EV?

[aj84]

Hello, new member here.

I believe this is the place to ask my questions, please excuse my english as it is not my primary language as an Norwegian.

I am upgrading the elecric system in my off-grid cabin, last owner has passed away and i have no idea how old this current system is. It could be as new as 2015.

Anyway, this system is not delivering the power my family requiers for more than one day. (heating comes from woodstove and cooking from propane) I have not tested this AGM 290Ah battery but i assume this is 10 years old and not as it once was.
Upgrade is in progress now, i have bought:

used 24VDC-230VAC 600W pure sine inverter. Got a real great deal on this quality inverter (Mascot 2286240000)
New 30A MPPT solar regulator (Sunwind PeakPower)
New 360W solar panel (Sunwind Grid 360)
2 free used 180Ah lead acid batteries that tests good from a roadgrinder (start batteries for now, yes i know... but what harm does it do when these was picked up from the recycle anyway)

Used EV batteries are a source for off-grid cabins here since we do have a lot of EVs around here (never tried one personally)
But i have not talked to anyone that have made one, so here i am.

First i see this forum mainly uses LifePo4 but the majority of EVs uses Li-ion cells.
I can get a great deal on a used 16kWh battery from a 2011 Mitsubishi i-Miev, this battery contains 88 Lithium-ion cells in series. Youtube has some good teardown videos on these.

Cells are 3.7V 50Ah GS YUASA LEV50, these have bolted connections.

And here is some of my questions:

Is there a reason Li-ion batteries are more widely used in off-grip applications?

Can i charge Li-ion in cold tempratures with low current? i have planned to build this in a heavy insulated box, but mabye i need a heating element? was thinking mabye a heating element from a heavy duty equipment rear view mirror typical 24V 35W but what circut shoud control this if i need one? (can be as cold as -25 degrees fahrenheit here but we dont normally use the cabin under 5 degrees fahrenheit, yes i live above the artic circle so we do not see the sun in winter months and there is only a couple of hours with daylight, but in the summer it does not get dark at all)

If all cells tests good (higly unlikely thou) i could build a 7S 12P out of these but could i charge them with this smal system? or what is the biggest this system can handle? In addition i have this generator from 1995 and 24V 10A smartcharger from a wrecked electric wheelchair to supply with. Need the generator running anyway when the vacuum cleaner is in use.

Do i need a smal BMS for every 7S bank and then parallel each bank or hard wire all banks in parallel and a single big 7S BMS?

What current size BMS?

Is DALY a safe brand on BMS?

What else equipment shoud get?

I do get a little paranoid of batteries like this so i was thinking in mabye have a fuse between each cell in series instead of a busbar in addition to whats normal, do this do any good?

We mostly use the cabin in weekends, mabye a couple times a month.

Thank you for your time

Regards from Norway

 

[sunshine_eggo]

used 24VDC-230VAC 600W pure sine inverter. Got a real great deal on this quality inverter (Mascot 2286240000)
New 30A MPPT solar regulator (Sunwind PeakPower)
New 360W solar panel (Sunwind Grid 360)
2 free used 180Ah lead acid batteries that tests good from a roadgrinder (start batteries for now, yes i know... but what harm does it do when these was picked up from the recycle anyway)

A single 360W panel will only provide about 1.5kWh of energy in good summer sun (maybe much worse in Norway).

Is there a reason Li-ion batteries are more widely used in off-grip applications?

Do you mean Lithium-iron (phosphate), LFP?

Can i charge Li-ion in cold tempratures with low current?

No. 3.7V Lithium will still be damaged when charged below freezing. Yes, you can charge at low currents, but without published data from the manufacturer, doing so is very risky. You should use a BMS that refused to charge below about 5°C.

i have planned to build this in a heavy insulated box, but mabye i need a heating element? was thinking mabye a heating element from a heavy duty equipment rear view mirror typical 24V 35W but what circut shoud control this if i need one? (can be as cold as -25 degrees fahrenheit here but we dont normally use the cabin under 5 degrees fahrenheit, yes i live above the artic circle so we do not see the sun in winter months and there is only a couple of hours with daylight, but in the summer it does not get dark at all)

An insulated heated box will help.

here is one solution in Resources:

Simple, Indipendent Battery Box Heater

To get the document, click on the orange button at the top of the page. This is a simple 20W battery Box heater that operates independently of the rest of your system. I use this for storing unused cells in a very cold climate, but it can be...

diysolarforum.com

If all cells tests good (higly unlikely thou) i could build a 7S 12P out of these but could i charge them with this smal system?

Yes, but as I indicated above, a 360W panel will only provide a small amount of energy daily. Your 30A controller could provide up to 30A * 29.4V = 882W to a 24V battery, so 3 360W panels would be more preferable (okay to go a little over power limit).

or what is the biggest this system can handle? In addition i have this generator from 1995 and 24V 10A smartcharger from a wrecked electric wheelchair to supply with. Need the generator running anyway when the vacuum cleaner is in use.

Biggest what?

A 24V 16kWh battery could easily provide up to 3000-4000W of power. A proper inverter could run your vacuum cleaner.

The 10A chargers might work provided they do not go above 29.4V and preferably closer to 27.4V.

Do i need a smal BMS for every 7S bank and then parallel each bank or hard wire all banks in parallel and a single big 7S BMS?

Preference

A single battery in a 12P7S arrangement (12 cells in parallel, then 7 of those groups in series) needs only 1 BMS, but that BMS must handle all of the needed current.

7 batteries connected in parallel (7S12P) would need a BMS for each battery.

What current size BMS?

Depends on the current. If you go with a 4000W inverter, you need:

4000W/25.9V/.85 = 181A

Is DALY a safe brand on BMS?

It is a common brand, but there have been several reports on this forum of failures. One individual had four, and two of them failed.

What else equipment shoud get?

Depends on what you want/need.

I do get a little paranoid of batteries like this so i was thinking in mabye have a fuse between each cell in series instead of a busbar in addition to whats normal, do this do any good?

Fusing EV cells is pretty common. Some cells have built-in fuses. The best thing would be to store the battery in an area where it could catch fire and only cause limited damage.

 

[aj84]

Do you mean Lithium-iron (phosphate), LFP?

Sorry for the typo,
Is there a reason Li-ion batteries are not more widely used in off-grip applications? (compared to LifePo4)

No. 3.7V Lithium will still be damaged when charged below freezing. Yes, you can charge at low currents, but without published data from the manufacturer, doing so is very risky. You should use a BMS that refused to charge below about 5°C.

I can't find datasheet for LEV50 but datasheet for LEV50N claims charge current at -25°C to be 10A, i don't know the difference between these batteries. But mabye they wear out much faster regardless to datasheet when charging at low temperatures?

found datasheet for LEV50N here: https://pushevs.com/2015/11/04/gs-yuasa-improved-cells-lev50-vs-lev50n/

An insulated heated box will help.

here is one solution in Resources:

Simple, Indipendent Battery Box Heater

To get the document, click on the orange button at the top of the page. This is a simple 20W battery Box heater that operates independently of the rest of your system. I use this for storing unused cells in a very cold climate, but it can be...

diysolarforum.com

Great idea! but shipping to northern Europe kill most amazon deals. Found some 18V "MTTP 22W" panels on ebay dirt cheep. Can something like that be used instead of the amazon deal?

Biggest what?

A 24V 16kWh battery could easily provide up to 3000-4000W of power. A proper inverter could run your vacuum cleaner.

The 10A chargers might work provided they do not go above 29.4V and preferably closer to 27.4V.

Biggest battery for the 360W panel and 30A solar regulator, i understand you mean a 4P7S is more in balance to this setup.

Preference

A single battery in a 12P7S arrangement (12 cells in parallel, then 7 of those groups in series) needs only 1 BMS, but that BMS must handle all of the needed current.

7 batteries connected in parallel (7S12P) would need a BMS for each battery.

i ask because i found this picture and wondered if this was the norm:

Depends on the current. If you go with a 4000W inverter, you need:

4000W/25.9V/.85 = 181A

I'm not planning to use that kind of draw, mabye a quart of that. Mabye in the future? who knows...

It is a common brand, but there have been several reports on this forum of failures. One individual had four, and two of them failed.

Any recommandations?

Depends on what you want/need.

I was thinking of a shunt and temperature surveylance, mabye more?

Fusing EV cells is pretty common. Some cells have built-in fuses. The best thing would be to store the battery in an area where it could catch fire and only cause limited damage.

My plan is to keep this at the cabins shed, a standalone little building but i believe i can jump between roofs...

 

[sunshine_eggo]

Sorry for the typo,
Is there a reason Li-ion batteries are not more widely used in off-grip applications? (compared to LifePo4)

Safety, cost and availability.

I can't find datasheet for LEV50 but datasheet for LEV50N claims charge current at -25°C to be 10A, i don't know the difference between these batteries. But mabye they wear out much faster regardless to datasheet when charging at low temperatures?

found datasheet for LEV50N here: https://pushevs.com/2015/11/04/gs-yuasa-improved-cells-lev50-vs-lev50n/

Those are likely Yttrium doped - a way to make Lithium batteries more low-temp charging tolerant. If I was certain the specification applied, I would use it.

Great idea! but shipping to northern Europe kill most amazon deals. Found some 18V "MTTP 22W" panels on ebay dirt cheep. Can something like that be used instead of the amazon deal?

That's a DIY option. I'm sure you can find similar components in your country.

Biggest battery for the 360W panel and 30A solar regulator, i understand you mean a 4P7S is more in balance to this setup.

I don't follow you.

i ask because i found this picture and wondered if this was the norm:
View attachment 142878

I am not familiar with those specific modules. If the cells can't be paralleled, each individual battery would need it's own BMS.

I'm not planning to use that kind of draw, mabye a quart of that. Mabye in the future? who knows...

Best way to not waste money is to plan the final system and then figure out how to do it in pieces or stages.

Any recommandations?

JBD is pretty common and seems to be pretty reliable. I have a few.

My plan is to keep this at the cabins shed, a standalone little building but i believe i can jump between roofs...

Most LFP users aren't concerning themselves with this.