What cells should I buy?

[that_yeti_tech]

I'm trying to learn how to build my own solar batteries, but I'm having trouble figuring out which supplies to buy. So I'll start with cells: I'm looking to buy some LiFePo4 cells to use in backup/emergency power batteries. I want to be able to run things like LED plant growing lights, small electric heaters, basic kitchen appliances etc.

What voltage and AH cells would be best for this? And how many?

Any information or tips are appreciated! Even if it's unrelated to this question.

 

[chrisski]

Need to do a kWh requirement, max votlage. and how long you want the battery to last without the sun, and then look at the solar data for your area.

Not quite sure if you mean a 500 watt heater or a much less energy consuming heater for a fish tank or to keep water from freezing for livestock. Same thing for the LEDs; whether its a 20 watt string or a 250 watt light bar, or five 30 watt draw LED light bulbs. My basic kithen appliances run from 230 watts for a crockpot to 1800 watts for the air fryer.

This link helped me a lot: https://www.solarpaneltalk.com/foru...el-systems/5140-solar-off-grid-battery-design

 

[that_yeti_tech]

Need to do a kWh requirement, max votlage. and how long you want the battery to last without the sun, and then look at the solar data for your area.

Not quite sure if you mean a 500 watt heater or a much less energy consuming heater for a fish tank or to keep water from freezing for livestock. Same thing for the LEDs; whether its a 20 watt string or a 250 watt light bar, or five 30 watt draw LED light bulbs. My basic kithen appliances run from 230 watts for a crockpot to 1800 watts for the air fryer.

This link helped me a lot: https://www.solarpaneltalk.com/foru...el-systems/5140-solar-off-grid-battery-design

Thank you! I'll definitely look into all of that and check out the link
This is a project I'm working on for my whole family, so I'll have to ask them about the things they want to run.

 

[Rednecktek]

Thank you! I'll definitely look into all of that and check out the link
This is a project I'm working on for my whole family, so I'll have to ask them about the things they want to run.

If you ask the family, expect the answer to be "Yes, and the MargaritaMaster-9000 as well."

When it comes to heat of any kind (room, food, fish, etc) the general response is "Anything but Solar" because of the massive system required. To give you a little perspective, a bog standard 100ah LFP battery will run a bog standard electric heater for about 45 minutes before it's dead.

If you want to poll the family for their needs, rather than ask them what they want to run, list out different things (fridge, aircon, internet, Margarita-Master-9000, etc) and have everyone rank them from most to least important. Then figure out how much system you want.

Once you have your power audit (how much inverter + how much battery + how much panel) then you can figure out what kind of battery you'll need and go from there.

As for which cells to get, it's going to depend on one other factor and that is portability. Can you build a honkin huge battery on a shelf in the garage or are you going to need to pick it up and move it around? Trying to move a 16s EVE280k battery is MUCH different than a 4s 100ah battery. Physics and your back are gonna "Have Words" if you don't take that into consideration.

The current Bang-For-The-Buck cells seem to be the EVE-280k's for high density. Considering you can buy a 100ah LFP for about $170 now, but the same cells alone are about $220, building a battery isn't really as cost effective as it once was. The advantage to building is the higher capacity cells are a better value and it's a LOT more fun.

 

[hwy17]

You will almost certainly want an expandable system, everyone does.

That means you should start with a 48v 16s Lifepo4 battery.

The minimum entry point for that is either one server rack battery like a Lifepower4 for $1250, or a DIY pack starting at $2500ish for 16 280's or 304's and a BMS.

It is possible to DIY a 100ah pack, but I think the value proposition is low on that. If you are going to take the time and effort to make a DIY pack it really might as well be 280/304's.

The limitation of the single server rack battery option is the peak output. A single Lifepower4 cannot start something like a clothes dryer with most inverters. It will go into short circuit protection mode. If you run into this problem though, it is temporary and adding more batteries will solve it.

If you have the budget for it, then you could start with a 280ah powerpro as well.

 

[that_yeti_tech]

If you ask the family, expect the answer to be "Yes, and the MargaritaMaster-9000 as well."

When it comes to heat of any kind (room, food, fish, etc) the general response is "Anything but Solar" because of the massive system required. To give you a little perspective, a bog standard 100ah LFP battery will run a bog standard electric heater for about 45 minutes before it's dead.

If you want to poll the family for their needs, rather than ask them what they want to run, list out different things (fridge, aircon, internet, Margarita-Master-9000, etc) and have everyone rank them from most to least important. Then figure out how much system you want.

Once you have your power audit (how much inverter + how much battery + how much panel) then you can figure out what kind of battery you'll need and go from there.

As for which cells to get, it's going to depend on one other factor and that is portability. Can you build a honkin huge battery on a shelf in the garage or are you going to need to pick it up and move it around? Trying to move a 16s EVE280k battery is MUCH different than a 4s 100ah battery. Physics and your back are gonna "Have Words" if you don't take that into consideration.

The current Bang-For-The-Buck cells seem to be the EVE-280k's for high density. Considering you can buy a 100ah LFP for about $170 now, but the same cells alone are about $220, building a battery isn't really as cost effective as it once was. The advantage to building is the higher capacity cells are a better value and it's a LOT more fun.

Yes from what I've gathered solar definitely isn't the best for heat unfortunately. This is why I'm only looking to use it for emergencies, even so, it looks like I'll still need more batteries than I originally thought.

Good point. Fortunately they're all old enough to understand that this system will only be for necessities lol. Still this is a good thing to consider and I will do so.

Thank your for all the info! I'll definitely look into these cells. I've been a bit overwhelmed with all the options out there so this really helps. And true, building batteries is a lot more interesting than just plugging things in to other things.

 

[that_yeti_tech]

You will almost certainly want an expandable system, everyone does.

That means you should start with a 48v 16s Lifepo4 battery.

The minimum entry point for that is either one server rack battery like a Lifepower4 for $1250, or a DIY pack starting at $2500ish for 16 280's or 304's and a BMS.

It is possible to DIY a 100ah pack, but I think the value proposition is low on that. If you are going to take the time and effort to make a DIY pack it really might as well be 280/304's.

The limitation of the single server rack battery option is the peak output. A single Lifepower4 cannot start something like a clothes dryer with most inverters. It will go into short circuit protection mode. If you run into this problem though, it is temporary and adding more batteries will solve it.

If you have the budget for it, then you could start with a 280ah powerpro as well.

I can already tell this is very true.

48v was my guess, glad to have someone confirm this. This might be a question with an obvious answer, but I'm very much a beginner haha. What does 16s stand for?

Thanks so much for all the info!

 

[hwy17]

I can already tell this is very true.

48v was my guess, glad to have someone confirm this. This might be a question with an obvious answer, but I'm very much a beginner haha. What does 16s stand for?

Thanks so much for all the info!

You're welcome, happy to share it.

16s means 16 individual cells in series to make 51.2V, instead of 15 cells to make 48v.

Everyone has standardized around 51.2 so it's not as common to run into this problem, but some Pylontech and Kong batteries have come in 15S before. 15S and 16S batteries cannot be mixed. All 48v EG4 batteries are 16S.

 

[hwy17]

If you have the budget, I think going straight to one powerpro is a good idea. There's no such thing as too much battery.

I went DIY and my project is approaching the cost of a powerpro for the same capacity, but I got a bit carried away with the design and chose an extremely complicated Orion BMS.

 

[that_yeti_tech]

You're welcome, happy to share it.

16s means 16 individual cells in series to make 51.2V, instead of 15 cells to make 48v.

Everyone has standardized around 51.2 so it's not as common to run into this problem, but some Pylontech and Kong batteries have come in 15S before. 15S and 16S batteries cannot be mixed. All 48v EG4 batteries are 16S.

Ohh makes sense, good to know!!

 

[that_yeti_tech]

If you have the budget, I think going straight to one powerpro is a good idea. There's no such thing as too much battery.

I went DIY and my project is approaching the cost of a powerpro for the same capacity, but I got a bit carried away with the design and chose an extremely complicated Orion BMS.

Unfortunately I don't have the budget at the moment, but maybe it's something I can work towards, or slowly build an equivalent system.

 

[hwy17]

Oh and back to the original question, which cells to buy: Ezealco and 18650batterystore are the community favorites right now for buying cells. Pretty much all of them made by EVE. Avoid the EVE 280ah unless it says it is V3 (Ezeal still doesn't say if their 280's are V3).

 

[that_yeti_tech]

Oh and back to the original question, which cells to buy: Ezealco and 18650batterystore are the community favorites right now for buying cells. Pretty much all of them made by EVE. Avoid the EVE 280ah unless it says it is V3 (Ezeal still doesn't say if their 280's are V3).

Awesome thanks!