diy solar

diy solar

Power station build - choosing battery

Jahlovje

Jahlovje

New Member
Joined
Feb 2, 2024
Messages
16
Location
Slovenia
Hello!
I'm completely new, be gentle :)

As many, I've watched probably tooooo much youtube, and rather spending a whole year on youtube and looking for some answers, I thought better to ask people, who know what they're doing.

I'm looking to build my DIY power station.
So first a little background. As for the power station, I'm looking to equip it with the regular, power it mainly with my AC-DC charger at camp sites, and while driving for topping it up. Later in life, I want to hook up some solar power if needed for being completely off grid.

My needs aren't big. The biggest need is probably an induction cooker, used for max an hour a day. Then there are some LED lights, two phones, maybe a tablet, 12v refrigerator (50w), and an electrical scooter (20ah battery).

I know that a 100ah battery would probably suffice, but looking for a 200ah battery (2560wh), for wanting to maximize the number of days I can potentially be off grid, if I wanted to in the future. We probably agree so far? :)

And then I've stumbled on the YT channel of Will, and he gave me another perspective. Mostly budget wise.

Grade A Lifepo4 300ah 302ah 304ah 320ah Catl Lifepo Batteries 3.2v 310ah 320ah Ev Lfp Lithium Ion Battery Cell For Solar Packs - Buy Docan Technology Official Store Catl Lifepo4 320ah Lf280k Alibaba Germany Warehouse In Weekly Deals Lifepo4 310ah,Bas

Grade A Lifepo4 300ah 302ah 304ah 320ah Catl Lifepo Batteries 3.2v 310ah 320ah Ev Lfp Lithium Ion Battery Cell For Solar Packs - Buy Docan Technology Official Store Catl Lifepo4 320ah Lf280k Alibaba Germany Warehouse In Weekly Deals Lifepo4 310ah,Basen Lifepo4 280ah Battery Lithium Ion Lifepo4...
www.alibaba.com

Could this be real?
Do I understand correctly? A cell that is 300ah at 3.2V?
Combining 4 would then give me a 12.8V system, and 3865Wh?
For the price of 435$ or 513,56$ with shipping?

I understand I would need a BMS, topping it up to 650$, but thats way cheaper than a 400ah battery?
Is there a catch? :)

Then again, do I need it?

Thanks for all the help, I'm in a pickle.
 
The catch is having the tools to do the wiring and the willingness to do the work yourself. I've made a few batteries that size and it was a lot of fun, but the initial investment in tools hurt the first time.

The other catch is that once you've built your first battery, you start thinking about what you'll do different for your second battery, and then your third, and your fourth... 😆
 
haha, you're probably right :cool:

Other than that, this seems "legit"? It just that it sounds like somewhat to good to be true :unsure:
 
No, that's pretty common on here. The first time is always the hardest because you're scared. Then you get done and realize that wasn't nearly as bad as you thought it would be.

The other catch is that there are a LOT of scammy sellers on Alibabexpress so finding a reputable seller can be a chore. Fortunately your link is to Docan and they're very well regarded and also sell from a US warehouse for faster and easier shipping.
 
Overkill? No such thing unless you're talking about an Overkill BMS.

Fridges are notoriously power hungry over time so a large battery is always a plus. A 300ah battery can pull 150a without batting an eye so it powers cooktops easily. Cloudy days really put a dent in things so being able to last longer between charges is a good safety net.

All in all, a big battery, especially in such a small foitprint, is always a goid idea.

Another thing to consider is the value of higher density cells. If you go to Docan's site and look at 100ah cells, it'd cost you $220 for just the cells. You can buy a 100ah battery for about $170 that's complete, so it's not a good value. However, when you get the larger cells for $650 with a better BMS but in a MUCH smaller footprint it becomes more of a value.
 
Last edited:
Go for it! Things to look for in the BMS:

Low temp protection
150-200a discharge
Bluetooth

Some people swear by JK, I prefer JBD, Daly is a decent beginner BMS as well. Make sure it's a Smart BMS, 4s, LFP and you'll be good to go.

For a container, I've used quite a few of the Noco Group-31 battery boxes with 3/8" terminal studs and about half a dozen 2-1/8" nylon washers (to buy space inside the box) to build in. Some red heat shrink 1/4"-M6 ring terminals, 4awg silicone wire, terminal lugs (3/8" & 1/4") and crimpers. It's a little tight but fits nicely.

20240125_100457.jpg

That thermostat is for a pet heating pad under the cells because I have to worry about cold temps, but that's advanced level stuff. This is an example of the 2 I just built for my camper build.
 
Not for your build, they top out at 100a. I'd go with JBD or Daly for that 150-200a range you need to feed that cooker. Overkill are just rebranded JBD's anyways. Avoid the 3-20s BMS's and just go for a regular 4s, they're much simpler to wire up.

The rest of the system should be 2000w MAX pure sine wave inverter, 800w MINIMUM on solar, and 80a of true MPPT charge controller. Pro tip: if the charge controller has USB ports on it, it's really a cheapie PWM and you're getting ripped off.
 
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With respect to your copy/pasta from alibaba.com ...
I've said it before, but i think it's still valid; getting ripped off when you have no pre-existing relationship with a foreign supplier is the norm (for some countries), particularly for cells/batteries, where B,C,D grades etc are hard to spot from A grade.
Not so bad for cable, breakers, and mounting gear, where its generally pass/fail and the grade is visible.
What incentive does the supplier have to make you a happy customer and come back for another order when they know you wont be back? (unless they think you like being burnt twice)
 
How many watts does your induction cooker pull? Seems like using gas would drop your needs considerably.
 
Whats_per_question said:
With respect to your copy/pasta from alibaba.com ...
I've said it before, but i think it's still valid; getting ripped off when you have no pre-existing relationship with a foreign supplier is the norm (for some countries), particularly for cells/batteries, where B,C,D grades etc are hard to spot from A grade.
Not so bad for cable, breakers, and mounting gear, where its generally pass/fail and the grade is visible.
What incentive does the supplier have to make you a happy customer and come back for another order when they know you wont be back? (unless they think you like being burnt twice)
Click to expand...

To understand, you believe I would be ripped off?
 
Whats_per_question said:
With respect to your copy/pasta from alibaba.com ...
I've said it before, but i think it's still valid; getting ripped off when you have no pre-existing relationship with a foreign supplier is the norm (for some countries), particularly for cells/batteries, where B,C,D grades etc are hard to spot from A grade.
Not so bad for cable, breakers, and mounting gear, where its generally pass/fail and the grade is visible.
What incentive does the supplier have to make you a happy customer and come back for another order when they know you wont be back? (unless they think you like being burnt twice)
Click to expand...
Fortunately he's linked off to Docan which is a well regarded supplier, and not AliStore8675309.
 
Bluedog225 said:
How many watts does your induction cooker pull? Seems like using gas would drop your needs considerably.
Click to expand...
2000w.

I understand It would drop my needs significantly, but I'm not sure I want to keep buying gas cans, its a nuisance :ROFLMAO:
 
I was afraid of that. You may want to sharpen your calculations regarding your consumption and battery size.
 
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