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EG4 LiFePOWER4 24V vs DIY

Kent F

New Member
Joined
Jan 22, 2025
Messages
1
Location
Toronto, Ontario
Hello Everyone. I'm new to the forum, but I've been visiting for years. Thanks to everyone who has been contributing to this resource.

I'm fairly novice when it comes to battery storage, and even more so with LFP batteries. I have an existing 24v setup with Magnum Energy components and 1200ah of AGM batteries. My batteries are aging, and I think it's time for an upgrade. Given my novice nature, I'm deliberating between off the shelf batteries or a DIY kit. I've priced out both and it seems like the DIY option is substantially better. I'm not trying to do this on the cheap and I generally believe in buying the right thing once. That said, it's hard to ignore the savings. Currently I'm deliberating between two options: 1) 5x EG4 LiFePOWER4 24V V2 Battery (USD $5,745) 2) 4x DIY batteries, possibly built into Seplos 25.6V 280Ah DIY cases. (4x350=$1400, 32x77=$2464, Total $3,864). It would appear to me that the second option provides ~10% more capacity for ~2k less. I suppose I have 3 questions:

1) Would you recommend either option?
2) Assuming I'm reasonably competent, follow the instructions, read the forum and watch the videos - how long should it take to get the DIY system working?
3) Am I missing something, such as extra costs or considerations? Of note, I can and will set a custom charging profile for the new batteries.

Thanks for reading and I appreciate any advice you can offer.
 
You need around $200 to $300 in tools, some of which you may have.

The diy kits are good as long as you are good with attention to details. There are many parts and they all need to be put together perfectly to be safe. So consider your assembly quotient...

That said, I would say the average person with minimal electrical background needs to read and understand stuff in the forum for a month or two before making a battery from scratch. If you want a crash course read the up-in-smoke forum for a week or so and understand as many ways as there are to screw the pooch.

For reference i have a solid background in electronics 30 years ago and have been studying all things solar for 18 months. I have just now been bitten by the bug to build a few batteries. Part of it is the financials... reasonably priced midgrade batteries are super cheap these days. For lower capacity batteries they are cheaper to buy. For higher capacity batteries the prices make sense to build, for the lower capacity it makes sense to buy.

What tipped me over was a 12v300ah wattcycle that turned out to be 280ah and have a crappy BMS... I probably would still have kept it but everytime I move it the lid pops off. So I bought a bms and once ii took it apart I decided to build 2 more..314ah
 
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I'll make the opposite argument. I really enjoy designing, and don't mind building, but a battery build is tedious, and the cabinetry is non-trivial. Batteries keep plummeting in price, I just don't think the effort is worth the savings. If you have lot's of space and just need a sh-t ton of batteries, and you can scale up your cabinetry, maybe, but the minute you start buying rackmount or wallmount cabinets the cost savings begins to diminish.

For me shoving 6 rackmount batteries in a pre-fabbed rack with bus bars was enough work. Building out bus-bars, and wiring up bms's is not difficult, just tedious.
 
Our owl friend has a point...

But if you do decide to build after considering things carefully you can likely get better prices from Amy on Albia for your cells and cases.
 
Your tools can be a lot cheaper if there's a Hobo Freight in your area.

Small batteries? Buy.
Large batteries? Build.

I remember doing my first battery, sweating bullets that something was going to explode, working with budget tools...

That was it? That was so EASY!!!
 
In the sub-forum here called Up in smoke...learn from my mistakes, the only posts I've seen in there where a garage burned down, a house burned down, or some sort of fire, big and small involved DIY battery packs. And I would say the people that suffered these fires were experienced DIYers. But somehow, things went wrong. There was one post where a manufactured battery started smoking (probably venting). But it did not catch fire.

Take a read for yourself: https://diysolarforum.com/forums/up-in-smoke-learn-from-my-mistake.83/
 
Your tools can be a lot cheaper if there's a Hobo Freight in your area.

Small batteries? Buy.
Large batteries? Build.

I remember doing my first battery, sweating bullets that something was going to explode, working with budget tools...

That was it? That was so EASY!!!

Sigh,

One area i really really disagree with you on is cheap tools, especially harbor freight quality.

The harbor freight hydraulic crimper is metric marked in awg and it will make a crimp with wings nearly every time. The same goes for the AMZCNC brand off amazon and other websites.

Harbor freight quality tools make for a frustrating time.

You can get a reasonable clamp meter there that reads DC amps just fine. But you can also end up with one that won't read the same battery voltage twice in a row.

And I buy hand tools to work on the car if it is something I am not going to use but a few times or things they can't make to cheap or they won't work at all. But, I bought a front end kit there ones and ended up having to return it the first time I tried to use it, the jaws were unevenly ground and one of the fingers on the spring compressor snapped while I was trying to get the coil spring off the truck.

One of the first things in the book 'The Idiots guide to keeping your VW alive" says is to always buy quality tool... they won't break when used and when things go wrong you can always polish your tools knowing they were not the cause.

Anyways, if you decide to build batteries. Don't cut corners and use some of the savings or a Temco crimper and an $80 to $120 clamp meter. And buy Ancor,Selterm, or Temco brand lugs.

I have many suggestions in my answer thread.


I think the real problem with DIY batteries is the Dunning–Kruger effect - people that over-estimate their competence. And even when you really do know what you are doing a tiny mistake now may cause issues for you in a couple of years.


 
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Gonna have to agree to disagree on the HF tools. The wire strippers and crimpers, 10mm ratchet, heat gun, all of those do the job just fine. I have one of their amp clamp meters that I've been using here on the ship for the last 8 months that's working well still and we love the heat shrink butt connectors that actually hold up to salt water and weather.

The hydraulic crimper isn't great but sizing down 1 when I crimp always leaves me with a super tight connection that I have hung from (in testing) and if I can hold my 250lb ass off the ground by the lug, it's good enough.
 
I guess I am soured on them. I've had a ratchet come apart on first use. Pneumatic tools the same. Wire cutters and strippers that get dull or ruined cutting edge cutting copper. Box end wrenches that either don't fit or need adjustment so they do. Only socket I have ever shattered was their Pittsburgh line of tools.

General poor quality... and part of my opinion is I can afford good quality tools.... and I have bought and used enough of their stuff and better stuff and in the case of tools with that you get what you pay for.

All that said,I saw something saying they are trying to improve their quality and image. It has been 20 years, maybe I should visit again.
 

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