For every positive experience, we've seen a dozen negative ones. I'm just hoping that those new to the game have a good experience, and Aliexpress tends to be more risky.
Build a LiFePO4 battery or buy one already made?
- Thread starter BeerBrewer
- Start date
For every positive experience, we've seen a dozen negative ones. I'm just hoping that those new to the game have a good experience, and Aliexpress tends to be more risky.
OTRwSolar
Solar Enthusiast
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- Apr 5, 2021
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Quite a few posts discussing ways to achieve a balance between a "normal" charge profile vs. a charge profile that allows the BMS an opportunity to provide good cell balancing using the very low 50-100ma of balancing/bleed current typically found on most BMS's. Most solutions involve a dance between these two charge profiles, not to mention the extra baby-sitting time.
Unless I was dealing with a sealed, off-the-shelf battery/pack with an active warranty, I think I'd much prefer to install an active balancer. If we need to balance, we turn-on the active balancer for an hour or two (with the cells above 3.4v). Once the delta is below our preferred threshold we turn the active balancer off. We then use our normal/regular/preferred charge profile until such time as the cell deltas get too high again---maybe a few weeks, a month or so later, who knows. At that point, rinse and repeat.
Unless I was dealing with a sealed, off-the-shelf battery/pack with an active warranty, I think I'd much prefer to install an active balancer. If we need to balance, we turn-on the active balancer for an hour or two (with the cells above 3.4v). Once the delta is below our preferred threshold we turn the active balancer off. We then use our normal/regular/preferred charge profile until such time as the cell deltas get too high again---maybe a few weeks, a month or so later, who knows. At that point, rinse and repeat.
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hardtop
Solar Enthusiast
So far the cells have balanced out just fine. Cell volt diff is about .02 during the final few minutes of charging at 3.5V. There are 56+ cycles with 17k cycle capacity on the battery and I've been using it daily for months. I did have one cell that was .2V low at end of charge after several months of use, but I found the bus bar bolt came loose. I tightened it back up and after a few charge/discharge cycles it went back to normal. Maybe I will need to top balance later, but right now I see no evidence that I need to.
RockOn
New Member
So folks just to keep this topic alive, I will post status and results for what I have just ordered (yes actual order in so $ is actual)
Between the Will's videos and also Nate's DYI Solar, this seems to be the way to go to support a full house system.
32 3.2v 280ah LiFePo cells (rated for 300 actual ah so effectively 600ah)
2 DIY battery boxes with JK 200amp BMS w/ touch screen, PCB, circuit breaker, etc
$3,024 all in cst with shipping
$3k/30kw = $100/kw
Closest example of pre-built rack mount that I can find is $900-1,000 for a 100ah battery or $180-200/kw
At this point in time DIY is 50% of premade batteries.
If someone can provide something that shows different, I would really like to see.
I will post sources and status of the build once I can start some testing.
Between the Will's videos and also Nate's DYI Solar, this seems to be the way to go to support a full house system.
32 3.2v 280ah LiFePo cells (rated for 300 actual ah so effectively 600ah)
2 DIY battery boxes with JK 200amp BMS w/ touch screen, PCB, circuit breaker, etc
$3,024 all in cst with shipping
$3k/30kw = $100/kw
Closest example of pre-built rack mount that I can find is $900-1,000 for a 100ah battery or $180-200/kw
At this point in time DIY is 50% of premade batteries.
If someone can provide something that shows different, I would really like to see.
I will post sources and status of the build once I can start some testing.
Where did you get it from? Also keep in mind many of the circuit breakers included in these DIY kits are not safe when you start adding batteries in parallel. They simply do not have high enough interrupt current rating.
RockOn
New Member
Allibaba but based on a lot of feedback and review on which store/mfg to buy from.
Agree the CBs are more of an easy on/off switch…. Each bank will have a + terminal fuse.
fatjay
Solar Wizard
There's a couple vendors in the US that are selling cells that are just a hair over the price of cells on aliexpress/alibaba. If you're weary about quality or don't want to wait for long lead times, that might be a good route to get you started.
And it depends on how much power you are going for. I need 90kwh, and the cheapest prebuilt with any sense of quality is 1k/5kwh, or $18k without shipping. Buying sells individually, I can build 15kwh for $1200 with bms and compression case included, and that's $7200 shipped.
The more you need, the faster the gap grows, which means it makes a lot more sense to diy pack with higher capacity.
And it depends on how much power you are going for. I need 90kwh, and the cheapest prebuilt with any sense of quality is 1k/5kwh, or $18k without shipping. Buying sells individually, I can build 15kwh for $1200 with bms and compression case included, and that's $7200 shipped.
The more you need, the faster the gap grows, which means it makes a lot more sense to diy pack with higher capacity.
Do you have list of those US sellers? 18650batterystore.com in the US has been called out for selling cells with terminals that are not properly welded on so they are popping off.
fatjay
Solar Wizard
Then 18650batterystore should be liable for the products they sell. Not saying they will do the right thing, but here's hoping.
I have gotten 4 packs off batteryhookup.com so far no issues, they've been flexible, and they're local. But their prices shipped don't seem unreasonable.
dareggaemon
New Member
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- Nov 10, 2022
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I completely agree. Anyone who wants to have battery power for more than one day without the grid is going to need a huge battery bank of 50K or more. That's four EG4-wallmount indoor batteries, which is $13,196 before tax and shipping. You could build this yourself for $7k tax and shipping included. And, you could build it for a lot less if you build your own enclosure.
Keep in mind that generally the grid goes down during storms when you don't have sunlight to easily recharge your battery bank. And, if you have an electric car you will need a larger battery bank.
there was nothing wrong with the ones I got from them.
OTRwSolar
Solar Enthusiast
- Joined
- Apr 5, 2021
- Messages
- 296
There's a limited number of US based lifepo4 cell vendors. They *all* have issues of one kind or another. Pick your poison. If you're not comfortable picking one, you may want to consider going with an off-the-shelf unit (with a warranty that's hopefully worth the paper it was written on) as a plan B.
For what it's worth, we've purchased a number of cells from 18650. Granted, they don't have the most timely, responsive communication, but all said and done they stepped up to the plate when we needed them to.
BarracudaBob
Harvesting free photons from clean fusion
I like my batteries in a metal enclosure. The enclosure with a securely bolted down BMS with nice from or side panel with communication ports. And the older I get the more I like things on wheels.
Figure out what enclosure you are going to use and that seems to be the hardest starting point for me. Add up all the parts and if it is over the price of a commercially produced battery with free shipping that that answers it for me.
Figure out what enclosure you are going to use and that seems to be the hardest starting point for me. Add up all the parts and if it is over the price of a commercially produced battery with free shipping that that answers it for me.
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DustyDesertDweller
New Member
Are there any commercially produced batteries cheaper than DIY box builds? I don't think I've found any but I'm interested. I'm in the market for two 15kwh 48v batteries with coms. I'm usually finding the DIY boxes to be at least $1000 cheaper than buying commercial batteries.
I found I wanted an outdoor battery so I went with the Midnite powerflo16 battery. It has a built in 2” hole for conduit so I don’t need to get an external conduit box which makes the install cleaner.
BarracudaBob
Harvesting free photons from clean fusion
BarracudaBob
Harvesting free photons from clean fusion
with 2A active balancing, nice
Also is heated but doesn’t matter in CA weather. The other secret is sign up at current connected and you will see a very nice price compared to eg4 power pro, etc. I’m waiting for another free shipping promotion before I get a second one.
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