Inspected and tested before shipping, and with a decent warranty. You can get the "same" BMS from other sources, but there are multiple versions that are very similar, and if you order from Alixxx and don't get what you expect or it fails you are SOL. Even being inflated, Overkill solar isn't very expensive compared to REC or similar.
What's the best BMS?
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Checkthisout
Solar Wizard
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My Daly fried and I just replaced it with yet to be operated JK.
What went went wrong with your Jk?
Rednecktek
Solar Wizard
Both of the JK's did this same thing after only a few hours of operation each.
I never got any answer as to why this happened but the Daly I threw in there ran like a champ the rest of the time I was up there.
I wanted a JBD but couldn't find a 150a in 8s, just the 3s-54397s versions and wouldn't get it in time, so the Daly delivered tomorrow won out.
Checkthisout
Solar Wizard
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Was looking for JBD but also can't find one right now.
So went with jk.
Daly worked fine until it got cold out.
Rednecktek
Solar Wizard
I did notice on mine that the default charging temp was -40c, I adjusted that up to +1c to be safer. Granted, most of my builds have heating pads and thermostats involved. Cold is a thing in my world.
Checkthisout
Solar Wizard
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Yeah. Maybe yours are a different and newer model and will work better than mine did.
No one seems to have mentioned the Seplos BMS yet. I haven't quite figured out if it is its own brand, or just a model of the JK BMS, but it seems to be featureful and well recommended from what I've heard. I've been considering it myself, based on what I have access to in my location. The DALY BMS has one major thing going for it for my climate, and that is it is better sealed, perhaps even moisture proof, from what some have said. But, as with anything, there are pro's and con's, and some of the other features I've been looking for have led me toward other options. I'd appreciate hearing from those with experience with the Seplos.
This is something I've been struggling with. The record cold for Thailand is officially about -2 Celsius, and unofficially about -5 Celsius up on the tallest mountain (Doi Inthanon). How often this might occur is debatable--we just had a 60-year low sweep through the entire region about seven years ago and records were set--some say they saw snow in northern Laos, a country first, if true.
As with everything in life, there is a cost/benefit ratio to consider; and I wonder if it is worth investing in something that will shutoff the battery in the event of a cold snap when the odds may be less than 1/1000 that it would drop below zero for this location anytime in the next 15 years. How lucky or unlucky do I presume to be? The coldest I've ever experienced here was probably about 6 degrees, and it felt even cooler. My installation will be up in a mountainous area.
It's too bad they don't make every BMS with freeze protection by default.
The cold protection is a charging stop not a discharge stop. So if it gets really cold the batteries just won’t charge until it warm up. But they will still discharge.
For me this is would be just losing a few hour of morning sun - when it’s not very strong anyway…
For me this is would be just losing a few hour of morning sun - when it’s not very strong anyway…
My understanding has been that the charging is what must stop at the freeze point, or ruin the LiFePO4 battery. If I've not misunderstood, the discharge won't harm it, only attempting to charge it. Now, perhaps there is a reduced rate of discharge? I'm open to being taught from those who know more.
Tulex
Solar Wizard
I think Seplos doesn't get mentioned because they cost a bit more, aren't as common and thus a little less known about how to handle them, and until recently, didn't have active balancing.
I've got three running, many other more experienced members on here use them. I've had no issues.
As far as I know, they are their own brand.
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Rednecktek
Solar Wizard
Doesn't Seplos only do 16s? I don't think I've ever heard of a 4s from them. 
Tulex
Solar Wizard
Looks like they only go down to 7S, and that's NCM, and 15/16 for LFP.Doesn't Seplos only do 16s? I don't think I've ever heard of a 4s from them.
That is also a good reason for their lack of popularity now that you bring it up.
Of course they can offer a warranty when they have a 200% mark up!
200% might seem like a lot. But it's $50 on top of a battery bank that may cost thousands.
And the risk is real. I bought "the same" JBD BMS from Amazon as a test unit for another project. When I removed the heat sinks only half the FETS were populated on the board. It would easily pass as the same BMS to anyone not taking it apart. $50 is good insurance that you get what you pay for.
Cuemaker
New Member
I'm happy with my choice going with OverKill BMS, like Will said, they just works like it's supposed too, every time!!!
They are not approved for medical use for nothing, there has to be something to it.
Maybe the OverKill rejects are sold under a different name, who knows.
Try to save a few $$$ on a very critical piece of the overall build is not for me, I like to gamble playing pool but not with my solar system.
Just me 2-cents.
They are not approved for medical use for nothing, there has to be something to it.
Maybe the OverKill rejects are sold under a different name, who knows.
Try to save a few $$$ on a very critical piece of the overall build is not for me, I like to gamble playing pool but not with my solar system.
Just me 2-cents.
42OhmsPA
What's in a title?
3 JBDs working pretty much flawlessly here. Some minor issues with SOC / low current reading but that seems to be inevitable regardless what you choose at this price point.
I do wish Overkill had the contactor version JBDs, they would have gotten my business; I did order the USB com adapters from them.
I do wish Overkill had the contactor version JBDs, they would have gotten my business; I did order the USB com adapters from them.
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Ampster
Renewable Energy Hobbyist
I bought two Overkill BMSs for the service and availability. I received value for my purchase.
If you feel overpaying 200% extra for the service and availability...good for you. Your choice.
For me, the JBD plus a spare for less money than buying one Overkill was a better value.
I recently bought the 4S version. https://batteryhookup.com/products/12v-lifepo4-smart-bms-w-low-temp-cutoffI have an idea of what I want, but I know next to nothing about BMS's so I'm open to hear any advice. I plan on building one (possibly two) 48v 16s 280AH LiFepo4 batteries. I saw someone on youtube use this BMS for the same system and I am considering buying it: https://batteryhookup.com/products/7s-21s-24v-75v-300a-lithium-ion-bms
Is this what I would need? Is there a better one out there?
Any info is appreciated
It is a JBD/xiaoxiang. Tests out as advertised and passive balance is working very well.
