Overkill worth the premium?

Gould

Solar Enthusiast
I'm in the frigid white north so need a BMS that has a reliable low and high temperature cutoff and I'm new DIY batteries so looking for something relatively straight forward. I consider myself quite handy and more than capable of learning the details - and will in time - but this is one piece of a fairly large solar build so simplifying where I can is important.

Daly comes up quite often but my understanding is it does not offer the reliable temperature cut off. I've been focusing in on the Overkill but being in Canada with conversion, shipping, and most likely UPS brokerage fees, they will push $175 each times 2. This seems pretty lofty for a 120a BMS. Guess I'm looking for someone to help me justify the expense :), or is there something else I could be looking at?

Battery configuration, 8 CATL in 4S2P.
 

HRTKD

Boondocker
Support by phone, email or online (reddit). No questions asked warranty. A real user manual.

Look around to see how many folks on the forum have actually had to use the warranty. Not many.

I'm not paid for this endorsement. I'm just a satisfied customer.
 

Sillyputty

Solar Enthusiast
I've been focusing in on the Overkill but being in Canada with conversion, shipping, and most likely UPS brokerage fees, they will push $175 each times 2. This seems pretty lofty for a 120a BMS. Guess I'm looking for someone to help me justify the expense :), or is there something else I could be looking at?

Battery configuration, 8 CATL in 4S2P.
My test battery is installed in an unheated trailer that is currently connected to shore power (a WFCO 8855 55A charger/power center) until I get solar back up and running. The BMS disconnects the charging (enables charge protection) whenever it dips below 1 degree centigrade which occurs almost nightly here.

1) It has low temperature disconnect protection. Very few BMS' offer this (idk why not) and it works, as do the other protections such as cell over-voltage, pack over-voltage, etc.
2) Bluetooth range is good within 12 feet and works up to 20 feet. App works well with lots of info and programmability.
3) The 12V 4s model that I have is rated for 120A *continuous* and I believe it. (I pulled slightly over this testing it for several minutes with no problems)
4) IT IS UNCONDITIONALLY GUARANTEED!!!
5) Very good instruction manual.
1613159813043.png
 

Johncfii

Solar Addict
No doubt that Overkill Solar offers a good product, fast shipping, good service, and a great warranty. And they deserve to make a profit for what they deliver. The BMS they sell are made by JBD, in China. I own three of them from Overkill, and they have been great.

However, if funds are tight, and if you can wait four to six weeks for delivery, you can buy the same BMS direct from “The JBD BMS Store“ on the AliExpress site for about 40% to 60% lower cost, depending on what exactly you need. You can get them there in all kinds of pack configurations, and current capacities, with the same low/high temperature protection. I have three from this site as well, and they are just as great. Just be sure you read the product descriptions carefully, because the options can be confusing. And be sure you either order the BT dongle, or choose a package that includes one.

And in either case you will need to pay a one-time cost of $5.99 to buy the “Pro” version of the BT app. This is needed to allow you to customize the alarm set points.
 
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Gould

Solar Enthusiast
Thank you all for the great input. Regardless of the direction I'm happy to hear that performance on paper matches real world experience.

Being shiny new to all of this I think I'll go with the Overkill for added piece of mind.
 

gtxltd

Solar Enthusiast
Edit-Disregard this post thanks to information below. Hi Guys just a heads up on the JBD BMS. Being that my funds are tight I purchased this BMS direct from the JBD store. It came with three 8 AWG wires on each side. It looks great. It works great for high and low voltage cutoff. I used the android app and the PC program.
BUT-WARNING- IT DOES NOT HAVE LOW TEMPERATURE CUTOFF. You can set all the parameters in the app and the PC program but it does not function. I double checked this and then I noticed the spec sheet only calls out high temp protection. It seems to be a firmware shortcoming because it definitely has the hardware required for this task. I sent an email to James but it's still new year so we will have to wait and see. Just thought I should let you all know. (Tested twice in my kitchen freezer)
 

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DavidSTexas

Solar Enthusiast
I bought 5 JBD 12V 120A BMSs direct from the JBD AliExpress store as well. I would be interested in hearing what they have to say about the low-temp protection too.

I do not need it often, but this morning was one of those rare occasions. It was 12 degrees F when I woke up this morning and about 24 F inside where my batteries are. Knowing it was going to be cold, I shut off the solar panels last night because the JBD BMSs are new and not thoroughly tested yet.

Before I turned the heat on, or the solar, I logged into the PC application. All the batteries were at less than 1 degree C, which is my cutoff. All 4 packs were between 0 and 1. None of the icons for the FETS showed they were off though.

I played with the DISCHarge temps, and verified that the icons worked in the software, but the charge FETS were still on., no matter the set temps.

After turning the heat on and waiting for the batteries to heat up, I tuned the solar on. I set one pack to a higher low-temp setting. Once the solar amps coming in turned from negative to positive, that BMS shut off its Charge FET.

So on my BMSs, the LOW temp protection seems to be working but only activates when incoming power is detected. More testing will be necessary....
 

gtxltd

Solar Enthusiast
My testing was done with a bench power supply as a charge source. I could see the charge current was still on. I was at least 10 degrees below my set cutoff temp. I could manually shut off the charge fet and that worked properly. Does anyone know how to get the firmware version information out of the BMS? I would like to know if DavidSTexas has the same firmware as I do? I am actually hoping that my problem can somehow be resolved with a firmware change.
 

gtxltd

Solar Enthusiast
Thank you DavidSTexas!!! You are correct. In my test I was only using a small amount of charge current. After reading your post I retested with more current and saw that the low temp protection did indeed kick in. I will edit my original post.
 

DavidSTexas

Solar Enthusiast
Awesome. Mine had me scared this morning too. (If I had not shut off the solar...) I think it may be a power-saving feature.
 

sshibly

Solar Addict
3 Answers -
1. Yes
2. Yes
3. Yes

What premium?
aliexpress one does NOT include bluetooth, on/off switch, instructions, add that and other stuff they charge you are very close to OK's price, add the superfast local shipping, I did it to support him. :)
 

Just John

Solar Addict
So on my BMSs, the LOW temp protection seems to be working but only activates when incoming power is detected. More testing will be necessary....

That's how it works on my Daly as well. Until you give some current to charge with, it shows as still enabled. As soon as you give it some current, it shuts off.
 

tbloesch

New Member
3 Answers -
1. Yes
2. Yes
3. Yes

What premium?
aliexpress one does NOT include bluetooth, on/off switch, instructions, add that and other stuff they charge you are very close to OK's price, add the superfast local shipping, I did it to support him. :)
Looking at the listing on this page, it appears that a bluetooth module is included. Of course, the listings on Aliexpress are not the easiest to understand. https://www.aliexpress.com/item/32858179124.html?spm=a2g0o.store_home.productList_8327557.pic_3.
 

HRTKD

Boondocker
Hi guys,

I'm going to build a 8S LifePo4 battery. I need one with temp cut off.
Which one do I pick here? Is it the
  • 8S Lifepo4 100A UART ?

Does it come with the bluetooth module?

Thanks!

That's not the one from Overkill Solar. If you order from Overkill Solar, it's easier to understand what you're ordering.
 
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