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BMS Advice Sought

HammerToe

New Member
Joined
Apr 11, 2021
Messages
35
Guys, I would appreciate some advice/suggestions if anyone can spare the time.

I currently have four 3.2 volt 280 Ah LiFePo4 cells (finally, after 3 ½ weeks) ‘in transit’ from China and presumably somewhere other on the ‘surface of the earth’ (though God only seems to know where because this International Tracking stuff could use some additional ‘work’) but I anticipate they will probably be here within about a month or so.

I have been trying to locate and purchase a, actually ‘THE’ BMS I decided I wanted to purchase from someone, ANYONE, ANYWHERE but so far haven’t been able to find anybody who has any stock of the EXACT BMS ‘Plus Options’ that I would like to get.

To get to the point, the specific BMS I decided on was one recommended by Will Prowse the ‘Overkill Solar’ 12v 4S 120A with Low Temperature Charging System. (I really do want and feel I need a BMS that Really Does Have a WORKING Low Temperature Cutoff).

Other things – to the extent that I understand this stuff – that kind of ‘sold me’ on this BMS is because (a) it appeared to be Highly Configurable using/via a kind of ‘attractive’ Android app which which could be used to both monitor the status of the battery (various parameters) and provide all kinds of nice historical information about how it had been used (and arguably, it abused) AND because – as I understand it – for just a few extra ‘shekels’, in the Pro version of the app, you can gain the ability to configure all sorts of these parameters that you cannot configure with the free version of the software. And (b) that there appeared to be - and this is where it starts to get a little more unclear in my mind - Free Windows PC software which will let you do pretty much the same thing as with the android app (more or less; I haven’t looked at it in great detail but it looks like something I would want to be able to do) WHICH MAY OR MAY NOT REQUIRE (I am afraid) some particular ‘add-on component’ either integral with/perhaps on the BMS itself causing me to worry about the fact that if I don’t order the right parts and options, I may forever cut myself off from being able to use the PC software. (I think the odds are that I understand all this stuff correctly but I just want to be sure).

Bottom line – I figure – just to be safe – I would order the ‘whole 9 yards’/’the Kitchen Sink’ because the extra bits and pieces and options were pretty inexpensive anyway.

However, here begins my problem: I would really like to be able to find somebody who has stock of this specific BMS and so far, it either seems in most cases ‘nobody’ has stock (I managed to find only one searching around so far on EBAY and it was only the 100 amp version and I would really like to get the 120 amp version because…. WHY NOT? Won’t hurt…

My current understanding of what I would essentially have to order and wind up receiving with regard to this particular BMS would be three basic hardware pieces:

  • The BMS itself.
  • A Bluetooth card so that I could communicate with it from an android cell phone using the particular app in question.
  • And finally some additional ‘Stuff’/’Parts’ – perhaps it’s that USB adapter listed on Overkill’s site?
I would really like to get all this stuff and I don’t want to make any mistake by ordering – say – the BMS itself plus only in addition the Bluetooth adapter and then find out for some reason or other, I have cut myself off from the possibility of one day being able to use the PC software.

So, with all this background in mind:

  • I would really appreciate it if some of you guys who understand this stuff all hell of a lot better than I do might be able to clarify this whole situation for me. Exactly what should I order/must I ultimately wind up with in order to do everything I want to do in terms of ‘hardware’.
  • Assuming I decided to compromise and simply ‘go with’ in order for only the BMS itself and the Bluetooth adapter, I could simply order additional components I might require later to enable the extra functionality so that I can use the PC software?
Then, does anybody have any suggestions/no anyone who might have these things in stock through which I could place an order?

ONE OTHER POSSIBILITY:

As mentioned above, I was attracted to this particular BMS because of several factors – Will’s recommendation, it’s configurability (as evidenced through the particular Android app) and thus, the app itself, the ability to connect up to it using Windows PC software, the fact that it seemed to actually have a FUNCTIONAL/WORKING Low Temperature Cut off, and finally, because of its price, which did not seem outlandishly high for what you were getting.

HOWEVER, and especially if I can’t get the one I want, I would be open to suggestions about possible other BMS is that I might (be forced to) consider if I can’t get the one I want within the next 4 to 8 weeks.

The information I provided above indicates broadly what I’m looking for in terms of functionality AND capacity (120a) AND – IN PARTICULAR – programmability through and VIA The Specific Android App THAT WORKS APPARENTLY WITH THIS PARTICULAR BMS.

However, as mentioned – I would be open to suggestions in this area AND the one/a one specific parameter in terms of my specifications that I would consider modifying would be the amperage rating. The system I am contemplating building would be capable of about a 140 A discharge rate at 0.5 C and of course, even beyond that, one could if one wish to ‘push it higher’ Inso far as the batteries themselves are concerned.

The 120 amp rating of the BMS that I’m currently trying to purchase would – at most – be limited to/max out at (maybe!) 1500 W ‘in terms of an inverter’ and so if I were to consider a different BMS, I might be prepared to shell out some additional cash for something rated around 150 A or even 200 A in order to preserve the possibility of going all the way up to a 2 kW inverter. So – bottom line – a higher capacity BMS/recommendations would also be acceptable to me… (Unless the price gets really, really stupidly expensive).

Anyway, sorry for going on so long - I just would like to try to make it ‘PERFECTLY CLEAR’ EXACTLY what I’m looking for in the situation I’m in, by clearly and completely outlining my requirements/specifications and also to try to answer in advance any questions that anyone might have to try to go ‘back-and-forth’ in an extended dialogue on this forum/thread.

Thanks in advance, and ‘Cheers!’.
 
Order from Overkill. They were out of stock when I ordered on April 4 and it was delivered May 13. You probably have time.
 
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