ISO 12v BMS that can handle series 36v, high burst and iPhone bluetooth app

[Fish Freak]

My question will help many others, I'm sure, that are in the same boat;

Will's vids convinced me it'll be super simple to build my own LifePO4 power storage, not for solar, but for my fishing boat. I like the idea of DIY, learning, and using top quality parts compared to the 'cheap' drop-in lead-acid replacements. Found some great prismatic cells he tested, but then when I got to BMS I keep finding that they 'cannot be used in series' and no iPhone (android only) monitor app. I'm on the verge of giving up because I don't believe the Alibaba, ebay listings that say 'low temp protection' when Will proves that most don't work.

Who makes a battleborn grade BMS that also has a bluetooth app for iOS, not just android? A configurable app, not just to 'view' the SOC, Ah, etc.?

I run 4 group 27 to 31 big heavy lead agm batteries; 3 in series for 36v (or 2s for 24v) trolling motor (57 amp max draw) and one single 31 agm for starting a large boat engine (need burst, about 300 amps) and powering many electronic devices onboard all day. Going to LifePO4 represents a HUGE weight savings, and performance benefit. So what I'd like to understand is, why can't most BMS' be used in series? Why does a 12v BMS even care that it's in series? I could see if you were drawing AND charging in 36v like you would with solar, however, in our boats we use a 4 bank waterproof lithium charger that pushes say 20 amps to 4 leads, so each of the 4 batteries are recharged individually in 12v. Does charging individually in 12v negate that 'no series' warning?

My last goal would be to have one of my 4 DIY LifePO4 batteries be able to start an IC gas engine, needs roughly 300 amps for a quick burst, but then needs to power all sorts of electronics all day. So the BMS needs to be tough, right? Does one exist yet for a fair under $100 price? How about over $100?

Part of what's bugging me is there is a CHEAP $$ line of drop-in lead acid replacement batteries called Ionic, that can be used in series, can do the burst amps for starting an IC, and they have a bluetooth app for iPhone, and I'm wondering HOW they're doing all that so cheap? I'd love to see Will cut one of them open!!

BTW I found some cool waterproof cases I think would be slick for battery cases with see thru tops, by Bud Industries, many sizes in their NEMA PTQ series:

Bud Industries waterproof case with threaded stand-offs inside

 

[Craig]

The thing is I think most of the DIY BMS out there are for smaller voltage cells in the 1.5 to 4.0 volt range.

what you might need is something like this https://batteryequalizer.shop/Battery-Equalizer-Battery-Balancer/Battery-Equalizer-24V
I just googled it so I know nothing of its quality. Just an Idea

 

[Fish Freak]

The thing is I think most of the DIY BMS out there are for smaller voltage cells in the 1.5 to 4.0 volt range.

what you might need is something like this https://batteryequalizer.shop/Battery-Equalizer-Battery-Balancer/Battery-Equalizer-24V
I just googled it so I know nothing of its quality. Just an Idea

Hmm, maybe I should have said it as simply as this: I'd like to 'DIY' two different LifePO batteries with bluetooth iOS iPhone control, so like lead-acid replacements in these capacities;

1. One for deep-cycle use (group 27 lead replacement), shooting for 100Ah, about 60 amp draw max and used in series for 36v, and...

2. One for combo use (been using a group 31 style lead), deep cycle/engine starting battery, and I'm targeting about a 125Ah LifePO4.

Here's where I'm just speculating:
It appears that LifePO4 'cold cranking amps' are different than lead batteries, and guys right now are successfully using 100Ah to 125Ah LifePO4 drop-ins, like Battleborn and Ionics, that have about 250-300 LifePO4 burst 'cranking' amps in replacement for 1,000-1,100 amp lead-acid CCA's. Now, I don't really think that these drop-in batteries really have 250-300 amp BMS's, as Will revealed when he cut open a Battleborn 100Ah (or was it 125 Ah?) battery, the BMS clearly says on it: 100 amp charging/discharging current. Is that possible? Can a battery with a good quality 100 amp BMS, for 2-3 seconds, deliver 300 amps without overheating the mosfets, without relays, without triggering it's protection, with no problems over time?

If not no biggie, I'll pay a little more for a better BMS because I only need one cranker, and for that one I'd really like to duplicate the quality on this BB, I mean, check out those FIVE 8 gauge wires, in and out, and that massive brass bus bar going to each strong flat terminal!! If you know of a BMS that can do this, please, PLEASE chime in!! WILL?!? I'll be using either or 4 Fortune 100's, or 4 RJ Energy 125's (Lol, or used sinopoly) prismatic cells.

Battleborn's 100 amp BMS with big brass bars ! Say that 5 times real fast...