Author Topic: Recommendation of 12v LiFePo4 Battery Management System & question about mid-battery fuses...  (Read 3702 times)

Offline AdamB

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Can someone please recommend a good bms for LiFeP04 rated for 12V 10Ah (i.e. 4S1P) that ideally incorporate a feature that uses LED (like ping packs) to visually indicate individual balance/percent charged?

It doesn't need to be crazy high power, say continuous 2C & peak 3C range is fine (won't go that high typically but if need be for short periods, I'ld like to be able without frying my BMS/battery)...

I'll be getting a whole bunch, so cost's a factor... Yes, to be clear- I like Scooteretti approach of only having 12V base packs that combine to meet users' needs...

But I hate that nothing is replaceable or serviceable, so if anything goes wrong you can't do anything besides replace the whole battery... Heck, you can't even find out what's wrong or test individual cells- just throw it out & buy a whole new one:( You can't even check to see if a wire is loose without permanently destroying the casing!

However I really love GM's simplicity & common sense making everything replaceable/ serviceable/ rebuildable! If something goes wrong, the battery can be opened, tested, damaged components replaced & then rebuilt! That means if just 1 cell dies, I'm back up & running for $35... Compared to $200-$300 if a Scooteretti cell dies!

Plus sticking with 12V base packs means I can use a stock auto electrical system without needing a DC-DC converter or like!

My last question is about fuses... In particular mid-battery pack fuses (I'm using other types too but it's the 1 in debate ATM). I like that if something goes wrong, the fuse in the middle prevents it from continuing on & restricts the damage to half the pack... It's cheap insurance, especially when you are as unlucky as I am!

I found a fuse on ES  (Here- https://endless-sphere.com/forums/viewtopic.php?f=2&t=26114 ) it's the 1st mentioned in the thread & there's a picture of it in the 1st post.

My brain being what it is... I got to thinking, can I use a fuse like that to replace a busbar (used in lue of wires) to make serial connections in a battery pack (like here-  http://www.goldenmotor.ca/FAQ/questions.php?questionid=11 ) the last 4 pics at the bottom (pics 9-12 show it) show the busbars (I.e. copper bars being used in lue of wires)...

I was thinking it may need a bit of modding but shouldn't be too hard! The configuration I was thinking about was 4 cells wired in series like so...
           V 2nd busbar
Cell1 ([+)____-]----- 12V - line
Cell2 ([-)___(+]) < 1st half of fuse
Cell3 ([+)___(-]) < 2nd half of fuse
Cell4 ([-)____+]------ 12V + line
           ^ 1st busbar

Hopefully this rough diagram posts ok... For reference the straight brackets & lines represents the cell edges & rounded brackets represents the busbars around the terminals (as seen in Gary's page disassembling GM battery pack)...  The image represents 4 cells wired in series with 2 busbars as series connections on left side & 1 fuse in lue of a busbar on the middle of the right side & 2 lines running off the negative/positive connections on either end of the right side...

So let me know what you think... Btw- if you have a recommendation on what size & source is best for the mid-battery pack fuse, that be great too!

Adam

Edited to show correct term I couldn't remember earlier...
« Last Edit: October 03, 2015, 06:32:18 PM by AdamB »