docnjoj wrote:A good BMS like Cellmans or Pings or the European one agniusm is using will work with a good charger.
tome wrote:docnjoj wrote:A good BMS like Cellmans or Pings or the European one agniusm is using will work with a good charger.
Do I understand correctly that a BMS can somehow "disconnect" a cell within a pack if that cell's voltage goes too low during discharge (load)? If so, how does it do this? I thought there was a single wire tied to the top ( +) of each cell that ran to the bms and allows the bms to sink some current in order to drain a cell down a bit during charging in order to balance cells. That makes sense to me, but I read somewhere that it can also keep a low cell from being drawn down during discharge and I don't see how that is possible with only a small wire that can only handle 2-3A...
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual. RC Electronics, Inc.
10.5 Balancing Battery Pack Cells. You don't want battery pack cells going below their minimum safe voltages for safety and battery life reasons. A battery pack whose individual cells are all balanced delivers the most energy since all cells are exhausted at the same minimum voltage. If any cell is "out of balance" it may reach the minimum safe voltage before the others and continued pack discharge will damage the cell.
ohzee wrote:Holy crap that's a nice swing.. That water pretty deep there ? Looks pretty awesome you build that contraption ?
Can I come live with you for a while ? looks like such a pretty place.
sergio helder wrote:better ulpoad that vid again....
agniusm wrote:Here is that vid
agniusm wrote:Here is that vid
tome wrote:arkmundi wrote:We have to understand there are a lot of approaches to doing "battery management," many different devices that can be applied.
Thanks for the replies, but I guess I didn't ask my question correctly, let me try again.
There are BMS's that (I think) claim to shunt current during the charge process in order to keep all cells charging whilst removing the ones at HVC (by shunting). To do this, you only need to bleed off a little current (2A or less) and so with a tap wire of, say 24AWG or so, I see how this is done. However, these BMS's also claim (I think) that they "remove" cells that have reached LVC from a pack during discharge. In my head it seems the only way to do that is for the entire pack current (potentially 100s of amps) to be passing through the BMS. The BMSes don't look like they are beefy enough for this to be the case, so I am wondering how do BMS work (how are they wired into the battery pack) that can protect a pack during the discharge phase?
whatever wrote:I'm a bit worried about the guy in the forest with shotgun and axe, seeming to enjoy a little bit too much destroying the cells....."oh yes'
Hi Tom was hoping to find some information to aid in answering your question.
As Arkmundi was referring to, there's many different ways.
This area is like opening a can of worms and was looking it up too in relation to lifepo4 and so hope the information on this excellent site by Albert Van Dalen ( who I think has contributed to this site a fair bit too). http://www.avdweb.nl/solar-bike/electronics/bms.html
Everyone seems to have a different take on charge/discharge bms parameters etc.
In relation to resistive types seems for simple operation they bleed charge from the good cells to drop down with the cell that hit the lvc mark first, which should be the lowest capacity cell.
I'm hoping the capacitor bms that Ohzee and myself have bought might help give better capacity in this respect, but havnt tested them yet too busy building etc.
There was another ES thread relating mainly to bottom balancing quite a few knowledgeable people inputting http://www.endless-sphere.com/forums/vi ... +balancing
Must warn I had a headache afterwards
tome wrote:megacycle wrote:Great! The links are exactly what I needed. Lots of good info in there including schematics and links off to other good sources of info from BMS chip makers.
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