tinkering with a 48v charger

[2007blueprius]

or at least this is what this thing is supposed to be

it was intended to charge a 48v 80 ah pack Lifepo4 pack, long storry but common concept within the users forum it is adequate ( I am not sure about that so I took it apart and brought it here ), I am not even sure what category this charger falls into, but for the most part it is advertised as a dumb charger 55.5 v at 15 amp non adjustable.

now I do not know much but I have tinkered with PC power supplyes and this looks to me very simmilar, I want to say it is a plain SMPS much simpler than a computer one since it only has one output, that beeing said voltages and amperages should be adjustable to a degree. and heres some pics :


this looks like a control daughter board and I don't know but there are a lot of turn pots there, also couple of these chips are labeled lm 324n, I came across that label before, I think they are used for voltage regulation

otherwise here are some more pics as to the rest of the components:

This section looks very simmilar to any PC power supply, I don't remember what to call all these components ( can you tell I am a bit green at all this? ) but from what I read about SMPS this section has some smoothing components, capacitors, I think there is 2 bridge rectifiers, at least one I could recognise, so in theory this section converts 110v AC to 220V DC ( feel free to corect me at any time)

there's the 2 large caps and what I think to be the bridge rectifier

the large transformer and a bunch a switching FET's ( or so I believe they are called )

this is the output section, another one of those smoothing coils ( I realy don't know the proper term ), what looks to be like a relay, probl to finish charge I guess
The backside :

ok so why tinker with it? It does work, but is is really suited for charging lithium chemistry in the first place?
the kit it came out of is a cheap knockoff, nothing about it seems right, I have been lurking on this forum for years reading about everything I could understand and as soon as I got this kit it dawned on me right away that this is nothing like I have been reading it should be.
It is from a plugin kit for a toyota prius, the pack is made out of 16 blocks in series, each block made out of 4 rfe 20 ah pouches,
The system is functional and I bought it used, it has allready destroyed a pack at that time, and it is not a fluke these were never reliable, there is no charge control just first cell to hit HVC ends the charge,
now that I got a replacement pack I would like to set it up properly and get long term use out of it.
I have read that a proper lithium charger is CC/CV there are stages, and I do not think this one does not do any of that.
my understanding is initially they cet charged in CC stage as the charge gets toward the end it is swithced ti CV mode than the amps turned down, so a charge balancer can even the cells, zenid I think is a brand of charger that works in such manner.
It has been suggested to me that lowering the charge current towards the end of charge ( even manually )will help in the top off process, so that is why I opened it to see if I can do that, but I do not know enough to acomplish such a task
also in a perfect world 55.5v/16 = 3.46875v per block, bit low for lithium, I believe the norm is 3.9, the bms ( if you can call it that) that came with it had a HVC set for 3.8v, even that proved to be too high for these cells, considering charging 80 ah blocks at 15 amps that is 0.1875c, among users 3.65v should be max, most ate confortable with even less for longevity purposses, also the rest of the system seems to be a joke there is no balancing at all, common practice is to manualy perform a bottom ballance every 6 months, and rely on HVC in the mean time.
I have not been able to find any diagram or model number, http://www.enginer.us is the manufacturers website and while it is still active they are out of bussiness.
Anywho I could use some help with this, I can take some better pictures but wont be able to post them here, I have a photobucket account for this project http://s1365.photobucket.com/user/2007blueprius/library/?sort=3&page=1#/user/2007blueprius/library/?sort=3&page=1&_suid=138519090894007512453209954883
let me know what you all think and wether you have a clue how to porced or if I need to zoom in on any components, here's an overview:

 

[dogman dan]

About 900w of charger. So it won't pop the typical house breaker.

I wonder if a better approach might be a set of 2 400w RC chargers . Two 8s units? Or some kind of combination like that that gets you a balanced charge when you want it.

Does the pack have a bms? If so, then you perhaps just need a charger that shuts off when a cell hit's lvc, but then turns back on when that cell drops voltage enough again. This is what is typical with the bike size lifepo4 packs.

 

[2007blueprius]

my batery pack is broke down into 2x24v boxes 8s, they then get conected in series, so 2 24v chargers may work, I just dont know enough about what is out there,
as for the bms, has jst9 pin conectors to monitor each box, but unfortunately thats pretty much all it is good for.
the system relyes on an hvc 3.8v to terminate charge, and it does not cycle back on, and a 2.5v lvc to terminate discharge, they had a balance function but it was a bad idea and now it's disable.
this whole setup is infamous for puffing lithium pouches, it's almost like it was made for it
I was considering building one of those zephers but it kind of goes without saying I need to be able to dial in my charge voltage in the first place if I am going to get this right, it would be even better if I can figure out how to dial in the current too, it's just a SMPS, I think.
you brought up an interesting point about tripping the breaker

 

[2007blueprius]

so I am trying to figure out how to go about experimenting with this thing, in lack of any diagrams, I know one is not supposed to plug in a power supply without a load, however on this system the bms can interupt the charge while the charger is still on , so I figured maybe it has a dummy load well see attached pics, that's what those 5w resistors apear to be:
so my question is how would one go about powering this thing up without doing something stupid, the 48v anderson goes to the bms and that is it, there are led's that indicate weather it is charging or not, so I suppose it has a way of telling weather it is under load or not?, what is a good way to go about it?

 

[2007blueprius]

bump nothing huh?

well I done some diging couple of those turnpots adjust the voltage and amperage so that is great news, I still dont know what the other 3 could be for, aparently it is a cc/cv somewhat smart charger to be conservative, I recon one of those pots could be for the swichover point, the other 2 I am clueless for now.

is anybody familiar with cc/cv chargers? I honestly don't know much, any thoughts, even if theoretical.

 

[dnmun]

in your last picture there, the voltage between the collector of the high side IGBT and emitter of the low side IGBT is about 340V DC. it can be very dangerous.

 

[2007blueprius]

in your last picture there, the voltage between the collector of the high side IGBT and emitter of the low side IGBT is about 340V DC. it can be very dangerous.

I don't know what IGTB stands for? or an emitter/collector for that mater, but like any other power supply yeah I was aware there are some nasty voltages involved even if unplugged those capacitors are pretty good size.
there is a lineup of turnpots couple of them are volt and amp adjustment which for the most part should be all I need to dial in the zephyr, I have been told it is a cc/cv charger, and at some point it switches over, that may be another pot to set that voltage, I am afraid I do not know a lot to go by, I read some articles last night to try and get familiar with the concept, the TS/elcon in question was a different animal can bus and stuff, lcd display, command for voltage, command for amps.
guess the question at this time would be what other adjustments can be made to such a charger, i'm sure those pots are there for a reason but I can't imagine it.

 

[dnmun]

Insulated Gate Bipolar Transistor

you can read about transistors in wikipedia

the trimpots are there to adjust the final voltage and the current output maximum and the current level where it goes from CC to CV and the light turns green.

 

[2007blueprius]

I think I know which ones the first 2 are,
is there a thread that discuses such adjusting procedures?
I was not sure if I can even plug it in by itself, there are 2, 5w resistors, I think they are dummy loads but not sure,
I got my paws on some instructions but it only points out the voltage and amp pots, I am asuming that is for final voltage and max amps, it is getting clearer.
and now I am confused again, if the first stage is constant current, I asumed that would be max current and it is constant, than you speak of the curent level where it swiches, do you mean voltage?, either way one of the pots adjusts the swichover point in theory.
I figured another could be for an EOC function, as in once below a certain current it shutts off, that leave a last one unknown.
you see I am not even familiar with such chargers mode of operation, I get the idea, but not knowing what it is made of can't figure whar could be adjusted, does it look like it has an EOC function? could that big relay be a giveaway?
I think it should, but i never seen it make it that far, no one that ever owned this sistem did, this is from that funny setup I was telling you about, first cell to blow charge terminated :lol:
granted when use with the zephyr, I only need to dial in the voltage, the board pretty much takes care of the rest, it would be nice to be able to tune in the swichover point, these particular RFE cells like to run away, especially since they have all been used and abused, I have a good pack now, but I figured I can tune down the amps to the point the zephyr can keep it in check, those are 80 ah cells on 15 amp curent sounds like those bleed resistors may have some work to do