Amberwolf's first RC LiPo...experimental repair thread

Batteries, Chargers, and Battery Management Systems.
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by mdd0127 » Jan 25 2012 2:34am

My friend jumps off of cliffs and his frame is aluminum so bending it back,welding it, or modifying it is risky stuff since we don't have a proper oven to cook it in. I think he's going to be fine with the Haro though and he was super stoked to get it. This guy is one of the coolest humans I know so it was really a pleasure for me to be in the position to hook him up. I'm going to go look at his bike tomorrow and if we determine it's unfixable, his son needs a bike worthy of his skills too so the Haro will go to him. He rides so smooth it makes me sick. Anyway.....I'll let you know how things are looking as far as me getting down there as soon as I know something.
Turn it OFF!!!

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jan 25 2012 2:41am

ah, ok. i guess nothing i have would exactly be suitable for cliffs...more than once. ;)



oops. my meanwell is an sp-320-48, not 350. i cant' read. :oops: so it is the pfc-type series i linked above.

i got the pics posted up.

http://www.endless-sphere.com/forums/vi ... 17#p523617

mine has no shunt at all, at least, not as a wire-jumper type, unless i am just blind, as well as illiterate.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jan 25 2012 2:53am

whle i was adding the sb50 anderson for main paick connector on the 12s3p, i also annotated all the internal connectors in case i have to take it apart for any reason, so i will know ahead of time how to put it back together. since there are six packs, i used dots like dice or dominoes have, on the andersons. on the pack balance connectors i just wrote pack numbers, and then on the final output balance connectors i just put + or - so i'd know which was most positive and which most negative. shouldn't ever matter but makes it easier if i'm measuring things later.

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also the dogs got bored with everything several times.
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by neptronix » Jan 25 2012 3:32am

Oohh... you got one of those power supplies... uncharted territory. If you can get it to be useful at all, you get mad props.

It would work well in series with another current-limited power, supply however.
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jan 25 2012 3:41am

if i can get it working again, i can easily use it in series with the big sorenson, and had planned to do that for the higher voltage pack i will have on the newer bike.

but i'd still like to figure out how to use it for the 12p3s pack or other similar ones. i guess whatever i find out about it i'll also put in it's repair thread. :)

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jan 25 2012 4:10am

now that i'm seraching for the right model number, i've found info on this one going back to at least two years ago jan 2010:
http://www.endless-sphere.com/forums/vi ... 38#p228838
as one example.

so they're not new and untried, but i havent yet found enough info to tell me what i need to know to fix it and use it.

unfrotunaely most of the pics i would like to have for reference are missing or trashed. :( edit: but aussiejester's site still has the hires ones he took:
http://members.ii.net/~aussiejester/ind ... 48v%20PSU/

even some partial schematis
http://wookware.org/pics/meanwell/002-IMG_2371.JPG

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by cor » Jan 25 2012 6:52pm

Hi Amberwolf,
Cool that it is a PFC supply. It should have 3 functional blocks: first the AC input with rectifier and PFC switcher, ending in the big caps that store the upconverted DC (usually 200 or 400V). Then comes the PWM controller and switching FET(s) to turn the HV DC into a square wave that drives the transformer.
Third, at the output of the transformer a rectifying diode, filter and shunt with current measurement, feeding back to the PWM controller, together with the voltage feedback. I did not see opto couplers on the pictures. Are they hidden next to the transformer? On the NES they are right next to the transformer.
For fixing, you can check if the PFC stage is still making high voltage DC and then check the final stage for voltage (and current) control and other feedback (on the NES there is also overvoltage and overtemp protection feedback) before you try to attack bringing the PWM stage back to life, since the other parts affect the operation of the PWM controller.
Success!

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jan 25 2012 7:18pm

cor wrote:Cool that it is a PFC supply. It should have 3 functional blocks: first the AC input with rectifier and PFC switcher, ending in the big caps that store the upconverted DC (usually 200 or 400V). Then comes the PWM controller and switching FET(s) to turn the HV DC into a square wave that drives the transformer.
everything up to the hvdc works fine; it has ~160VDC on the caps. i haven't gotten back to it yet to know about the next step.
Third, at the output of the transformer a rectifying diode, filter and shunt with current measurement, feeding back to the PWM controller, together with the voltage feedback. I did not see opto couplers on the pictures. Are they hidden next to the transformer? On the NES they are right next to the transformer.
yes, there are two. in this pic
http://www.endless-sphere.com/forums/do ... p?id=74372
they are to the upper right corner of that top transformer in the main switching section. i will have better pics of both sides of the board later, tonight if possible. have to set up the camera on tripod cuz i cant hold it still enough.

For fixing, you can check if the PFC stage is still making high voltage DC and then check the final stage for voltage (and current) control and other feedback (on the NES there is also overvoltage and overtemp protection feedback) before you try to attack bringing the PWM stage back to life, since the other parts affect the operation of the PWM controller.
Success!
i've been following your reverse engineering of the other mw with great interest. :) i've had to do that kind of thing before, but don't like it much. :lol: if i have time i will compare your existing schematic as drawn into program by neil, and update it for this version where i find differences. i definitely appreciate you dropping into this thread to help out. :)

link for others to the section of the first thread where schematic capture began
http://endless-sphere.com/forums/viewto ... &start=255
and conversion into machine format
http://endless-sphere.com/forums/viewto ... 14&t=36114

i've copied all this over to the actual repair thread too
http://www.endless-sphere.com/forums/vi ... =2&t=36100
where i am documenting the process.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by cor » Jan 26 2012 12:39am

Hi Amberwolf,
If you get only 160V on the caps then that tells me that the PFC is not working, as that is the normal voltage of rectified 110V AC, not the boosted voltage of a PFC stage, so I would certainly recommend to test if the PFC switching FET is actually working and whether the ML4800 PFC and PWM controller is working. I noticed that you already found the datasheet with a reference schematic here: http://www.fairchildsemi.com/ds/ML%252FML4800.pdf
The 900V 9A PWM MOSFET 2SK2082 from Fuji Electric can be found in many places, for example: http://pdf1.alldatasheet.com/datasheet- ... 82-01.html and the PFC FET IRFP460A from IR can be found here: http://www.irf.com/product-info/datashe ... fp460a.pdf it is a 500V 20A N-channel MOSFET.
Please note that the voltage of the caps C5 and C?? is 400V, which is a typical PFC boost voltage from anything between 90-260V AC.

The location of the optos and the array of diodes under the transformer looks like the NES setup, but due to the extra complexity of PFC, the controller section is about twice as busy and you have an additional switching FET and rectifying diode.

I love troubleshooting/reverse-engineering a circuit. I have to take care that it does not conflict with my job and other things in life too much...
My interest is that I want to know how things work. I have been known to buy a brand new product and first take it apart, even before plugging it in for the first time (also of course voiding the warranty), but I *had* to know how it worked... Now I mostly buy second hand products so I don't need to bother about warranty when taking them apart, fixing them, improving them if needed...

BTW, I wonder who Willis Lu is, who put his name on the PCB.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jan 26 2012 12:59am

cor wrote:If you get only 160V on the caps then that tells me that the PFC is not working, as that is the normal voltage of rectified 110V AC, not the boosted voltage of a PFC stage, so I would certainly recommend to test if the PFC switching FET is actually working and whether the ML4800 PFC and PWM controller is working.

i found earlier and posted in the repair thread that the the pfc and pwm chip is not working--it appears to be internally shorted:
http://www.endless-sphere.com/forums/vi ... 03#p524103
:(

just posted a minute ago in there that it's definitely shorted, and links to where i might be able to buy a new one.

feel free to post in that thread if you like, with any info you come up with. i'm going to copy this post over there, too.

I noticed that you already found the datasheet with a reference schematic here: http://www.fairchildsemi.com/ds/ML%252FML4800.pdf
The 900V 9A PWM MOSFET 2SK2082 from Fuji Electric can be found in many places, for example: http://pdf1.alldatasheet.com/datasheet- ... 82-01.html and the PFC FET IRFP460A from IR can be found here: http://www.irf.com/product-info/datashe ... fp460a.pdf it is a 500V 20A N-channel MOSFET.
Please note that the voltage of the caps C5 and C?? is 400V, which is a typical PFC boost voltage from anything between 90-260V AC.
ah, ok. i have a lot to learn about pfc, having rarely fixed any psus with it, and so far only having to replace bad caps that boiled from high temps in sealed units, or blown fets or output diodes from the caps having died.

regarding the mosfets i actually have some spares of these out of other dead psus that had leaky caps and such, or were simply scrapped by someone else due to age, or not being needed, so i harvested all the parts i could.


The location of the optos and the array of diodes under the transformer looks like the NES setup, but due to the extra complexity of PFC, the controller section is about twice as busy and you have an additional switching FET and rectifying diode.
i was following your schematic on the nes version, and this one is definitely a lot different, presumably because of pfc stuff and using the combo chip rather than just the simpler nes method. still, i will probably be able to take your schematic and modify it to match this one, with the output section being mostly the same, i think. i havent' tested or measured or traced anything on the output area yet.



I love troubleshooting/reverse-engineering a circuit. I have to take care that it does not conflict with my job and other things in life too much...
My interest is that I want to know how things work. I have been known to buy a brand new product and first take it apart, even before plugging it in for the first time (also of course voiding the warranty), but I *had* to know how it worked... Now I mostly buy second hand products so I don't need to bother about warranty when taking them apart, fixing them, improving them if needed...
i know how you feel. i can't count the number of things i've disassembled just to see how they did what they did, starting with when i was too young to even know what any of the stuff inside was. sometimes the things i took apart actually belonged to me, too. :lol:

over the years i did learn to test and document them before opening up, though, so i would know what to look for when they didn't work after reassembling them, since my memory is not always that good and i rarely have enough time all at once to take it apart and put it back togehter in one sitting.


BTW, I wonder who Willis Lu is, who put his name on the PCB.
i'd guess willis lu was the layout designer, so he or she "signed" the work. :) might be the actual engineer designing the whole psu, too.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Feb 06 2012 3:18am

More RC LiPo to repair:

PDF donated three 6s 5Ah Turnigy packs to me for the cost of shipping that all have a dead cell (same one in each pack, which seems wierd: the one just above the most negative one.). They arrived Friday, same time as the chargers from Dirtdad/Comcycle, but I haven't gotten around to posting about them until now.

An odd bit of story to them is that even though he packed them VERY well and completely labelled them as they should be, the UPS store employee that took the package in from him decided it would be better to hide all that scary hazardous materials labelling by repacking it into a larger box with a bit of packing around the smaller original box. :roll:

Anyhow, some pics of the stuff. Hachi has taken over the chief inspector's position vacancy left by Bonnie:
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The UPS Store's packing around the smaller box, inside their box, which I guess was adequate:
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PDF's labelling:
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PDF's excellent packing, in two separate layers of packs:
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Then the individually-packed and wrapped packs isnide that:
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Note that two are wrapped in painter's masking tape to prevent any shorts because they are both partly disassembled and/or unwrapped, while the third hadn't yet been worked on.


Next, I did a quick cell-check at the balance taps with first the crappy MaxPro, which doesn't even try to read actual pack voltage nor does it bother to display any cell that is "below" (on the more negative side of) any dead cell. :roll:

The first one only reads one cell, at 3.70V.
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Next one (still shrink wrapped) only reads three cells, and the Maxpro thinks it's only 3.70V pack voltage because the first cell is that, and then for some reason it can't read the next cell (it has problems liek that a lot; each time I use it I am reminded of why Methods didn't want it anymore :lol: and sent it to me as a donation to play with as I felt like it. :)
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Same problem reading the next pack, though this time it gets a red LED lighting up; presumably because one cell it can read is actually below 3.6V (or maybe 3.5V)? It still thinks pack voltage is only 3.75V.
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Next I checked them with a Battery Medic donated by Mdd0127. At least it can read all the cells and the actual pack voltage, even when there is a dead or missing cell!


The first pack it can't even power up from.
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The next pack it powers up ok and shows me one dead cell, and the rest in the 3.67-3.7V region.
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The third pack has the same dead cell position, and two lower cells than the rest, which are 3.7-3.74V. The low cells are 3.43 and 3.52V.
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Opening up the tape I find the reason for the first pack's readings:
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The disassembly on it includes disconnecting most fo the balance wires, and one cell is completely removed already (inserted in the pack with the tabs wisely taped off to prevent shorts).
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I havent opend the tape on the third pack yet, but the most positive end cell (3.52V) is puffed up; not as clear in the pic as it is viewing it in person.
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Voltage readings on the cells in the first pack:
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For now they're stored in this Freecycled old 50-cal ammo can, with the lid left caught on the latch but not fully closed:
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Will try to get to them to at least remove the bad cells and puffy ones Tue or Wed on my next days off.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Feb 17 2012 4:13am

Have not had enough time at once to do the pack surgery. I need a backup pack for a longer work commute the next two days (will be helping with a store remodel 12miles+ away from home), just in case I'm unable to recharge the main pack for any reason. It's planned that I will park inside and charge while we're working (overnight), so there shouldn't be a problem. But...just in case, I am making up a 14s2p pack using the two 2s packs (which I still haven't fixed teh balance taps on) and four of the six 6s packs out of the built-up 12s3p pack from Mdd0127.

I used the existing paralleling harness, just without the last pair of packs hooked up. Then I made a simple Y-connector to plug in the 2s packs in parallel, and be able to plug them in series with the other packs by putting them between the Anderson quick-disconnect plugs that was already in place on the original setup from Mdd0127, that connect the two halves of the pack in the middle (the other end is brought out to + and - on the main Anderson connector). That way I didn't have to rebuild any wiring and can return the pack to it's original setup if I find I want to (more likely I will make it 18s2p once I have a controller fixed up and tested that will safely operate at that voltage, for sure).

That will be about half the capacity but the same voltage as the main pack on the bike, and should be enough to get me the rest of the way home if for any reason I can't recharge at work. Theoretically I have at least 20 miles range on the main pack but I have not done a full rundown test and would rather not find out the hard way a couple miles from home. :lol:

It will all fit inside an ammo can another local friend gave me, and I am going to notch the top edge of the box (using the angle grinder) for the exit wires and for a vent in case of failures. This can will then be secured to the center frame of the bike, probably with reusable pallet-strapping like I used on the main battery box.
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Charging is being done just one pack pair at a time inside the box, lid open, in case anything goes really badly wrong. :lol: At least I'll only lose one pair at worst.


I've not yet wired up the throttle cut-out, but I am going to setup the Methods LVC/HVC boards on the main pack (been planning to for a while, keep not quite getting around to it), but also setup in a way that I can easily unplug them from that pack and plug them into this backup pack, if I have to use it. I'll need to fix the balance plugs on the 2s packs, probably just by wiring them both to the single good replacement one that was sent with them.

I used the Venom charger (monitored via USB with Logview) to top off the first pair of 6s packs, and had already done this before with the two 2s packs. Right now the second pair of 6s packs is charging, but the SLA being used to power the Venom will likely run out of juice before it's done. I had been sitting there eating dinner with the dogs around me hoping for crumbs :lol: and watching Space:1999 on youtube while the first pair charged up, but after that went ok and I started the second pair, I came in here (around the doorway) where I can hear the Venom running, to type up this post.
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So to be sure that I'll have a second set of SLA that's ready to use, I have a pair of them on the 5A 24V powerchair SLA charger (topping off from the 12.8V they were at when I started, after having used them during some experiments with the Venom's menu settings).
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Only took 49 minutes to top off the first pair, at 5A "fast charge" setting, what amounts to 0.5C to the pair, for 3190mAh. We'll see what the second pair takes in a little bit. Balance on the first is pretty good, 4.15V for four middle cells pairs, and 4.18 for the top and 4.17 for the bottom. Probably well within the tolerances of the actual meter (HK Battery Medic).
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Feb 17 2012 5:22pm

So the charging finished up ok, with virtually identical Ah results and BM readings. After several hours of fitful catnaps, I modified the box a bit, by angle-grinding slots into the top edge, where it will be under the overhanging rim of the lid to protect against direct water or debris ingress.
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The rim of the lid itself has been bent outward a few degrees to prevent a seal that would cause pressure buildup in case of severe battery failure.
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Then I packed the cells and wiring into the box with some closed-cell foam padding to keep things from moving around or rubbing. The main output wires go out one of the slots, and both slots and wires have been lined with electrical tape to prevent chafing/cutting of wires.
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Tests ok at 58.0V no load. Loading tests will be done on the bike.
http://www.endless-sphere.com/forums/vi ... 48#p536248


Probably not going to have time to finish the LVC/HVC board cabling before I have to leave. :(

Forgot to take pics of the serial connections and the Y adapter last night:
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Keyed the serial different from the parallel, so no mistake can be made. ;)
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Apr 02 2012 10:41pm

I forgot to post the results of the above, but the ammo can pack worked well in the test rides so far, both on CrazyBike2 and DayGlo Avenger; there's info in those threads with a little detail.
http://endless-sphere.com/forums/viewto ... 48#p536248
Image


Today I received some more RC LiPo with bad cells, this time from Ohzee:
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Some of them appear pretty puffed up, so I stuck them all in a separate metal box in my oven for now.
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I haven't had time yet to do anything at all with them, other than to note they have some covers over the back half of the balance plug, which appear to be for gripping it so you don't end up pulling on the wires when unplugging them. If frequently cycling connections, this could be quite helpful in preventing damage to the wires. If they work as well as they appear they should, I'd recommend them to anyone that frequently balances their packs or otherwise handles the balance plugs.
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I ought to be able to make a couple good packs with these, plus use some cells to fix some of the other packs.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Apr 03 2012 12:59am

Ok, I had a couple minutes and got voltages, and a quick peek under the tape on one still-shrinkwrapped pack. Turns out it has a ruptured cell; I could smell a sweet smell as soon as I lifted the tape, and a closer look shows a yellowish liquid along a tear in the pouch, which is probably the one that reads 0V.
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Another pack has a bunch of bad cells, including two that don't even show up on the Battery Medic's display--it thinks it's a 4s with less than 10V total on it. One cell that does show up is less than a volt, and another is just under 3.1V.
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It also has some burn mark on the most negative pin of the balance connector:
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The next one has none at zero, but one is significantly lower than the others, at 3.7V while the rest are 4.1V. Not sure if this indicates a severe problem with the low cell or the high ones.
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The last has two at zero, one pretty low at 2.69V, rest 3.23-3.33V.
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by Kin » Apr 03 2012 11:13am

I find it interesting your cells read 0v on the battery medic. Mine don't even read any voltage. I suppose that's because my 0v cell is at the end of the balance wire, so it thinks I'm simply showing a 5s cell.
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Apr 03 2012 11:38am

That'd be my guess. It's probably why that 2nd one above doesn't show but four cells out of six--the last two on the positive end are probably dead, too. Haven't checked yet. I assume it only skips showing 0V cells on the positive end, as it's measuring up from the negative end, since it does show the 0V cell on the last pack that's at the negative end.

Also, remember that there are at least three different versions of the BM around, either different revisions or simply different clones of whichever is the original, and they could all use totally different methods of displaying the data they are reading. :?

Some battery monitors like the MaxPro thing don't even show 0V cells, they just don't even show them on the display, "condensing" it so that cells that do have voltage show in the spot where the 0V cell actually is. Makes it danged tough to figure out what's wrong without using a DMM or opening up the pack, etc. Also could lead inattentive users to destroy the whole pack by just glancing at it and thinking "oh, these cells all look good, let's just use it anyway", not noticing the total pack voltage is missing a cell's worth. :roll:

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by Kin » Apr 03 2012 11:56am

That was almost my disaster. :). Well, it was a blessing/curse that I had the balance leads paralleled. Blessing in the sense that then my 5s+1sdud with 6s wouldn't pull the 6s voltages down to disaster, but a curse because I think my discharge to 0v happened before i used the cell (so my bad cell also shelf discharged the would-be-fine cell on another pack).

I actually ended up going for a mile or so on my 11s pack simply discharging [~30A] through the 0v cell. My case might be an exception, though, because the pack is not puffed. I will check resistance sometime.
New to endless-sphere? Notice a lot of signatures recommending Ebikes.ca? That's because it's the best place for a quality and manageable, (but still 'real'), first build. Justin is a solid supporter of electric bike development, and a good source of equipment.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jul 05 2012 3:08am

I repaired three more packs tonight, pulling out a dead cell in each and replacing them with cells salvaged from packs with 2 and 3 dead ones. Have one more pack that has 3 cells left in it, and one more good cell, plus an unknown condition cell from Methods' most recent care package, which is at 3.8V but has quite a bit of surface indentatinos and markings, and some undecipherable remains of writing on it. I'll have to run that thru testing before I stick it in a pack, if I ever do.

Packs now just need cycling to verify capacity so I can mark them.



Also, just to see if this stuff really is anything like as scary as has been said, I combined Independence Day celebration and RC LiPo testing. :)


The power supply in the vids is capable of up to 100A, at over 5V, for at least short periods (probably minutes). I figured that ought to do for cooking off a 0V cell.

The first one was very puffy already, almost hard puffy. No idea what caused that, as it came to me that way via pack-needs-repair donations (same for the second cell, except it was not puffy at all).

In both cases, I ramped up the voltage from 0V to max, with one pouch tab clamped in the positive terminal's bolt/washer, and the other tab wrapped around an SB50's terminal on an 8G wire. Other terminal was clamped in the negative terminal's bolt/washer. I could've made a better connection, but figured this was enough for a quickie and if it worked, well, it worked. :)

Polarity of first cell is unknown; I forgot to check as I installed it. Second cell is correct polarity. First cell I even stabbed thru with a screwdriver to try to get it to ignite, but it wouldn't.

Second cell test has ammeter starting at 30A reading, though it is actually 0A. no idea what happened to cause that. :? It did, however, ignite. :)

Both cells are now sitting in a metal trashcan out in the yard until daylight so I can see the remains without bringing the smelly carcasses inside. ;)

Dunno if you can hear the gunshots in the area as poeple "celebrated", but there were quite a lot of them, in addition to regular fireworks both official and otherwise. \








There are a few more 0V cells awaiting future experiments, in an old grill out back.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by mdd0127 » Jul 05 2012 11:25am

I'll pay the shipping if you want to send those burned up and stabbed cells back to hobbyking :twisted:
Turn it OFF!!!

Apocaloptimist! (thx Kiwi!)

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by ohzee » Jul 05 2012 1:50pm

haha nice man thanks for the show.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Jul 08 2012 8:45pm

You're welcome. :)

I got a chance today (first day of a week's vacation; too short but all I get right now) to charge/balance each of the packs fixed above (3x 6s, 1x 3s). First, I fully charged each one at 5A, using the Venom charger's regular "LiPo charge" setting, powered by my big Sorenson at 14.1V (as I am also recharging some paralleled SLA, and the Sorenson can easily handle both loads). This got each cell to about 4.2V, plus or minus a few hundredths.

Then I discharged them at 5A, using the Venom's "LiPo Discharge" setting. I had trouble with the second 6s pack's discharge, as something is goofy with the Venom's display sometimes, and it scrambles all teh characters on the LCD. It appears to be actually still doing what it is supposed to, but it requires a power cycle to reset the display, losing the data (as I haven't fixed the laptop to be able to log the data; desktop computer is not portable to move it to the Sorenson in the utility room).

I didn't actually run them all the way down to the discharge's lower limit, but rather stopped each manually when I saw either a cell below 3.6V, or reached 5Ah of discharge. 2 of the 6s reached 5Ah before the cells went below 3.6V, and 1 of them hit cell 5 at 3.6V at 4.9Ah. The 3s pack hit 5Ah just as cell 1 hit 3.6V. So I guess that's pretty good, makes them all usable predictably for now, though I don't know what they're like under a "real" load yet. Once I get the other packs (3x 6s I think) repaired and tested the same way, I will build another "ammo can" pack and test it on the Fusin Test bike and/or on CrazyBike2.

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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Nov 17 2014 1:35pm

Opened this one up to check on individual cells again (I do this every so often, it's always been ok so haven't posted about it so far).

Cell voltages are still pretty much ok, though they're farther out of balance than previously, however they are all eitehr puffed or beginning to puff. :(

It's really obvious on the 2s packs, because both cells are on the outside, neither is held compressed by other cells surroudning it. The pair of 2s packs together are about as thick as the 6s packs. :shock:

One of them has swelled so much it's split the shrink wrap.

So, well, this pack is on it's way out. Since I may still need it for range extension sometimes I can't just toss it, so I packed it back in the ammocan case, and stored it in the oven like I do with the rest of my not-in-use batteries. I'll just have to be careful with it and charge it only outside.

I guess if it does go off we'll find out just how well the vented ammocan does at stopping a big conflagration. ;)


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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by Kin » Nov 17 2014 3:35pm

I think I've seen degassing instructions here before.
Basically involved pricking the outside surface, then covering it with something (like hot glue, is what I remember, though I despise hot glue.)

Any reason why you don't want to do that? I suppose you encourage more contaminants to enter the package, but probably not much if done well. I just don't like the idea of the pressure produced by the gas.
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Re: Amberwolf's first RC LiPo...experimental repair thread

Post by amberwolf » Nov 17 2014 6:01pm

I thought that I recalled that once packs reached this stage, they have already got problems inside them that can't be rectified by depuffing--it's just a removal of the symptom, and not a cure for the problem itself.

But at the mometn I can't find the threads where that was discussed.


I did consider doing it while I had it open, but the biggest issue is that it would require disassembling every cell from every other cell (since AFAICT without openign the shrink wrap, they're all puffed to one degree or another), and I was having enoguh trouble with my hands aching from the colder temperatures (I think it was already around 60F at that time of night) that I didn't think I could do it, especially since the adhesives that hold the packs together are harder to get apart when cooler.

(yes, I could've done that work inside the house with a heater in the room or simply using a heatgun or hair dryer to help separate the packs, but I'd rather do it outside so if I really screw up and short something and cause a fire, I don't have to try to hobble outside with the stuff, and worry about the dogs wondering where I'm going and following me and ending up with fur on fire or something. so ti'll have to wait for a day I can dedicate to starting it when it's warm and sunny and I have the time to do it all right then, cuz i wont' be able to leave it sitting around partly done).

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