Milwaukee v28 Charger Fault

[ort5]

Hey guys,

I FINALLY got my bike running and it's AWESOME! 25mph and pulls up hills like they're not even there. I LOVE it!

I'm running a 2s3p configuration of V28 batteries...much like many on here. I've verified the connections and they are all great. The state of charge LEDs on the batteries all match during discharge too.

After my maiden voyage of around 15 miles, I had drained them to around 1 bar each. I put them on my 3 bay charger and 2 of them have given me the RED-GREEN flashing indicator. This means a battery fault according to the charger manual. I removed them and let them sit for a while and tried swapping them to different charger bays. They still gave me fault codes, but after a few tries they both indicated green, or fully charged.

Has anybody with V28 experience seen this happen? What am I doing wrong? I'm worried I screwed something up, but I can't see how.

For reference:
36V rated Heinzmann motor with a 30 amp fuse (haven't blown it yet...even with full throttle starts). I blew a 20 amp one though.
2s3p configuration.
30 amp brushed DC, 48V motor controller.

Thanks guys! I'm addicted now Pictures to come at some point.
Dave

 

[pwbset]

Has anybody with V28 experience seen this happen?

Every time this happens to me it's been related to heat. My "workspace" gets baked by the sun in the afternoon and the batteries simply won't charge until night time and less than <80 deg ambient... I've since started putting a fan on the chargers and that allows me to charge in 90deg ambient. The chargers kick off a LOT of heat by themselves.

Also... if you get the green full charge even if you suspect they didn't get a full charge go ride around for a minute or three and then re-charge. Hot off the charger my batts are reading 29.0-29.2v. I have gotten the green light at 28v before, but rode around a sec, hit the charger again and pow... 29+ again.

Let us know how it goes.

 

[ort5]

Hmm...heat is a possibility. I think there is a separate fault code for overheat though (red flashing)?

The batteries were not noticeably warm to the touch, but perhaps they were warm inside.

To be clear, you have seen the red-green flashing before?

Anybody else?

 

[pwbset]

To be clear, you have seen the red-green flashing before?

That's all I ever see is the red-green-red. I've never seen the red-flashing alone. It may be worth noting that sometimes I let the batteries sit for 1+ hr before attempting a charge... you know... to let them catch their breath after a long ride. Sometimes I let them sit until 10pm or later and they charge every time then... of course here in Montana we still get down into the 30s at night even in July so that helps (Frickin frost warning tonight. Sheesh!).

 

[pwbset]

The batteries were not noticeably warm to the touch, but perhaps they were warm inside.

It may also be worth noting that my batteries have never, ever.. and I mean ever.. been even slightly warm to the touch. I'm only pulling 84v/20a max, which may have something to do with it, but they stay totally ambient no matter what. They are rated for many more C discharge than I'll ever give them without bypassing the BMS. It's the chargers that overheat I'm pretty sure. Those really do get warm... and are flaky to boot.

 

[tostino]

I'm actually getting the flashing red-green with one of my six batteries too. I don't have a fully assembled bike yet, but I finally got my controller in, and tested everything out (which worked fine). After I was done testing, I put the battery on the 3 bay charger, and it came up flashing. I've let it sit, and it still does it. It's been two days now, and still no luck.

Looks like I am going to be giving a milwaukee service center a call...

 

[ort5]

Hmm, that's too bad tostino. Mine seemed OK after a resting period and a few tries. I wonder if jondoh can chime in? I know he's been using this setup for quite a while?

I'm using the same setup as in the jondoh video, so I'm discharging through the BMS. I know I have the warranty, but it's a bit disconcerting that I got an error on 2 batteries on my first charge cycle! Seeing as I never blow the 30 amp fuse, I shouldn't be pulling more than 30 amps from the 3p setup, or around 10 amps per battery. That seems fine, right?

Regards,
Dave

 

[pwbset]

10 amps per battery.

10 amps per pack... that's like 1.43A per cell, which is like 1/2C. Each cell is technically rated to handle 20 amp/6C discharge by itself... 'course you wouldn't get very far sucking on them that hard.

So 140A per pack theoretical max discharge, but each pack's BMS is rated to something like 20A so 3p @ 60A theoretical, which would blow your fuse like you say.

Again... if I were a betting man I'd say yours and tostinos batts are fine, but the chargers are getting too hot or are flaky. One ES member (lazarus?) had most of his Milwaukee chargers go bad and said they sucked (I'll try to find the post). What do you expect for $20 a charger. Heh, heh!

 

[jondoh]

I've been noticing the red-green flashing thing too. It happens to me on days when the battery gets hot. The funny thing is that only three of the ten are susceptible to the red-green thing. If the red-green flashing happens all the time no matter how hot or cold, then there's a problem with the battery and you should be able to take it in to be replaced.

 

[ort5]

Hey pwbest,

I think your math is off on the current per cell. You said:

10 amps per pack... that's like 1.43A per cell, which is like 1/2C. Each cell is technically rated to handle 20 amp/6C discharge by itself... 'course you wouldn't get very far sucking on them that hard.

But actually it's 10A per cell if the battery is being discharged at 10A. The V28 battery is a 7s1p configuration of the emoli cells.

So my 30A per 3p configuration of the v28 packs means that each pack sees around 1/3 of that, or 10A. That's around 3C for the cells. Certainly within their limits, and hopefully within that of the BMS. I would say that I only see 30A momentarily, and probably usually do more like 20A (my CA is not here yet!).

I took another ride today for around 13 miles. It went really well and waited to charge the batteries for around 2 hours once I got back. The same 2 batteries that gave me the red-green flash the first time decided to flash again. The others are just fine. After letting those 2 batteries sit for a bit, they went solid green eventually on their second try on the charger. I may try to exchange these two packs in hopes for 2 "good" ones eventually. I'll keep everybody posted.

Dave

 

[pwbset]

I think your math is off on the current per cell.

Wait, what? "It was my understanding there would be no math involved!" - Chevy Chase. :wink:

I'm new at all this for certain I just know the emoli spec sheet lists 20A continuous discharge per cell. A 7s1p Milwaukee pack should then in theory be capable of 140A sustained without a BMS no? People like Lazarus and mlrosier were bypassing the BMS on discharge and getting mad power out of these packs.

*sigh* Like you said I probably have it backwards. Anyway, they kick ass and will provide more power than I'll ever need that's for sure! Can't wait for their next-gen cell next year, which they are claiming has the rate and cycle life of lifepo4.

 

[pwbset]

*sigh* Like you said I probably have it backwards.

Yeah I definitely had it backwards. A 1s7p would be able to handle 140A, which totally makes sense @ 20A per cell in parallel... duh. Can't believe I'm so dyslexic on some of the basic core ebike principles. Sorry if I'm confusing people... I'll sign off now and quit posting blather. :?

 

[tostino]

I'm pretty sure it's not my charger thats bad, or over heating (it's in a room at 75f). And I have tried the battery on all 3 of the charger bays (each bay has it's own individual charger hardware that is independent of the other two).

I really don't think a cell is bad, because I was getting full power out of it... So I really don't know, i'll just have to give the service center a call and have this situation resolved.

 

[tostino]

Just wanted to give you guys a heads up, but I took my battery to the milwaukee service center closest to me, and they just hooked it up to their little tester thingy, and were like "yup, it's bad". They went in back and got me a brand new v28 still in the package, and had me fill out my info (name, address, battery part number, etc) and that was it. I left with my brand new milwaukee battery to replace the broken one in under 10 minutes.

Very happy with the way they handled the warranty.

Now if I could only get the people who sold me a faulty throttle to replace that, i'd be golden... =/ too bad they're being jerks about it (It was longer than their 15 day policy since I couldn't test it without a controller that worked with my motor).

 

[ort5]

Awesome, glad to hear it! I may do it too, if I have problems in the future. After my last ride, everything seemed normal.

It would be sort of obvious to ask for the "bad" packs back after they gave you the new ones, right I'd love to harvest some emoli cells for a booster pack!

 

[jondoh]

After a long... about 20 mile ride, i had a lot of trouble charging two of my packs. After they had a chance to rest for about 2 hours, i had no problems getting them to charge. The obvious explanation is that these two packs have joined the union and union rules stipulate that after discharging more than 70%, they cannot be fully recharged without a 2 hour break.

Seriously, it looks like i'll be taking these two packs in to be checked out. Otherwise they seem fine when cool or when discharged less than 50%. Since I'm running 10 packs, I rarely go more than 50% discharge.

 

[tostino]

Awesome, glad to hear it! I may do it too, if I have problems in the future. After my last ride, everything seemed normal.

It would be sort of obvious to ask for the "bad" packs back after they gave you the new ones, right I'd love to harvest some emoli cells for a booster pack!

Yeah, they did take the bad pack when they gave me the new one . Still not a bad deal though, I get a new warranty with the new pack as well, which is really cool.

 

[Parker]

This looks like this is the thread I should tell my story in. I did buy mirosiers bike and I had a great 10 miles or so. It is a beast, 30mph+ easy. But in my haste to enjoy the bike, mistakes were made... First, I'm afraid I drained one the batteries too far because it won't charge. I didn't charge all 6 batteries only 3. I temporarily forgot they are not wired to charge at the same time, each BMS being intact and functioning for charging and all. I did one side of each two pack set.. I was getting that green-red-green thing. I did something else with the same 2 battery block. I was reading about how I shouldn't drain down the batteries completely in the manual. So after I ride and lose power I start to get worried I've damaged the pack. So I get the(probably) stupid idea of hooking up my single 12v 3A sla smart charger to it to get a little juice in it. So I test one pack and determine it's the low one. Later I found out, I was incorrect on this. I set it aside thinking I will unplug it in 15 min. Over an hour later I hear this smallish pop which I didn't connect with anything. 2 minutes later I hear another pop. Alarm bells start going off in my head. I run over and feel the batteries. They are very warm. I take the clips off and I hear another pop. I feel the batteries and they are warmer almost hot. They are still heating up even though I unplugged them! I am extremely alarmed at this point having watched videos of batteries on fire and I don't know if LiMn are as safe as LeFePO4s. I decide I want to get this battery out of my house NOW. I take them on to a concrete back porch area and put them in the center. I hear two more pops. I figure there is some thermal safety mechanism of last resort that's popping. After awhile I start to calm down ,the batteries are still hot but I can touch them and they stopped getting more hot. Eventually it starts cooling and I'm sure it won't blow up but I'm also pretty sure I fried one pack.

Now when I put either of the two packs in a charger I get a blinking red light AND it makes a high pitched beeping or cheeping sound that goes along with the red light. What might that be?

 

[tostino]

I think the blinking red light is the thermal sensor warning. You probably did fry the pack.

 

[Parker]

"Fried" is not really a technical term is it.

 

[tostino]

"Fried" is not really a technical term is it.

No, no it isn't. However, if you opened the pack up and measured the voltages on the individual cells, I can take a guess and say they won't be close to normal, if there is any at all.
I am going to assume the popping was the cells venting (safely, like LifePo4). I highly doubt it is just the BMS that is stopping your pack from working properly, and I don't think your pack will ever be the same again.

 

[Parker]

Yes I know the pack is finished, live and learn. The thing that I'm curious about is the sound, the high pitched beeping. It sounds more like it has to do with the function of the charger.

 

[Parker]

I found out the red light with that sound means the pack is drained(or has somehow gone)
beyond the lowest point that the BMS can recognize. I say this because I was able to "jump start"
my totally drained pack with my 12v sla charger for about 5-10 mins and now it's charging
fine on the Milwaukee charger. I suspect I did degrade it some but it will still be usable. Yay I
still have 5 packs not 4. I was on the right track. I'm surprised I could kill that other pack with a
12v charger. I think it was the trickle charge the sent it over the edge.

 

[pwbset]

Happy you're figuring it all out as it helps the rest of us Milwaukee-heads learn. Mlrosier's decision to bypass the BMS was both a good and a bad thing. I envy the power available to you as these are really powerful cells, but don't envy the potential pitfalls that you are discovering. I'm going to try and take my, warranty in tact, packs to 30+ amps with diodes, solder on the controller shunts etc. etc. I'll let you know how it goes. I'm fully prepared to eat crow and admit my own stupidity in these endeavors, but at least if I fry them I'll be able to claim innocence at the local service center and plead for new packs. :wink:

 

[tostino]

I found out the red light with that sound means the pack is drained(or has somehow gone)
beyond the lowest point that the BMS can recognize. I say this because I was able to "jump start"
my totally drained pack with my 12v sla charger for about 5-10 mins and now it's charging
fine on the Milwaukee charger. I suspect I did degrade it some but it will still be usable. Yay I
still have 5 packs not 4. I was on the right track. I'm surprised I could kill that other pack with a
12v charger. I think it was the trickle charge the sent it over the edge.

So wait a second, you got the pack that made poping noises to charge again? Or was it the other pack?