Lipo Scare

[boppinbob]

How many of you lipo users have scared the crap outta yourself connecting a lipo wrong? Today I put on my new Maxxis Hookworms after coming home from vacation. My wife said, "lets go for a ride" after giving me grief about the new tires which I didn't really need. My 4 5s8Ah lipos were at 3.9v so I decided to balance charge them to 4.1v and then go for the ride. My wife was in a hurry so I tried to hurry and crack,sizzle,pop I plugged in a balance tap backward or shorted it somehow. It's still a mystery. I unplugged muy pronto and rechecked all cells with a battery medic. Reconnected the charger (right this time) and finished charging and rechecked all cells. Everything is ok so far. I almost sent my lipos to battery hell.

 

[neptronix]

Don't worry about the balance leads. They will blow WAY before the battery will receive any damage. I've even done crap like plug the battery into the controller backwards, guess what happened? it blew the solder right the hell off the interconnection board :lol: :lol:

Not that you should do this gallavantly. But don't be skurred...

 

[sflorlando]

Stuff like this use to happen to me all the time. Id plug my lipo in and close my eyes hoping for the best.

I remember one time I plugged my lipo in and immediately sparks, I checked to make sure I was plugging it in right and tried again. Zap! I also felt like tossing all of the lipo into the trash. I thought the chemistry was just too volatile.

After talking to a few users online I realized what was happening and the mystery disappeared. I use to play with my battery configurations, adding batteries/removing batteries. At times I would take a nearly empty pack and add it to my big pack. THis was causing current to flood from the full pack into the empty packs to equalize the voltage. Zapping the connectors. I bought a battery medic and check voltages of all cells before I plug them in. If the voltage is slightly off, I balance and charge the packs so they are all the same before plugging anything in. Mystery solved.

Probably not the same thing you were doing...but maybe it will help someone.

 

[Pure]

It's not just you lipo guys. Any one running higher voltages, regardless of chemistry, makes one hell of a spark. I know mine scared the sh*t out of me when mine did!

 

[dogman dan]

Like the routines I used to get a balloon ready to fly, I developed a set procedure for hooking up my lipos in series. Once a set routine is used you stop making mistakes that connect the wrong leads + to -, and stop having KFF's.

It's when you are doing something new that you are really vulnerable to making a mistake. One really easy one to make is connecting a bunch of packs paralell at the balance wires to bulk balance them. Leave one series connection in place, and whamo, sparks.

 

[cor]

It's not just you lipo guys. Any one running higher voltages, regardless of chemistry, makes one hell of a spark. I know mine scared the sh*t out of me when mine did!

Even at 30V you get a bad spark if the input of the controller has a big capacitor and you connect the pack directly.
So, I soldered a small resistor to one of the leads - begin by connecting the other lead, then touch the resistor to the second lead for a few seconds and immediately connect the big plug to it. This process is called pre-charge and every larger EV has a separate relay that turns on when you turn the key to "start" to fill the caps before the main contactor comes on.
Until now I have not make connection mistakes with the balance leads versus the power leads, but I always double and triple check before making a connection.
I did have a few times that I wanted to manually balance the lower two cells (which got unbalanced by the Battery Monitor) and accidentally touched two contacts at the same time when connecting the wire probe. They are a bit discolored now...

 

[parabellum]

My favorite is trying to died short them (24s is my personal record), normally connectors spits liquid metal and evaporates before real fun starts.

 

[Stryker16]

got my lipo a week ago and the charger showed up monday. i balanced charged them all separately up to 4.2v and then decided to hook two up in series to the board to discharge. (i am using the icharger 101B+, which can handle 10s and i have 5s batts)

hooked the two balance connectors up to the balance board (the charger was off) and then tried to plug the positive of one batt to the negative of the other. it popped and i went
the plug connectors are now fused together, i cant pull them apart. i cut them off and checked the balance leads with a cellmeter and all cells seem OK but what the hell did I do wrong?
i am ready to give up after less than a week

also the balance lead insulation has melted on the red wire of one batt and ground of the other.
im afraid to do anything else

 

[amberwolf]

If you parallel the balance leads, and then try to series the packs via the main leads, you just shorted across a whole pack.

You must parallel both balance and main leads, or else leave balance leads not connected to anything and then series the main leads. Can't do both at once.

I highly recommend reading thru the various RC LiPo "noob" threads before continuing, to be sure you are using it the right way, and don't have any more oops moments.

 

[jonescg]

Or just use a properly assembled LiPo pack which doesn't need to be plugged and unplugged! Seriously guys, KFF is way too easy if you have to keep fiddling with leads and connectors!

 

[Stryker16]

Or just use a properly assembled LiPo pack which doesn't need to be plugged and unplugged! Seriously guys, KFF is way too easy if you have to keep fiddling with leads and connectors!

well i plan on assembling these into a pack eventually, but seeing as how i just got them and haven't even put the bike together yet, i haven't gotten there yet.
i am not even sure what voltage i will end up using, 10s, 15s, 20s so i can't put them together until then.

just trying to cycle the batteries to make sure all is good.

 

[Stryker16]

If you parallel the balance leads, and then try to series the packs via the main leads, you just shorted across a whole pack.

the balance leads were connected to the balance board to make 10s, this is a series connection correct? i don't think i paralleled the balance leads (or main leads)

 

[amberwolf]

Ah, if they were in series then I guess it would be ok. I assumed like most people taht when you plug them into a balance board, you'd plug them in parallel; sorry about that.

If that isn't the case then I have no idea why it would have fried things the way it did--but it certainly will do what you describe if they are plugged in balance parallel / main series.

 

[Stryker16]

Ah, if they were in series then I guess it would be ok. I assumed like most people taht when you plug them into a balance board, you'd plug them in parallel; sorry about that.

no problem. here is the board i have http://epbuddy.com/index.php?main_page=index&cPath=26_16 so i'm sure now its a series board.

doing some research, i think i may have connected the first pack to power and not ground main lead. and the second pack (second on the board) to the ground main lead.
the balance connectors are different in that balance port 1's ground wire goes directly to ground and balance port 2's ground wire goes to balance port 1. and this can cause a short if hooked up backward.

is this right? still confused. got from this guy's thread: http://traxxas.com/forums/showthread.php?492570-dual-lipo-charging-with-icharger-208B

btw i did read the lipo faq (a few times) before i bought all these batteries, but dont remember reading about this. also read the entire 1010b manual and they never mentioned this. seems strange to me.

 

[Racer_X]

(the charger was off)

The Charger has to be on before you connect batteries. You could blow the charger if connecting batteries to a disconnected charger.

 

[SniperGaulois]

i hope they dont have to recall 2 million cells from customers that would be indeed a lipo scare, unlike what your title suggests, which is in fact referring to lipo plugged wrong way.

 

[cal3thousand]

I recently tried to make a harness for LiPo setup and got my first introduction to arc welding. Bullets were mangled in what was literally a flash. Lesson learned and 2 bullet connectors to now re solder.

 

[Punx0r]

Check before soldering, check after soldering, check with a voltmeter, connect