Fat Lipo batteries?

[pjdog]

Had a problem running the Gato today. I put everything together for sailing. Put the travel box with the Gato in the truck and went to my friends house with the pool. After about an hour I noticed that the Gato was running a little low in the bow. I messed with it for maybe five minutes before I got it out of the pool. Decided I needed more foam. Put everything back in the truck. Sat in Susan garage and drank a abita beer and admired her 2004 Corvette z06 z16 option. Damn what a car. Then went home. Pulled the boat out of the box and noticed everything was foggy in the sub driver. Crap - a leak. Sure enough the battery end of the S/D leaked. Enough to get a little water to the radio and motors. Popped the ends off and water came out. Lots of water. I dried it out. checked to see if I still had everything and I do.

Now the question to the RC sub gods. Why are the Lipo batteries swollen. They recharged. They show a full charge on the Lipo guard. They were not swollen before I went sailing. Should I be concerned or just use them and not worry about it. I thought they would go down after a while but it's not happening. They are still fat.

Jack

[He Who Shall Not Be Named]

Jack,

Hey! ... why the leak in the SubDriver?

And did you do a proper inspection and blow-down/drying of the wet circuit boards (that means taking the receivers and other devices out of their protective cases/shrink-wrap and insuring the boards are dried out)?

First things first, pal!

Now, as to the puffed up LiPo battery -- sounds like you over-discharged the poor thing. You *******! No biggie I'm running puffed up batteries in a few of my boats. They just don't give me the run times a healthy battery gives.

Swollen means you've killed some of the batteries capacity -- you might have a battery there that is now 50-80% efficient. Not the end of the world, keep using it -- we're not flying ducted-fans here. Oh, on that note: if you have flying buddies tell 'em you want their 'trashed' LiPo's -- they can't use them, you can!

I bet you left the SD's mission switch on after packing the boat up for the trip back home and/or you are operating that thing without one of Kevin's LipoSaver circuits in the loop -- that's how you clobbered that battery, Jack.

If I can cram a LipoSaver into a 1/230 SKIPJACK, you can get one into your GATO SD.

Which is it?! ... TELL ME! Fess up!

Oh! Just re-read your post. You're using a LipoGuard. Never mind. Did you leave the SD mission switch on (remember, with the LipoGuard activated, battery current is still going to the devices within the SD, you just can't operate the gas system, so it's vital that the mission switch is 'off')?

David,

[KevinMc]

I stand to be corrected on this, but to my knowledge the "marshmallow effect" is caused by internal heat build-up from charging or discharging too quickly. (Is it possible the water that leaked in to the batter space caused enough of a short to do this?)

So far as I'm aware over-discharging a LiPo will destroy capacity without leaving any physical evidence...

[He Who Shall Not Be Named]

I'm smart enough to listen when Kevin speaks.

So, Jack, do you think you saw a short in there or maybe you jammed too much current into the battery during the charge?

Thanks, Kevin.

David,

[pjdog]

I think testing the Gato without the deck in place caused the inside of the S/D to heat up and blew the battery side end cap out at the bottom. It's really hot in Louisiana this time of year. When I pulled the S/D out of the sub the end cap was pushed out pasted the o ring at the bottom. Which I would not see while testing the blow hole. I have a problem with the blow hole bubbling after the first time I use it. It's always done it. A little oil doesn't correct this one. I did do an adjustment on that.

I'm sure I did not over charge the batteries. I always stay in the room when charging and watch the lights on the wall charger while playing my favorite computer game (Silent hunter III). Also I took your advice and got ADF and Lipo guard for all my subs. They are in place.

The only thing I did in regards to water in the S/D once I realized it was wet was to remove both end caps, use a towel to suck up the water with the new hemostats you made me buy (12''). Very little was in the motor end but it was pooled. The battery end was full to the tube to the motor end. All I could think was water got into the Lipo's ? The receiver was not wet, the cardboard cover. The ADF and Lipo guard showed some clouding under the protective covers but they are clear now. Everything works. Even the fat batteries. I have the Lipo guard installed so I can see them from the top of the sub with the deck off. I never run them with out four green lights showing. Here in Louisiana the pool is so small I really don't get much run time. Only the type VII can negotiate a turn. The Gato don't have a chance. He just goes back and forth with a little diving. Remember I'm new to this and learn something new every trip to the pool. I asked Susan to build a bigger pool but she made a funny sign with her finger. I need a big pool bad. The house is for sale so we can move to Florida and buy a house with a big pool. They are almost giving them away there.

Can't think of anything else. If the batteries are usable I'll go with it. Again, when playing rc submarine batteries are of little consequence. If they poop out get new ones. Just wanted to be sure I was playing with trouble.

David, Don't forget about my poor little type VII trudging around on one screw. I need another port motor replacement. And a little bench running time before you return it. I did get some really nice telescoping couplers for the type VII. Seemed a little pricey for couplers - Twenty two bucks each (Graupner no. 475.2 - $22.00). They are frail but will work with no pressure on the motors. I have one on the starboard side running now. Easy to put the S/D in the type VII and took up the couplers. I had to drill them out and a little filing to get them to 1/8 but them work real good and are so quite. I love the little type VII.

Didn't mean to write a book here, Keep me posted on the motor fix, later.

Jack

[pjdog]

All I really know is they were not fat when I went to the pool and were fat on the way home?

Wonder if the heat from the sun with the deck off while tinkering cause the problem?

Jack

[He Who Shall Not Be Named]

Naw, sounds like you presented a high load (nearly a short) to the battery as a consequence of the flooding incident.

That sound right to you, Kevin?

David,

[pjdog]

ok. I'll live with that. Use the batteries until they crap out.

Jack

[KevinMc]

Naw, sounds like you presented a high load (nearly a short) to the battery as a consequence of the flooding incident.

That sound right to you, Kevin?

That sounds highly plausible to me... I agree with the idea of using it (under careful supervision) 'till it gives out.

[Outrider]

Ditch the battery. It's very likely to be a fire hazard in its present state.

Please see this post for a good examination of LiPo puffing issues:

http://www.rcgroups.com/forums/showthread.php?t=209187

David Merriman can afford to fool with puffed batteries, but mere mortals like me can not. Why is he special? (I'll leave this as a rhetorical question, but as a former Torpedoman, he's already been exposed to more than a few propulsive hazards.)

Let's look at the risk-reward equation this way... A subdriver kit is about $375 for the lexan, copper, servos, motor(s), endcaps, seals, etc. Then add the receiver, ADF, ESC, and the $15-30 battery. Merriman waves the wand and five new subdrivers appear. For everybody else, there's Visa. LOTS of Visa.

Beyond the issue of money, I can hardly think of a good place for a LiPo fire, but inside an expensive sub-driver is definitely a bad place.

[He Who Shall Not Be Named]

A well presented and most persuasive argument.

(Damn!).

David,