Rich404

Hello everyone,

I have been running boats for a long time (mostly scale) but am now entering the LI-PO arena.

Recently, I bought a RTR Racing Boat that runs on a 2200Mah LI-PO battery pack. The boat also came with a LI-PO charger/balancer which also made things easy. After the boat was charged, I took it down to the pond for its maiden voyage. Within 7-8 minutes in the ESC cut out without much warning and the boat was dead. I went swimming and got the boat back to shore. Since then, I recharged the LI-PO battery. After charging, noticed that the battery pack swelled up on one side as if there is an air bubble under the shrink wrap. A few days later, I took the boat back to the pond, put it into the water and when I hit the throttle, the boat took off about 20 feet out it slowed down and died. The ESC started chirping but it was very weak, the rudder moved, but did not have the power to turn the prop. It took more than 20 minutes to get the boat back. (I ended up swimming for it again)

When I brought it home, the battery charged in about 10-15 minutes. When I plug it into the boat, it is very weak/almost dead but I am getting a “fully charged� reading on the charger. What is going on here?


-Rich.

ghostofpf1

sounds like you over discharged the lipo pack and ruined it in the process...

You should never run beyond the time that you see any power loss or lower than about 80% disharged.

Good Luck
Ghost

headhunter23

Ummm... which boat did you buy? And where? From what I've read, you've managed to pull too many amps and the lipo couldn't supply it. Puffy not good, means pack is on it's way out. Hows the shaft, no binding issues? If it's binding, motor will pull a lot more amps than it would normally. My one boat I tried first run with binding, didn't think it would make a difference, supposedly I should have pulled 35amps, instead I pulled 84. Not good for either pack or esc.

Esc shutting off means it's generally overheating by pulling too many amps and not enough cooling.

More info on the boat should help in diagnosing.

Ivan.

Rich404

Hi Ghost,

This was an expensive lesson learned. I have never had a boat cut out on me with very little warning. Usually they slow down enough to get back to shore….oh well.

Is there anything I can buy to help me better monitor LI-PO’s or any other suggestions that can help me avoid this on my next pack?


Hi Headhunter,

The boat I bought is V-24 Racing boat from Importhouses. The motors/speed control was cool to the touch after the run, so the set up seemed ok. After Ghost's post, I am guessing that after the ESC cut out, the LI-PO was over discharged and ruined while I was trying to retrieve it.

Here is the boat.

Thanks guys.

-Rich

Rich404

Hi Ivan,

I don’t think that there are any binding issues, but who knows. The boat has a 1520 motor with 40 amp ESC. The Motor is coupled to a steel shaft that comes out of the transom. On the exterior of the transom is the shaft that connects to a stainless steel coupling that reattaches to another shaft built into the rudder with the prop attached. Pictures are the easiest explanation.

-Rich.

Rich404

Ivan,

How do I find out how many amps this thing is pulling?

-Rich.

headhunter23

wattmeter from hobbyking or what used to be called united hobbies. 40 bucks but worth it, ya can't tell by slapping voltmeter on, unless you have one that can take the amps, mine only does 10 which is no help for the higher amperage dc stuff. What C rating was the pack? 20 25? If your motor can pull 40 amps I would get a larger pack anyways something in the 4000-5000mah range. How many cells are you running?

Does the esc have a lipo shut off? for example, if you have the configuration stuff, does it allow for what voltage the esc is to shut down. This would be the over discharge, but you can still blow packs by drawing too much power.

Nice looking boat other wise.

sorry, guess wattmeter is more now, was 40 a couple months ago when I bought two. There 53 now.
http://www.hobbycity.com/hobbycity/s...idProduct=6380

Rich404

Hi Ivan,

The battery is currently an ABF 20C 11.1V 2200MAH Battery which will be replaced with a battery in the 4-5000 MAH range.

The speed control is a Stock brushless 40A 2-3 Cell water cooled ESC.

The ESC is equipped with a LI-PO shut off, but the ESC instructions are vague on how to set it. (I will make sure to set it correctly)

I just checked out the boat, there doesn’t seem to be any binding issues from the motor to the prop.

Thank you for pointing me to the Wattmeter. I would rather buy the tools now than have to needlessly spend on new battery packs.

Funny, but today I got a LipoSack in the mail that i ordered a week ago.

Thanks![sm=shades_smile.gif]

-Rich.

headhunter23

Let us know how it turns out when you retest her. If you have the same packs I have(says abf 2200mah) it's really a 2100, which drops down to a 1700mah rather quickly, don't ask me why. Anyways mine are rated for 20-25c, which brand new put the pack at able to supply 44-55amps(at 2100mah) but as it dropped to 1700mah, that only allows for 34-42.7amps. Still good cheap batterys though.

Ivan.

ibyte69

hey rich404 sorry to hear about your lipos, they are unforgiving if not cared for properly. for me i have a couple thousand dollars in lipos and nimh combined and i still use both. the nimh batts go into my rescue boats i put 4 boats in the water at a time lol i just like the way they all look in the water. the sv is the only boat i use lipos on and when i run and stop, i use the retrival boats to bring it back in. the price of good lipos have starved my children and cost me two marriages just kidding they are pricey and a big loss on the wallet so heed any advice from members who post about them as many of them have been down you and mys road lol. good luck buddy!!

ryan_t888

A cheaper way of determining how many amps a motor pulls is heat. Monitor heat in the ESC, motor, and cells. If anything is over 140F you are pulling too many amps.

In order to not discharge more than 80% capacity monitor how many mAh are put back in the pack. Run the boat for a few minutes and note how much capacity is replaced when the pack is fully charged again. From this you can gauge how long you can run the boat.

A proper LiPo charger will not allow the LiPo pack recharge if any cells are below 3.0v. Purchasing a decent charger will allow better monitoring of the LiPo's.

Ryan

SV27dayton

Ryan,
Can a Lipo shield be used in the boat? I don't know how they work but I've heard of people putting them in the SV. I read that the new UL-1 studders at a certain point to warn the operator that it time to bring it in. I'd like to see that on more ESC's

ryan_t888

Yes but I don't find it necessary. If you hit any voltage cut off, the LiPo has drained too far in my opinion. 80% drain maximum of total capacity.

Ryan

Rich404

Thanks guys for all the great advice!!

-Rich.

1RiverRat

Not true. Our club has many people using lipo cutoffs. We all run till it cuts in then bring her in and my lipos are as good as the day I bought them. Some cutoffs are set to low. Here is the safest one we found. About half way down the page. Its a no brainer must have. http://www.kintecracing.com/Supervee_27_upgrades.html

SV27dayton

That's a nice site. Lots of useful stuff.

ryan_t888

If you continuously drain your LiPo's past 80%, life is dramatically reduced. This can be seen especially when drawing larger amount of current pushing the LiPo's harder.

I have been running LiPo's for over 4 years now in my planes and one of my first mistakes was draining them too far. These days they take more abuse but the issue is still there. You must compare to see results, I have already done this.

Ryan