Speed - Electric For all your electric boating needs.

LiPo Q

Reply

Old 10-04-2010, 05:01 PM
  #1  
Tundrahog
Member
Thread Starter
 
Tundrahog's Avatar
 
Join Date: Jun 2007
Location: Oswego, IL
Posts: 88
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default LiPo Q

Did a couple speed runs with my DF 16" hydro. 3695kv motor, 2200 11.1v 3s 25c LiPo, 90a esc, BEC, and Octura 435 prop. Motor and esc not that warm. Battery was warm to hot.

Battery was swollen/puffed up about 1/8 inch top and bottom. It still took a charge. Did not use it yet. Never had this problem with aircraft/heli LiPo's. Still new to boats.

Is it safe to use? I have two other batteries as backups.

Just got my radar gun today. Now I can see how fast she is.

Thanks!
Tundrahog is offline  
Reply With Quote
Old 10-04-2010, 05:42 PM
  #2  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo Q

Unfortunately it's already damaged. I don't know your set-up, runtime, or current , but I think you may be ok with 2 of those packs in parallel. This would cut the load in half. The other possibility could be that the pack was ran down to "too low of voltage"
guver is offline  
Reply With Quote
Old 10-04-2010, 10:37 PM
  #3  
Tundrahog
Member
Thread Starter
 
Tundrahog's Avatar
 
Join Date: Jun 2007
Location: Oswego, IL
Posts: 88
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo Q

Runtime 10+ seconds per run. Four runs flat out. Setup listed.?. Twin batts out of the question, hull too small. There has to be a basic formula for current even with different props.?.

I' ve been looking for that formula since I started electric boats.?? []
Tundrahog is offline  
Reply With Quote
Old 10-05-2010, 08:24 AM
  #4  
pompebled
Senior Member
 
Join Date: Jan 2004
Location: Sneek, NETHERLANDS
Posts: 2,451
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo Q

Hi John,

Running lipo's in a 'hot' set-up requires pre-heating the lipo to 40°C prior to the run, failing to do so may result in bloating.
This is a 'normal' response of a Lipo that's been put 'cold' in the boat and 'tortured' with high ampdraw.

I didn't know that and have a few packs that are bloated, I still run them without any problems, other than some drop in capacity.

Pre-heating the packs makes the difference, specially is you're running budget Lipo's like I do.

Regards, Jan.
pompebled is offline  
Reply With Quote
Old 10-05-2010, 11:41 AM
  #5  
Von Ohain
 
Join Date: Jun 2005
Location: trondheim, NORWAY
Posts: 365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo Q

P=U²*(1/R)

What that formula says is that you must increase your cell count, and reduce your motor KV, and then you get a reduction in amp draw and a increase in power.
Von Ohain is offline  
Reply With Quote
Old 10-05-2010, 05:11 PM
  #6  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: LiPo Q

How much capacity did you use in 40 seconds?
guver is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy