Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: 1 2 3 [4]   Go Down

Author Topic: 30 inch brushless hydroplane project  (Read 11071 times)

Mad_Mike

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,597
  • Lincolnshire
  • Location: Lincolnshire
Re: 30 inch brushless hydroplane project
« Reply #75 on: September 09, 2012, 10:18:40 PM »

not trying to put a cat amongst the pigeons but the that turnigy 30 esc in that boat is a modern one and has a connector block on it to make it lipo compatible with a lvc on it.

Id just like to point out loveboat that lipos can be still used on old esc's. Its just that old esc's dont have low voltage cut off. To overcome the damage by over discharging you connect a low voltage alarm to the balance lead of the lipo and it beeps when you get to 3v per cell.
Logged

loveboat

  • Guest
Re: 30 inch brushless hydroplane project
« Reply #76 on: September 09, 2012, 10:35:54 PM »

If I've made an error I've made one just gone off what I was always told when I use to race rc cars , think some of you need to chill out a bit though some off you are quite offensive , mad mike thanks for explaining mate
Logged

spearfish99

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 311
  • Location: Northampton
Re: 30 inch brushless hydroplane project
« Reply #77 on: September 09, 2012, 10:45:27 PM »

err yes you can use lipo's with brushed motors so long as the esc is lipo compatable ( whether you use a brushed esc with a low violtage alarm or a or low volt cutoff )

  It is my understanding, like Stormbringer, that Lipos ,like any other battery, supplies dc current at its nominal voltage which the 700BB is very happy with, (and will work quite a bit above its rated voltage as well).  The same is basically true with many ESC's , they are only controlling incoming dc current within their voltage range, irrespective of the type of cell supplying it.

 Where you have to be careful is that with the high energy density of LIPO's compared to NIMH or nicad cells, they can supply that dc voltage at high amps so the motor and ESC have to be able to cope with the load applied to it.  By that, I mean, that just because a LIPO can discharge at high amps, it doesn't mean that it just will. It should only supply the level of power that the motor demands of it depending on prop size etc. A simple safety measure when using LIPOs in any i installation, brushed or brushless, is the inclusion of an inline fuse of appropriate rating in the wiring from the battery to the ESC

Probably the biggest issue with LIPOs is running them down below a certain voltage which will ruin them .  Again, note "certain voltage" as people will argue till the cows come home on the various forums  (fora?) just what that value should be. Like Stormbringer said, most lipo compatible ESCs  will either have a suitable set value or a choice of several values, which when reached will either cut the supply to the motor or reduce it to enough to get the boat to shore.

 If using a brushed esc then a simple and cheap alarm can be used that plugs into the balance plug of the lipo, which when the low limit is reached will sound a very loud and obvious alarm. If you don't take notice and end up with knackered cells, don't say that you weren't warned.

  Lipos can breath new life into old models, especially those who were tight for space for nimh packs as there can be a considerable size advantage.

  The only other issue is to get used to the slightly more stringent charging routine which you need to use for lipo cells
Logged

Mad_Mike

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,597
  • Lincolnshire
  • Location: Lincolnshire
Re: 30 inch brushless hydroplane project
« Reply #78 on: September 09, 2012, 10:46:07 PM »

well its water under the bridge now, dont take offence fella sometimes things are written down that seem a bit off but were not intended to be.

anyway i asked u why youn gave up so early? heck you only just got to the lake, ahwell so it goes 10 mph but thats just the hull not the gear. Put that stuff in a monohull and i dare say youl be pushing 50
Logged

spearfish99

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 311
  • Location: Northampton
Re: 30 inch brushless hydroplane project
« Reply #79 on: September 09, 2012, 11:03:24 PM »

Hi Loveboat

  You aren't going mad, mate.

When I pulled the boat out of the garage, it had an old and past it Digifleet set in it with one of their esc's . I popped the Turnigy in it to check for space etc before deciding whether to go brushless or retain the 700BB. Just addded that to the original kit list in error! Another grey moment!!

 If the pictures were better, you could also see one of Giant Cod's 2.4ghz receivers tucked in there, which were very definitely not around in the 80's either!

 There is a huge amount of confusion around using lipos and lots of myths out there.  We do need to be careful to avoid any accidents which potentially might cause harm to any of us.  I appreciate your comments which were obviously intended to save me hassle  or disappointments.
Logged

Andyn

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 690
  • Location: UK
Re: 30 inch brushless hydroplane project
« Reply #80 on: September 10, 2012, 07:38:30 PM »

You can't use lipos with a brushed setup



Yes, you can.
Logged
Pages: 1 2 3 [4]   Go Up