Topic: esc , nimh or sealed lead acid bats ?

[radio joe]

Hi guys. Just got a 6 to 12 volt 15 amp navy esc  , set it up as usual with a servo and one 12 volt motor, plugged a nimh 7.4 volt battery in and it works just as it should, but when I plug a 12 volt lead acid battery in the servo works but the motor won't run put the nimh back and it works fine any thoughts.

[colin]

Hi Joe,
my only thoughts at the moment are....

1. is the ESC defiantly for 12v...
2. is the 12v battery OK, do the volts drop under strain...

Probably the 12v battery is not up to the Amp's that are being drained.... and there for the volts collapse, there might be 4 volts for the servo but not enough Amp's and Volts for the motor...

[radio joe]

hi Colin
the  esc is a Graupner navy 15 amp 6 to 12 volt and the battery is a new  12 volt 7ah, quite a large battery I have run esc's off of lead acids before with no problem, I suppose the battery could be faulty. the reason for using a lead acid 12volt is firstly I'm using a 12 volt geared marx pile motor and secondly I'm going to use a 12 volt smoke unit which performs better with a 12 volt battery, I've test run the motror and the smoke unit directly off the same 12 volt battery and they work fine.

[colin]

strange to say the least, Joe...

my comment just remains, it should work no problems...

presuming the ESC gives its BEC to the receiver... which it does because the servo works..!!

did you install some gremlins..??  ha ha ha

i am lost on this one Joe, i would have to have the ESC on my test bed to give you a better answer, sorry..

[radio joe]

yes got me beat too, I think I'll use a couple of 8.4 v nimh batterys instead, the 12v motor runs ok on 7.4v so it should be fine

[mikearace]

Joe

May be a bit drastic but have you considered slipping out (or being really drastic and cutting) the power lead from the ESC pin that makes it BEC and trying a separate 4.8v battery pack to power the receiver?  The BEC may be drawing too much from the LA battery which causes it to drop below a consistent voltage.

[karlgalster]

Joe
One of those strange illogical problems. Have you got a multimeter so you can measure the voltage? Possible cause is a bad connection. How have you connected the battery to the ESC? I see the Graupner v15 ESC has a Tamiya type connector for the battery input - can you measure the voltage on the ESC side of this connector? Got a similar problem on one of my boats - works 95% of the time then the motor will not run. Waggling the ESC input and/or output power lines brings it back to life but despite much fiddling about I cannot trace the fault
Robin

[radio joe]

I'm thinking it must be something peculiar to the Graupner navy esc because I have plugged the lead acid battery into my pilot boat that has an etronics esc and everything works fine, I have also plugged the la battery into my solebay that has two deans esc's and guess what everything works fine. I looked up the spec on the Graupner esc and it does say nimh/nicad 6 to 7 cell bats. I had always thought that providing the voltage was ok you could use any battery (well maybe not lipo) as they say you learn something everyday , I've ordered an Mtronics marine 30 which the spec says nimh/nicad/lead acid bats, I'm sure the Graupner navy will get used sometime

[paul swainson]

On the subject of ESC  I have used these in my Perkasa and they are great, the cost is low and have not blown one yet.

http://www.ebay.co.uk/itm/RC-320A-Brushed-Brush-Speed-Controller-ESC-1-8-1-10-Car-Truck-Buggy-Car-Boat-/221038350619?pt=UK_ToysGames_RadioControlled_JN&hash=item3376e9911b

[radio joe]

well Paul  I've had this Graupner navy 15 esc in the drawer since building the tug which has the lead acid battery, so I thought I would use it in Bramble as it works fine with nimh bats  and it was about ?30 so did not want to waste it.

[paul swainson]

Yes I agree do not waste items that can be used. If these are of use for the cost they could be put into the draw for the next build.    I put it up as info for others to think about.

[shipmate60]

Have you checked the charged voltage of the Lead Acid Battery.
When fully charged these batteries should exceed 12 volts to about 13.5 so could be tripping overvoltage.

Bob