RCCrawler Forums

robbio4422 · 03-25-2009, 09:10 PM

i have been crwling for almost a year now. running 2-hitec hs645mg servos for front and rear stearing i decided i wanted to make the leap into competing so for the last few weeks i have been trying to up my rig.

i bough this servo http://www.amainhobbies.com/product_...ducts_id/18804

and im still waiting for my thunder power 2 cell (7.4V/1345mAh) to power my rig... my old set up was working fine with a 7 cell 1500mah saddle pack but now i just dont have the power... can this issue be solved with my lipo? or is this servo just to powerfull. its a freashly charged pack so im just curious to what i might be doing wrong.

my first comp is on sunday... grrr im stressed. i just installed my first dig unit and im needing some time to get a feel for it and im hoping my first run isnt going to be at the comp

JeremyH · 03-25-2009, 09:42 PM

Well, you did step down in voltage (juice). You went from your 7 cell (1.2V x 7cell = 8.4V) to 2 cell (3.7V x 2 = 7.4V).

The servo is drawing more current than your previous servo. What ESC are you using? If it can handle the 3s (11.1V), then you might want to step up in battery size. While you are at it, install an external BEC.

robbio4422 · 03-25-2009, 09:50 PM

Quote:

Originally Posted by JeremyH

Well, you did step down in voltage (juice). You went from your 7 cell (1.2V x 7cell = 8.4V) to 2 cell (3.7V x 2 = 7.4V).

The servo is drawing more current than your previous servo. What ESC are you using? If it can handle the 3s (11.1V), then you might want to step up in battery size. While you are at it, install an external BEC.

currenty using a rooster that has the 2 cell cut off... thats why im getting a 2 cell battery.... very very new to lipos so i need to learn before i step up. my next "up grade" will be a brushless motor and esc. hopefully by then ill be comfortable with my lipo experience and wont need a cut off

forget to say that im still running the 7 cell sadle pack.... waiting on ups for the lipo to come (tomorrow, i hope)

JeremyH · 03-25-2009, 09:58 PM

Well, if by "cut off" you mean "low voltage cutoff".....you will always need one of those. Lipos are not that much different than other battery types (other than the obvious chemistry). They do, however, require some method of stopping them from completely draining down to zero voltage, unlike NiMH or NiCad. Most medium to high end ESCs will have a built in LVC. I have had good luck with the Castle Creations Sidewinder ESC. It can be programmed on your computer if you purchase the Castle Link. This allows you to easily set the LVC and to switch between different types of motors (brushed or brushless). It will also be able to handle a 3S lipo (has a limit of 6S, IIRC). When hooked up in conjunction with the Castle Creations BEC, you'll have enough power for your servo and motor!

robbio4422 · 03-25-2009, 10:07 PM

Quote:

Originally Posted by JeremyH

Well, if by "cut off" you mean "low voltage cutoff".....you will always need one of those. Lipos are not that much different than other battery types (other than the obvious chemistry). They do, however, require some method of stopping them from completely draining down to zero voltage, unlike NiMH or NiCad. Most medium to high end ESCs will have a built in LVC. I have had good luck with the Castle Creations Sidewinder ESC. It can be programmed on your computer if you purchase the Castle Link. This allows you to easily set the LVC and to switch between different types of motors (brushed or brushless). It will also be able to handle a 3S lipo (has a limit of 6S, IIRC). When hooked up in conjunction with the Castle Creations BEC, you'll have enough power for your servo and motor!

so by this im going to assume your telling me these little saddle packs just dont have the juice to push brood 35turn and my new "big-boy" servo

JeremyH · 03-25-2009, 10:10 PM

It sounds like they dont. Personally, I have not tried a 2S saddle pack on a similar setup, but I can tell you that the jump to 3S will give you much more wheelspeed!

robbio4422 · 03-25-2009, 10:12 PM

sweet. well when my lipo gets here tomorrow ill see hw she does. im hoping that it will be an easy solution to a stubborn issue. thanks for the info.

03-25-2009, 09:10 PM	#1
robbio4422 Rock Crawler Join Date: Nov 2008 Location: kansas city Posts: 692	getting enough juice? i have been crwling for almost a year now. running 2-hitec hs645mg servos for front and rear stearing i decided i wanted to make the leap into competing so for the last few weeks i have been trying to up my rig. i bough this servo http://www.amainhobbies.com/product_...ducts_id/18804 and im still waiting for my thunder power 2 cell (7.4V/1345mAh) to power my rig... my old set up was working fine with a 7 cell 1500mah saddle pack but now i just dont have the power... can this issue be solved with my lipo? or is this servo just to powerfull. its a freashly charged pack so im just curious to what i might be doing wrong. my first comp is on sunday... grrr im stressed. i just installed my first dig unit and im needing some time to get a feel for it and im hoping my first run isnt going to be at the comp Last edited by robbio4422; 03-25-2009 at 09:41 PM.

03-25-2009, 09:42 PM	#2
JeremyH I wanna be Dave Join Date: Sep 2005 Location: Houston, TX Posts: 16,952	Well, you did step down in voltage (juice). You went from your 7 cell (1.2V x 7cell = 8.4V) to 2 cell (3.7V x 2 = 7.4V). The servo is drawing more current than your previous servo. What ESC are you using? If it can handle the 3s (11.1V), then you might want to step up in battery size. While you are at it, install an external BEC.

03-25-2009, 09:58 PM	#4
JeremyH I wanna be Dave Join Date: Sep 2005 Location: Houston, TX Posts: 16,952	Well, if by "cut off" you mean "low voltage cutoff".....you will always need one of those. Lipos are not that much different than other battery types (other than the obvious chemistry). They do, however, require some method of stopping them from completely draining down to zero voltage, unlike NiMH or NiCad. Most medium to high end ESCs will have a built in LVC. I have had good luck with the Castle Creations Sidewinder ESC. It can be programmed on your computer if you purchase the Castle Link. This allows you to easily set the LVC and to switch between different types of motors (brushed or brushless). It will also be able to handle a 3S lipo (has a limit of 6S, IIRC). When hooked up in conjunction with the Castle Creations BEC, you'll have enough power for your servo and motor!

03-25-2009, 10:10 PM	#6
JeremyH I wanna be Dave Join Date: Sep 2005 Location: Houston, TX Posts: 16,952	It sounds like they dont. Personally, I have not tried a 2S saddle pack on a similar setup, but I can tell you that the jump to 3S will give you much more wheelspeed!

03-25-2009, 10:12 PM	#7
robbio4422 Rock Crawler Join Date: Nov 2008 Location: kansas city Posts: 692	sweet. well when my lipo gets here tomorrow ill see hw she does. im hoping that it will be an easy solution to a stubborn issue. thanks for the info.

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