Servo And Battery Questions

[Rich Jones]

Hi all. I’ve been out of the hobby for 20 years and getting the bug again. So I’ll be buying some new radio gear, etc... I’m going to build a Blazer Backlash to begin with. Realistically, how much torque is needed to turn a boat like this? I see these Savox servos with like 400 oz in of torque and I am skeptical that this isn’t overkill. Back in the day I’d use servos like the 1/4 scale Futaba s-134 or a 9304. The 9304 with roughly 70 oz in could turn an 1/8 scale at 60mph no issues and I had the metal gear version of the 134 in my E hydro And that was not much more than 100oz in. So any thoughts on this subject would be appreciated. What would you recommend? Do I need some Life or Lipo 7.2v pack or is a 6v Nimh pack adequate? Any recommendations on this would be great too.

Thanks In advance!

Rich

 

[Mark Anderson]

You are going to get all kinds of information. Some good, some not so much. In my opinion, if it takes over 100 oz in. to turn an inboard, there is a geometry problem. My go to servo is 133 oz. in. Your linkage needs to be designed so that you are using all of the servo travel. If you are using the end point adjustment, you are loosing torque and resolution.
AA nimh. is ok. I would prefer nicad. I have converted to all LIFE batts. They have near 0 shelf discharge and have performed well for years. Smaller package and higher output then older chemistries.

 

[Rich Jones]

You are going to get all kinds of information. Some good, some not so much. In my opinion, if it takes over 100 oz in. to turn an inboard, there is a geometry problem. My go to servo is 133 oz. in. Your linkage needs to be designed so that you are using all of the servo travel. If you are using the end point adjustment, you are loosing torque and resolution.
AA nimh. is ok. I would prefer nicad. I have converted to all LIFE batts. They have near 0 shelf discharge and have performed well for years. Smaller package and higher output then older chemistries.

Good stuff thanks Mark! What do you use to charge your LIFE packs?

 

[Mark Anderson]

I have a two channel Orion charger and a two channel Hyperion that will charge all chemistries. I also have a small field charger that will also charge anything that I use when we travel. There are a lot of good options out there for chargers. Like all things, prices very from affordable to a bit more then that. I fly electrics and race a few electric boats other wise I would not have the big chargers.

 

[Rich Jones]

I have a two channel Orion charger and a two channel Hyperion that will charge all chemistries. I also have a small field charger that will also charge anything that I use when we travel. There are a lot of good options out there for chargers. Like all things, prices very from affordable to a bit more then that. I fly electrics and race a few electric boats other wise I would not have the big chargers.

Thank you Mark that was helpful!

 

[Daniel's Racing]

I sell the LiFe batteries and have chargers too. Manufacturers section. Not sure if charger ad is there or if it is current but I have them.

 

[Grimracer]

Rich,

You have some good advice here.. Truth is even those old servos will still get the job done today.. but as you can imagine things have changed and newer servos are VERY nice.. I like Digital AND S-BUS servos. (I race Futaba systems). I can VERY simply change the profile of the servo using my TX. (neat stuff.. but TOTALY not necessary.

Another point.. speed and power for servos comes in an abundance! Now days its EASY to get plenty of power for your steering. If you select a servo that has a tick more power.. OK.. thats cool.. no harm done. I like AT LEAST 150oz in every thing I race. (I can not always get there) but its what I like. Tunnel boats get 250 of more..

Regarding battery's LiFE is indeed the way to go.. fire dangers are way lower.. an LiFE does not have the energy density of a LiPO BUT.. we just dont need that for our boats. Mark is dead on.. idle discharge is SUPER LOW.. having said this.. its "best" NOT to store then fully charged.

I have a few chargers as well.. (maybe to darn many).. for my day to day I like my Hitech X2AC (2 ports).. works a charm!

Here are a few videos to view.. maybe helpful.. maybe not.. but here they are non the less.



Grim

 

[Rich Jones]

Thanks a lot Grim I’ll watch those videos later tonight. I really appreciate the analysis of today vs yesterday on the servos. Very helpful man thanks again! Rich

 

[Tom Foley]

Part of the servo equation is the ability to survive tail first crashes at speed . Personally in my Whiplash GV there is a Hitec 5645 MG in it and it has survived mind numbing wrecks at full speed and with other boats invovled . I am totally amazed at the toughness of these servos . In my Twin Nitro Rigger I have been using Hitec 805 MG for YEARS without failure and countless wicked wrecks . I use LiFe batteries exclusively now for the reasons aforementioned .

 

[Rich Jones]

The crash thing makes a lot of sense. I can see your point.