Evo 13

iTrader: (2)

[QUOTE 1Speedy

"I have been using Futaba BLS157HV servo’s in my Xray GT8 for 3 seasons without any form of a glitch with a 7.4v, 2500mAh, Li-Po battery."

1Speedy,

Do you run a regulator with that lipo? If so, which one and how much voltage is it regulated to. I considered going lipo before to extract the full 514 oz of torque; But didn't want to risk blowing up the car do to ignorance on regulator set ups.

*1speedy

iTrader: (12)

I never run a regulator, my Futaba receiver can handle it and so do my Servo's. Now make sure you are running HV servo's and you will be fine too.

I have been using this exact set up for almost 3 years.... I don't see a problem


Now my radio I use a LiFe battery, that's just because they last a VERY long time & I really only charge that about 3 times a season at most lol.

British Menace

What 1speedy says is exactly right.
High voltage servo's and receivers can do just that .... they can handle the high voltage LiPo battery's deliver.

Be careful though that you check out your receiver, to make sure it can handle 8.4V.
I had High Voltage servos
then realized at the last moment my reciever will not handle the higher voltage.
So I got a Regulator that brought down the Voltage of the LiPo from 8.4V to 6.5V
At this voltage it was ok for my receiver and any 6V servo's I would use also.

Regards,
BM

Evo 13

iTrader: (2)

This may be a stupid question BM, but I'll ask anyway. If the regulator drops the voltage down to 6.5, wouldn't I just be better off with the life (no regulator) giving off 6.6v? Or does going lipo (in this context) make the case for reducing overall chassis weight?

Grenade10

iTrader: (40)

In one of my DM-1s I have high voltage servos, s use the lipo with out a voltage regulator. On the other car I run Life cells, so as you stated does not need the regulator. Less things to go wrong and weight. Life and Lipo's battery's weigh about the same.

Mark

tonylunatic

iTrader: (45)

Your best bet is to first find the servos you want to use.
Then figure out the power source.

Remember the servos outputs(torque & speed) various and changes from the voltage input.

If you go HV servos these perform best and full potential running off 7.4v, you can go down to 6.6, 6.5 even 4.8 in some servos. They will still work but not put out the torque or speed you may require.

Evo 13

iTrader: (2)

Right, I understand everything you stated. Take Futaba BLS157HV Ultra-Torque as an example. My question was if the regulator is required with lipo and will REDUCE the voltage to 6.5v, why not just use a life with 6.6v and no regulator? You get more voltage with less risk. The only argument for using the lipo in this sense would be the weight advantage. But according to Grenade10, there is no advantage because the lipo and life weigh about the same.

tonylunatic

iTrader: (45)

The only reason regulators even came to be was because when Lipo RX batteries first came out many RX boards were not designed to handle the 7.4v of Lipos. I know for a fact the Futaba and KO RXs would either shut off due to over heating or glitch.

Now most RXs can handle Lipos, so shouldn't be an issue.

I would never run a regulator, just another piece of equipment to worry about.

I guess my point is use what ever power source that will yield you the best performance from your servos and you RX can handle.

The weight between Lipo and li-fe is very minimal if any. The biggest difference is capacity I run Lipos because my packs have 2200mah @7,4v, I have yet to find a Li-fe with that capacity.

I know many that have had lost races due to low battery in a long main. I rather have more then enough juice, then not enough. Especially when you run HV High output servos.

Then again even if you do find a high capacity Li-fe what's the advantage there, you just decreased your servos performance going from 7.4v to 6.6v.

haha

Can you tell me what type do you use savox servo?

British Menace

Some of this has already been metioned or eluded to but ....

With LiPo you have the ability to use 7.4V power output at the servo, if you have that capacity and as long as your reciever can handle that also.
As Tony mentioned, you get better speed and touque at this higher voltage output.
The batteries come very light, in comparison. The only advantage the LiPo's have over the LiFe is that of size/weight against capacity. If you get what I'm saying. For the same size and weight of LiFe battery you get a LiPo with higher capacity aswell as higher voltage.

If you decide or have to run 6V servos or have to use a reciever that can not handle the 7.4V output of a LiPo, you can bring down the voltage output with a regulator. This will slightly increase the performance of your 6V servo, protect them and your reciever from the higher voltage and will slightly increase the run times/ capacity availability of your LiPo.
For example: The 2100mAh LiPo ran through a regulator will last slightly longer then if not ran through the regulator.
Remember also that the power draw from your "LiPo safe" servo's, if using them, will be slightly higher also. You need to take that into account when choosing your set up.
As far as weight advantage .... there really is not one from either direction you choose.
Ideally ..... you would have a reciever that can handle the higher voltage of LiPo, run HV servo's (choosing the smallest/ lightest available to meat your power/ speed needs for the car), no regulator. As 1speedy does.....

The only real advantage of LiFe is if you have 6V servo's or reciever you have to use .... they are then lighter then the NiMh we previously used and you get a slight increase in servo performance.
Same with using a LiPo, + regulator with 6V servo's and reciever. You get the weight savings of the LiPo (even with the regulator) and the extra run time.

I hope this helps.

BM

Evo 13

iTrader: (2)

Thank you all. I didn't take the capacity differences into account.

Rockin G

iTrader: (6)

Burned up a Savox 1258 steering and 1251 throttle recently ran @ 6v in my Cobra GT. I realize that by the adage of being over 300 oz, I was well short of that. My question, is there any budget friendly, low voltage servos that will get me close? With our hobby continually evolving, just wondering I if there is something new out there that is already proven. Or would I be better off biting the lipo bullet? At this point, I want dependability and hopefully longevity. I realize sometimes ya get what ya pay for...well most of the time...but a tight budget requires me to ask. .

Pit-racer

iTrader: (4)

Yea, Ditto on what he said but using lipo and smaller words.

*1speedy

iTrader: (12)

I personally run Futaba BLS157 for steering and throttle with a Lipo but Radio post has a higher end "black" signature series servo that has good specs.

Here is a link, btw the spline is the same as Futaba.

http://www.absolutehobbyz.com/produc...ducts_id=14679



.

JLock

iTrader: (4)

I still use NiMH Rx packs and have not had any issues "burning up" servos. However, I did build a couple of 6v regulators to use if I had to go to a LiPo Rx in a pinch.

During the very short time I ran 8th scale offroad nitro buggy, I noticed that a lot of digital servos (no specific brands) did not like a lot of input (like we do in throttling). Digital servos used for throttle tended to fail at a higher rate than non-digital (analog) servos used in the same spot. So, I started using good analog servos for throttle and a strong, high torque & speed digital servos for steering. If you look at it, we don't input as much on the steering side of the ledger than we do on the throttle side. By doing this, the last servo I had fail on my was in 2010.