Help with connecting servo directly to battery
 

I'm running an old Novak GTB esc that only has 6v on the bec. I'm also using a Hitec D645MW servo that is rated for 8.4v. My servo works good but is a little slow so I tried connecting the power wires directly to the battery at the deans connector.
The problem I'm now having is that upon hard acceleration or deceleration my servo jumps to the left for a fraction of a second. Is there a better way to be connecting my servo or a way to buffer it? Should I just be using an external bec?

This is on a 2wd 22sct, 6.5t motor, GensAce 5000mah 50c 2s battery.

Randy

Are you running a capacitor on your ESC? Wondering if there's a voltage drop causing this when the trigger finger is mashed.

Subscribed. I tried connecting my savox 1267TG direct to the battery wires, and had a similar issue.

Yes, the ESC does have a capacitor on it.

Thanks,
Randy

Should've bought a servo w/more speed.

How did you wire it? Did you connect both the power and ground wire to your battery and leave only the signal wire to the receiver, or did you only run the power wire to the positive battery cable and leave the ground and signal wire connected to the receiver?

your going to add a glitch buster inline with servo to deans. that will fix the problem.might take 2 .racers edge makes them and a few others. gl...https://www.amainhobbies.com/novak-g...18waAs4v8P8HAQ

I ran both servo power wires to the deans connector, only the signal is connected to the receiver.

I had considered the glitch buster but haven't picked one up yet. If I've already got a capacitor on the ESC which is parallel to the + and -, are you suggesting putting one in series on one of the servo power leads?

My suspicion is that a glitch buster is not going to help in this scenario. A glitch buster supplements a voltage sag coming from the BEC when running the servo directly off of the receiver, since you are connected directly to the battery I do not believe this is the scenario here. You can also try running the ground wire back to the receiver and only running the power wire to the battery to see if it makes a difference. Again I'm speculating here, but generally a capacitor helps with a "brown-out" which is caused by a momentary loss of power, it doesn't sound like that is what is causing you issue. The symptom of a brown out is usually a loss of control.

a glitch buster attached to the+/_ wire going to the servo will prevent voltage sag making servo slower...gb will make servo operate at its speed..?did you program this servo to run at 8.4??in above post that is not how gb will be run please follow my information.

No I didn't program it. It's a 6v-7.4v servo but is rated to 8.4v.

To make sure we understand each other here. My ESC already has a large capacitor attached to the + & - connections. My servo is connected to both + & - at the deans connector. If I add a glitch buster to the servo, it would just be adding another capacitor in parallel to the one already there. Unless I'm missing something I'm not sure how that would help unless that added capacitance in parallel helps overcome the lag.

I'll give it a shot, and I'll also try and connect the ground at the receiver to see if it helps.

Thanks guys,
Randy

Exactly. When you run a glitch buster in the receiver, it is supplementing the voltage provided by the BEC to the radio equipment/servo since it is a separate circuit all together. Since you already have the servo connected to the battery this is not your scenario, I assure you that the servo is not pulling enough power to make your battery voltage sag, the power system pulls quite a bit more power than a servo.

Well as I suspected the extra capacitor did nothing. I tried connecting the negative to the receiver and the positive to the battery and my esc was very unhappy. If I hit the throttle, it cogged and skipped so hard I thought it was going to strip my gears. I'm done experimenting before I fry something. I'm just going to get a 7.4V BEC and be done with it.


Thanks,
Randy

BEC is the proper way to do it, thank you for the follow-up and letting us know the results.

Do you have any high C rated batteries?

Capacitors also come in various flavours - large does not neccesarily mean good because like batteries, capacitors also somewhat have a cap on the amount of current they put out. Capacitors should also be used in parallel with voltage sources - placing the negative on the RX and positive on the battery seems a bit odd to me.

Capacitors in parallel effectively lowers the ESR (equivalent series resistance) allowing more current to be discharged from the capacitor bank and in doing so reducing the voltage sag you may get from a very high and sudden power requirement (can replace with sudden acceleration). Try adding another capacitor in parallel with the one you're using at the moment. I see folks out here try to get around lower C rated batteries by using multiple capacitors e.g. I'm running a super cap and electrolytic cap bank in parallel connected to the +/- of my ESC to help the battery out.