hum noise from hitec HS645 high torque servo.

[tony]

Group, I use a hitec HS645 servo for my Jib trim. when it gets slightly loaded by pulling on it, (simulating a load on the jib sheet from the jib boom) the servo hums constantly. Do any others have this and does it kill the battery life substantially? I was testing my new boat the other day and went through 2 battery packs in 1 hour. I put it down to an improper charge on the batteries but now i'm reconsidering this theory. your comments and experience is much appreciated.

best,
tony 82

[Rick West]

Any servo under stress will hum. When they hum they are using energy. The jib servo is under stress continuously because it is the sheetline servo for the jib, not the winch.

You may have missed it and it is just my experience; I had three of these servos fail to heat in three years in my travels. I canned them and moved to digital.

Others have good success with them but I do not trust them.

The answer to you question is yes, they will hum under stress. I think all servos do.

...94

[tony]

thanks Rick.

[Chuck Luscomb]

Hi Tony,

Strange that you mention that about the 645.

We just recently sailed in Newport and I loaned out my second boat to a new sailor. Both my boats are set up the same way. Both have RMG's, both have 645's for rudder servos. The jib trim servo's are different. One is a 645 and the other is something light like a 311 that I had on hand.

The boat that had the light jib trim servo went through batteries like crazy. The breeze was blowing about 12kts or so. The boat I was sailing did not use up batteries.

I thought it might be the RMG because the boat kept loosing sail trim but not rudder. This turned out to simply be the low voltage fail safe on the winch.

I am going test the amperage load of the jib trim servos on each boat to see how they differ. The only thing that can be causing it is the jib trim servo trying to stay in place and fighting the load of the jib.

Back shortly,

Chuck
#84

[bigfoot55]

Tony- mine is a HS645MG and as you know, no problems. Could be a bad one.
Tom

[Rick West]

Re the power consumption:
It would be my reasoning that if a servo is getting warm it will draw more. Additionally, if the board is drawing more power than usual the voltage will drop and when in high load conditions the voltage will drop further. This was learned in NZL in winds over 12 knots. A battery at float levels around 6.4 did, at times, cause the winch to lock out at a broad reach position.

Three failures in three years along with the Phantom in the Bilge was a wall for me on the HS645. I am a serious competitor and cannot affort that kind of failure. The refit of fall 2006 I installed the FUT 9350 digital for NZL and it is still on the board I am using today. I did NZL to over 20 knots, Charleston and Newport, all what I feel was heavy air.

I have learned much about power draw when all is under stress. I am very happy right now becasue I feel I can depend on the servos. Now the damn RX is another story that will be address. Newport was the first regatta in 8 years I had a RX on the board than on the underside of the deck. I got caught. No more on both, I hope.

...94

[Chuck Luscomb]

Hi Tony,

I tested both the 311 and the 645 in my boats. The 311 drew .25amp at stall and the 645 actually drew over .5amp at stall. No load, both drew next to nothing but given that the jib trim servo is constantly fighting the load of the jib in a breeze, you will see this servo draw more.

I did not test a digital servo to see if there is a similar load curve.

Chuck
#84

[tony]

thanks guys for your comments. I'm going to test some servos tomorrow pondside. My previous boat has futaba servos and has been rock solid reliable in the meanest conditions. probably go back to futaba. i'll get back to you soon once the problems solved.

best,
tony

[Chuck Luscomb]

Hi Tony,

Don't throw Hitec out with the bathwater! I have been using Hitec for years as well as Futaba and never have I seen this issue until two weeks ago.

In my rather basic test of these servos, I was not able to determine how much torque I was applying to get the results I was seeing. Stall amps are just that. When the servo stalls or stops moving. I was pushing the servo past stall which produces a much higher reading.

Chuck
#84

[bigfoot55]

Tony- my boat started eating batteries and winch started going half way out erractically at Mationals and last few times I sailed it. Thought it might be black wire or something. Found that the 645 now has a very loud humm when any. even light load is applied. Could not hear it at the pond. Replaced it and did not have the same hum. If we sail Sunday, wind should be up and we'll know if it was the 645 trim servo. Had that servo several years, the humm is new. Tom P