ship's power...what's the correct voltage?

[Les Ervin]

I recently borrowed a boat from someone. I'm new to RC boating but am a competitive RC airplane pilot. The boat came with a 7.2V pack but from my experience with aircraft 5 cells (6.0 V) is the maximum number of NiCd or NiMh cells a person should run the RX and servos from. This pack has 6 cells. Any thoughts? I should also tell you that when I move the sail winch the rudder servo oscillates briefly and then re-centers.

Les

[greerdr]

What reciever? Are you using an RMG ? (you should)I run a lot of volts + amps into my RMG (it will handle 9 volts) and have almost no problems.Use a voltmeter and know where you are.

R.C.Greer

[Les Ervin]

Since my post above I have discovered that my boat has the 2 channel futaba receiver, pn: FP-R122JE and has what is called a BEC (Battery Eliminator Circuit) which is really a voltage regulator that allows the receiver to operate at up to 8.4V. So that is why it is OK to run a 7.2V pack.

[PegLeg]

Les

The 8.4 rating on the receiver is for a max. anything less is OK. Most servos (aircraft) have been operating and rated for 4.8v (4 cell) due to the desire to minimize weight.

With larger sail craft where weight of the batteries is less of a factor but the power needs are higher we seem to have drifted to 5 cells (6v). The added voltage gives higher torque and faster speed, the added battery weight usually is placed low for the effect of added "ballast".

Still there are trade offs. I use a 2500 Mah Nimh pack (5 aa cells) in light conditions and a 5 cel 4/5a (4000 mah Nimh)heavier pack in heavier air.

My recomendation is that you worry less about the voltage and concentrate more on the amp capacity of the cells. That is where the "time on water" will come from. Incidentally using the 2500 mah pack I get a full day of racing in most winds.

Good luck

[yachtie]

Down under in NZ I am using 3300maH 7.2V NIMH Sub C 6 cell car racing batteries that weigh about 320 grams (just over 11oz). These have seen use of 28 races over 2 days without recharge in NZ C rig conditions (US Storm)and a few weeks back a 28 race 2 day event in A and B (US C) and then another 1/2 day 4 weeks later without recharge.

I know this is abuse by not recharging [;)] but I have 1 battery I am deliberately running till it "dies" and have 2 spares fully zapped and ready in the wings. I am doing this and noting the use to see how good they really are as IMHO most people recharge after use and I do not think this is necassarily the best for these type of batteries.[:0]

The weight is not much of an issue to me as wher they are placed in the boat is dependant upon conditions.

Chris
NZL1 Longtack
NZL110 Swept Away NZL128 Ketch me if U Can