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Note: Many sailors have switched to 5 cell, NiMh, rechargable batteries with great results. The packs can be sealed to keep water out, and typically offer 1600 to 2500 Mah capacity.

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AA  ALKALINE BATTERY LIFE IN VICTORIA RADIO CONTROL APPLICATIONS

BY: ROBERT L. ROWE, P.E.

[Editor's note: Robert Rowe: a retired mechanical engineer who has worked most of his 40 yrs in aerospace. He has a captains license and has fished or skin dived most of his leisure life. The Victoria is his first sailing experience. He can relate to the similarity in jet engine airfoil design and sail design. Seeing batteries being tossed out every race day, he thought skippers were throwing away batteries that still had 1/2 life left but could not prove it. His goal was to sail until the boat became out of control on a set of batteries.]

 Batteries are the heart of Radio Control devices and the purpose of this article is to share data that I have collected on Alkaline (manganese dioxide) batteries.  A lot of Victoria owners started with Alkalines and may have switched to rechargeable but keep Alkaline’s on hand just in case their NiCd or NiMh batteries suddenly die. 

.This effort is not endorsing any brand but if your interested in which is best, there are many sites on the web that you can draw your own conclusions. Table 1 shows some data that came from several web sites. However, I felt that data available did not represent Vic conditions so I chose to collect my own to determine how many hours one may sail. The objective was to sail day to day with a set of batteries until either the transmitter and/or receiver quit or drains the cell voltage limit to 0.75 volts, which ever came first.  Data from back-to-back tests were collected with two sets of batteries and found the curves plotted over each other. 

RAYOVAC Maximum’s were selected for their less weight and the price was right ($10.00 for a 24 pack in K Mart.).  As a word of caution, not all non-rechargeable are Alkaline.  For example, the RayOVac HEAVY DUTY are Zinc-Chloride’s which are less weight, provide about 1/3 the life, but the price is not that much less as compared to alkalines.

TABLE (1)

AA Alkaline Battery Data    
  WEIGHT LIFE*
BRAND GRAMS HOURS
Energizer, LR6 23 18
Duracell Coppertop, LR6 23.8 19
RayOVac, Maximum, LR6 22.9 19
RayOVac, Heavy Duty, 18.4 7.7
 

REF. WEB SITES:

   
www.energizer.com    
www.duracell.com    
www.rayovac.com    
     
*  SHUTOFF  @ 0.9volts, 10ohms resistance    
     

Build-of-material HiTec Ranger II controls were used except the sail servo was a Futaba S3802. To measure voltage, I used a digital multimeter.  I sail with the Palm Beach Gardens, Florida Victoria squadron and typically we sail about 1 1/2 hrs on Sunday’s and Wednesdays. The data was collected between January and April of 2002.  The winds during were fresh in the 8-12 mph range  with wind gusts exceeding 15mph. These conditions are very demanding on the receiver/servo batteries. 

Measuring across a battery that is not loaded, open circuit voltage (OCV), will give a higher reading than measuring closed circuit voltage (CCV) across the batteries when the switch is on.   Measurements of CCV and OCV voltages were made before sailing and then immediately after sailing and the total time that the transmitter switch was on.   The transmitter total voltage was measured across the right upper and lower posts as viewed from the rear…cover removed and the receiver total voltage was measured (across the two smaller chrome rivets) at end of battery holder that has the3 chrome rivets.

All Pre-sail data was reduced to a single cell voltage and is shown on table (2) below.  The OCV is included for those who chose to measure voltage of batteries not installed.   Data were plotted using Microsoft Excel Chart Wizard program for both the transmitter data, figures (1) and the receiver/servo data, figure (2).  It should be noted that voltage recovers approximately 10% after resting between sailing days.

                                                             TABLE (2)

AA CELL DATA, PRIOR TO SAILING
           
  SAIL XMTR XMTR RCVR RCVR
Time, HRS DAY OCV CCV OCV CCV
0 0 1.61 1.53 1.61 1.59
1.42 1 1.46 1.37 1.47 1.45
3.03 2 1.41 1.34 1.43 1.4
4.42 3 1.38 1.3 1.41 1.38
5.59 4 1.36 1.28 1.39 1.34
7.17 5 1.34 1.23 1.36 1.33
8.34 6 1.32 1.17 1.34 1.31
8.95 7 1.3 1.16 1.33 1.29
10.67 8 1.25 1.03 1.3 1.25
11.84 9 1.18 0.97 1.26 1.19
12.35 10 1.15 0.96 1.21 1.15
13.9 11 1.13 0.89 1.15 1.06
15.34 12 1.08 0.73    

 The transmitter was still functioning at the end of 12 sail days (15 hours) down to 0.73 cell ccv and maintain transmission range of 120 yards. I concluded that the transmitter batteries could be safely used safely to 0.75 volts without any problems. .  During these tests, I noticed that the transmitter Red (idiot) light started blinking at ~8.1 volts (~10 3/4 hrs) but no problems were noted.

 
FIGURE (1)

The receiver/servo battery was functioning for ~13 3/4 hours  (11 sail days) but noticed the sail servo was lacking muscle and response.  However, the rudder servo was responsive enough with wind abeam to the beach.  The receiver/servo cell voltage was 1.06 ccv.  I concluded that the servo could function safely at 1.1 ccv in winds around 8-10mph.   I suggest, that you replace them at ~12 hours but save them for use in the transmitter.

Figure 2
FIGURE (2)


Victoria Class Secretary