Date: Tue, 19 Nov 2002 11:49:26 -0700
Reply-To: Larry Chase <lchase@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Larry Chase <lchase@ATTGLOBAL.NET>
Subject: Electrical Consumption & Battery Recharge Calculations
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Electrical Consumption & Battery Recharge Calculations.
Based on all the input I got from List Members and helpful
Product reps at Optima, Crutchfield, Arizona Solar and Uni-Solar ....
This is an overly simplistic, but I hope useful summary.
Please challenge and suggest areas where my calculations may be off.
My Usage Assumption One:
Power Consumption ... (running off batteries only)
Per night = 20 amp hours * 12V = 240 watts per night total
Details,
18 LED Strip Light = .180 amps per hr * 3 hrs = .72 amps
18 LED Reading Light = .180 amps per hr * 3 hrs = .72 amps
LCD TV = 3amps per hr * 4 hrs = 12amps
Sat Receiver = 1amp per hr * 4 hrs = 4 amps
Misc Ghost Usage = .500 amp per hr * 4 hrs = 2 amps
Total per night = 19.44 amps or 233.28 watts
Recharging:
Solar Panels ... Two Uni-Solar 32 Watt Flexible Panels @
64 watts * 4 hrs per day = 256 watts
http://www.solar-electric.com/usf-32.html
Solar Charge Regulator & Controller: ....to be determined
Battery:
OPTIMA D750 Yellow Top Deep Cycle Battery = 2 (one is the starter
battery)
Reserve Capacity - Minutes: 124
Capacity (C/2 rate) - Amp Hours: 52
Capacity (C20 rate) - Amp Hours: 65
Total Amp Hours with 2 batteries = 104
Needed Amp Hours = 20
Extra Capacity = 84
Battery Charger: (to be used when 110V is available)
Deltran Battery Tender Charger designed for Optima Batteries
110 VAC Optima/Hawker / 12V 6amp
http://www.batterystuff.com/battery/deltran/onboard_charger.htm
Notes:
1. Second Optima is starter Battery ... also backed up by a Jump Starter
PowerPac
http://www.batterytender.com/catalog/product_info.php?products_id=36
3. Largest Uni-Solar Flexible Panels available are 32 watts output.
4. Usage estimates are based on my own needs calculations on actual
products I plan to use.
My Usage Assumption Two:
Running the Vehicle Stereo instead of the LCD TV & Sat Receiver
(not included in the above assumptions).
Average Power Consumptions for a Vehicle Stereo System (actual system
not purchased yet)
CD/Receiver = 6-10 amps per hr
Satellite Radio Receiver = .500 amp per hr
Amplifier = 10-20 amps per hr
The mean average is approx 23 amps per hr.
The nightly usage would be 23amps - 4 amps (LCD TV & Sat Rec)) = 19
amps per hr additional
The extra battery capacity of 84 Amp Hrs would enable the stereo to be
played for approx 3.65 hrs.
But the problem is recharging the batteries.
You would need to recharge 104 amp hrs / 1240 watts instead of 20 amp
hrs / 240 watts
The current Solar assumptions will get you 20 amp hr / 240 watts,
leaving a delta of 84 amps / 1000 watts
If I assume a 75% efficiency on the VW 90 amp alternator then I would
need to run the engine approx 1 1/4 hrs to supplement the Solar.
Disclaimer .... none of this assumes three staging Charge rates/times
required by Deep cell batteries. But have built in a large "Fudge
Factor" in excess of 15% to compensate for this.
In conclusion.
Solar will recharge "Usage Assumption One UNASSISTED.
Solar plus 1 1/4 hrs of the VW Alternator will recharge "Usage
Assumption Two".
The actual system will also be supplemented by a small 1000kw Honda Gas
Generator.
But that's a whole other discussion.
Comments Requested
Hitting the Trail Soon,
Larry Chase
Email: lchase@attglobal.net
Web: www.roadhaus.com - Under Construction
What: The Great North American Road Trip
When: 01.02.03
How: RoadHaus - 1990 2.2 L VW Westfalia Syncro
Today: Mesa, AZ - 12V Stuff
From: Mesa, AZ
