remote fish tracking system

Re: remote fish tracking system

If you do not have enough solar power for the system, then you really don't need a solar charge controller. The job of the controller is to keep the battery from being over charged. If you do add enough solar panels / reduce loads -- then you will need some sort of charge controller to protect your batteries (and equipment from over voltage).

Simple charge controllers are not expensive ($100-$300). The "expensive" ones are >$500 each (probably one maximum for your system).

Solar panel wise, it would be very nice if the solar panel is "shade free" from at least 9amp to 3pm. Solar PV panels simply require full shade free sun to charge the battery bank (as your system is currently configured). If there is any shading at all the output will be significantly reduced. If the panel is in mottled shade--it will produce virtually no useful output.

You only know he estimated load for one of the two antenna systems... If the average load is 1 amp at 12 volts for the pair:

• 300 AH / 1 amp = 300 hours of storage (until the batteries are dead)

For your solar panel, it is probably 65 watts at 17.5 volts or so...

• P=V*I
• I=P/V= 65 watts / 17.5 volts = 3.71 amps

The solar panel for this time of year would collect 2.38 hours of sun per day:

• 3.71 Amp*Hours * 2.38 hours of sun (November) = 8.83 Amp*Hours per day of solar power

So, the estimated life of the battery bank would be:

• 1 AH of load * 24 hours = 24 AH per day energy usage
• 300 AH * 1/(24 AH per day load - 8.83 AH per day of solar) = 19.8 days to dead

Now, in real life--we really don't want to see the batteries cycled below 50% state of charge per day, and you should never discharge below 20% state of charge (80% state of discharge)--Below that, you run the risk of permanently damaging the battery bank.

And operating the battery bank for days/weeks/months below ~75% state of charge will dramatically shorten the life of the battery bank (batteries sulfate and lose capacity if they are not promptly recharged when cycled below 75% state of charge). Just a guess, but you only expect months or 1 year of battery life of life from a usage cycle when operated in your current setup.

Depending on your system's life (only operating a few months of the year for the next one or couple spawning cycles--for example)--then why not continue as you have been.

If the system is intended for 24x7x52 weeks per year for years/decade to come--then you probably need to figure out a more cost effective solution.

For example, say you go out once a week to recharge the battery bank with a portable genset:

• 300 AH * (7 days / 19.8 days of capacity) = 106 AH per week deficit (for November)

Battery rate of charge from 5-13% (rule of thumb for flooded cell):

• 300 AH * 0.13 rate of charge = 39 Amps

Get a good quality 40 amp charger and a Honda eu2000i genset:

• 106 AH * 1.20 (20% extra power to recharge) * 1/40 amp = 3.18 hours

Add at least 2-4 hours at gradually reduced (tapering / reducing current) until battery is recharged.

So, 5-7 hours per week plus 2 gallons of gasoline per trip... and you have 24x7 power for your setup.

In the summer months (4.26 hours of sun or more):

• 3.71 Amp*Hours * 4.26 hours of sun (November) = 17.1 Amp*Hours per day of solar power
• 1 AH of load * 24 hours = 24 AH per day energy usage
• 300 AH * 1/(24 AH per day load - 17.1 AH per day of solar) = 43.5 days to dead

Go out every and recharge every 2-3 weeks for 8 months of the year.

Or, same as above but skip the generator, bring out a second set of charged batteries and recharge the first set back at the shop.

I would suggest:

• Measure the loads. Need to know Amp*Hours / Watt*Hours used per day. If the power used over a 24 hour period (sometime more power, sometimes less) then you a DC Amp*Hour / Watt*Hour meter to measure the energy used over time.
• Define your service interval (week/month/year)
• Define your system life (1 season, one year, years to come)
• Define your costs (more panels in field, use cheap batteries and replaced often, use better batteries and more solar panels, vs more time in field with existing setup for recharging/swapping batteries, etc.).
• Do a couple paper designs and weigh costs vs security (Vandals/thieves) vs time of site. See what best meets your needs.

-Bill

PS: You should also know the length of wire run and gauge of wiring. Long wire runs, small gauge wire, operating at 12 volts nominal can further reduce panel output because of excessive wire resistance and voltage drop.

Also, the other use of a solar charge controller is to reduce self discharge by the solar panels at night... For a 12 volt battery bank, the self discharge of the panels is not all that great. For a 24 or 48 volt battery bank, you really do need a blocking diode, or a real charge controller (recommended).