A few power/electrical related questions

Nov 11, 2003 7 Replies
S

I appreciate anyone who can provide some insight on a few questions I have.


  1. Does anyone have any good or bad input about Coleman power inverters?
  2. Here's the scenario for this question: A 2000 watt continuous / 4000 watt peak power inverter powered from a 12 volt car/motorcycle battery. Powering a garage door opener, roughly 700 watts / 1300 peak, used approx 4 times a day at the most, but more likely twice, once for up and once for down during the summer months. Also powering a 1300/1500 watt ceramic heater for about

15 minutes every hour during the winter months. In order to keep the battery charged, I plan on using a solar charger. Therefore, my question is, what type of solar charger would you recommend to maintain a proper charge to eliminate discharging. faster than it can charge?

I had a third question but can't seem to remember. Perhaps when it comes to me I will ask.



Any other input, help and/or suggestions are greatly appreciated.



Thank you


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K

have.

watt

Powering

during

battery

What is the period they specify for 'peak' power loads? You are up at (or probably over) the continuous power rating with both devices on, so if the time period is too long you risk losing the inverter.

For power usage, assuming it takes a minute to open/close the door, and you do it four times a day (being conservative), you'll use in the order of

50Whr per day. For the heater though you use in the order of 1300x1/4x24 = 7.8kwhr per day. That's without even worrying about inverter efficiency. Since > 1/2 the day is dark during winter, you need a BIG solar array. You cannot realistically expect to do that economically with a domestic solar power system (even for summer), unless you've got loads of money and don't care how it's spent, in which case give it to me instead. :-)

Ken

to

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S

Keep in mind.....I don't have to use the heater as much as I stated. Perhaps a lower wattage heater or less time it is on will help. This is why I ask for suggestions as well.

Thank you

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S

No. The peak power for a brief start up for the opener is 1500 watts top, which falls under the continuous wattage of the inverter. Therefore, that one is safe. The peak wattage for the heater is roughly around the 2000 wattwhich also meets the continuous of the inverter. The average peak starting time is 2 to 4 seconds which is sufficient for both.

you

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P

The 1500 watt heater will draw about 135 amps from the battery. Running 1/4 of the time, it will consume 810 Ampere-hours per day. during the winter months, you'll only have 8 hours, or less, to replenish that (and battery charging is not 100% efficient), so your solar panels will need to deliver well over 100 amps to keep up.

It is widely recommended that batteries should not be discharged below

50% to obtain a good lifetime, so you'll need about 1000 ampere-hours of deep-cycle batteries to handle this load.

Using battery power for heating is a Bad Idea. Correction: using battery power for heating is a VERY BAD IDEA!!

I suggest you consider an oil or gas fired heater, rather than electric.

Running the door opener from battery is probably practical, but I'd suggest something larger than a car battery, as you'll be drawing around 100 amps each time you operate the door (although only for a minute or so at a time). I'd suggest a pair of 6 volt "Golf Cart" batteries (Trojan T-105 or equivalent - 225 AH). If you operate the door four times a day, you'd only consume about 7 AH per day, so a fairly small solar panel should be able to handle it.

Peter Bennett, VE7CEI new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca
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S

Don't use a car battery. Deep discharges will kill it quickly. Use a deep-cycle battery, such as an RV house battery.

It will be difficult and expensive to run an electric heater from a solar-charged battery. Look for another source of heat.

-- Steve
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J

The big question is: What chance is there that your solar cells will get covered with snow?

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S

Always a good chance but once the sun hits, it will melt.

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