So, lets say you have a 50w TV and you want to use it for 2 hours. 50w x 2h = 100watth
Then you have 4 12w light bulbs that you run for 3 hours. 4 x 12w x 3h = 144watth
Add them up
100wh + 144wh = 244watthours
Now we need batteries to run all of this. Assuming that everything is 12v we need at least 244 watthours worth every day, but you should always have much more than your daily allowance in order to keep your batteries in good shape.
224watthours / 12v = 18.7ah
Seeing that we need about 19ah, that 75ah battery you have would be an ideal start.
Now, as for the panels. My experience is that when everything is added up, I get roughly 4-5 hours a day of rated wattage of my panels. So,
224 / 5h = 44.8
If you have a good source of sunlight, 50 watts of solar should recharge your battery each day. I would advise you, however, not to get those garbage HF panels. They are cheap because, well, they are cheap. Thin film panels are tempting because of their initial low cost, but deteriorate quickly and my own have rarely ever seen 1/2 their rated wattage.
I disagree that they are garbage, in the winter I've seen more than their ratings. It is possible you got a bad batch. Another long time poster (NothingToLose) has gotten bad ones and merely had them replaced.
Cheers;
Bruce S[ Parent ]
Maybe the HF ones are of higher quality than this? I was just making a generalization based on my own experience and others who have experienced similar results.
Myself, I just got a 30w crystaline panel and am MUCH happier with my array now.[ Parent ]
Hope I wasn't too rude:-)
Cheers Bruce [ Parent ]
As far as solar panels, amorphorous panels will probably never compare to poly-, or mono crystaline panels. I mentioned the HF ones for "starter" purposes, they matched almost exactly wattage-wise the charging you'd need for what you have, and I'm familiar with them (have a set). I've had them about 17 months now & no problems (except the crappy controller). In fact, I'm very close to getting them on a new "tower" on a semi-automatic 2-axis tracking mount! Hopefully within a week if everything goes right. Wish I had a working camera to post pics, but that "fix-it" job is way down on the to-do list!Rural McG[ Parent ]
There are ghurd's controllers if you need a fine grain approach to charge control (adjustable dump load controllers). Also, the better quality charge controllers have a charge cutoff which is variable. I would be hesitant using a charge controller which isn't made (or modified) for use with nicads. An adjustable constant current constant voltage power supply, used for electronics, would be better than a cheapie lead acid charger. If you had one of these, not only could charge them in a pack, but you could test each cell individually with controlled charges and discharges (using a large resistor) and match the similar capacity ones in strings (if you were doing 12v)
Those cells look alot like the bb600 spec ones EV people are using in their cars. There's even a yahoo group dedicated to them..
On the fieldlines (this) site is maybe some of the best info on wet cell nicads (on the whole web) if you want to search you will find the good stuff. Maybe search using google instead of the in built search function as it works better. Some of the info posted above is not very accurate to the care and attention these cells deserve. As looked after they should last a long time. Just don't keep them in the same company as PbA batteries![ Parent ]
