Tim F's posts

Ken,

Thank you for the very helpful and informational response. It helped confirm a few things except the charging rate.  That is far longer than I had ever anticipated to recharge the battery. Of course, I won't have all the lights and so forth going at once, but I would rather "oversize" my system as quickly as possible so I can at least enjoy a few days of amenities.

Is a DVM better than a hydrometer at determining when a battery is at a particular % of discharge?

Also, I guess there's 1 thing in particular I'm not getting. It is the CC and LVD issue. Is there a CC with a "built-in" LVD that you can use for both functions at once? I just read a paper from 1993 that implied that they were using such a device way back then. And the manufacturers literature implies as much, too (excepting the C-35).

I'll stop with those questions as I feel I've used up my quota of Q&A time.

Thanks for the all the help. I really need it.

Tim

T.A.S.,

Just read some of the papers and still reading others. Very, very helpful. And so far not too technical as I would think coming from Sandia Labs, etc.Thanks for posting the links.

Tim F.

OK, where do I start. Bought a small, week long (at most) cabin/RV to use for a few weeks a year.

It came with:
42w Uni-Solar panel (yeah, I know...)
1 - 12v marine battery, 105 Ah
1 - ETS brand 16 amp charge controller w/o LVD
1 Fuse (20amp?) between panel and controller
1 - 2300w generator

runs at most if all were on:
6 - 12v auto bulbs, 2 - 12v fluorescent lights

plus RV stuff incl:

12 - 12v lights, 1 - 12v fan, 1 - 12v Shurflow pump, 1 - propane Refer (only electronic monitor), 1 - RV furnace blower, 1 - 120v sump pump for well off of generator (23'deep)

So, just a few questions:

I just bought 2 - 6 volt GC batteries (210ah ea.) and will run in series for 12v. That means 210AH / 2 = 105 usable AH @ 50% discharge

1) At 50% discharge how long will it take, theoretically, to charge the batteries to full volts (13.7?) with the 42 watt panel (say 4 peak hours/day)?

2)  Second, if I didn't destroy the battery when last up there, it has 105ah at full charge (52.5Ah at 50%), then if I connect it in parallel to the 2 new batteries, will I be decreasing the 100% Ah to 105 from 210 for all 3 batteries due to the lower Ah of the marine battery? And thus lose 105 Ah?

3) Third, can (should) I even PUT a 12 volt, marine battery in line with the other 2 - 6v batteries (even though they are in series = 12 volts) to "increase" battery capacity?

4) I want to get an 85-100 watt panel (Kyrocera, etc.)? Can I use the charge controller I have to hook up both panels (or even just the 85-100 watt panel?

5) I would like to get a new C-35 or SunSaver 20 amp CC. Would that be a wise choice?

6) If I get multiple panels and the voltage = say 36 volts, will the CC take that voltage and process it down to 12 volts, so as to not mess up my battery bank?

7) If I run a battery bank at 24 or 48 volts, how do I run 12 volt loads off of that? Do I need to step it down to 12v and if so how do I do that?

Finally, (sorry), If I get a C-35 or SunSaver 20, if I have the panels go to the CC, then to the battery and then  go from the battery to the load, how does the LVD cut the power off when the battery bank  gets too low? Or do I have to put an external LVD between the battery and the load?

Whew......Sorry about the long post but I have been reading tons of stuff (on-line and in books) and as it usually goes, the more you learn, the more you realize you don't know. I'm simply trying to not have the lights, etc. go dim after 2 days of no sun ( and that happened!).

Thanks,

Tim