Charge contoller replacement needed or a luxury?

Re: Charge contoller replacement needed or a luxury?

According to the C40 display, the most Ah I have seen would be about 80 during June and July.

Most of the time, my electrical loads are such that 30-50 Ah would bring the 12 GC's to float.

These batteries have lasted since 1996 but have pretty much given up the ghost as of this season. 19 seasons (6 months per year) is nothing to sneeze at.

So, in answer to one question, I'm guessing I would normally have kept discharge to about 10% of nominal capacity give or take.

Probably what saves the batteries is my propane fridge which I figure takes a lot of the load off of the system.

I suppose 4 L16's could be another option but I'm aware that adding a second bank of four at a later date is not recommended.

As to generator use, never until this year when the batteries started gassing and losing capacity. Last year, the hot tub pump was left on overnight and that probably ran them down to nothing, otherwise they may well have lasted another season or two.

Re: Charge contoller replacement needed or a luxury?

Answers to some of the questions from posts # 9 and 10:

My C40 is set to charge to 28.0 volts and float at 27.0.

When I initially had an AMPS on/off controller, some water had to be added monthly. With the C40, water needed to be added only once a year; probably 2oz/cell.

The batteries are now pretty much shot (cases starting to bulge, lots of corrosion on the connections that never happened before, lower capacity large voltage swings) and will need replacement.

"Bulk" charging never really existed with a maximum sustained charging current of 13-15 amps, but the batteries typically would reach float (two hours at 28 volts at the C40) by days end at which point the Trace would limit the charge current to between 0 and 1.0 amps.

When I originally set up the system, I purchased 7 fried Arco's from some decomissioned solar farm (in Arizona I was told) each of which generated Voc of about 5.5 volts. These 7 are in series (generate around 42 volts open circuit) and paralleled with 4-65 watt Astropowers in series parallel configuration.

Obviously, this worked for many years but makes me reluctant to go MPPT in that in a series string, I can't imagine this collection to have similar ampere outputs. With PWM I don't think this matters as much.

I checked out recent solar panel prices and am simply amazed at how cheap they have become compared to what I had to pay in the 90's.

So, as suggested, I could add another two panels and get up to 1.0kw or so and maybe go with less battery. I m reluctant to have less capacity as before (660ah) and hence the thought of getting 740 Ah of L16's.

Just this evening, I compared the energy consumption of a recently purchased Samsung french door fridge and found it to be only about 30% more than a 19 cubic foot Sunfrost. If so, it should be possible to run a newer electric fridge from my system to get away from the problems with propane.

But after reading several times that new batteries shouldn't be added to older batteries, my biggest decision is whether or not to get 4 L16's or 8 to provide cloudy day capacity.

While the panels are cheap, there is only so much free space on the roof.

And one last question: Scrap the existing array described earlier or just add to it?

(As for the hot tub, it is cedar, 6' diameter and is heated by an external stainless steel boiler similar to a Chofu, but far better quality. Could post a photo if deemed of interest)

Re: Charge contoller replacement needed or a luxury?

Wow, sure learned lots in the last few days! I never heard of Canadian Solar panels, but now can see how much cheaper panels have become. From what I can see, I should be able to replace what I have with somewhere between 1000 and 1500 watts for around $1000-$1200 plus shipping and still have space on the roof. Groups of two or three panels would still be in a liftable weight range as compared to a monster single array.
My existing pwm controller would still work with an Outback mppt for a future upgrade. I should still be able to get maybe 75% efficient battery charging due to my 24 volt battery configuration (not as much loss as those trying to charge 12 volt banks with ppm).
One definite advantage I can see with the mppt would be the supply voltage from the panels. In future, I could put the two array groups in series to boost Voc to around 60 and drop this down to 24 volts at the batteries. This would reduce losses in my supply line which is doubled up 8 gauge (giving me 6 guage equivlent) but about 65' to the batteries from the panels.
In any case (I'm still leaning towards 8 L16's) I can't see any damage occurring to the batteries even with my exisitng array so long as I can keep them charged to float.
As always, it comes down to buying what I can afford, bit by bit.

Thanks all to your suggestions and advice!