Searching for appropriate Solar Charger

Almot wrote:

NinerBikes wrote:
Because the OP is running GC2 batteries, he will need an adjustable voltage solar charger that is programmable and capable of 15.0V bulk charge rate at the battery terminals to run in conjunction with his solar panels.

And fat wire, 10 gauge, and a short run of wire from the controller to his batteries, 5 feet or less.

The goal is 100% state of charge, not 97%, or 98%. Hard to do with 1 ah or more constant parasitic loss when the fridge is on propane and the circuit board is on constantly.

Adjustable setpoints means - a charger other than the one included with the kit.

1A parasitic loss - I think it's 1A, not 1AH 'cause 1AH per 24 hours isn't worth talking about - does make 100% SOC difficult, with 120W panel. It's all about energy usage. If you only use 30 AH in 24 hrs, then 120W panel would bring it up to Abs at upper 90-s SOC on a good day, and - if needed - would keep on pumping more amps than 1A parasitic plus 1 or 2A of some odd small load like fan or TV, until it's 100%.
Seems like the store run out of 120W kits - good. Didn't like it anyway :) ...

It is difficult if you rely solely on solar.

I like being diversified with my options, hence a choice of generators, Eu1000i, because I had it long before I had my travel trailer. Eu2000i, because it makes using the microwave feasible. Progressive Dynamics 9245, because the Eu1000i will run it, albeit in taper mode if the amps are too much initially for the Eu1000i in bulk mode, perhaps for a 5 or 10 minute span, then into bulk mode at 14.4V to do the hard part for an hour or two that the solar panel might not handle in a day of cloudy weather. When I picked the Honda Eu1000i up 5 years ago in near mint condition, used, for $350, solar panels per watt were an expensive proposition per watt. Price per watt has dropped a lot. It'll be a while before 12v batteries can run a microwave oven on a 21 foot travel trailer, pulling 1350 -1400 watts.

I suspect the 120W is the best, and most portable, for the size, for most applications. It's fine for me

NinerBikes wrote:
Because the OP is running GC2 batteries, he will need an adjustable voltage solar charger that is programmable and capable of 15.0V bulk charge rate at the battery terminals to run in conjunction with his solar panels.

And fat wire, 10 gauge, and a short run of wire from the controller to his batteries, 5 feet or less.

The goal is 100% state of charge, not 97%, or 98%. Hard to do with 1 ah or more constant parasitic loss when the fridge is on propane and the circuit board is on constantly.

Adjustable setpoints means - a charger other than the one included with the kit.

1A parasitic loss - I think it's 1A, not 1AH 'cause 1AH per 24 hours isn't worth talking about - does make 100% SOC difficult, with 120W panel. It's all about energy usage. If you only use 30 AH in 24 hrs, then 120W panel would bring it up to Abs at upper 90-s SOC on a good day, and - if needed - would keep on pumping more amps than 1A parasitic plus 1 or 2A of some odd small load like fan or TV, until it's 100%.
Seems like the store run out of 120W kits - good. Didn't like it anyway :) ...

Well, from my observation, it seems that this thread has depleted the inventory of 120W portable solar panels at Solar Blvd, as they have now removed the listing. Which means you can still get the 160W version instead, for a few bucks more. Or find someone with a lightly used 120W setup for sale.

If you go much higher in charging rate than 33% with low batts you don't get any constant amps at all because you are already on the absorption curve.

That is different in a way (it is sort of violent) from using lower amps but starting at a higher SOC where you also would be on the absorption curve right away.

I just prefer having a few minutes of constant amps, then see it taper instead of hitting it with a huge charging rate and getting a monster voltage spike to Vabs right off. Seems too drastic to me. Seeing at least a little constant amps at first makes me think everything is going the way it should.

So(14.8v) it stays longer in constant current but the 'curve' would be steeper?

I believe the point of the exercise is to find that a ~32% of C20 can get ya to 90% in 2 hrs, not its precision, but a tool.

"trend 'n tendencies" suggests laughing to the bank using 40% @ 14.8v, by reducing petrol consumption.

In the newbie popup/folding world, folks wanna get a 5A tender to use with their generator, simple math of returning 20-40 ah takes a long time.

red31 wrote:
took license with BFL13's data for us single 100 ah or less battery users to illustrate that 1A ticklers take a very long time.

Has anyone charted this when you bump the Vabs to 14.8 V or 15.0V, for example, for a pair of GC-2 Costco 6V batteries at 210 amps or 225 Amps? Not sure anymore what they really are.

Or how about for a Trojan T-1275 12V at 150 Ah's at 50% SOC, needing 75 AH to top it off to 100%

She cleans up pretty good!

took license with BFL13's data for us single 100 ah or less battery users to illustrate that 1A ticklers take a very long time.

Because the OP is running GC2 batteries, he will need an adjustable voltage solar charger that is programmable and capable of 15.0V bulk charge rate at the battery terminals to run in conjunction with his solar panels.

And fat wire, 10 gauge, and a short run of wire from the controller to his batteries, 5 feet or less.

The goal is 100% state of charge, not 97%, or 98%. Hard to do with 1 ah or more constant parasitic loss when the fridge is on propane and the circuit board is on constantly.

My ugly graph applies to solar charging too. Charging is charging. However, the charging rate with solar is quite low, so the graph may not show that low. Also I don't show the 90-100 part.

You are at 90% SOC at about 5 amps per 110AH of bank as you can see at the very bottom going across at 10amps. By the time you are at 3 amps per, you are near 97% SOC, and some people define "full" as when you are 1-2 amps per. (Not me! 98-99 is NOT 100!!!) Solar is more into the part above 90% so you get into that where you don't with gen/charger stopping at 90%

If your solar can do 10 amps all day on your 220AH bank, that is only a 4.5% charging rate. In real life your solar amps go up and down all day, so you have to assume some average amps for the charging rate. It all works out pretty much the same way in the end.

What is different with solar from generator/charger near the end is the way the IV curve for a 12v panel can also taper the amps as battery voltage goes higher, which is super-imposed on the battery SOC factor that tapers amps.

You don't get much of that IV taper in real life because your high set-point is maybe 14.6, well before the I falls off the cliff at 15v