Recharging via generator and/or solar panels

[NinerBikes]

Since I have both options, from a power management perspective, since the 120W folding panel has diodes... must I only run one, or the other, and have a complete disconnect of the input from the solar panel while running the generator, or not? IE, do NOT run both at the same time? After all, this is DC current, not AC.

[NinerBikes]

WTF? That's almost 45-50% drained, running absolutely no other goodies, in a 24 hour period, for your basic cheesy group 24 battery with 75AH at 20 amp load? I think it's GC-2 time reaaaal soon.

pianotuna wrote:
Hi nine,

The usual number quoted is about 30 to 36 amp-hours for running the fridge on propane, and all other parasitic loads.

NinerBikes wrote:
How many amp hours do you think that fridge and propane detector draw in a 24 hour period?

[pianotuna]

Hi nine,

The usual number quoted is about 30 to 36 amp-hours for running the fridge on propane, and all other parasitic loads.

NinerBikes wrote:
How many amp hours do you think that fridge and propane detector draw in a 24 hour period?

[RJsfishin]

Expensive ? Smoke the battery expensive !
When I got my first 100 watt panel, and waiting on the controller, I connected directly to a 1/2 a$$ed.....1/2 charged 20 AH AGM battery, and in less than an hr, the whole carport smelled like battery acid. Won't do that no more !!

[NinerBikes]

christopherglenn wrote:

Where things get exciting is if you are closer to 90% SOC, then several hours of clear sun can get expensive.

Expensive? please elaborate.

[NinerBikes]

christopherglenn wrote:
Not much. The 120 watt panels at 17.2 volts generate just under 7 amps, 225 AH @ 75% you are down 56 amps. In theory you will need 8 hours of direct sunlight just to fill the bank. With the fridge and propane detector running at the same time you are likely closer to 10 hours. On a cloudy day you may be seeing 30% output - which doesn't matter, as there isn't 10 hours of daylight anyway.
Where things get exciting is if you are closer to 90% SOC, then several hours of clear sun can get expensive.

How many amp hours do you think that fridge and propane detector draw in a 24 hour period?

[doughere]

I have a wall mounted Volt and Amp meter installed, so I have a pretty good idea of what's going on.

With 120 watts through a controller, and a 100 watt panel un-controlled my 2 GC's voltage only gets into the 15 volt range when battery is close to 100% and un-controlled panel is facing bright direct sun. Unless you were close to full, you aren't going to run into problems. If you were to leave for a day, you might briefly over-charge; the sun will only be directly on panel for a short time. I wouldn't worry about it.

I have a controller on the 2 60 watt panels as they are fixed on the trailer. The 100 watt panel (not controlled) is portable, and used as needed.

Regards,
Doug

[christopherglen]

Not much. The 120 watt panels at 17.2 volts generate just under 7 amps, 225 AH @ 75% you are down 56 amps. In theory you will need 8 hours of direct sunlight just to fill the bank. With the fridge and propane detector running at the same time you are likely closer to 10 hours. On a cloudy day you may be seeing 30% output - which doesn't matter, as there isn't 10 hours of daylight anyway.
Where things get exciting is if you are closer to 90% SOC, then several hours of clear sun can get expensive.

[pianotuna]

Hi nine,

Bypassing the controller will do nothing to improve charging.

Bypassing might, in theory, if there is a break in the clouds, burn out several many control boards--for the fridge for example. You really *don't* want to exceed 15.4 volts.

[BFL13]

There is no difference between direct and with PWM controller until the controller starts controlling as it nears its Vabs set point.

So in that scenario, no diff. You won't get to the set point voltage either way.

[mena661]

NinerBikes wrote:

If I bypass the controller, and run straight off the set of 120W panels on that cloudy day only, what's the worst case that can happen running straight from the panel to the battery on that cloudy day?

Voltage will probably be low anyways from the clouds so more than likely no problems.

[NinerBikes]

OK, next power generation management question.

Assume I look at the weather forecast, and it's going to be cloudy most of the mid day... and I'm looking at getting maximum efficiency our of my measly 120 Watt 17.2 volt portable solar panel, and I am at 75% OC of 225Amps with 2 GC2 batteries.

If I bypass the controller, and run straight off the set of 120W panels on that cloudy day only, what's the worst case that can happen running straight from the panel to the battery on that cloudy day?

[doughere]

I have 2 60 watt panels tied to the battery through a small PWM controller, and have the charge wire from the truck connected whenever we're on the road, now and then need to run the generator leave all tied in. Also have a 100 watt portable panel without a charge controller, when I use it I just throw it in the mix too. Whoever has the highest voltage does the most work. Never had any problems.

Regards,
Doug

[pianotuna]

Hi,

You can run both. In fact, I charge with solar, converter, and alternator all at the same time.

Mena, I often see more charging from the converter (and/or alternator) than the solar panels--even though the solar charge controller output has a higher voltage during cold weather.

When I charge with solar and alternator the solar voltage is "dragged down" by the alternator. But when I charge with solar and the converter the solar voltage is NOT dragged down. If I charge with all three sources voltage is again dragged down to by the alternator.

I imagine if I had 600 watts of panels the opposite might be true, under perfect solar conditions.

[mena661]

You can run both but the charger with the higher voltage will put out the most amps with the other putting out less or none. BFL13 is the multiple charger king so hopefully he'll weigh in here.