Is 35 amps enough capacity for a charge controller? - Page 3 - Fiberglass RV


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Old 04-17-2016, 10:40 PM   #29
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Originally Posted by Bill Stanton View Post
Ransom,
One of the reasons why someone might upgrade their converter/charger is to pump more amps into their batteries like you stated, most of the old converters are only providing 6-8 amps on a old fashion taper charge (hummmm). Newer chargers offer much higher amperage with multi-stage charging that monitor the batteries much closer. They have much cleaner electric, no hum, less RFI and have provisions for AGM and Gel Cell batteries which charge much faster than lead acid batteries.

If you're boondocking a lot for extended periods and running a generator to charge the batteries, upgrading the charger and batteries will probably make sense. If you're weekending and vacationing in RV parks with electric why bother unless there is a problem.

I have no earthly idea why a Casita would need 55 amps? I guess it isn't hurting anything.

Bill

Bill
Bill, when boondocking I'll use solar, no generator. No gas either.

On Amazon the 35 amp Arterras cost more than the 45 amp units. Maybe Casita puts in the larger 55 amp units for marketing reasons, as their oem cost difference is probably negligable.

I have reviewed all published specs for available charge converters and not one has acceptable, truly smart charge parameters.

Iota, for example, does not do a constant
current bulk charge.

None of the conveter chargers let you match the voltage at each charge stage to that correct for your battery.

To save cost these controller chargers simply put the battery on the same circuit as the supply for the load, so they cannot sense what is happening to the battery, so they don't even know what charge parameters to use when. They just guess, set time limits, set fixed voltages for each stage for given class of battery (flooded, marine flooded, renewable energy deep cycle-a good choice for these trailers, AGC, gel).

So we unknowingly lose a year year or two of battery life.

I think there is a much bigger market for the solar chargers, so in that category there are some good options. Also, the solar power systems users are often more technically savvy and know what to look for/demand.
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Old 04-17-2016, 11:59 PM   #30
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Ransom, how do you plan on having hot water for showering or cooking while boon docking? We have a generator and only have to run it for about 15 minutes to have enough hot water for the two of us to take showers. I haven't looked into the feasibility of using an inverter to run the water heater, though we camped with "beetlefreak" (FGRV member) this winter and he ran a crock pot off his batteries that were being charged by 400 watts of solar panels.
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Old 04-18-2016, 12:52 AM   #31
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Ransom, how do you plan on having hot water for showering or cooking while boon docking? We have a generator and only have to run it for about 15 minutes to have enough hot water for the two of us to take showers. I haven't looked into the feasibility of using an inverter to run the water heater, though we camped with "beetlefreak" (FGRV member) this winter and he ran a crock pot off his batteries that were being charged by 400 watts of solar panels.
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David, if yiu arent using an inverter, what are you using with the generator to get your hot water?

In my case, butane burner stovetop to heat water for washing dishes if greasy, otherwise cold water is fine. Advanced Elements Solar Shower for outdoor or in Snoozy shower area for showers, or just sponge bath with bucket and mixture of cold and butane stove heated water.

I have lived 10 years in Mexico and cold showers, washing dishes with cold water, and cold water only in kitchen and bathroom sinks is common. Often I prefer a cold shower.

For the most part I'll stick to warmer climates since the Snoozy doesnt have the insulation for cold climates.

It seems that in a Snoozy configuration 10 days is an approximate comfortable limit for boondocking.

Beyond that the fresh water runs out, the grey water fills, the cassette toilet fills, time to go to the supermarket, the battery may get depleted if there are to many cloudy days (charging the battery from the tow vehicle could allow extending beyond ten days), but if there are reasonable periods of sunshine the battery can go indefinitely with the 100 watt panels.

The only significant draw on the battery is the fridge at 2.2 amps at 50% duty cycle.
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Old 04-18-2016, 01:07 AM   #32
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Ransom, when the generator is running it is producing 120 volts, which is what the water heater runs on. The two of us are able to boon dock for 5-6 days before running out of fresh water, and needing to empty the porti-potty.
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Old 04-18-2016, 04:34 AM   #33
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How does that work, Raz...?

If the voltage from the charge controller is, say 14.4 volts (bulk charge level), current flows through the shunt (resistance) and into (through?) the battery.

Trying ohms law, using 99 ohms for the shunt, you get i = .145 amps, and for shunt of 101 ohms you have .143 amps. But actual current at 100 ohms shunt is .144 so accuracy is .001 volt, or 0.69% accuracy, very accurate.

This math can't be right because the battery, at bulk charge, would draw many amps, and, you advise the current reading accuracy is much worse.

Can you explain?
You wish to measure the current entering or leaving the battery. You cut one of the wires and place a resistor between the two ends. As current flows, a voltage developes across that resistor. That resistor is the shunt and that voltage is proportional to the current by ohms law, I=V/R. The battery voltage will not be across the shunt , it will be across whatever you are connecting to the battery. The shunt voltage does in fact subtract from the battery voltage but by making the shunt very small the loss is negligible. A typical shunt voltage will be less than 1/10 of a volt. The Bogart shunt is designed to produce 1 millivolt for each amp flowing. That's 0.001 volts for each amp. Further, they seem to suggest you can measure down to 0.01 amps or 10mA. That's micro volts. I'm skeptical.

I couldn't find any accuracy specs on the Bogart site, but 1% of full scale is considered very good for volt meters.

All that said, some folks turn this into a hobby. They have fun building their system. Learn something new. Chat with others.... Nothing wrong with that.

Buying a $200 battery monitor so you can get the most life from a $100 battery even if the data were accurate?
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Old 04-18-2016, 07:18 AM   #34
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Originally Posted by Ransom View Post
I am wondering, Jon, what happens to the monitor readings if the converter charger and the solar charger are connected to to the battery at the same time.

Or, even if not connected simultaneously, how does the monitor handle power input coming from different sources at different times.

I suspect it will give unreliable results and that to avoid this it would be best to, in general, not connect the battery to the converter charger.

Just not sure if the converter charger loses any capability by not being connected to the battery when running on 120 volts.
If the shunt is properly placed (usually in the negative line as close to the battery as possible so that there are no connections between it & the battery), all current goes through it, whether it comes from the solar controller, the converter or the tow vehicle. The individual currents from the different sources add together, so the shunt sees the total. Same for all current coming out of the battery.

If you have a clip on portable solar panel & connect it directly to the battery, it won't charge through the shunt, so won't be recorded. To accurately keep track of the panel you would need to connect the negative from the solar controller to the non-battery side of the shunt.
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Old 04-18-2016, 09:03 AM   #35
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Our 30 amp World Friendship converter it has has 2 duplex AC breakers each a 20/15 split) and 4 DC circuits and a main 30 amp reverse polarity protection fuse. Right now the only DC I have is 2 led and 2 incadescent lights (will be replacing soon with LED's), a heng's roof vent fan and our water pump. On the a/c side we run our Emerson refrigerator, a 5000 btu a/c unit or a ceramic heater depending on the season, a toaster oven or skillet and a couple of phone charger. Our Fastair instant water heater runs on propane and 2 "D" size batteries for the ignition. Never blown a fuse or tripped a breaker.
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Old 04-19-2016, 05:44 PM   #36
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Our 30 amp World Friendship converter it has has 2 duplex AC breakers each a 20/15 split) and 4 DC circuits and a main 30 amp reverse polarity protection fuse. Right now the only DC I have is 2 led and 2 incadescent lights (will be replacing soon with LED's), a heng's roof vent fan and our water pump. On the a/c side we run our Emerson refrigerator, a 5000 btu a/c unit or a ceramic heater depending on the season, a toaster oven or skillet and a couple of phone charger. Our Fastair instant water heater runs on propane and 2 "D" size batteries for the ignition. Never blown a fuse or tripped a breaker.
so no microwave, right? you can use the toaster oven for toast, no need for a toaster, but how else do you use it?

is it really worth toting around? i also dont think a microwave is worth giving up the space (and weight, they are heavy), but am not sure how useful a toaster oven is (they are light and can be very compact, but how useful?

are they good for baked potatoes?

can you bake a souffle, maybe a small banana bread, an alternative to an oven?
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Old 04-19-2016, 06:41 PM   #37
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Originally Posted by Ransom View Post
so no microwave, right? you can use the toaster oven for toast, no need for a toaster, but how else do you use it?

is it really worth toting around? i also dont think a microwave is worth giving up the space (and weight, they are heavy), but am not sure how useful a toaster oven is (they are light and can be very compact, but how useful?

are they good for baked potatoes?

can you bake a souffle, maybe a small banana bread, an alternative to an oven?
It depends on the size of the toaster oven. I have a 6 slice toaster oven Cruisinart TOB 155 that I can only use when connected to a pedestal (it draws 17 amps @ 120V to start, although once it reaches the set temperature it varies between 0 & 10 amps). As to what I can cook in it - a 12" pizza, blueberry pies from scratch, baked potatoes, a roasted chicken or small roast, frozen burritos, etc. Just about anything that a RV oven can do. I can use in on a table inside, or take it outside on the picnic table in hot weather.

I'm also experimenting with a gas fired Volcano grill combined with a dutch oven to bake with when dry camping.

I carry a 2 slice 900 watt standard toaster that I can use with my 1000 watt inverter to make toast or English muffins when camping without hookups. No microwave...
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Old 04-19-2016, 07:37 PM   #38
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so no microwave, right? you can use the toaster oven for toast, no need for a toaster, but how else do you use it?

is it really worth toting around? i also dont think a microwave is worth giving up the space (and weight, they are heavy), but am not sure how useful a toaster oven is (they are light and can be very compact, but how useful?

are they good for baked potatoes?

can you bake a souffle, maybe a small banana bread, an alternative to an oven?
Ours is a Hamilton Beach located here: http://www.kmart.com/hamilton-beach-...&blockType=G10

We bought it because it has broil, bake and toast functions so we can heat up nearly anything we could do in a microwave (may take longer though) but can also toast bread, cook a pizza or casserole, bake a cake or brownies, etc. I could even broil steaks, chicken, etc. in it. I have never used a microwave much anyway except for reheating a plate or melting butter, tried defrosting meat but didn't like that too much. It takes less space than a microwave too...

Bottom line is I like the flexibility of it for the case of inclement weather where we might need to cook inside...
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Old 04-19-2016, 07:38 PM   #39
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Originally Posted by Ransom View Post
so no microwave, right? you can use the toaster oven for toast, no need for a toaster, but how else do you use it?

is it really worth toting around? i also dont think a microwave is worth giving up the space (and weight, they are heavy), but am not sure how useful a toaster oven is (they are light and can be very compact, but how useful?

are they good for baked potatoes?

can you bake a souffle, maybe a small banana bread, an alternative to an oven?
I toted a light weight toaster oven around in my Scamp. Did not take up much space. ... but due to the counter space it used up I also carried a separate toaster which was used far more often than the toaster oven. I mainly used the toaster oven for baking items for FG meet pot lucks ( I do not have a microwave) and for cooking in winter months. I reality I did not use it all that often and only used when plugged in. There are other ways to toast toast or bake items, without eating up precious power.

My new to me trailer has a propane oven and maybe due to the low/no power draw & the fact its not taking up counter space I may find I use it more than the toaster oven or it may be it ends up as just another storage place ;-)
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Old 04-19-2016, 09:26 PM   #40
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I toted a light weight toaster oven around in my Scamp. Did not take up much space. ... but due to the counter space it used up I also carried a separate toaster which was used far more often than the toaster oven. I mainly used the toaster oven for baking items for FG meet pot lucks ( I do not have a microwave) and for cooking in winter months. I reality I did not use it all that often and only used when plugged in. There are other ways to toast toast or bake items, without eating up precious power.

My new to me trailer has a propane oven and maybe due to the low/no power draw & the fact its not taking up counter space I may find I use it more than the toaster oven or it may be it ends up as just another storage place ;-)
we're a bit off topic, but its interesting and relates to current draw.

the key is to haul the minimum of appliances - weightvand bulk and have maximum flexibility.

I have found can bake banana bread and brownies as well as any oven in a 3 quart slow cooker (adjust for longer cook time). dont need baking dish, just use slow cooker crockery.

If i find it also works in a 2 quart slow cooker, i will buy one for the camper. easy way to bake, cook, cook rice, defrost, provide extra "burner" (heat soups, liquids hot water for iced tea/ice tea) when other burners in use. can haul one less burner. no need for regular oven or extra burner. and, you have a slow cooker.
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Old 05-30-2016, 11:28 AM   #41
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Is 35 amps enough capacity for a charge controller?

I'm 6weeks late here, but having set up the same exact system ransom is considering I'd like to add that the proper converter (really just a battery charger) is about one-tenth the battery's C20 spec. Has nothing to do with DC loads.

A good energy meter is necessary to monitor your electric use when boondocking. Yes the battery life is extended by stopping discharge before it gets too low but it also lets you predict when it's going to get too low.

I use a 30 amp iota smart battery charger, a 10a PWM solar controller with a 100 amp solar panel, a Victron BVM700 meter and two 6v 220ah batteries.

Note on the BVM700, it uses a 500 amp shunt and resolves current to 10ma, that's 0.01 amps.


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Old 05-30-2016, 01:16 PM   #42
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I'm 6weeks late here, but having set up the same exact system ransom is considering I'd like to add that the proper converter (really just a battery charger) is about one-tenth the battery's C20 spec. Has nothing to do with DC loads.

A good energy meter is necessary to monitor your electric use when boondocking. Yes the battery life is extended by stopping discharge before it gets too low but it also lets you predict when it's going to get too low.

I use a 30 amp iota smart battery charger, a 10a PWM solar controller with a 100 amp solar panel, a Victron BVM700 meter and two 6v 220ah batteries.

Note on the BVM700, it uses a 500 amp shunt and resolves current to 10ma, that's 0.01 amps.


Denny Wolfe
Wanderingourway.wordpress.com
Whether a 30 amp converter is large enough depends on a number of things. Do you plan to winter camp with a roof top solar panel (when the sun angles are low & the days are short? Depending on your amp hour usage, you may find you need more than a 100 watt panel (I think you have a typo of 100 amp solar panel - that would be great, but would cover the roof of most houses).

The solutions are more panels, portable panels that can be aimed at the sun, a generator, or hooking up to a pedestal for a couple of days every week or so.

If you are going to use a generator to recharge your batteries, a larger converter would be useful because the higher initial charge rate would cut down the generator run time. If you plug into a pedestal every couple of days, you will be able to deal with the longer time the smaller converter takes to charge the batteries, and possibly not need the generator.

Personally, I prefer to depend on solar alone. I have 195 watts (2 panels) on the roof & a portable 160 watt panel. I don't need the portable during the summers, but do during December & January, even in the Arizona desert. I use around 35 - 40 amp hours per day & also have a pair of 232 amp hour batteries. I don't carry a generator, and survived 93 days wintering in Quartzsite without hookups.
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