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2oldman

NM

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Posted: 06/23/21 11:55am Link  |  Quote  |  Print  |  Notify Moderator

cliffy49 wrote:

I am still here. Been busy trying to get the trailer ready.
Cool, thanks. Batteries can stay charged for quite a while if they're disconnected.

Almot

out there

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Posted: 06/23/21 04:20pm Link  |  Quote  |  Print  |  Notify Moderator

cliffy49 wrote:


As far as batteries, I have 2 Deka GC2's wired for 12 volts. At this time I am just lookinig to keep the batteries charged when the trailer is in storage.

I had a feeling the question was about storage again. Every few weeks somebody is asking this, without telling that this is for storage.

Deka GC2 exist in both flooded and AGM version if I'm not mistaken.

Fully charged flooded batteries are fine in storage at 77F without charging for a month or two. If longer, you need 30-50W solar to keep 200 AH bank topped up when they are disconnected from all the loads - no radio on standby, no propane detector, nothing. Panel of this size is small enough to attach on top of A/C box. There will be a faster self-discharge when it's hot.

Fully charged AGM are fine for 3-5 months without charging - again, shorter time when it's hot.

pianotuna

Regina, SK, Canada

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Posted: 06/23/21 05:36pm Link  |  Quote  |  Print  |  Notify Moderator

The cooler it is the longer between needing charges. I, too, recommend a small solar panel system.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

wintersun

Monterey

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Posted: 06/23/21 05:45pm Link  |  Quote  |  Print  |  Notify Moderator

With two flooded lead acid 125Ah batteries being charged by two 100W solar panels the draw from the fridge and freezer would take the batteries down to 50% SOc after two days and no actual use of the fridge. With a 3-way fridge the juice to power the fridge electronics is very small and with our prior camper going for weeks with only two 100W panels was not a problem and we did not take a generator.

When I replaced the lead batteries with lithium phosphate ones of equal capacity I found that the solar was better able to keep up with demand as the controller could provide a higher level of charge and the batteries charge much faster and so make better use of available light.

I want as much battery capacity as will fit in the RV and as much in the way of solar production on the roof as I can find space for on the roof. Panels are cheap at roughly $115 for each 100 Watts of panel output. By far the most expensive aspect of adding solar is doing the wiring runs inside the RV.

dieseltruckdriver

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Posted: 06/23/21 06:24pm Link  |  Quote  |  Print  |  Notify Moderator

Boon Docker wrote:

cliffy49 wrote:

I have read where folks suggest any where from 1 to 2 watts of solar per ah of battery. My question, is this based on battery rating (ie 215 AH) or is it based on useable amp hours(105)?

All replys are greatly appreciated.


Do 1.5 watts of solar per AH of battery and you should be fine.
(300 watts of solar for 215 AH of battery)

I currently have 210 AH of battery, and 420 watts of solar, and I plan on adding another 200 watts of solar this fall.

My DW said she wants to live like normal when we are boondocking, that means we run the inverter to watch tv etc. Our use averages about 50 AH per night, and we get fully charged daily, as long as there is sun. Not as good if it's cloudy.


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Boon Docker

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Posted: 06/23/21 06:33pm Link  |  Quote  |  Print  |  Notify Moderator

dieseltruckdriver wrote:

Boon Docker wrote:

cliffy49 wrote:

I have read where folks suggest any where from 1 to 2 watts of solar per ah of battery. My question, is this based on battery rating (ie 215 AH) or is it based on useable amp hours(105)?

All replys are greatly appreciated.


Do 1.5 watts of solar per AH of battery and you should be fine.
(300 watts of solar for 215 AH of battery)

I currently have 210 AH of battery, and 420 watts of solar, and I plan on adding another 200 watts of solar this fall.

My DW said she wants to live like normal when we are boondocking, that means we run the inverter to watch tv etc. Our use averages about 50 AH per night, and we get fully charged daily, as long as there is sun. Not as good if it's cloudy.


I have a 225 AH battery bank and use 40 AH per day. My GC2's are back up to 100% SOC by early afternoon each day with 200 watts of solar.

StirCrazy

Kamloops, BC, Canada

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Posted: 06/24/21 06:17am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

2oldman wrote:

StirCrazy wrote:

I learned a new method of sizing yesterday while I was reading. for a 6V GC battery the recomended charge amprage is 10% of your total amp hour capacity at the 20h rate of your entire battery bank. now how you adjust this for other loads I havent figured yet but from a charging stand point for your batteries you want to get about 21 amps from your panels. for myself, I would probaby double this and call it good
With Li's you can go way over that.


Acceptance rate for a 100 amp-hour flooded lead acid at 85% state of charge is 12.5. That translates to 12.5%, not 10%. Further lead acid are self regulating--that's why it takes nearly the same time to get from 50% to 85% as it does from 90% to 100%

Battleborn recommends 0.5 c for longest life, but 1c is safe.


2.5 percent, it is just a quick sizing guide on a 6V GC2 manufactuers web site I read the other day and it makes it easy to find a starting point for your pannel sizes, but at least use all my quote which could have been some one else snipping it but it will give you more context of what I actualy said so I'll add it.

Steve

* This post was edited 06/24/21 06:29am by StirCrazy *


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StirCrazy

Kamloops, BC, Canada

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Posted: 06/24/21 06:20am Link  |  Quote  |  Print  |  Notify Moderator

2oldman wrote:

StirCrazy wrote:

for a 6V GC battery the recomended charge amprage is 10% of your total amp hour capacity at the 20h rate of your entire battery bank.
With Li's you can go way over that.


yup, I am totaly aware of that. you can go way over that with normal batteries as well but do you need to is the question......I have roughly just over that 10% in my camper and as loog as there is sun during the day I will never drop below 80%, my 5th wheel is only at 5% but because that 5% is still way larger than my use the results are the same.

Steve

wintersun

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Posted: 06/24/21 03:29pm Link  |  Quote  |  Print  |  Notify Moderator

So much has changed with regard to electric only refrigerators and electric convection ovens and induction cooktop burners and large screen televisions and other "necessities" that there can be no rule of thumb other than more solar and more battery bank capacity is a worthwhile investment. I went from one extreme with a camper with a 3-way fridge and propane oven and cooktop and 200W of solar on the roof to a new motorhome with a DC only fridge and induction cooktop and convection oven and AC heat pump with only 200W of solar on the roof and 125Ah of usable lead acid batteries and so the need to frequently run the generator (my previous camper was without any kind of generator).

With the electric only fridge and cooktop and oven and microwave the use of lithium phosphate batteries become essential if one want to operate off the grid and without running the generator for a couple hours each day. To that end I added 290W of solar panels to the roof and replaced the lead acid batteries to lithium-phosphate ones.

Cost of these two upgrades was $4,000 but for us it was price to be paid for the configuration of our 2021 Navion. But the Navion was one of very few new motorhomes available for immediate purchase in 2020.

cliffy49

Blue Grass

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Posted: 06/24/21 04:13pm Link  |  Quote  |  Print  |  Notify Moderator

wintersun wrote:

So much has changed with regard to electric only refrigerators and electric convection ovens and induction cooktop burners and large screen televisions and other "necessities" that there can be no rule of thumb other than more solar and more battery bank capacity is a worthwhile investment. I went from one extreme with a camper with a 3-way fridge and propane oven and cooktop and 200W of solar on the roof to a new motorhome with a DC only fridge and induction cooktop and convection oven and AC heat pump with only 200W of solar on the roof and 125Ah of usable lead acid batteries and so the need to frequently run the generator (my previous camper was without any kind of generator).

With the electric only fridge and cooktop and oven and microwave the use of lithium phosphate batteries become essential if one want to operate off the grid and without running the generator for a couple hours each day. To that end I added 290W of solar panels to the roof and replaced the lead acid batteries to lithium-phosphate ones.

Cost of these two upgrades was $4,000 but for us it was price to be paid for the configuration of our 2021 Navion. But the Navion was one of very few new motorhomes available for immediate purchase in 2020.


I have been lucky in that regard. My toy hauler is old fashioned in that every thing except for the outlets, A/C, micro wave and tv are the only things that run off of shore power.

The micro wave is something that we very rarely run and if we do need the a/c or want to watch the tv I can always use the genny for the a/c and get an inverter for the tv.


cliffy49
2016 F150 Ecoboost & max tow (Gone)
2021 Silverado Custom 2500HD
2018 Catalina TH26 Toy hauler


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