Watts needed

wa8yxm wrote:
Ok re-charging rates.. Recommendations vary from both battery manufacturer to manufacturer and from Others as well

Xantrex for exmple recommended 30% C/20 as the peak
Trojan 10%
Lifeline originally 30% as the MINIMUM initial current later reduced to 20%
(That is only for their AGM batteries)

Generally speaking the lower the recharge rate (Down to a point) the longer the overall life of the battery. I suspect that point is Trojan's 10%

I ran around 550 AH of batteries with 80 amps peak for 9 years.

ya, and to get around the worry of to much, you could also use tempature compensated solar charger. I have this set up alredy, just have to add another pannel before I need it yet.

Steve

cliffy49 wrote:
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.

There are still many units like this in production. They sometimes put all-electric fridge but not everybody wants it, propane fridge draws so little DC current that you will run out of water and propane before running out of battery. Not that I'm thrilled with propane fridges but they are easy on battery.

Propane fridge will draw 8-12 AH per 24 hours. If furnace is not needed, an energy-savvy couple could make it on 30-40 AH a day, most of this will be fridge and water pump. Limited use of microwave could add another 30 AH. As noted, many things people "want" to have in boondocks but it is a question whether those are necessities, and the list is truly endless. To harvest reliably 80 AH you need 400-600W flat solar. A smaller array won't cut it on cloudy days.

Ok re-charging rates.. Recommendations vary from both battery manufacturer to manufacturer and from Others as well

Xantrex for exmple recommended 30% C/20 as the peak
Trojan 10%
Lifeline originally 30% as the MINIMUM initial current later reduced to 20%
(That is only for their AGM batteries)

Generally speaking the lower the recharge rate (Down to a point) the longer the overall life of the battery. I suspect that point is Trojan's 10%

I ran around 550 AH of batteries with 80 amps peak for 9 years.

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.

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.

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

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

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.

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.

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.