Reviewing Solar and batteries for retirement

[bdoyle]

Hello, I have a fiver that hasn't had it proper share of use and we are now getting ready to fix that issue. We tend to dry camp but will utilize campgrounds if available. We had solar (120 X 2) and inverter (Xantrex 458 2500 combi) installed in 2003. Batteries have always been an issue due to lack of use and maintenance. I have gone thru 2 sets of batteries (6v X 4) and ready for a third set. Uses lots of water and was thinking that the solar was cooking them. Controller is a Mark PV 22 by Specialty Concepts. Charge was set to 14.4 but I just backed it down to 14.1, so I hope to make them last a bit. We tend to hit the batteries hard in the morning but they can charge up all day with the solar.
Usage:
Hair dryer: 1600 Wts 20 min 53 amps @ 12v?
Coffee maker 870 Wts 20 min 29 amps @ 12v?

Maybe I need 2 more batteries for a bank of 6.
Thanks!
Brian Doyle
Silver Springs, NV

[red31]

temp comp. newer controller will have it

[Almot]

Panels lose efficiency every year, from the day they were made. At the rate less than 1% a year.

Drop 0.3V after controller? Possibly. Depends on what cable and how long.

With more solar wattage he will have to replace the controller anyway. Morningstar MPPT 45 has terminals for voltage sensing wire, they call it "battery sensing". This is a thin wire that carries no power, to ensure correct voltage reading on the controller unit. It still shouldn't be too long - I think 20ft max.

I am against reading too much data, this is why I tucked my display in a corner where I won't see it often :)...

But, controller should be set up properly first. For some people monitoring amp-hours is a good idea, too. $25 on Ebay.

[pianotuna]

Hi skipro3,

So how do you size the wattage needed with no data? Or the amp-hours of battery bank? (Gosh, honey, the batteries are dead and the 50 watt solar panel doesn't seem to be charging them fully)

I agree that panel failure is rare--but it does happen and did to one of our members here.

skipro3 wrote:
I've installed, maintained and repaired DC battery plants that charged off solar for part of my working career. To me, many here way over think the value of 'data'. Charge 'em, float 'em, use 'em. In ten years, replace 'em. Routine maintenance was to fill 'em. I suppose having a system designed by professional engineers using commercial grade components makes a difference, but I've found that even those parts are available to recreationalists if they care to search them out.
It's an RV after all. Supposed to free us up from the drudgery of daily work and able to just relax. My advice; buy the good stuff. I have Morningstar controller, Interstate batteries (cost effective to replace every 5 years as pre-emptive maintenance), Solarworld panels. Everything made in USA and solid warranties if there is a problem. My controller acted up and I called Morningstar. An engineer called me back. They mailed me a replacement and a return label for the one I had. Batteries purchased through SAM's or Costco will get you free replacement, no questions asked, every two years if you've the notion to. Solar panels loose efficiency over time, like 25 years or so, and I've never had one just up and fail out of the hundreds I've installed.

[MrWizard]

Hair dryer: 1600 Wts 20 min 53 amps @ 12v?
Coffee maker 870 Wts 20 min 29 amps @ 12v?
That was just the time the device was actually operated. Just thinking of fuel used over time. Guess I was not only incorrect but confusing as well.

fuel aka ampHrs or Watt Hrs ..not..'amps'
amps is like saying gallons per minute, it is a 'rate' of use not a 'volume' of use

you figured 53 AmpHrs ? using 20 minutes , 1/3 of an Hr
can i assume the measured power being used 159 amps ?
giving us that 'real number' what ever the value, is more helpful
that many amps equals more than 1600w, at anything but the lowest cutoff voltages for the inverter, 159a @ 11v is 1749 watts, at 12v over 1900w

again your biggest problems, not reaching full charge voltage at the batteries
and too large a load for only (4) batteries

on a MW for 1 or 2 minutes for a cup of hot water / coffee etc.. OK
20 minutes for the hair dryer, thats pretty darn heavy

if they lasted more than (2) yrs you were lucky

"charge and use em" is correct, but they must be fully recharged
running that honda in the morning for the hair dryer, would be a good idea
IF its not going to disturb other campers

just food for thought
can the DW wash her hair in the evening, when the honda is in use
if her hair 'needs' to be washed from the days dust while rock hounding
why not do it at night, instead of sleeping on dusty hair

everybody has their routine, but camping routine and 'home/work' routine do not need to be the same

[Ski_Pro_3]

I've installed, maintained and repaired DC battery plants that charged off solar for part of my working career. To me, many here way over think the value of 'data'. Charge 'em, float 'em, use 'em. In ten years, replace 'em. Routine maintenance was to fill 'em. I suppose having a system designed by professional engineers using commercial grade components makes a difference, but I've found that even those parts are available to recreationalists if they care to search them out.
It's an RV after all. Supposed to free us up from the drudgery of daily work and able to just relax. My advice; buy the good stuff. I have Morningstar controller, Interstate batteries (cost effective to replace every 5 years as pre-emptive maintenance), Solarworld panels. Everything made in USA and solid warranties if there is a problem. My controller acted up and I called Morningstar. An engineer called me back. They mailed me a replacement and a return label for the one I had. Batteries purchased through SAM's or Costco will get you free replacement, no questions asked, every two years if you've the notion to. Solar panels loose efficiency over time, like 25 years or so, and I've never had one just up and fail out of the hundreds I've installed.

https://www.amazon.com/Morningstar-PS-30M-PG-Prostar-30-Meter-Farms/dp/B00OQJNB5C/ref=sr_1_9?s=indus...

Not sure they still make that one, it's what I have. However, there seems to be a new verson;
https://www.amazon.com/Morningstar-Prostar-PS-30M-Controller-Regulator/dp/B005XDHZLG/ref=sr_1_cc_1?s...

One button sheds load, another will shed the solar input. Realtime charge voltage, charge current and load read-out on the display. LVD and HVD, Over current disconnect I believe too.

[time2roll]

bdoyle wrote:
Well, found a bit of funny business, Solar controller shows battery voltage is 14.4 but with a meter (old fluke 77) at the battery it shows 14.08. Not getting a good charge this way.
The solar controller is mounted in the coach mid way between panels and batteries. Can you say voltage drop? Guess new controller should have a remote display?

Move the controller closer to the battery or get a controller with voltage sensing.
Or maybe controller is just shot.

[Almot]

Display on controller is what I am using to monitor the charging. But it provides tons of data, compared to most other standalone controllers.

Without battery monitor that keeps track of amper-hours going in and out of battery, you need other pointers. Ex, how much time controller stayed in Absorption, what was the current when it exited Abs and went into Float, how many hours it stayed in Float afterwards, and total amp-hours it generated from down to dusk. All this is stored in memory and available for reviewing for the last 30 days. It's still not the same a proper battery monitor, but for my pattern of energy use it's good enough.

[bdoyle]

"May I ask, what "equipment"?"

Display on Mark PV solar controller display. Just being lazy. But it looks as though it has been lying to me.

"There isn't much to read about controllers, for your purpose. You have PWM type, it only works with 12V panels in parallel. To add more panels without changing the wire from roof to controller, you need to wire panels in series and use MPPT controller. Amps rating of controller will depend on the array size. "

See more reading... (just kidding)

[Almot]

bdoyle wrote:
Out in the desert, usually full sun all day. Don't really know if the batteries are "fully" charged but my equipment says so. In the afternoon when we get back, I'll usually run the generator so we can use the air and I let the Xantrex charge for a while.

May I ask, what "equipment"?

Solar in desert works like a charm, nothing to block early morning sun. However, even in desert, 240W will barely put 80AH into battery, if the last of these AH is to bring it to 99.9%. Running generator in the afternoon doesn't help, as the system is already past the (too short, I suspect) Absorption stage, and doesn't need more current than solar is generating.

Panels prices dropped, but technology hasn't improved much, IMO. You may keep old panels and add more. Especially if they are Polycrystalline. But you will need a better controller.

There isn't much to read about controllers, for your purpose. You have PWM type, it only works with 12V panels in parallel. To add more panels without installing a thicker wire from roof to controller, you need to wire panels in series and use MPPT controller. Amps rating of controller will depend on the array size. If you buy MPPT, you could remove old 12V panels and install a couple of 24V panels, -280W each, instead of adding 2 more 120W panels. MPPT will convert extra volts into more amps. Or add 2 more 120W panels.

[bdoyle]

Well, found a bit of funny business, Solar controller shows battery voltage is 14.4 but with a meter (old fluke 77) at the battery it shows 14.08. Not getting a good charge this way.
The solar controller is mounted in the coach mid way between panels and batteries. Can you say voltage drop? Guess new controller should have a remote display?

[bdoyle]

Hair dryer: 1600 Wts 20 min 53 amps @ 12v?
Coffee maker 870 Wts 20 min 29 amps @ 12v?
That was just the time the device was actually operated. Just thinking of fuel used over time. Guess I was not only incorrect but confusing as well.

[MEXICOWANDERER]

2Oldman
When I was working I often was buried up to my ears for days at a time.

[bdoyle]

Well, I know my math is correct but miss applied. Just thinking along the lines of fuel used per hour but only running for 20 minutes. Same draw but shorter period.
Anyway, looking at a new solar controller but have not made any decisions yet. Lots of reading to do. Will be getting new batteries as these have not had a good life.
Typically our camping trips are with rockhound clubs for field trips. Get up at 5am so wife can shower / dry hair, I make coffee and we are ready to leave by 7:30. Out in the desert, usually full sun all day. Don't really know if the batteries are "fully" charged but my equipment says so. In the afternoon when we get back, I'll usually run the generator so we can use the air and I let the Xantrex charge for a while. Don't like to run the generators but the Honda 2000 (2X) work real well. So we are gone all day and the panels do what they can.
The controller shows 8amp charge, but that doesn't seem like enough to replenish what we took out.
Appreciate all comments but I have more reading / decisions to make before I throw any real money at this. Trying to spend once.

[2oldman]

OP wrote this:
Hair dryer: 1600 Wts 20 min 53 amps @ 12v?
Coffee maker 870 Wts 20 min 29 amps @ 12v?

I don't get both the "20 min" or the amp figures.. but I do get the "?" But he hasn't been back.

[time2roll]

MEXICOWANDERER wrote:
But is it a universal truth that the larger the inverter, the larger the idle draw? Some I used to see had ridiculously high idle currents.

About one amp per thousand watts as best I can tell. (12 volt input)

My 2000w idles at 2 amps. My 300 watt idles at 260 milliamps.
GoPower sine wave.