Peter_n_Margaret
Adventurer
3.5ft x 2ft is no where near 300W. Not technically possible. About half that I reckon, maybe 180W tops?
Cheers,
Peter
OKA196 motorhome
Cheers,
Peter
OKA196 motorhome
I'm killing batteries -- time to go LiFePo4?
- Thread starter monkeyodeath
- Start date
Showing fully charged does not indicate how well it will power a load. Have it load tested or make a simple load tester. My 12v fridge varies from about 3.5-5.0 amps. A 60 watt incandescent headlamp connected to the battery with a voltmeter attached should indicate the mid-twelves for an extended time, dependent upon amp-hour rating. If it rather quickly drops to the low twelves or below, battery time.
I've gambled. The least expensive 100ah AGM I could buy has resided in the heat of the engine compartment, along with a PWM solar charge controller for nearly eight years, no problem running a 12v fridge.
Battery voltage is important, but battery voltage measured at the load (fridge), while starting and running is a better indication.
I've gambled. The least expensive 100ah AGM I could buy has resided in the heat of the engine compartment, along with a PWM solar charge controller for nearly eight years, no problem running a 12v fridge.
Battery voltage is important, but battery voltage measured at the load (fridge), while starting and running is a better indication.
Hilldweller
SE Expedition Society
You'd easily maintain a 100w LiFePo4 battery with that from what you're describing. I'm maintaining mine with 200w.
It even gets the battery there on cloudy days (all day). On a sunny day I'm full before lunch.
ps -- my charge controller tells me in real time what the panels are producing, how much they've put into the battery, etc. In good sun I'm way over 13 amps. Does your controller give you details like that?
Which Victron, and what is the output voltage of your panel? You stated that you left it for a few months, how dirty is / was the panel? In my experience, you should be easily able to run an ARB fridge from 100-200 watts of solar indefinitely with the right battery. A lead acid battery is fine with the right water top-off and wire size. What size is your wire?
clydeps
Member
Not even that by my calcs. 3.5x2 ft is 7 sq ft, so about 0.65 sqm, at 1000W/m2 irradiance and 20% efficiency that's only 130W. And that's assuming that's the active area. Unless the panel is moved around during the day you will only see around 400-500Wh maximum from it in a day (with full sunshine.) If the fridge draws 5A and has a 50% duty cycle it will use around 700Wh per day. So the panel is too small, and replacing the battery will not help.
monkeyodeath
Member
Re-measured the panel and it's about 5' x 3'. It's a Sunpower residential panel rated at 305W.
I really don't think solar is my bottleneck here. I've monitored the MPPT and the historical logs and there has never been a day when the battery did not get fully charged from the solar panel, usually before noon, even in cloudy SW conditions. In daytime there's almost always enough power to run the fridge and bulk charge the battery simultaneously.
I'm using a Victron 100/20 MPPT.
I'm going to throw a multimeter on the plug to see what the battery load is like when the fridge is running. I could probably be using thicker wiring from the MPPT to the dinky lugs on the ARB power plug.
However, the fact that I'm seeing the battery voltage level (as measured by the MPPT) dip down to 11.8V seems like a strong indication that I just don't have enough battery. Wondering if the fridge fault is happening because the voltage is dipping so low at the fridge connection that it disrupts the electronics on the unit. Can anyone indicate what the target minimum voltage should be a on a LA starter battery? My hunch is that I'm dipping below that.
I really don't think solar is my bottleneck here. I've monitored the MPPT and the historical logs and there has never been a day when the battery did not get fully charged from the solar panel, usually before noon, even in cloudy SW conditions. In daytime there's almost always enough power to run the fridge and bulk charge the battery simultaneously.
I'm using a Victron 100/20 MPPT.
I'm going to throw a multimeter on the plug to see what the battery load is like when the fridge is running. I could probably be using thicker wiring from the MPPT to the dinky lugs on the ARB power plug.
However, the fact that I'm seeing the battery voltage level (as measured by the MPPT) dip down to 11.8V seems like a strong indication that I just don't have enough battery. Wondering if the fridge fault is happening because the voltage is dipping so low at the fridge connection that it disrupts the electronics on the unit. Can anyone indicate what the target minimum voltage should be a on a LA starter battery? My hunch is that I'm dipping below that.
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Peter_n_Margaret
Adventurer
Adding extra battery is like opening another bank account without changing our income. You won't be financially better off.
The battery only has to run the fridge when the sun is not shining.
Either your battery is stuffed or your loads are higher than you think or your charge is lower than yo think. Don't do anything until you know which and why.
Cheers,
Peter
OKA196 motorhome
The battery only has to run the fridge when the sun is not shining.
Either your battery is stuffed or your loads are higher than you think or your charge is lower than yo think. Don't do anything until you know which and why.
Cheers,
Peter
OKA196 motorhome
So your panel open circuit is 64V?
Is your fridge connected to the battery or to the load terminals of the solar controller?
How much water is missing from your battery?
Internet diagnostics are worth the price paid, but I would bet you trashed your battery by having it in the SoCal heat and it needs to be replaced. Replace with a large marine deep cycle and you will be good to go.
Is your fridge connected to the battery or to the load terminals of the solar controller?
How much water is missing from your battery?
Internet diagnostics are worth the price paid, but I would bet you trashed your battery by having it in the SoCal heat and it needs to be replaced. Replace with a large marine deep cycle and you will be good to go.
Hilldweller
SE Expedition Society
I've always used 12.2v as a rule of thumb. But your battery's spec sheet should give you the manufacturer's answer.
Happy Joe
Apprentice Geezer
Given that solar panel makers are typically excessively optimistic (lie about specs). I would;
verify the power consumption of the fridge with a fully charged battery and monitor it to see that it is well ventilated and does not consume excessive power during its cycle during the heat of the day., then check it to see its estimated charge level at the end of the day; this should give you a good idea of how good/adequate the battery is for your application.
Assure the solar panel(s) is/are clean.
Carefully align it/them with the sun.
Verify the panel output voltage and current using a digital volt meter.
both before and after the solar controller.
Fully charge the battery at home before leaving.
Monitor the panel to assure that ther are no shadows creeping over the solar cells during the day.
Realign the panel(s) with the sun and check its/their output every 45 minutes to an hour.
(I hate baby sitting solar which seems to be necessary at shady/desirable campsites or when using undersized (low output) panels and/or batteries that have been abused/degraded).
I too am a fan of LiFePo4 batteries, but I only try to recharge using solar (not a big fan of solar) for trips longer than 4 days or so. I have a 20 amp dc to dc charger to recharge the battery from the vehicle alternator if I'm on the road (don't let the battery(s) run clear down or your alternator will hate you/you could kill it).
Currently using up to 200 AH (2x100) of LiFePo4 (2400 + watt hours); they can run just my (small) fridge for about a week without a recharge. For quick weekend trips a cooler is easier for me than hassling with the fridge or solar. When using only the cooler (no fridge or solar) and some LED lights a 50 AH LiFePo4 is plenty for my needs.
I have/have used, solar systems ranging from 14 watts to 400 (advertised) watts; with either MPPT or PWM controllers, and found it/them (solar systems) to be a lot of hassle/trouble.
Enjoy!
verify the power consumption of the fridge with a fully charged battery and monitor it to see that it is well ventilated and does not consume excessive power during its cycle during the heat of the day., then check it to see its estimated charge level at the end of the day; this should give you a good idea of how good/adequate the battery is for your application.
Assure the solar panel(s) is/are clean.
Carefully align it/them with the sun.
Verify the panel output voltage and current using a digital volt meter.
both before and after the solar controller.
Fully charge the battery at home before leaving.
Monitor the panel to assure that ther are no shadows creeping over the solar cells during the day.
Realign the panel(s) with the sun and check its/their output every 45 minutes to an hour.
(I hate baby sitting solar which seems to be necessary at shady/desirable campsites or when using undersized (low output) panels and/or batteries that have been abused/degraded).
I too am a fan of LiFePo4 batteries, but I only try to recharge using solar (not a big fan of solar) for trips longer than 4 days or so. I have a 20 amp dc to dc charger to recharge the battery from the vehicle alternator if I'm on the road (don't let the battery(s) run clear down or your alternator will hate you/you could kill it).
Currently using up to 200 AH (2x100) of LiFePo4 (2400 + watt hours); they can run just my (small) fridge for about a week without a recharge. For quick weekend trips a cooler is easier for me than hassling with the fridge or solar. When using only the cooler (no fridge or solar) and some LED lights a 50 AH LiFePo4 is plenty for my needs.
I have/have used, solar systems ranging from 14 watts to 400 (advertised) watts; with either MPPT or PWM controllers, and found it/them (solar systems) to be a lot of hassle/trouble.
Enjoy!
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concretejungle
Adventurer
sorry to hijack this thread, but I was messing with my victron charge controller and can't see where the lead acid setting is? I am running one of the group 31 lead acid deep cycle from Costco (interstate battery).
There are AGM, lithium and several others, but none say lead acid? I am talking about the presets btw.
There are AGM, lithium and several others, but none say lead acid? I am talking about the presets btw.
monkeyodeath
Member
I looked and there isn't one. People seem to use the AGM preset or input their own parameters (which are really close to the stock AGM ones).
monkeyodeath
Member
Thanks for all the advice and suggestions.
Spent some time watching my solar setup and measuring things with a multimeter and I'm pretty convinced that I've got plenty enough solar power. Even on a cloudy day, my panel is able to come up with enough amperage to both charge the battery and run the fridge. There's never been a day where the battery hasn't been fully charged by noon.
My guess is that my battery capacity is borderline for hot nights with this fridge. I'd also wager that leaving it outside (in a battery box) for 2 hot months, along with drawing it down pretty deeply on multiple occasions, has probably cooked it a bit (though the water levels look fine).
I'm going to replace this battery under warranty from Costco and see how it goes, probably trying to take a little better care of it. If it's still dying in a couple months, I'll either shop LiFePo or look into a higher-capacity or more deep-cycle appropriate LA battery. (I'm using a Group 34 currently)
Spent some time watching my solar setup and measuring things with a multimeter and I'm pretty convinced that I've got plenty enough solar power. Even on a cloudy day, my panel is able to come up with enough amperage to both charge the battery and run the fridge. There's never been a day where the battery hasn't been fully charged by noon.
My guess is that my battery capacity is borderline for hot nights with this fridge. I'd also wager that leaving it outside (in a battery box) for 2 hot months, along with drawing it down pretty deeply on multiple occasions, has probably cooked it a bit (though the water levels look fine).
I'm going to replace this battery under warranty from Costco and see how it goes, probably trying to take a little better care of it. If it's still dying in a couple months, I'll either shop LiFePo or look into a higher-capacity or more deep-cycle appropriate LA battery. (I'm using a Group 34 currently)