Lithium Deep Cycle Battery Discharge

[c_tiboni]

Hello,

Recently went dry camping in Yosemite with two fully charged lithium deep cycle wet batteries. Utilized a 100w solar panel during the day 3-4 hours and ran a generator a few hours a day during heavy power use. On the 3rd day the batteries seemed to discharge with no power going into the trailer. Solar panel read 12.7 volts still charged between the two batteries. I only utilized the batteries for LED lighting and minimal water pump use. Fridge was running off propane only. Is this normal? Seems like a fast discharge for two deep cycle batteries. Wondering if there’s a bad cell. TIA

[babock]

Originally Posted by c_tiboni

Hello,

Recently went dry camping in Yosemite with two fully charged lithium deep cycle wet batteries. Utilized a 100w solar panel during the day 3-4 hours and ran a generator a few hours a day during heavy power use. On the 3rd day the batteries seemed to discharge with no power going into the trailer. Solar panel read 12.7 volts still charged between the two batteries. I only utilized the batteries for LED lighting and minimal water pump use. Fridge was running off propane only. Is this normal? Seems like a fast discharge for two deep cycle batteries. Wondering if there’s a bad cell. TIA

No such thing as lithium deep cycle wet batteries. Take a picture of what you have.

BTW..a 100W solar panel with a PWM controller will give you 5A max for the typical 100W 20V solar panel. At his time of year, if you get 15AH out of them perfectly aimed, you are lucky.

Your 12.7V with the solar connected doesn't tell you anything which is why using voltage to measure SOC is pretty much worthless. In order to measure SOC, you have to remove all charging and discharging for a couple hours and then measure the volatge.

[c_tiboni]

Originally Posted by babock

No such thing as lithium deep cycle wet batteries. Take a picture of what you have.

BTW..a 100W solar panel with a PWM controller will give you 5A max for the typical 100W 20V solar panel. At his time of year, if you get 15AH out of them perfectly aimed, you are lucky.

Your 12.7V with the solar connected doesn't tell you anything which is why using voltage to measure SOC is pretty much worthless. In order to measure SOC, you have to remove all charging and discharging for a couple hours and then measure the volatge.

Also attached to my battery charger with same output on both batteries after I got home from the trip.

[rsdata]

lead-acid group 24 battery is what you have... even two of them is not much capacity...

you also have several parasitic loads in trailers, like radio, propane/CO detector(s) that are pulling current constantly...

a 4 amp charger will take a full day + to fully charge one discharged battery

hopefully you never let the battery charge get below 12 volts or you will permanently damage the capacity of the battery(s)

A fully-charged 12-volt battery, allowed to “rest” for a few hours (or days) with no load being drawn from it (or charge going to it), will balance out its charge and measure about 12.6 volts between terminals. When a battery reads only 12 volts under the above conditions, it's almost fully depleted.

[c_tiboni]

Thanks for the info. Is it better to swap these batteries out? Perhaps I was on the wrong setting with the solar charge controller

[rsdata]

before you do anything, read up on a TON of forum discussions on batteries and boondocking... much to learn by searching previous forum posts...

[SlowrideHD]

Here is my solar panels for my remote cabin. 3.3 kw. These feed my MPPT charge controller to a battery bank that consists of 16 Trojan T-105 six volt golf cart batteries hooked to a 3600 watt pure sine wave inverter.

A 100 watt panel isn't going to do very much.

[The Evil Twin]

With a pair of those batteries you have 280 minutes reserve cap. That is about 8 hours at 11 amps. The fridge, smoke alarm, CO/ LP alarm and radio will use power all the time. Water pump uses a good bit of power when running. Using a 100w solar panel is not going to replenish much of that energy in 4 hours. Running the generator will help charge it through the converter but how much depends on the converter. It may get you 5 amps tops. That is a hair above a battery tender.
So what does it all mean? You are likely using more power than you can replace. So you either need to charge more, use less, or get bigger batteries. I dropped in an 8D battery with 480 minute RC, but we have plenty of room in the hold for that size cell. Thing is, it takes a good bit to charge also.
I will have to disagree with previous posts on minimum voltage. Typical lead acids are depleated at 1.9 volts per cell and AGM deep cycle down to 1.8 volts per cell. Granted, going down to 10.6vdc on a battery will shorten its life if done repeatedly but it can be done and the battery brought back to life. Most folks assume the battery is done because it wont take a charge. Thing is, most modern (keep people safe nannies) chargers will not charge a battery below a specific voltage. All you have to do is parallel that battery to a good one and fake the charger out. I have a 6 year old battery in a motorcycle that I took down to 9 volts and brought it back from the dead 4 years ago.

[c_tiboni]

Ok it sounds like unless I have a solar panel field I’m f*ed. I just need resonance on the two batteries I have. Thanks for the
Info all

[c_tiboni]

Originally Posted by The Evil Twin

With a pair of those batteries you have 280 minutes reserve cap. That is about 8 hours at 11 amps. The fridge, smoke alarm, CO/ LP alarm and radio will use power all the time. Water pump uses a good bit of power when running. Using a 100w solar panel is not going to replenish much of that energy in 4 hours. Running the generator will help charge it through the converter but how much depends on the converter. It may get you 5 amps tops. That is a hair above a battery tender.
So what does it all mean? You are likely using more power than you can replace. So you either need to charge more, use less, or get bigger batteries. I dropped in an 8D battery with 480 minute RC, but we have plenty of room in the hold for that size cell. Thing is, it takes a good bit to charge also.
I will have to disagree with previous posts on minimum voltage. Typical lead acids are depleated at 1.9 volts per cell and AGM deep cycle down to 1.8 volts per cell. Granted, going down to 10.6vdc on a battery will shorten its life if done repeatedly but it can be done and the battery brought back to life. Most folks assume the battery is done because it wont take a charge. Thing is, most modern (keep people safe nannies) chargers will not charge a battery below a specific voltage. All you have to do is parallel that battery to a good one and fake the charger out. I have a 6 year old battery in a motorcycle that I took down to 9 volts and brought it back from the dead 4 years ago.

Thanks for the info. Battery was parallel to extract as much juice as possible. Definitely going to have to using different batteries “AGM” to be more
efficient when off grid. Batteries were fully maintained but didn’t do the job. Along with a generator and solar panel is saddening but I understand your reference. Have to make an adjustment

[bikendan]

Yep, you have a plain old dual-purpose marine battery. NOT a Lithium nor a true deep cycle battery.

[Mrprovy]

I'm a complete noob to camping, having just picked up our first camper a few weeks ago (Geo Pro 16BH). Our immortal search for a camper want so much to travel, as it was to spend weekends at the beach. After researching a ton, mostly here and YouTube, I've determined that or bat course of action for boondocking 2-3 days will be Battle Born batteries; so, I am already anticipating the $2K expensein the spring, once they release their next gen with built in monitoring and heating. 200Ah + 100w solar + generator (mainly for a/c to keep DW happy) should easily get me through a weekend in the summer.

Since picking up the camper, we're already talking travel, but most of the talk includes RV parks (Lake George, Hershey, Gettysburg, etc) with full hook up, so battery capacity is less of an issue beyond the stops we'll be making to rest during the travel.

Just an idea of where I'm at with a similar set up.

FWIW, we killed our battery the on or way home from picking ours up from the dealer (12 moor drive). Even though it was plugged in all day at the dealer, I mistakenly left the inverter on, which kept the aux 120v fridge powered on (I was told it only got power when plugged in), and the heat was out 2 hours into our rest (no power to fire up the furnace)... lesson learned, inverter stays off unless necessary and the extra fridge is gone.

[rk06382]

Originally Posted by Mrprovy

I'm a complete noob to camping, having just picked up our first camper a few weeks ago (Geo Pro 16BH). Our immortal search for a camper want so much to travel, as it was to spend weekends at the beach. After researching a ton, mostly here and YouTube, I've determined that or bat course of action for boondocking 2-3 days will be Battle Born batteries; so, I am already anticipating the $2K expensein the spring, once they release their next gen with built in monitoring and heating. 200Ah + 100w solar + generator (mainly for a/c to keep DW happy) should easily get me through a weekend in the summer.

Since picking up the camper, we're already talking travel, but most of the talk includes RV parks (Lake George, Hershey, Gettysburg, etc) with full hook up, so battery capacity is less of an issue beyond the stops we'll be making to rest during the travel.

Just an idea of where I'm at with a similar set up.

FWIW, we killed our battery the on or way home from picking ours up from the dealer (12 moor drive). Even though it was plugged in all day at the dealer, I mistakenly left the inverter on, which kept the aux 120v fridge powered on (I was told it only got power when plugged in), and the heat was out 2 hours into our rest (no power to fire up the furnace)... lesson learned, inverter stays off unless necessary and the extra fridge is gone.

Battle Born batteries was the best addition to my motorhome. I think you will need more than 100 watts. 100 watts is only about 6.5 amps if pointed at the sun. With ten hours of sun, you would only get about 65ah. You will need more solar panels to boondock.

[Mrprovy]

Originally Posted by rk06382

Battle Born batteries was the best addition to my motorhome. I think you will need more than 100 watts. 100 watts is only about 6.5 amps if pointed at the sun. With ten hours of sun, you would only get about 65ah. You will need more solar panels to boondock.

I'm going to have to expand my system slowly, initial cost is way up there. I have the coin for the batteries already budgeted, and just got a generator which was a requirement for a/c (DW needs cool air to sleep). Even if I fully deplete the batteries in 2-3 days (doubtful), I have a 30A shore connection at home to replenish the batteries.

[dontay]

To the original poster:
Your setup sounds a lot like mine except I have group 27 batteries which are slightly more in amp-hours. I assume the picture is of your solar controller and shows the state of the battery at 12.7 volts. Can you select a view of the solar panel output voltage? On mine I can cycle through solar panel output voltage, battery input voltage, and battery input current from the solar system. During the summer in the mountains of Wyoming my solar panel output voltage usually reads 14.8 volts or more during the middle of the day. The battery voltage is 13.8. The current is usually only a couple of amps but can go up to just under 4 if the sun gets really intense. (At home in Florida I easily get 6 amps.)
At the end of the day with no charging going on the battery voltage drops and settles at 12.7 volts which is correct for a fully charged battery. However, I almost always have a 1 amp discharge current caused by the refrigerator which is running on propane. A tiny part is also propane and CO detectors.
I have a Link 10 battery monitor which tells me the true state of the battery including amp hours. If you dry camp a battery monitor is very important. Otherwise you are just shooting in the dark trying to figure out if your battery is okay or not.
If you plan to dry camp a battery monitor would tell you exactly what is happening before you start throwing money at new stuff.

[dontay]

In the above post I forgot to add that you should periodically wash your solar panel. These things get as dirty as your roof and that cuts down on their usefulness.

[bedubya]

Originally Posted by bikendan

Yep, you have a plain old dual-purpose marine battery. NOT a Lithium nor a true deep cycle battery.

Correct. One key to that is "550 CCA." Any battery that lists cold cranking amps isn't a true deep cycle battery.

[c_tiboni]

Thanks for the info

[tomkatb]

Got to study up on batteries etc. 12 volt systems.

You have cheap mismatched(bad) boat batteries.

Solar works to provide a small amount of charging in states where appropriate. I.E. not the Midwest , south, Northwest etc. Mostly desert states.

Not for ac. Not for heaters etc. Furnaces use a lot as well.

in twenty years they will evolve.

For now get two or more 6 volt batteries. A good voltmeter or other meter to monitor your batteries. Full discharge of them as you did harms them.

Learn what various items use. How much you have. When you need to use your generator.

Your batteries could have provided 80 or so amps of juice. A 100 watt solar panel could provide 15 amps on a good day. 1/6 of what you might need!

[Sam54]

Agreed. Would ideally run 4 200 watt panels to re-coup the energy you're using, but if budget is limited you can add 1 more with a Y connector to get more juice. I'm currently testing 2 100watt flexible panels I bought at Amazon, and will have them permanently roof mounted if they seem efficient enough.