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Old 08-05-2020, 07:20 AM   #1
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Battery Performance While Boondocking

We are involuntarily boondocking for the first time because Isaias knocked out our power. We were able to fully charge (12.66v) our flooded cell battery using the generator. We then turned everything off in the trailer (inverter, lights, water heater, etc.). The fridge is running on propane. Within 30 minutes, the battery charge (tested with a multimeter at the battery terminal) was down to 12.55, another 20 minutes later it was at 12.51, this trend continued with the battery quickly drawing down until we were at 12.4 within just a few hours. Are we missing something? Is this normal? Is there an energy vampire somewhere that I may not have considered...HELP!!
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Old 08-05-2020, 07:33 AM   #2
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I think the battery was not truly fully charged. You have to let the battery sit 30 min or so to measure the voltage after charging. I expect the battery will perform a little better going from 12.4 down to 12 or whatever you use for the lower limit. I doubt if you have missed a draw that big. Do you have an aux. fan in the fridge? A vent fan running? TV booster on? leaky water pump? light on in a storage compartment? I find the best way for me to run using a generator is to run it every day, maybe short runs twice in the day, and hope to get actual charge over 12.5 on the little voltmeter I use. I tend to run my batteries below the recommended 12.2 and I replace them every year or 2. That just seems to be the way I get enough power to get by on. If I boondocks much I would look at lithium. But we do it less and less now and I am too old to use up a set of lithiums for the long term savings.
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Old 08-05-2020, 07:53 AM   #3
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Its hard to say what is excessive without know what trailer you have. But every trailer has parasitic draws. For instance, you have the inverter turned off, but (on my trailer) the inverter draws .15 amps just being wired up, more when turned on without load. I have it on its own battery switch. Then there is the radio, propane monitor, etc. My 20' with a small refer draws .5 amps with "everything" turned off but the refer (inverter switched off). Others with larger rigs have reported background loads of 1 to 2 amps.

Good luck.
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Old 08-05-2020, 09:11 AM   #4
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I would say in our case the radio was surprising at how much it draws on idle. Other-wise, what Bill said. Check for compartment lights etc. Bear in mind in a pinch you can charge the batteries from your TV using jumper cables but it's not a long term solution. Before we added solar and a genny we would run the batteries down to 11.9 indicated in the cabin operating with a little cigarette lighter volt meter knowing that the actual voltage @ the battery was around 12V. 12.4 is actually OK as Bill mentioned that the time from 12.4 to 12.0 will be longer than 12.6 to 12.4 in our experience. - Brad
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Old 08-05-2020, 09:20 AM   #5
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Welcome to the forum!

Good advice so far. Please provide more details as requested by others, about trailer model/age, battery age, and so forth.

Also these recent boondocking/battery threads have a lot of good info to review:

https://www.airforums.com/forums/f44...ng-212334.html
https://www.airforums.com/forums/f44...ng-212280.html

"parasitic phantom battery loads" -- https://www.google.com/search?ei=e84...eSQAP0Q4dUDCAs

Also FYI:
Batteries etc. sub-forum: https://www.airforums.com/forums/f449/
Boondocking forum: https://www.airforums.com/forums/f382/
Full-timing sub-forum: https://www.airforums.com/forums/f314/

Good luck,
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Old 08-05-2020, 03:53 PM   #6
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Also, the fantastic fans draw extra current If not in use and not switched to zero
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Old 08-06-2020, 11:35 AM   #7
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The voltage drop you see is normal.
A lot of what you see depends on battery and its condition.

A fully charged lead acid battery/AGM open circuit voltage (after at least 4 hours of rest) will be 13.0 volts for a 12-volt battery. Open circuit is where the battery is disconnected and there is no load. https://lifelinebatteries.com/knowledge-center/

If your battery is 'fully charged' and is 12.66v then you may have a problem with either the battery or the charger.

The energy vampire could be sulfation build up in the battery plates. This reduces the capacity of the battery. A new 100ah battery is good for 50ah of use. Without proper constant charging and periodic equalization, capacity loss will happen quickly. So a 100Ah battery that is 30% sulfated will give only 35Ah of usable energy. In other words, you see a quick voltage drop with minimal use.

Based on the Trojan battery manual link below - 12.4v indicates a 70% state of charge.

The biggest cause of failure with lead acid/AGM is lack of proper maintenance.

Proper maintenance is more than adding water and making sure there is enough electrolyte to cover the plate. Lack of proper maintenance will lead to sulfation, stratification and premature battery failure.

Per Trojan batteries https://www.trojanbattery.com/pdf/Tr...UsersGuide.pdf

1. Batteries should be fully charged after each use. “Use” is defined as 30 minutes or more of runtime.

2. In applications where batteries are infrequently used, it is desirable to compensate for self-discharge
by keeping a low charging voltage on the batteries. This is called the float voltage. Avoid using continuous float charging on flooded batteries that are charged more than once/week.

3. Equalizing (flooded/wet batteries only)
When batteries are used in a battery bank, over time some of the batteries can drift to a lower state of
charge than others. This charge imbalance can lead to sulfation and premature battery failure.

Equalizing is an overcharge performed after fully charging deep-cycle flooded/wet batteries. An
equalizing charge prevents electrolyte stratification and reduces sulfation, which are leading causes of
battery failure. Trojan recommends equalizing for 2-4 hours in the following situations:
a. Periodically (every 30 days)
b. When batteries have a low specific gravity after charging (<1.235) or when the range of specific gravities between cells is > 0.030 points

Be warned that when lead acid batteries die - they die quick. You may be in the market for new batteries soon.

You might consider looking into purchasing lithium batteries as they require no maintenance, store better, have better voltage and last longer.
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Old 08-06-2020, 11:48 AM   #8
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We have regular marine wet cell batteries, they are in the battery box just behind the gas tanks, I notice that when the temperature drops in the evening and overnight, the voltage and charge drop precipitously, with the warmth of the sun, the voltage "magically" goes up again. I like the idea of Lithium, but am concerned the temperature dependent voltage drop would be even worse, and worry about occasional camping with temperatures below freezing. I understand the physics behind it but have not come up with a workaround.

My question to others is - do any of you try to keep your batteries warm overnight? and if so how?

We spend most of our camping time boondocking in National parks, have a pretty good solar set-up, but would like to be able to run the furnace occasionally.
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Old 08-06-2020, 08:55 PM   #9
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Your fridge could be the source of your power loss even on propane. Some models have a condensation heater at the seal area that can draw about 1 amp continuously. You may have a switch to turn it off. Check your owner's manual.
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Old 08-07-2020, 03:53 PM   #10
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A "12V" lead-acid battery (wet cell, maintenance free, or AGM) measures 12.6VDC at its terminals when fully charged, disconnected from all loads and chargers, and allowed to rest for at least 15 minutes, but more accurately several hours, to allow surface charge to bleed off. A 12V nominal lead-acid battery has six cells (in series) and a fully charged cell is 2.1VDC. The charging voltages required for Bulk, Absorption, and Float are all greater that 12.6VDC. If the converter/charger and/or solar charge controller are not producing the correct voltages, the battery will either not get to full charge, or take a very long time to do so. Most 3-stage chargers use a time parameter for the Absorption phase. If the time is not long enough, the battery won't get to full charge.
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Old 08-07-2020, 04:56 PM   #11
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Quote:
Originally Posted by Toasterlife View Post
We have regular marine wet cell batteries, they are in the battery box just behind the gas tanks, I notice that when the temperature drops in the evening and overnight, the voltage and charge drop precipitously, with the warmth of the sun, the voltage "magically" goes up again. I like the idea of Lithium, but am concerned the temperature dependent voltage drop would be even worse, and worry about occasional camping with temperatures below freezing. I understand the physics behind it but have not come up with a workaround.

My question to others is - do any of you try to keep your batteries warm overnight? and if so how?

We spend most of our camping time boondocking in National parks, have a pretty good solar set-up, but would like to be able to run the furnace occasionally.
For lead acid batteries, while voltage drops with temperature, current capacity is largely unchanged, so total power loss at say 20 degree temperatures vs. 60 is maybe 5-7%. I suppose you will have to judge if that is worth the effort to relocate them. If you want to move them permanently you should switch to AGM as they are "sealed" and tend not to vent under normal conditions.
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Old 08-08-2020, 03:35 AM   #12
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Quote:
Originally Posted by Kvraspa View Post
. . .
. . . Are we missing something? Is this normal? Is there an energy vampire somewhere that I may not have considered...HELP!!
Wondering if you [OP] have sorted this out?

Thanks,
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Old 08-08-2020, 04:25 PM   #13
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Quote:
Originally Posted by Toasterlife View Post
I like the idea of Lithium, but am concerned the temperature dependent voltage drop would be even worse, and worry about occasional camping with temperatures below freezing. I understand the physics behind it but have not come up with a workaround.

My question to others is - do any of you try to keep your batteries warm overnight? and if so how? .
Lithium batteries perform better at low temperatures than lead acid/AGM batteries. Although there is still a drop in available energy, it is not as significant as LA/AGM.

Lithium-ion batteries have much better performance at colder temperatures than lead-acid batteries. At 0°C, for example, a lead-acid battery’s capacity is reduced by up to 50%, while a lithium iron phosphate battery suffers only a 10% loss at the same temperature.

The most common way to keep a battery warm is with a heating pad or heat blanket. Some companies, like battle Born will sell you a heat pad. Other companies like ReLion have a self heating battery (the LT series. An alternative is to go out and purchase a 12V heat pad with a thermostat and place it under the battery or batteries.

You do not have to run multiple batteries in parallel. You can opt for a larger battery (200ah, 300ah or 400ah) and reduce the footprint and required heating.

Lithium Battery suppliers to consider

AMPS Lithium
https://lithiummarinebattery.com

Battleborn
https://battlebornbatteries.com

LiFeBlue Battery
http://www.lifebluebattery.com

ReLion
https://relionbattery.com

Renogy
https://www.renogy.com

SmartBattery
https://www.lithiumion-batteries.com
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Old 08-09-2020, 05:24 PM   #14
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Don't forget AM Solar, I have their lithium system and it has been trouble free for 4 years now. If you place your lithiums under the bed they are out of the way and stay warmer in the winter and cooler in the summer. All the bed pedistal and beding insulate that area. I watch mine with a recording thermometer and if the trailer is heated to 40 degrees it never goes near freezing. The batteries are OK to use below freezing, just don't charge them until they are warmer.
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