What to expect. Ran a test

[mtflybox]

Sorry but I couldn't find much specificity about what to expect when I searched other threads. Don't want to waste anyones time...

But, I was wondering if my batteries are bad...

I ran a test for the first time this weekend after fully charging on shore power for two days. I wanted to see what I could do if I we boondock in VA next month.

In my new 2020 GT with one solar panel on a sunny day, both fantastic fans running on level 2, a couple of interior lights on, the airstream connect and the domestic refrigerator set on battery I only ran for 80 min till the batteries went below 9V.

When I plugged back into the pole and checked my meter, I was drawing 6A. With two supposedly fully charged 80 amp-hr batteries I fear something is not working properly.

[Joe15601]

If your fridge is a 3-way, try with it on propane.

[OTRA15]

I guess your 2020 fridge does not run on propane at all, correct? [Edit -- "Two way" in the AS parlance.]

You might want to check out the following threads and search results:

https://www.airforums.com/forums/f42...-s-202565.html
https://www.airforums.com/forums/f38...ng-210846.html
https://www.google.com/search?q=frid...=airforums.com

Also, the Boondocking forum has helpful threads: https://www.airforums.com/forums/f382/

Good luck,

[overlander63]

You DO NOT run your three way fridge on battery, ever, unless you are out of LP, and are using battery as an emergency stop-gap to keep your food cool as you go to get more LP. It WILL run your batteries dead in an hour or two. It is not a compressor driven system, you are running a heating element, basically a virtual dead short to generate enough heat to cool your fridge.

[OTRA15]

Guessing he has one of the new 2-way fridges . . . an Airstream "improvement" . . . . . . please see my earlier post.

[mtflybox]

Thx for the feedback.

Yes the fridge does run on propane, which is what I use when traveling etc. I wanted to see what I could get out of the the batteries.

I'll check the recommended threads as well.

[ROBERT CROSS]

What Terry said...👍

Thank goodness we have a Dometic 3662 two way.
AC or LP...

Bob
🇺🇸

[BayouBiker]

mtflybox, If I understand correctly the six amp draw represents current input into the converter which after allowing for resistance losses would be about max charge rate. But the 6 amps is not what the loads were on the battery.

The frig draws maybe 6.7 amps while cooling, the fans maybe 1 amp each lights about 1 passive always on loads 1 amp, wifi about 1-2 amps. These are WAGs so...

Edit: isn't the '20 globetrotter an compressor model? If not then what Terry said. That would account for the missing 10 amps.

So maybe 12 amps. I wasn't clear about how much the solar charger was helping so I am ignoring that for now. So 12 amps will draw you down to about 80% if we assume also the batteries where at the lower limit of a "full charge" and with a 12 amp draw the batteries with the draw will have a voltage loss of about 1.5 volts so you should have been at about 11 volts vs. 9 Volts (with load)

Indications are the batteries may not be much good. Or there was another 10 amps not taken into account, or you have some poor connections.

If your batteries are wet cells, get a hydrometer and test each cell. If they are sealed AGM, get yourself a battery load tester, or take them someplace close to have them tested. Most places are familiar with automotive starter batteries, so tell them your batteries are about 620 Cold Cranking Amps or 800 marine cranking amps. The will need to be fully charged to properly test them.

[wulfraat]

Your batteries are dead.

That compressor fridge only draws like 5 amps. Less if it's an LP fired fridge.

Even if you triple that with everything else that's on in the trailer that's 15amps current. 15 amps x 80min/60min = 20 amp hours from the batteries with no solar.

20 amp hours on a 200AH lead acid bank (100ah usable) is about 20% of your usable energy and batteries should land around 12.5v. not 9.

Fridge is not the problem. your batteries are.

Airstream have stopped shipping batteries in their trailers because sitting on dealer lots would destroy them with parasitic draws. Dealers are now supposed to install new / fresh batteries for the customer.

[uncle_bob]

Hi

6A off of 120V *into* the converter / charger is pretty much the max you would ever see. 3 or 4A is much more common as it tries to charge even a dead battery.

This *assumes* that the "6A draw" is at 120V.

===

If you have taken your batteries down to 9V, that's not a good thing. Keeping them above 12.0V is the goal. Anything much below 11.5V is getting into "danger" territory with the stock batteries.

===

As noted above, the "three way" fridge should be considered to be a "two way" with a suicide option. There is no practical way to use stock batteries to run that fridge for any noticeable length of time. All you will do is kill your batteries.

Even running the pair of fans on "full" is a bit exciting. They likely pull about 2A each set to high. That's a total of 4A of drain. Toss in a light string pulling an amp and you are up above 5A *without* the fridge.

====

Bottom line:

You have to be very careful about drain on the batteries. Either you have to know the drain of each device and add it all up *or* you need a shunt based monitor to do that for you. The only way to get a couple days on battery is to be frugal, very frugal ....

Bob

[jimdelane]

Originally Posted by mtflybox

In my new 2020 GT with one solar panel on a sunny day, both fans running on level 2, a couple of interior lights on, the airstream connect and the domestic refrigerator set on battery I only ran for 80 min till the batteries went below 9V.

When I plugged back into the pole and checked my meter, I was drawing 6A. With two supposedly fully charged 80 amp-hr batteries I fear something is not working properly.

The bottom line is how many watts are you using and what is the reserve energy capacity do you have.
How many watts does the fridge, fans and lights draw.
watts = amps x volts
If your pole is 120v and you draw 6 amps = 720 watts.
This is equal to 12V at 60 amps = 720 watts.

Solar is good. No mention as to how much solar you have.
Unless you have 720w solar, the solar will just suppliment your battery bank. Also, solar never puts out the spec numbers. Those are based on perfect sun, perfect angle. If you get 50-75% of rated solar watts - you are doing good.

Lets talk batteries.... if you continue to draw the battery down to 9v - you will (and may have already) permanently damaged that lead acid battery. You should never draw the battery capacity below 50% or voltage below 12.12V if you want a lead acid/agm battery to last 3-5 years.

When determining what you need for battery, you should focus on usable what hours, not Ah of the battery. So (2) 80Ah (Group 27) batteries gives you a total of 80 usable amp hours at 12v = 960 watt hours. That is 960 watts for 1 hour or 96 watts for 10 hours.

You should get 1 hour out of the batteries
(12v x 60A =720w) and at that point, you will be close to 50% discharged and the voltage should read 12.2v or so. Time to stop using them or you will kill them.

If your batteries sat in a less than 90%-100% fully charged state for an extended period of time (weeks or months), they will lose capacity due to lead sulfur crystal build up (sulfation) on the plates. You can try equalization or boost which will burn the crystals off the lead plates. Check out the Lifeline tech manual for info - http://lifelinebatteries.com/wp-cont...cal-Manual.pdf

It is possible that your batteries need replacing.
With lead acid batteries, you get what you pay for. The cheaper the battery, generally, the plates are thinner, the materials used are not the best and, consequently, they will fail sooner costing you frustration, time, labor and money to replace.

You have choices.

Flooded Lead acid is cheap.
(2) GC2 (T-105) 6V batteries (wired in series) will provide more energy and last longer than (2) 12v Group 31. Always buy a quality battery - I recommend Lifeline or Trojan. The cons are, you need to maintain them. Keep them 100% charged as much as possible, add watrer as needed, clean the terminal corrosion regularly, equalize periodically, etc. Propery maintained, you can expect 500-800 cycle life out of a good quality FLA.

Valve regulated lead acid (VRLA) - AGMs and Gels. Nice thing is these are mainenance free. They can vent corrosive gas when charged so the terminals need to be cleaned periodically. Being a lead acid battery, it is important to maintain the 90-100% charge or the battery can sulfate. Most VLRA manufacturers do not recommend equalization. Lifeline does, but only after a capacity drop has been noticed. Equalization causes the absorbed electrolyte to offgas which escapes through the valve. This drys out the AGM which will cause battery failure. But I guess, Lifeline figures that if the battery is dying anyway from sulfation - can't hurt, might help.
They cost more than FLAs. Propery maintained, you can expect 400-600 cycle life out of a good quality VRLA.

Lithium Iron Phosphate - LiFePO4
Any RV that has lithium batteries will tell you how great they are. No maintenance, faster charging, higher constant voltage, lightweight, etc. Lithiums can be used to 100% without damage to the battery. The battery can be stored partially charged without damage.

Cost has been the issue. The cost has dropped significantly in the past year. The cost of a lithium battery is a little bit more than the cost of (2) quality AGMs of the same usable watt hours.
Lithium batteries have a cycle life of 3000-5000 cycles.
Lithium batteries range from 105ah (1344 watt hours) 30lbs, 200Ah (2560Wh) 50-60lbs, 300Ah (3840Wh) 70-80, 400ah (5120Wh) 90-100lbs.

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

[GOUSC]

I recently ran a test for the factory solar on my 2018 Globetrotter with different results, see link below.

If you did use the battery for your refrig it will run the batteries down pretty quick. I used them in conjunction with Towing and the power from the TV and solar panels kept the batteries at a reasonable level for a 7 hr drive. Stand alone the battery option is a killer.

https://www.airforums.com/forums/f44...ar-210893.html

[Atwebs]

All the scientific equations apart, when you are boondocking and not plugged in, you need to conserve your energy. Lights when needed after dark, fan only when it is too hot to sit outside under a shady tree. Pump for water turned on when you need it.

We boondocked forever without solar, just on the standard Interstate batteries (propane stove & water heater) and generally we could go only about 48 hours before we ran out of power. Far less if there was something amiss with the batteries and often that was the case. We eventually got a fancy trickle charger that checked the wet cells and reported any problems and that helped some (not completely though), squeaked up to about 60 hours. Enough for a long weekend.

Now, our solar and AGM batteries make it possible to recharge every day and thus far (2019 GT but got it in 8/2018) we have never had to sit in the dark (or get out the generator, or tow the trailer just to recharge it).

[mtflybox]

Thanks to all for the thoughtful responses.

There continue to be some aspects of the Airstream model I'm disappointed in for the price, but the knowledge and support of this forum is a huge plus.

Foolishly, I wasn't doing the math some of you point out between 12 and 120V. Got it. As noted, refrigerator on battery = suicide option.

I'll get a tester for the batteries, but frankly if I'm not around my wife is not going to watch this stuff, so I may just upgrade the batteries to be safe.

[OTRA15]

Originally Posted by mtflybox

. . .
I'll get a tester for the batteries, but frankly if I'm not around my wife is not going to watch this stuff, so I may just upgrade the batteries to be safe.

Thanks for the update. If the batteries are possibly shot, you could take them to an auto store dealing with the same brand, and have them tested more accurately that most folks can do at home. You may even get replacements under warranty.

Good luck,

[love nest]

Originally Posted by mtflybox

Sorry but I couldn't find much specificity about what to expect when I searched other threads. Don't want to waste anyones time...

But, I was wondering if my batteries are bad...

I ran a test for the first time this weekend after fully charging on shore power for two days. I wanted to see what I could do if I we boondock in VA next month.

In my new 2020 GT with one solar panel on a sunny day, both fantastic fans running on level 2, a couple of interior lights on, the airstream connect and the domestic refrigerator set on battery I only ran for 80 min till the batteries went below 9V.

When I plugged back into the pole and checked my meter, I was drawing 6A. With two supposedly fully charged 80 amp-hr batteries I fear something is not working properly.

https://www.airforums.com/forums/att...4&d=1573837658

This a chart from another forum.

[uncle_bob]

Originally Posted by mtflybox

Thanks to all for the thoughtful responses.

There continue to be some aspects of the Airstream model I'm disappointed in for the price, but the knowledge and support of this forum is a huge plus.

Foolishly, I wasn't doing the math some of you point out between 12 and 120V. Got it. As noted, refrigerator on battery = suicide option.

I'll get a tester for the batteries, but frankly if I'm not around my wife is not going to watch this stuff, so I may just upgrade the batteries to be safe.

Hi

With some shunt based battery monitors, you can hook up an alarm to go off when you get to a certain point in the discharge curve. That way there is no need to watch anything. They get to here or there and the beeper starts beeping.

If that's still likely to be ignored, hook up a disconnect to the same type of monitor. When you get to X, the batteries go offline. ( and you have no power and the fridge starts to warm up and .....).

Bottom line, boondocking is *not* an auto pilot sort of thing. It's a pay attention to the details kind of adventure. If you want to be on auto pilot, stay at the KOA.

Bob

[OTRA15]

Originally Posted by uncle_bob

. . .
Bottom line, boondocking is *not* an auto pilot sort of thing. It's a pay attention to the details kind of adventure.
. . .

Bingo!

[TurkeyRun]

I own a fully gutted and renovated (not "restored") 68 Overlander, so I am not up on all the latest from Thor. When I boondock there is always a Honda genset for backup. But I never understood the 3 way fridge. Propane and electric require different cooling systems that means the fridge interior is smaller. I installed a 7cf Novacool with a bottom freezer, and it draws 5 amps when running. As monitored on a Blue Sea systems DC shunt breaker panel right next to it. And it only runs the compressor half the time if you are not in an out if it cooking. So it uses maybe 60 amp hrs per day. I have left it for 36 hours and my 2 Deka group 27 AGM batteries are still over 12v.
The 3 way Dometic is an energy and space hog.

[NevadaGeo]

I use a relatively cheap battery load tester, basically a resistance load short across the terminals. The voltage meter on the thing shows the voltage drop and the strength of the battery. About $20 at tractor supply. I’ve had new batteries from the store test pretty poorly. And they come from the store half charged or less, so I’ve killed a new battery dead and won’t come back the first night with the COAP machine.