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Old 10-12-2017, 08:54 AM   #1
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2017 27' Flying Cloud
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Battery drain on new AS

Hi,
Wife and I are in the road for the first time in our new AS. Tuesday night we stayed in a great community park in Muleshoe Texas and they had great 50A service. We left there yesterday completely charged up. We drove yesterday in "use" mode with nothing running but the refrigerator and arrived at a Crackerbarrel. I checked the batteries and they were at 12.5v. I turned on the inverter and ran the tv for maybe an hour and then turned it off. I forgot to turn off the inverter. I ran the radio for awhile and furnace came on a few times during the night. This morning I wake to find the batteries at 11.9v! What's up with that? Could the inverter being left on have cause this type of drop?

Thanks,
Bill
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Old 10-12-2017, 10:16 AM   #2
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Hi

Yes.

Some math:

At 12.5V your batteries are at maybe 80% capacity. Stop use is 50% or 12V.

Your battery set likely is a 180AH pair of group 24's. 50% would be 90AH. 30% would be 54AH. TV, radio for an hour at 180W is 15 AH. Inverter likely pulls 3A at idle. Running for 12 hours that's 36 AH. 15 + 36 = 52 of your 54 AH. Throw in a bit for the furnace and lighting. Fridge is a half amp or so. There is another half amp in the propane detectors and other weird loads.

Given that the 80% number is a bit optimistic, and the readings are all +/- 0.1V .... the math above may be a bit optimistic as well.

Bob
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Old 10-12-2017, 10:24 AM   #3
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The biggest draw ypu had during the night was the heater fan. The heater can kill the batteries in on cold night.

I never use the heater once we go to bed.
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Old 10-12-2017, 10:39 AM   #4
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Wlecome to Airstreaming, and the forum!

1. How many, and what size, are your batteries? Guessing two Group 24s, that is about 170 amp hours of capacity if fully charged. Overnight probably is not long enough to bring dead batteries up to full charge. Depending on the converter, that could take 36-48 hours or more.

2. I don't know what the idle current drain of your inverter is. If you have a manual for it, it may be specified. I wouldn't think it is more than 1 amp. That could account for 8 amp hours. Not enough to run good batteries down that low.

3. The inverter is not a good way to watch TV. I put a Vizio TV in my Safari 25 that ran from 12 volts with a "wall wart" power supply. I cut the cable off the power supply and wired it to a cigarette lighter plug so the TV ran from 12 volts. If your TV can't be run that way and you can't find a suitable replacement, I recommend getting a small inverter for the TV. Inverters are much more efficient at something close to their full load. You are taking 12 volts and stepping it up to 120 in the inverter, which is an inefficient process, and then the TV is converting the 120 back down to some lower DC voltage with an additional loss. That said, the TV shouldn't be drawing much more that 50 watts, so that would be about 4 amps at 100% efficiency. A really poor inverter might be at 50 percent, so say 8 amps. But you only ran the TV for about an hour so that's another 8 amp hours, totalling 16.

4. The furnace probably draws about 8 amps. Lets say it ran for 8 hours on a 25% duty cycle, 5 minutes on, 15 minutes off. That's another 16 amp hours.

So a VERY ROUGH estimate of the total looks to be about 32 amp hours. or about 18% discharge of two Group 24s.

Here's a link you can use to find out all you need to know about battery voltage v. capacity:
https://www.google.com/search?q=lead...WggRRIdTPKawM:

Two things about using voltage to measure capacity:
1. It isn't a very accurate measurement.
2. To get the best possible accuracy, measurements should be taken after a couple of hours of no drain/no charge on the batteries. If you measure the starting voltage with the shore power plugged in, you get an optimistic reading, probably significantly higher than the batteries would be when at rest. Since you measured them at Cracker Barrel, you probably got a pessimistic reading. When you measured the discharged voltage while under load, you got a pessimistic reading, somewhat lower than it would be when at rest.

Bottom line, I suspect that your voltage-based capacity measurement isn't giving you the true state of charge of your batteries at either end of the cycle. Charge your batteries on shore power for 48 hours. Unplug from shore power and disconnect the negative terminal of both of your batteries. Come back in about 2 hours with a digital voltmeter and measure the voltage. It should be above 12.6 volts. Connect the negative cables back up, use the trailer for several hours, and keep track of what load you put on the batteries. Disconnect the negative cables and let the batteries rest for two hours. Measure the voltage again and compare the the voltages you got to the charts referenced above.

The best way to determine state of charge is a battery monitor, such as the Victron. It monitors the current into and out of the batteries over time.

In case you don't know this, you shouldn't discharge lead acid batteries below 50% state of charge repeatedly. Every time you do you lose a little capacity.

Edit:
The one WFCO inverter I found specs on has an idle current spec of 3.6 amps. I think my TV estimate is closer to reality as my TV says it draws 57 watts. So my total would be more like 53 amp hours or 31% of battery capacity, leaving about 69% available.

Sorry for being so long winded.

Al
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Old 10-13-2017, 08:30 AM   #5
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Hi

When the TV comes on, the BluRay, the sound system, and all the other "junk" comes in as well. It's weird, but the second TV (powered off) is also pulling power once the 120V comes on. Off is no longer off in the world of remote controls and internet enabled this and that.

How much does this all add up to? Who knows ....

Next layer to the onion: The label talks about watts ( = energy burned). The inverter only cares about amps. If the power factor is poor, you get current, but energy is not burned. If the label talks about amps then that's different. Small power supplies (like phone chargers) are particularly bad for this. They also are famous for pulling the same current when charging as when not charging.

Yes, it gets weird in a hurry

Bob
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Old 10-13-2017, 11:14 AM   #6
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As a rule, when I am on Battery power, I am in ultra conservative mode. Lights on for just long enough for me to find what I need, no AC or heater, absolutely no ��., or microwave, no hair dryers or curling irons, Those things will eat up your power quickly. Coffee gets made on the stove, yucky, but better than nothing. Everything gets unplugged from the outlets. By using this method I know I will have enough power to use the water pump, trailer jack, an other essential items. I have solar and according to the thingy on the wall I usually have a full charge before going to bed, but a rainy or cloudy day can make solar useless.
Using battery power is great for emergency but I wouldn’t want to have to depend on it very much.
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Old 10-13-2017, 11:18 AM   #7
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Ok, so here is a new update. Yesterday I charged the batteries to 12.5V at about 6PM. We had the lights on low and the step light on. The only other thing we had running was the refrigerator. At 10PM the batteries were at 11.9V. To me, this is unacceptable on a brand new unit. We ran the furnace last night and batteries were at 11.8 this morning. The batteries are the stock Interstates.
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Old 10-13-2017, 01:07 PM   #8
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Quote:
Originally Posted by billrector View Post
Ok, so here is a new update. Yesterday I charged the batteries to 12.5V at about 6PM. We had the lights on low and the step light on. The only other thing we had running was the refrigerator. At 10PM the batteries were at 11.9V. To me, this is unacceptable on a brand new unit. We ran the furnace last night and batteries were at 11.8 this morning. The batteries are the stock Interstates.
A full charge on the batteries would be 12.7 volts. Maybe one or both of the batteries have a bad cell. You could pull them out and take them to an auto store to be tested under load. Some of the Airstreams sit on a lot for a while before they are sold. If the batteries aren't kept charged they will sulfate, ruining them. You could make a warranty claim on them to get a new set.
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Old 10-13-2017, 03:11 PM   #9
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Quote:
Originally Posted by billrector View Post
Ok, so here is a new update. Yesterday I charged the batteries to 12.5V at about 6PM. We had the lights on low and the step light on. The only other thing we had running was the refrigerator. At 10PM the batteries were at 11.9V. To me, this is unacceptable on a brand new unit. We ran the furnace last night and batteries were at 11.8 this morning. The batteries are the stock Interstates.
When did you read the 12.5 volts? Were you charging at the time? Discharging? If you were still charging when you read 12.5, full charge would be more like 13.2 volts or higher.

Al
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Old 10-13-2017, 04:31 PM   #10
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The heater fan will suck up your power from batteries pretty fast; inverter can also contribute depending what you are running. Need to make sure you have another source to charge the batteries in any case, if your going to be out for any period of time past a few days, as back up. We have portable solar and also propane generator now. Insurance!

All that being said, I would suspect bad batteries, however. There are several threads on this...AS installed single stage Converter systems in all of the pre-2018 models. We are seeing this same question many times with new owners with 2017 models and earlier...batteries seem to go bad after only few months with minimal loads...then never stay charged. Many of us believe they are being overcharged which ruins the wet-cell batteries. Happened to me for the second time this past summer on my new 2017 28' and also to a friends new 2017 23' AS. The batteries may or may not have been bad when you took delivery, but a good candidate for the problem is the stock Converter "over charged" your wet cell batteries, and now you have bad cells after only a few months usage. That seems to be a common problem.

You can of course, wait in line at your AS dealer to confirm and fix, or you can take them out yourself and go to an Interstate dealer to confirm, which is what I recommend. If indeed that is problem Interstate likely will give you new replacements or credit towards a more costly AGM or Golf Cart 6v batteries. I did this with my 2014 25' 4 months after taking delivery, and again with my 2017 few months back. Found same problem with friends 23' I mentioned.

Fix is a new multi-stage Converter...few options on models and there are a few active threads on this subject with replacement advise:
http://www.airforums.com/forums/f540...it-168615.html
and post #339 in the thread below on 26U battery and converter issues:
http://www.airforums.com/forums/f542...ml#post2016711

There are several others on this topic...enjoy!
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Old 10-13-2017, 07:05 PM   #11
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"The batteries may or may not have been bad when you took delivery..."

Mine (2017 International 27FB) almost certainly were, and from the tales of woe I've seen in these threads, I suspect it's a pretty common occurrence. Although rated at 100+ Ah, my Interstate group 24s had maybe 30 Ah of actual, usable capacity.

It's easy to understand how this happens: a trailer sits on the dealer's lot for weeks or even months; technicians and (in many cases) prospective buyers traipse in and out; people leave lights or the inverter on... batteries are beaten half to death by the time the buyer takes possession. The crude "brown box" converter/charger in most recent RVs does the rest.

I wasn't surprised by this, and had planned all along to replace my batteries ASAP. I now have a pair of Lifeline GPL-6CT AGMs (330 Ah) under the bed, and they're doing just fine, with the aid of a Blue Sky MPPT solar controller and upgraded wiring.
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Old 10-13-2017, 08:47 PM   #12
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Hi

Group 24's should each have about 70 to 80AH depending on which spec sheet you read. Group 27 AGM's will be up around 100AH, maybe a bit more on some spec sheets. There is more variance in performance vs spec than most people expect. A good brand may deliver 10 or 20% more capacity on a "typical" battery than the spec. A less than great brand might only rarely have an example that meets rated capacity.

Bob
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Old 10-13-2017, 08:48 PM   #13
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This happened to me too (the twice part!) Now using 3 stage smart charger and likely to switch out the converter.
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Old 10-14-2017, 08:46 AM   #14
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Hi

The converter (any of them) will get the batteries to >=13.4V when doing a charge. You need to stay on shore power at least to this point to even have 80% battery capacity ( = 30% usable). The normal approach is to stay on shore power for 24 hours *after* you get to 13.4V.

Yes, this assumes a few things. Checking your voltage monitor against even a cheap multimeter would be a good idea. Measure at the battery posts. Voltage drops do matter, but not a lot when watching for a final charge voltage. Big loads can mess things up. You don't normally run big 12V loads when on shore power.

One thing is sure: Discharging batteries a long way damages them / wears them out. Anything below 12V at 70F is a bad idea. At colder temperatures, even 12V is a bad idea. If 11.x V really is showing up on the batteries regularly, you are wearing them out very quickly.

Bob
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