Reply
 
Thread Tools Display Modes
Old 09-27-2019, 04:58 AM   #41
Senior Member
 
Join Date: Jun 2015
Location: Albuquerque
Posts: 595
If you only have one battery, and you are going to run the heater, you wll probably discharge your battery below 50% the first night. The heater fan is an amp hog. If you have a catalytic heater, that is different. If you go below 50%, you will shorten the life of your battery dramatically. I have two batteries, and I still don't run the heater at night. We just use sleeping bags, and use the heater to warm the trailer in the morning. Buy yourself a solar panel, and point it towards the sun. We have a 100 watt, and it charges our batteries up in no time. With a panel, you'll need a charge controller. I use a Morningstar SHS-6. Last year I switched to two 6 volt golf cart batteries (true deep cycle) wired in series to get 12 volts. It made a big difference. I seldom run them below 80%. But we camp in the summer in the mountains. We can boondock forever, as long as the sun shines.
__________________
2009 Roo 21ss + 2007 Superduty 6.0
mnoland30 is offline   Reply With Quote
Old 09-27-2019, 08:08 AM   #42
Junior Member
 
Join Date: Sep 2018
Posts: 7
Battery testing is no easy matter. 1 if the battery is subjected to improper over charging it will become unreliable in a shorter period of time. 2 if the battery is subjected to adverse conditions ( ambient temperatures either very cold or very hot performance will also suffer) hydrometer alone will only tell the state of charge and in no way indicates the condition of the plates. Amp hour meters and chargers that cycle wet cell batteries are the most reliable way to maximize battery life. Ask anyone who has experience with RC wet cell batteries and you quickly learn that this is how batteries are maintained . Their batteries are always subjected to high loads and fast discharges regularly so they try to get the most out of them. If a battery goes unused and not cycled its life will shorten very quickly. This is where most fail in keeping batteries healthy. Also amp meters, amp meters. Amp meters.A battery temperature rise and amp draw will tell you the capacity your battery is capable of.
murrayman333 is offline   Reply With Quote
Old 09-27-2019, 02:02 PM   #43
Member
 
Join Date: Mar 2019
Posts: 35
Quote:
Originally Posted by DavidJ View Post
I am getting ready to take our TT down south this winter. We will be boondocking once in a while and I need to know if our 12 volt battery is in good shape, or should I plan to replace it.

What is a simple test I can do with my voltmeter?

Thanks.
With a little math, you can do a reasonably accurate test with your voltmeter and a space heater.

If you have a big inverter, plug in your space heater and use it for a load. Start with a fully charged battery, turn off the other loads, turn off the AC charger and disconnect the solar controller (if it's night, you can skip the solar). Put the space heater on a power setting within what your inverter can produce.

Now measure the time the battery voltage takes to go from 12.6 to 12.0 volts (measured directly at the battery terminals).

The hours you measure multiplied by the watts of power drawn gives you watt-hours of energy drawn from your battery. A 100 Amp-hour, 12 volt battery gives you about 1200 watt-hours, so a healthy battery should give you about 600 watt-hours when it reaches 50 percent SOC.

But if your battery is old and hasn't been maintained, chances are it needs replaced.
nic7320 is offline   Reply With Quote
Old 09-28-2019, 10:17 AM   #44
Senior Member
 
DavidJ's Avatar
 
Join Date: Jul 2019
Location: Cedar Rapids IA
Posts: 148
Okay so everyone has their own opinion on how to charge and discharge a battery. Obviously most of you have much more knowledge in electricity that I do and that just confuses me. I admit it I am ignorant with this subject.

How about 2 simple questions...

1) Do I have to worry about overcharging a battery if I am simply using the shore cord plugged into my house or at a campground?

2) If I am boondocking, what is an easy way to see how far down my battery has drawn? Everyone says do not go below 50%. Can I use a Volt meter? To prevent me from getting up in the middle of the night to test my battery, is there an Inexpensive do dad to connect to help me monitor the draw on my battery?
__________________
David & Cindy in Iowa
2017 RockWood 2504S travel trailer
2015 Chevy Silverado 1500 LTZ
DavidJ is offline   Reply With Quote
Old 09-28-2019, 11:07 AM   #45
Senior Member
 
Join Date: Mar 2014
Posts: 2,287
Quote:
Originally Posted by DavidJ View Post
Okay so everyone has their own opinion on how to charge and discharge a battery. Obviously most of you have much more knowledge in electricity that I do and that just confuses me. I admit it I am ignorant with this subject.

How about 2 simple questions...

1) Do I have to worry about overcharging a battery if I am simply using the shore cord plugged into my house or at a campground?

2) If I am boondocking, what is an easy way to see how far down my battery has drawn? Everyone says do not go below 50%. Can I use a Volt meter? To prevent me from getting up in the middle of the night to test my battery, is there an Inexpensive do dad to connect to help me monitor the draw on my battery?
1. No, you do not have to worry about overcharging the battery on stock, modern (after 2005) campers. The converter, if working correctly, has multiple modes to prevent overcharging.

2. The 50% is a somewhat arbitrary number, used for planning and calculating. The battery does not self-destruct if you go to 49% SOC.

Now, the caveats.

The stock WFCO converter used on most campers has a poor track record - especially the 8735 used on small campers, pop-ups, and A-frames. It has a tendency not to shift out of the normal "mode" of 13.7V, even when it should.

Most people don't know this failure is happening because they never measure the converter output voltage. If the converter won't shift to trickle mode (13.2V), AND you leave the camper plugged in at home between trips, the converter will "overcharge" the battery, causing the water to evaporate at a faster than normal rate. If The low water level is not caught when it happens, the plates in the battery are exposed to air, and the battery is damaged. The battery will often remain usable at a lower capacity if the water levels are restored. The way to know is to check battery/converter voltage after a week of being plugged in - if it hasn't dropped to 13.2V, you have a problem. I have had this WFCO converter failure on my 2 A-frames. The second time I knew to measure voltage, and I replaced the converter a month after buying the A-frame.

I use a $7 voltmeter for a poor man's approximation of SOC, and to measure the converter output. I have 2 GC-2 golf cart batteries on an A-frame to carry me for 4 nights without recharging, so my current draw compared to battery capacity is pretty small, making the voltage a better indicator of SOC. I installed a digital voltmeter in the microwave cabinet near the door. I open the door, turn the voltmeter on, and get a reading of my battery or converter voltage.

When dry camping (no hook-ups), I check battery voltage in the morning. If it's 12.1 or less, I need to find a way to recharge the batteries. Reading the voltage just after unplugging from the tow vehicle is worthless. I have to wait a few hours to get a good reading. 12.6-12.7V is fully charged, 12.1 is 50%. Each tenth of a volt is about 10% state of charge.

When I'm plugged in, the voltmeter tells me what stage the converter is in. Above 14V, the converter is in bulk mode, and the batteries are less than 90%. At 13.7V, batteries are above 90% and slowly charging. I won't see 13.2V unless I'm plugged in for over 40 consecutive hours (by which time the batteries are fully charged). Note these figures are for a Progressive Industries converter, the thresholds are not the same for a WFCO converter.

Batteries lose a tiny bit of capacity with every charge/discharge cycle. Lead acid batteries lose more capacity when they are deeply discharged, and they lose more when you leave them discharged for a couple of days. Deep cycle batteries lose less capacity per cycle than starting batteries, but cannot generate large currents for starting motors.

Deep cycle batteries can do about 800-1200 cycles to 50% SOC before losing 50% of their capacity. An RV/Marine battery will do 300-400 cycles, and a starting battery about 10 cycles.

If you take a deep cycle battery down to 20% SOC it might do about 40-50 cycles, a starting battery will do 1 cycle.

hope this helps
Fred W
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
pgandw is offline   Reply With Quote
Old 09-29-2019, 12:58 PM   #46
larryandamy
 
Join Date: Apr 2016
Location: Escondido, CA
Posts: 143
Testing 12vdc battery

A voltmeter will only tell you the voltage level of the battery whichis only indicator of current charge level, but not battery capacity. A voltmeter could read 12.6VDC under no load. A good battery could hold a load like 80 amps for 30 minutes to 1 hour with the voltage dropping to around 11.4vdc or higher. While an old degraded battery could still measure 12.6vdc at no load, but the voltage will drop to less than 9vdc with 80 amp load in a few minutes or less. Take the battery to a battery store and they will measure it under load for you. But be careful as their job is to sell you a new battery. Have them test one of their new batteries of same type in front of you so you see the results directly. Then have them test your battery. If you don't want to do this, then you could do this at home using a voltmeter and your rig as a load. Having a built-in current meter telling you the current load is great, but if you don't have one, you can still do this. The biggest draw on an RV battery is from the inverter if you have one. Running my microwave off of my 2000W inverter draws over 110 amps from the batteries. If you don't have an inverter you could turn everything that runs on DC on... lights, furnace, stove blower, fridge on DC if you fridge has a DC mode, but the total current would be less than 20 to 30 amps. Less than 20 amps if you have all LED lighting. Still a good load, but it will take longer for the voltage to drop. If I measure 12.6vdc and turn on my microwave for 5 or 10 minutes, the battery voltage should not drop below 11.4vdc. (Make sure there is no charging from internal charger (camper unplugged) or solar (nightime) as charging boosts the battery voltage during charging.) My last test I ran my microwave for 19 minutes before the voltage dropped to 11.4vdc. Make sure not to let a lead acid battery drop too low (below 11vdc) as lead acid batteries degrade a little permanently if they are discharged over 50% to 75%. With a 20A to 30A load, you should be able to stay above 11.4vdc for 2 to 3 hours with a single good +100Ah battery. Hope thi helps...
larryandamy is offline   Reply With Quote
Old 09-29-2019, 02:15 PM   #47
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 9,427
Quote:
Originally Posted by larryandamy View Post
Make sure not to let a lead acid battery drop too low (below 11vdc) as lead acid batteries degrade a little permanently if they are discharged over 50% to 75%. With a 20A to 30A load, you should be able to stay above 11.4vdc for 2 to 3 hours with a single good +100Ah battery. Hope thi helps...
I agree with most of what you said but a TRUE DEEP CYCLE lead acid battery isn't as fragile as you indicate.

Golf Carts, Floor Scrubbers, Fork Lifts, etc, are discharged far more than 50% on a regular basis. Deeper discharges merely mean that the Lead Acid Battery will only yield a cycle count on the low end of the scale. Average number of cycles for these batteries runs from 200-300 so if one discharges below 50% their battery will only give them the lower number of cycles.

If a battery is "deep cycled" it's important that it be recharged FULLY as soon as possible after discharge. As indicated in almost all literature on Lead Acid Batteries a "full saturation charge" is required and this can take from 8 to 16 hours, not "a couple of hours of generator time in the morning and a couple of hours in the evening" as is a common practice.

The main issue is not how low one discharges a battery but also how long it's left in a partially charged state.

A battery "cycle" is a complete discharge (to minimum voltage, not dead) and recharge to 100% SOC. If one stops discharging at 50% SOC they only use a "cycle" every other time they do this. Following the 50% rule doesn't really extend the number of cycles, it only means that statistically it will last 50% longer (not twice as long) . If one recharges ASAP from a deeper charge may also extend the number of cycles available.

Again, this works on TRUE DEEP CYCLE batteries.
__________________
"A wise man can change his mind. A fool never will."

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Old 09-29-2019, 02:21 PM   #48
Senior Member
 
DavidJ's Avatar
 
Join Date: Jul 2019
Location: Cedar Rapids IA
Posts: 148
Does plugging into the truck umbilical cord and pulling the camper recharge the camper battery?

If so, then I could run the battery down while Boondocking and then charge it back up while driving to my next destination. Sounds like a solution.
__________________
David & Cindy in Iowa
2017 RockWood 2504S travel trailer
2015 Chevy Silverado 1500 LTZ
DavidJ is offline   Reply With Quote
Old 09-29-2019, 02:27 PM   #49
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 9,427
Quote:
Originally Posted by DavidJ View Post
Does plugging into the truck umbilical cord and pulling the camper recharge the camper battery?

It can if 12 volts is being provided to the 7 Pin Receptacle. Some trucks do with a relay that cuts this power when the engine is not running, some have the pin "hot" all the time, and some trucks require a relay or fuse to be added in order to power this feature up.

Older trucks will provide more charge current than newer ones that have regulated Alternator output.

For the most part it will act more like a trickle charger, keeping your batteries topped off unless some wiring upgrades are made and in some cases the addition of a DC-DC charger that will boost input voltage from as low as 8 volts to proper charge voltage for your battery type. This is pretty much a requirement if one expects to charge Lithium batteries from a tow vehicle or coach engine's alternator.
__________________
"A wise man can change his mind. A fool never will."

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Old 09-29-2019, 02:52 PM   #50
Site Team
 
bikendan's Avatar
 
Join Date: Jan 2007
Location: Camano Island, Washington
Posts: 23,093
Quote:
Originally Posted by DavidJ View Post
Does plugging into the truck umbilical cord and pulling the camper recharge the camper battery?

If so, then I could run the battery down while Boondocking and then charge it back up while driving to my next destination. Sounds like a solution.
Nearly all tow vehicles only provide a trickle charge at best, unless they have been setup with thicker charging wire.
So don't expect your depleted battery will get recharged by driving a few hours.
__________________
Dan-Retired California Firefighter/EMT
Shawn-Musician/Entrepreneur/Wine Expert
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity
bikendan is online now   Reply With Quote
Old 09-29-2019, 04:21 PM   #51
Senior Member
 
camaraderie's Avatar
 
Join Date: Feb 2014
Posts: 2,449
Quote:
Originally Posted by DavidJ View Post
Answers in Red
How about 2 simple questions...

1) Do I have to worry about overcharging a battery if I am simply using the shore cord plugged into my house or at a campground?
No...you have zero worries about overcharging with any modern charging system.

2) If I am boondocking, what is an easy way to see how far down my battery has drawn? Everyone says do not go below 50%. Can I use a Volt meter? To prevent me from getting up in the middle of the night to test my battery, is there an Inexpensive do dad to connect to help me monitor the draw on my battery?
No you can't use a volt meter. A true battery monitor is your only accurate way but about $150 bucks. A must if you will boondock a lot. Not at all necessary if you plug in almost always.
Amazon sells cheap current monitors that give you the ability to look at what is going on with amp draw at this moment which will let you project how many amp hour you will use over the next hours...but not provide any state of charge info that is reliable.
__________________
________
Cam
2015 Georgetown 280DS
2019 Vespa Primavera 150's (pair)
camaraderie is offline   Reply With Quote
Reply

Tags
12 volt, battery

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



All times are GMT -5. The time now is 03:23 PM.