Battery Charge

[frscott]

I have had my '85 Sovereign for about 6 months now, and accidentally left the fridge on and killed the two batteries. I was doing some maintenance and had the trailer plugged into the house, and decided to take out the batteries for recharge, only to find that the battery lines were very live! I am not an electrician, so I am wondering if power to the batteries means that they will recharge when the trailer is plugged in? Will the batteries get too charged if I leave the trailer plugged in?

[Mrcrowley]

When you plug in your trailer to 120 volt out side line they will charge so no removing of battery to charge is needed.

[campman]

In six months and no recharge, they probably are totally dead and cannot recharge. Doesn't your unit have a charger and 3 stage inverter hooked up to the batteries? If so, when not in use (and if water level is up and pH is correct..usd a hygrometer), they should keep a charge. I found two sets of info but am not sure of the exact forum or thread...that are just about the best education you could get on batteries and their care. Use the search feature. Here is the title of Part 2 of that information; it may help you find it: It is several pages and illustrations...top notch...
The 12 volt Side of Life Part 2.

Good Luck.

[Mrcrowley]

Originally Posted by campman

In six months and no recharge, they probably are totally dead and cannot recharge. Doesn't your unit have a charger and 3 stage inverter hooked up to the batteries? If so, when not in use (and if water level is up and pH is correct..usd a hygrometer), they should keep a charge. I found two sets of info but am not sure of the exact forum or thread...that are just about the best education you could get on batteries and their care. Use the search feature. Here is the title of Part 2 of that information; it may help you find it: It is several pages and illustrations...top notch...
The 12 volt Side of Life Part 2.

Good Luck.

Where do you find a load tester ?
That might be a good investment if not you can bring your battery's to a pep boys or autozone and have them load test it to see if it can still hold a charge.

[frscott]

Thanks to all for the help! I did have to replace one of the batteries, so you wee right about the concern for a dead one. I will do the search for the article mentioned, because I still have no idea where the inverter is-though I know there is one since I get AC inside the unit, but as far as a charger, I have no idea where to look. But at least I know to plug it in while it is parked! Maybe I need a week at Airstream training school??

[bryanl]

Yes, the battery lines will be live when you have 110v connected. That is the function of the RV converter. It 'automatically' charges the battery whenever you connect the trailer to 120vAC power.

Forget hydrometers and load testers. That is _so_ old tech! Hydrometers require hazmat precautions and have a good likelihood of contaminating your batteries. Load testing is destructive. Modern techniques use voltage and a conductance tester to determine the state of charge and state of health of a battery.

If your batteries were flat dead for any length of time, it is likely that they are damaged and need to be replaced. The easiest way to tell is to see how long they will keep the trailer lights bright (this is a simple load test).

Note that many RV converters will do OK to charge batteries but not so hot when it comes to storage maintenance. Storage requires particular attention to charge topoff and desulfation. The WFCO or PD+CW converts do this. The Battery Minder (tm) is another option.

[Mexray]

Whoa there...I've been in the Battery Biz for many years, and have seen those 'electronic' testors come and go over the years...but they really can't replace hydrometers and load testors when you're trying to find out what's going on inside your batteries!

All battery Mfg's indeed still use hydrometers AND load testors in their Mfg. process'. We use em' every day in our shop, too! I've never heard of a hydrometer contaminating a battery...???

A hydrometer is the only true way to check the state of charge of you battery...voltage only gives an 'indication' of the charge status, and only after it's been 'rested' for over 24 hours without any charge or discharge.

Load testing of a charged battery will NOT destroy it! Sure one could keep the load on the battery till it discharges completely, but that's not how it's used.

A load testor will indicate cell problems in your battery, IE if plates are shorted, etc, due to breakage or sulfate build up...

Also, it's not wise to replace only one battery in a two battery bank if they are older than two years...the new battery will not perform as well, as the older battery's internal resistance will be different, causing the charging system to shut down sooner and nor allowing the new battery to get fully charged.

Batteries need to be fully charged to give long service life...and they're life will be shortened if you discharge them below 50 per cent all the time, or let them 'sit' in an undercharged condition for any length of time, such as when in storage...the battery in your TV or car lasts for years as the alternator keeps it fully charged all the time...your RV deep cycle batteries are no different in that regard, keep em' charged up for longer life!

[campman]

Leipper...that is hyGrometer, not hydrometer...anyway, your technical advice is difficult for a novice like frscott. FRSCOTT; The converter/charger should be right in the same general space as your batteries (however, the batteries are always set off in specific space for safety). I found the REALLY GREAT BATTERY INFO SITE HERE:
WWW.CCIS.COM/HOME/MNEMETH/12VOLT/12VOLT.HTM
It is all easy to understand and will teach you a lot. I printed the first one off and then put the other one in my favorites for later learning.
Anyway, owning an RV or other unit is part of keeping you young by learning new things. Good Luck

[campman]

Sorry..I was way off base and wrong...it IS hydrometer. An hygrometer measures humidity. Stupid of me.. Anyway, they are cheap and easy to use and in no way could harm a battery. Get one.

[ostream]

FWIW -

- "Inverter" is an electrical device that converts direct current (DC) to alternating current (AC). An inverter allows you to use store energy in your batteries to power devices that require 120v electricity (i.e. TV, mobile phone recharger, etc.)

- "Converter" is an electrical device that converts 120v AC to 12v DC. In the RV world, converters generally also include a battery charger. This device supplies a 12v DC power source to everything in your trailer that requires 12v (lights, 'fridge, water pump, etc.) as well as charges your house batteries.

All Airstreams have a converter/charger. Inverter is a paid for upgrade.

[bryanl]

oh my, I really don't know why I rouse such hostile sentiments. And complaining that "your technical advice is difficult for a novice like frscott " when I didn't get technical is interesting, too. Oh well, for those who can keep an open mind, here are some references to check to find out where I got my wild, wacky, and offensive ideas.

It is indeed easy to get the d's and g's confused, but do check hydrometer vs hygrometer in the dictionary. If you take a look at proper use of hydrometers in batteries, you'll see that they require as many caveats about temperature, battery state, and other factors as does voltage testing. But let's be careful about getting too analytic and letting precision overrun accuracy in our RV battery measuring.

A couple of references on background for measuring state of charge include Battery State of Charge Determination and SmartGauge Electronics - Specific Gravity and State of Charge - these require careful reading to understand how specific gravity and voltage are related. As an example note that smartgauge basis its battery meter on an analysis of voltage. The smartgauge site has a number of very good essays on topics pertinent to RV battery systems.

The fact is that with modern DVM's and a proper measure and its interpretation, voltage can be useful for the typical RVer for determining battery state of charge. Considering the difficulty (or even impossibility in the case of sealed batteries) of getting to the battery cells plus the risks involved in dealing with battery acid, a voltage measure can do well enough.

re "have seen those 'electronic' testors come and go over the years" - nope, not those. I mentioned conductivity testors. They have been around since early 1990's. See Rapid testing of batteries at Battery University.com for a nice rundown on methods. Search 'battery conductance testing' to learn about this.

See Basic battery guidelines for some basic RV oriented guides and a link to all sorts of good battery information sites.

There is so much information out there about batteries that it can be confusing. And, on top of that, much of the discussion gets way past what an RV enthusiast needs in technical detail and laboratory precision. Used to be we were happy just watching how the lights dimmed when the water pump or furnace came on. Nowadays it seems folks want to know the exact minute when they will run out of juice predicted days ahead. Some things just ain't gonna' be.

[n2916s]

On my '86 Sovereign, the converter/charger is under the couch up front. If it is the original Univolt, you should be able to hear it humming whenever you are plugged into shore power.

mike

[Mexray]

Bryan,
I couldn't agree more...keep it simple when it comes to RV battery information.

I deal with RV battery problems every week in my business, and I believe about 90 percent of the RV'ers don't have a clue as to what's going on in their RV, battery wise!

Most contributors on this Forum aren't in that 90 percent group - they've taken to time to learn what goes on inside their AS to get the most out of them, etc.

I'm sorry though, most all electronic battery testors I've seen are akin to snake oil products...sure, they'll measure the voltage, maybe the internal resistance, and then flash some lights to indicate 'good' or not...but not much more...if you read some of the links in depth that you've listed, you will note they are talking about 'single cell' battey testing...when it comes to multiple cell batteries...IE, RV 6 cell (12 volt) or 3 cell (6 volt) batteries, these 'electronic' devices can only average out the results to give you a 'reading'....if you have one weak cell, it won't tell you squat - only the 'average' of the cells...

Sure, if you have a sealed top, maint free type battery, you can't use a hydrometer, and must use a voltmeter to get some kind of indication of the batteries condition...the load tester will be the only true device to let you know if their's a weak sell - and only AFTER the battery has been charged...you can't find a leak in a tire till you pump it up with air...same with batteries, you can't load test without first charging.

Also...if you have battery problems, seek out a Battery Specialist in your area...most local auto parts stores don't have the experience or knowledge to provide the answers an RV'er might need for his battery system...the Battery Specialist will give you the straight scoop...

In the vein of keeping things 'simple'...

1. keep your batteries charged when not in use.
2. keep the terminals clean and free of corrosion...use some heavy grease to coat exposed metal parts and cable ends will help.
3. Don't leave your AS plugged into shore power if you have an older Univolt converter/charger, as it will overcharge your batteries, evaporate the fluid, and ruin them.
4. always recharge your batteries as soon as possibe after use...use a daily charging schedule if you're boondocking to insure you're getting back to full charge.
5. larger battery banks are great for longer running times, but take lots more time to recharge...there's no free lunch here, what comes out of the batteries must be replaced!

[Mrcrowley]

Originally Posted by Mexray

Bryan,
I couldn't agree more...keep it simple when it comes to RV battery information.

I deal with RV battery problems every week in my business, and I believe about 90 percent of the RV'ers don't have a clue as to what's going on in their RV, battery wise!

Most contributors on this Forum aren't in that 90 percent group - they've taken to time to learn what goes on inside their AS to get the most out of them, etc.

I'm sorry though, most all electronic battery testors I've seen are akin to snake oil products...sure, they'll measure the voltage, maybe the internal resistance, and then flash some lights to indicate 'good' or not...but not much more...if you read some of the links in depth that you've listed, you will note they are talking about 'single cell' battey testing...when it comes to multiple cell batteries...IE, RV 6 cell (12 volt) or 3 cell (6 volt) batteries, these 'electronic' devices can only average out the results to give you a 'reading'....if you have one weak cell, it won't tell you squat - only the 'average' of the cells...

Sure, if you have a sealed top, maint free type battery, you can't use a hydrometer, and must use a voltmeter to get some kind of indication of the batteries condition...the load tester will be the only true device to let you know if their's a weak sell - and only AFTER the battery has been charged...you can't find a leak in a tire till you pump it up with air...same with batteries, you can't load test without first charging.

Also...if you have battery problems, seek out a Battery Specialist in your area...most local auto parts stores don't have the experience or knowledge to provide the answers an RV'er might need for his battery system...the Battery Specialist will give you the straight scoop...

In the vein of keeping things 'simple'...

1. keep your batteries charged when not in use.
2. keep the terminals clean and free of corrosion...use some heavy grease to coat exposed metal parts and cable ends will help.
3. Don't leave your AS plugged into shore power if you have an older Univolt converter/charger, as it will overcharge your batteries, evaporate the fluid, and ruin them.
4. always recharge your batteries as soon as possibe after use...use a daily charging schedule if you're boondocking to insure you're getting back to full charge.
5. larger battery banks are great for longer running times, but take lots more time to recharge...there's no free lunch here, what comes out of the batteries must be replaced!

Use a appliance timer and have it go one for a few hours a day. that would keep it from over charging.

[bryanl]

I'm sorry though, most all electronic battery testors I've seen are akin to snake oil products.

We must be talking about two different things, I think. I do not know what battery diagnostic devices you are familiar with but the good conductance devices I am thinking about are in wide commercial use and run around $1k or more. They essentially 'ping' the battery with a variety of frequencies and look at the time domain response to obtain an impedance for each cell in the battery. The analysis and battery modeling they use is fascinating.

A local geothermal power plant that was so impressed with one vendor's test device they got one for their own use. It has saved them quite a bit on battery maintenance and avoiding battery failure. (It also did quite well at a rally diagnosing battery state of health and state of charge to get results that correlated well with age and use patterns of the RV battery banks tested.)

Shorted cells and other such failures are in the low risk but readily apparent area which means you usually don't need fancy tests to figure it out. Most (80% or so) RV batteries fail due to sulfation buildup as an aging thing. The capacity of the battery just decreases over time and how quick that happens depends upon how they are used and abused.

As for "larger battery banks are great for longer running times, but take lots more time to recharge" - this would only be true if your charger was under rated for your battery bank. Most modern converters can provide full charging current for as big a battery bank as you'd find in a typical trailer. The limitation on charge time is usually due to the converters keeping to a safe voltage for the connected appliances - not the size of the battery bank. Many folks don't realize that it takes 8 hours or more to fully charge a typical RV battery properly because of the nature of the beast (it takes time for the chemistry to settle).

The best guide for sizing a battery bank I have seen is to make sure it is big enough you don't take it below about 12.0v measured after it has been quiet for a half hour or so but not so big you don't get at least get it down to 12.4v (after no significant charging or discharging for a half hour or so) as a regular thing.

The idea about an appliance timer is a good one and is essentially what the charge wizard or WFCO converters do automatically. You still need to keep an eye on electrolyte levels every few months to make sure the system you are using isn't drying out the batteries if you can.

re "if you have battery problems, seek out a Battery Specialist in your area" - I agree with this and with the sentiment that they are not so easy to find. I don't agree that you should take some the word of anyone, though, without qualification. There is so much BS, even from specialists who supposedly are giving you the straight scoop that you need to learn enough to see the context. A true 'expert' will help you learn and understand where his "straight scoop" applies and where it comes from (and he'll be open to the idea he doesn't know everything, as well, and be willing to learn).

[Mexray]

Bryan,
It seems interesting that you find some issue with my each and every point above...I was merely trying to impart some thoughts about how one might care for their on-board RV batteries...some generalized information, without getting too technical, that may assist frscott and others here, with some battery usage and diagnostic suggestions...I have dealt with these issues on a day-to-day basis for over 40 years, and my observations herein are based on my practical emperience...
Ray

[bryanl]

It seems interesting that you find some issue with my each and every point above

Let's try to be factually correct, what say? I agreed with several, expanded on one or two, but took issue with only one that was in error along with the reason why. I think you do not do anyone justice to complain that I "find some issue with each and every" - why address me rather than the ideas I present?

I do not think that the 'appeal to authority' type of argument is a good one, either. Neither is the straw man of 'too technical'. We need to help others (and each other) understand, at least on a conceptual level, what these issues are all about so we can make better decisions. It is up to all of us with knowledge and experience to educate rather than to inculcate. We should be sharing ideas rather than pronouncing ideologies, IMHO.

I provided examples, rationales, and references to support what I offered. Don't you think it would be better to address those rather than to just dismiss them or complain about the messenger?

[Newlyweds]

Blah blah blah... both of you! Your constant bickering is helping no one, but “thank you”, to you both for your input regarding batteries, etc.

[Mrcrowley]

Originally Posted by Newlyweds

Blah blah blah... both of you! Your constant bickering is helping no one, but “thank you”, to you both for your input regarding batteries, etc.

\

Like he said just get married and get it over with LOL...

[bryanl]

There is a name for this. When you decide that all behavior is equally acceptable, then you will find things perhaps not as you wish they were to be.

When you label things as they are not, you see what is not and that is an attempt to escape from reality. Sometimes useful but not usually productive.