How much battery do I need?

[james tillitt]

I'm fairly new to this, but I can't see using a full sized RV battery for a teardrop that will have two kitchen lights, two inside lights, a porch light and a car type stereo. Would a motorcycle battery or a lawn garden tractor (or similar) battery do the job. I also have a Battery Tender that will be on the battery when I am home.

Thanks

[Ken A Hood]

http://bart.ccis.com/home/mnemeth/12volt/12volt.htm

Here's a good 2 page read....lists the various battery types and pro's and con's to each

[Miriam C.]

And here is a second that will let you know how to figure what you will be really be using.

http://www.repairfaq.org/ELE/F_deep_cyc ... PCYCLE_008

Enjoy

[48Rob]

Hi James,

The information in the links provided will help remove most of the mystery.

In answer to your question, yes, no, maybe...?

A 12 volt disposable lantern battery will run all the items you listed.

A lawn mower or motorcycle battery will too.

The question you must understand and answer is

"How long will battery x run those items before giving out"

Once you know how much power you need for how long, you will be able to determine what battery, with what capacity will work best for you.


Kind of like driving across an open stretch of desert with no gas stations, and having three gallons of gas in your tank.

Is it enough to make it to the other side?


Rob

[james tillitt]

I am sold on a deep cycle battery. I am mostly concerned with size and weight. Any recommendations here? Also, can I run the Battery Tender while using the 12 systems or are there any issues with spikes or overheating the battery?

Oh yeah, I work for a company that does custom bus conversions so I have a wealth of information at my disposal, unfortunately I have a hard time getting them to think in terms of a teardrop.

[Kurt (Indiana)]

James, I've running a lawn mower battery with a 1.5 amp trickle charger for about four years now with no problem.
I run the inside fan, the TV, the DVD, XM radio and inside lights with it. As long as I have the charger working it's no problem. (sometimes all at once)

Without electrical hookup at CAMP ADK a couple of weeks ago, I was able to watch as many as ttwo (and a half) movies after I used my Honda 1000i to recharge for an hour or so. Didn't need the fan.

I use an LED light for interior and reading lights.

The DVD draws the most power but it did fine for me. It all depends on your needs.

[SteveH]

IMHO, batteries are like fuel on an airplane....the only time you have too much on board is when you are on fire.

[asianflava]

A 12 volt disposable lantern battery will run all the items you listed.

Yup, saw ReoRon doing this at Minden. Wire up 2 6V lantern batteries in series and viola!

[48Rob]

James,

Deep cycle is good, as they are designed for heavy duty discharge and recharge over a long life span.
Other batteries won't last as long, but are much cheaper.

Amp hours, you'll find, when reading up on 12 volt storage systems, is the measure used to tell how much capacity a given battery has.
In order for anyone to recommend a particular battery/size, you need to understand the Amp hour formula, and be able to answer how many amp hours you need to get you through the average weekend (or whatever time period) camping trip.

In answer to your question about using 12 volt items while connected to the battery tender...if the items are designed for 12 volt automotive use (like in a car) you will be fine.
If the item is runs on 12 volts supplied by a transformer that you have replaced with a 12 volt plug in, the battery tenders voltage may be too high.

12 Volts in the automotive/battery tender world can go as high as 15.5-16 volts while charging.

I have a television designed to run off a transformer, but have switched it to run off the 110 transformer when the battery tender is charging (since it also runs on 110) to avoid the high voltage.
It runs on the battery system when we are not plugged in, and is automatic via a relay.



Rob

[Dooner]

In answer to your question about using 12 volt items while connected to the battery tender...if the items are designed for 12 volt automotive use (like in a car) you will be fine.
If the item is runs on 12 volts supplied by a transformer that you have replaced with a 12 volt plug in, the battery tenders voltage may be too high,

Would that also include an invertor? I was going to run my laptop on a small invertor and would like the battery charger on when plugged to shore power. Would it be best to have a 110 outlet for shore power camping and only use the invertor in case of dry camping?

[48Rob]

Hi Dooner,

An inverter is designed to handle the high and low voltage of an automotive system/battery charger system.

The danger from high/low voltage only comes in when the appliance you have connected to the 12 volt battery system, is designed to run off 12 volts delivered from a transformer.
A transformer that supplies an appliance with 12 volts stays within a very close range, say 11.9-12.1 volts, as opposed to the battery storage/charging system which can range from 10 volts to 15.5 volts.
Appliances designed to run on an automotive system, say a flip down television or CD player, can easily handle the varying power.


Your inverter takes the range of 12 volt power supplied by the battery storage/battery charger system, and turns/transforms it into 110 volts.
The laptop is supplied via a transformer that you plug into the inverter, so it always delivers voltage in an acceptable range.
If the inverter system gets too much/too little from the battery system, it shuts down, preventing damage to your laptop.

Unless you're running very expensive and sensitive items, there is no need to have dual systems.
Some RV's do, some don't.

Some (usually inexpensive) inverters can use a lot of battery power to produce 110, in other words they are power hogs, but still better than connecting directly to the battery system (assuming the laptop runs on 12vdc.).

If you'll be spending a lot of time using a laptop, and will often be connected to shore power, having an outlet or two in the trailer that provide shore power is handy.

Be cautioned though, that some very (voltage) sensitive items may be affected by current ups and downs produced by inexpensive inverters, and also by poorly maintained campground electrical systems.
There are surge protectors, and lots of other safety gadgets available to make the world "safer", but as usual, if one gets too serious about covering every possible angle, camping is no longer fun...


Rob

[Joanne]

Hi James,

I just returned from a 5 night camping trip where we had no power available in our campsite. I had to borrow a friend's gel-cell car battery since my deep cycle battery is a goner. We ran the radio for a couple of hours, used two "porch lights" to light up the galley, used reading lights for a couple of hours and recharged two cell phones. By the last night I noticed that the lights were starting to dim. Unfortunatey I didn't have my volt meter with me to record the actual battery voltage levels.

I guess it all depends on how long you are going to be out camping, how long you want to run the lights/radio, and how often you can recharge your battery. I rarely camp where electricity available so I prefer to have a full size (group 27) deep cycle battery. Of course your milage may vary.

Joanne

I'm fairly new to this, but I can't see using a full sized RV battery for a teardrop that will have two kitchen lights, two inside lights, a porch light and a car type stereo. Would a motorcycle battery or a lawn garden tractor (or similar) battery do the job. I also have a Battery Tender that will be on the battery when I am home.

Thanks

[Dooner]

Hi Dooner,

An inverter is designed to handle the high and low voltage of an automotive system/battery charger system.

The danger from high/low voltage only comes in when the appliance you have connected to the 12 volt battery system, is designed to run off 12 volts delivered from a transformer.
A transformer that supplies an appliance with 12 volts stays within a very close range, say 11.9-12.1 volts, as opposed to the battery storage/charging system which can range from 10 volts to 15.5 volts.
Appliances designed to run on an automotive system, say a flip down television or CD player, can easily handle the varying power.


Your inverter takes the range of 12 volt power supplied by the battery storage/battery charger system, and turns/transforms it into 110 volts.
The laptop is supplied via a transformer that you plug into the inverter, so it always delivers voltage in an acceptable range.
If the inverter system gets too much/too little from the battery system, it shuts down, preventing damage to your laptop.

Unless you're running very expensive and sensitive items, there is no need to have dual systems.
Some RV's do, some don't.

Some (usually inexpensive) inverters can use a lot of battery power to produce 110, in other words they are power hogs, but still better than connecting directly to the battery system (assuming the laptop runs on 12vdc.).

If you'll be spending a lot of time using a laptop, and will often be connected to shore power, having an outlet or two in the trailer that provide shore power is handy.

Be cautioned though, that some very (voltage) sensitive items may be affected by current ups and downs produced by inexpensive inverters, and also by poorly maintained campground electrical systems.
There are surge protectors, and lots of other safety gadgets available to make the world "safer", but as usual, if one gets too serious about covering every possible angle, camping is no longer fun...


Rob

Thanks for the great info Rob. I think I will put a couple of 110 outlets inside with a surge protector. All my lights will be 12 volt, so I would rather use 110 for the laptop. I'll still have the invertor if I go dry camping. Till I get a generator anyway.

[nikwax]

might want to take a look at AGM (activated glass mat) batteries which are fully sealed and do not produce explosive gasses when charging (which means the battery area does not have to be vented), can sit around for long periods and not self-discharge, tolerate deep discharging, are highly vibration resistant, and have a good capacity for the size/weight.


Many of us use Odyssey batteries in our motorcycles, where they take a lot of abuse, and are very happy with them:


http://www.odysseyfactory.com/

[brian_bp]

Absorbed Glass Mat (AGM) batteries are really impressive, and don't vent in normal operation, but they can still vent under abnormal conditions. They should ideally still be in a sealed box with some ventilation to the outside.