Plugged in camping: Batteries or ext. power supply?

saburai

saburai

Explorer
Hi Gang!

I've been thinking about ways to power my increasing number of 12V "Glamping" accessories. I started a thread about "shore power" for my Electrowarmth bunk warmer, but I thought this topic might be more helpfully to all. I have a Edgestar fridge, LED lighting, laptop, GPS and phone, Ham and other chargers to power. The XJ has a pair of Diehard Platinum 880 CCA AGM batteries. I've got a small inverter to go 12V to 120V so I'm good enough there. What I'm trying to figure out is the best way to power the above mentioned devices when a 120V receptacle is available.
I can, of course just plug the fridge in as it has AC/DC compatibility. The bunk warmer is another story, I was thinking I could use an appropriately rated laptop power supply -due to my ignorance, I'm not sure that this would work satisfactorily.
I began thinking (with some help;)) that perhaps a systems approach would be better. A hard wired smart charger? It would sure be nice to top up the batteries... I need to keep costs down on this but still would like to do it right...
Thanks for the help...
 
kb7our

kb7our

Explorer
saburai said:
Hi Gang!

I've been thinking about ways to power my increasing number of 12V "Glamping" accessories. I started a thread about "shore power" for my Electrowarmth bunk warmer, but I thought this topic might be more helpfully to all. I have a Edgestar fridge, LED lighting, laptop, GPS and phone, Ham and other chargers to power. The XJ has a pair of Diehard Platinum 880 CCA AGM batteries. I've got a small inverter to go 12V to 120V so I'm good enough there. What I'm trying to figure out is the best way to power the above mentioned devices when a 120V receptacle is available.
I can, of course just plug the fridge in as it has AC/DC compatibility. The bunk warmer is another story, I was thinking I could use an appropriately rated laptop power supply -due to my ignorance, I'm not sure that this would work satisfactorily.
I began thinking (with some help;)) that perhaps a systems approach would be better. A hard wired smart charger? It would sure be nice to top up the batteries... I need to keep costs down on this but still would like to do it right...
Thanks for the help...
Click to expand...

Maybe not the best solution for your situation, but with somewhat similar power requirements, a Jeep JK with dual Platinums, I went the waterproof 5A Battery Tender route. Unit fit under the engine cowl up by the wipers, charge lines right to the battery, male marine AC outlet down on the passenger fender panel behind front wheel in front of passenger door. Also added a simple led bar style voltage meter inside JK on driver's side a-pillar. System is simple, <$100 for the charger, maybe another $40 for the meter, and works well with just a normal, grounded extension cord to power or to my Yamaha 1K gen when absolutely needed. Otherwise, a solar panel to the 12V cig socket or direct to battery is used when demands are lower. Once my ARB fridge is cold, 5A from the charger (you could do a 10A) is sufficient to keep up with the battery even with a 12V blanket and other small loads. Works for me until I need a better option. A "converter" like what I have in the RV would probably be my next logical step up for shore power to DC but that's overkill for a JK Habitat arrangement considering my requirements.

Quick funny story...I usually keep the JK plugged into an extension cord via the marine power socket to have batteries topped and one of my daughters saw that and asked if the Jeep was electric.
 
Last edited:
U

UglyScout

Observer
I like the idea of keeping everything on 12v all the time. Simple, easy no power wasted in converting from 12v to 120 or vice versa.

You will want more than a 5amp battery tender for your power needs. Look at RV/camper 120v to 12v power converter/battery chargers/maintainers.

An IOTA 15amp charger with the IQ4 dealio would probably be ideal.
 
saburai

saburai

Explorer
Thanks for the reply!

Do you have a link to the voltage meter? I've got a 62w foldable solar panel that works out well on the trail. I'll look in to the tender...
 
W

wrcsixeight

Adventurer
http://www.bestconverter.com/Iota-DLS-Converters-_c_135.html

RV converters are designed to power all 12 volt dc accessories while charging the batteries, or keeping them fully charged when there is access to 120v ac grid power. In your other thread I indicated I am using my battery charger as a converter. It works, but it is not designed for this application, where the Iota converters are.

I hate my inverter, and buy everything I can to be run on 12 volts. One of the best things is a Laptop DC to DC converter, that steps up 12.xx battery voltage to the laptops 19.5. An inverter used to power the stock wall wart or power brick takes battery voltage, converts it to 120 volts AC, then the power brick reduces it ond converts it back to dc, each step reducing efficiency. My laptop car adapter for my Dell uses almost 45% less electricity than my inverter would. My older Sony upto 25% less.

When I have grid power, I just use the laptop's original power bricks.
 
saburai

saburai

Explorer
Thanks Guys!

I hear you on the DC DC converter. In fact I linked to the one I have in the other thread. The Iota's look good...

What do you think about the down and dirty just for now solution of a 12V 100W lap top power supply for the the 6.2A bunk warmer?
 
kb7our

kb7our

Explorer
UglyScout said:
I like the idea of keeping everything on 12v all the time. Simple, easy no power wasted in converting from 12v to 120 or vice versa.

You will want more than a 5amp battery tender for your power needs. Look at RV/camper 120v to 12v power converter/battery chargers/maintainers.

An IOTA 15amp charger with the IQ4 dealio would probably be ideal.
Click to expand...

The IOTA is something I looked at and their smallest, the 15A I nearly went for until I found the very compact Battery Tender (albeit only 5A) and a completely concealed place to hide it. If my power needs increase this one is on my short list as an upgrade.
 
W

wrcsixeight

Adventurer
saburai said:
What do you think about the down and dirty just for now solution of a 12V 100W lap top power supply for the the 6.2A bunk warmer?
Click to expand...

Well It is hard to think of reasons it will not work. The 12 volt mattress pads have to work upto 15 volts as that is what can reasonably be expected with the engine running.

So even if the laptop power supply's voltage varies pretty wildly under the cycling load of the heating pad, it should still be able to provide enough to keep it functioning.

But honestly, if it were me, I'd rather use the laptop power supply to charge the vehicle's battery and have the battery as a big filter/capacitor keeping voltage swings to a minimum.

And If I am going to run a laptop charger as a 7 amp lead acid battery charger, well, I'd rather use a regular battery charger that is capable of at least 25 amps, to quicker recharge the batteries when the opportunity arises.
And since one does not know whether a battery charger will or will not be able to act as a converter with a fairly significant cycling load, which is designed specifically for such duty, it would be best to just get a converter.
 
dwh

dwh

Tail-End Charlie
wrcsixeight said:
http://www.bestconverter.com/Iota-DLS-Converters-_c_135.html

RV converters are designed to power all 12 volt dc accessories while charging the batteries, or keeping them fully charged when there is access to 120v ac grid power. In your other thread I indicated I am using my battery charger as a converter. It works, but it is not designed for this application, where the Iota converters are.

I hate my inverter, and buy everything I can to be run on 12 volts. One of the best things is a Laptop DC to DC converter, that steps up 12.xx battery voltage to the laptops 19.5. An inverter used to power the stock wall wart or power brick takes battery voltage, converts it to 120 volts AC, then the power brick reduces it ond converts it back to dc, each step reducing efficiency. My laptop car adapter for my Dell uses almost 45% less electricity than my inverter would. My older Sony upto 25% less.

When I have grid power, I just use the laptop's original power bricks.
Click to expand...


One thing you left out was power factor. A lot of laptop AC power bricks are not power factor corrected, so that introduces yet another loss from the whole DC->AC->DC scheme...

http://en.wikipedia.org/wiki/Power_factor

http://www.humaninet.org/laptop.html



I also use a DC-DC converter for my netbooks. Both my Acer and my HP netbooks use around 19v, but they have different power plugs. The DC converter I have, I bought for the Acer. When I got the HP, I cut the cord and spliced in a standard power connector. Now I can just attach either the Acer cord, or the HP cord to the converter and power either one.

The converter I have is the YD190-474:

http://sangertek.en.made-in-china.c...Gateway-Car-Charger-19v-4-74a-YD190-474-.html


Been using it for two years and haven't had any problems. I burned out a couple of cheaper converters before I finally found this one.
 
W

wrcsixeight

Adventurer
Using battery voltage to determine state of charge of the batteries only works on batteries that have not been charged or discharged for several hours.

They can give you a general idea of state of charge, especially if you watch it often and notice trends and tendencies, like voltage in the morning when the fridge cycles on, and how long it takes to rebound slightly after it cycles off.

Other methods involve counting the amps flowing into and out of the batteries.

The cheapest device for doing this is:
http://www.hobbyking.com/hobbycity/store/uh_viewitem.asp?idproduct=10080

Members on RV net have hooked these up to their vehicles. This thread has lots of info, and links to much more info about using the above product.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25049072/srt/pa/pging/1/page/1.cfm

But these monitor current flow in only one direction. 2 would be needed to count amp hours into and out of the battery bank and some minor math done to accurately determine state of charge or amp hours from full.

There are other amp hour counter battery monitors like tri metric which require all current flow to flow through a shunt.

I have one of these for my solar system.
http://www.blueskyenergyinc.com/products/details/ipn_proremote/ I wired it so that it also counts alternator amperage, so all my vehicle grounds flow through this shunt. A great tool which has opened my eyes about the effectiveness of alternator recharging.

Lemme say ignorance was bliss.
 
Last edited:
You must log in or register to reply here.

Forum statistics

Threads
189,906
Messages
2,922,046
Members
233,083
Latest member
Off Road Vagabond

Members online

Total: 1,166 (members: 21, guests: 1,145)
Top