Do I need an inverter?

[marigold]

I'm looking to add a very simple solar system to my van with enough power for lights, music and charging laptop/cellphone/camera. I'm thinking a 100w solar panel and an AGM deep cycle battery. From the research I've done, I thought I would need an inverter but my buddy insists that these are a waste of power and unnecessary and all I need is an ac/dc power adapter. I've had a hard time finding information on such a thing, any advice or input would be truly appreciated! Is there a general ac/dc adapter, or would I need a specialized one for each device I want to charge? Thank you!

[cowlitzcoach]

Any device that changes A/C to D/C is an convertor.

Any device that changes D/C to A/C is a invertor.

An A/C to D/C adaptor is just another name for a convertor--you are changing an unstored A/C power source into 12-VDC.

A D/C to A/C invertor is changing a stored power source to 110-VAC.

If you only have 12-VDC stored power and you want to recharge something or run something that needs 110-VAC you are going to have to have some sort of invertor. The more 110-VAC you are using the larger your storage batteries have to be and the larger the invertor has to be.

Most RV's today come from the factory with most of the lighting as 12-VDC because it uses less amps than 110-VAC. You can string a really long line of 12-VDC LED lights before you use as many amps as a conventional 60-watt light bulb.

But some appliances are much more efficient on 110-VAC which requires a different power source than a storage battery. Hence the reason why most RV's have invertor/convertor/battery chargers.

As far as devices are concerned, 12-VDC power points (cigarette lighter plug ins) are all you need for most small 12-VDC applications. You may want to have a + and a - stud so you can direct wire something that needs more amps than what a power point can deliver.

Once you get your invertor/convertor/battery charger wired in you can wire in conventional 110-VAC wall plugs for anything that needs 110-VAC.

Most systems that have a power cord that goes to RV plug in like you find in an RV park has the power going into the invertor/convertor/charger and the 110-VAC is fed through the 12-VDC storage batteries. In that way the batteries can take any surges that occur when power is being used and drops line voltage down (brown out)--picture how much power is required if ten RV's that are all plugged into the same circuit have the air conditioners cycle on at the same time.

I hope this has given you some clarity. If it has muddied the process for you ask some more questions.

Good luck.

[marigold]

Thanks, that is a lot of information and super helpful. It sounds like, yes I would need an inverter to run my computer/speakers/other 110VAC things.

Thanks so much!

[dond]

There's a Xantrex model 600 for sale in the classifieds ;););)

[frank-id]

Low wattage inverters are not of much value. Tha average inverter is about 2KW. For every 10 amps sucked from a DC battery back, the inverter gets 1 amp of 120 VAC power. The batteries are 12 volts DC and the AC is 120 volt. Nothing is free. Using an inverter without the engine running and keeping the batteries charged, the batteries will be drawn down. A good multimeter is required for monitoring the inverter input at the batteries and the inverter output. A battery showing 12.0 volts is 75% discharged. A full battery will indicate 12.6 volts. Frank

[dond]

That Xantrex draws .6a.

[bubb, the real one]

fyi
1 amp Ac equals ~10 amps Dc
If by chance you can get a DC plug adapter for all your devices then you may not need an inverter, since the inverter will use some power this will make the battery last longer,
You only want to drain your battery by half or less, which means if you have a 100ah battery then you only want to use 50ah before you charge it up again, the more drain you do past 50% the quicker you will age your battery.
AGM batteries charge differently than normal wet lead acid batteries, make sure you get a charge controller that has settings for an AGM, will increase the lifespan and usefulness of the battery.

[nat_ster]

Your buddy that says you don't need a inverter has no clue what he is talking about.

I would disregard most of what he says in life.

Nat

[bansil]

I must agree, do you need it?...if not?

After the first trip you will, just being able to run microwave, crock pots and such (rotisserie) on the road is awesome

Do you need it?no

But you will want it

[claydbal]

yes, you will want it. mine has been on for six months constantly. the freezer has to cycle. and its cool when i walk in and flip a switch and the lights come on!

[Zephod_beeblebrox2]

I saw a neat gizmo in Kmart yesterday - a box that plugs into a cigarette lighter socket that purports to heat and cool. It called itself a traveler 3. Probably worthy of further investigation.

[bansil]

Originally Posted by Zephod_beeblebrox2

I saw a neat gizmo in Kmart yesterday - a box that plugs into a cigarette lighter socket that purports to heat and cool. It called itself a traveler 3. Probably worthy of further investigation.

just remember the basic rules:

heat takes energy, watts are "heat"

so if it is plugged into 12v circuit, at say typical vehicle with a 10 amp fuse

using 8amp as safe that is only a 96-ish watt heat source, wont do much

it will heat tho

most of those are gimmicks, you can run a dedicated 12v line with fuse to power a 800 watt inverter, then you can use a small (less than 800wt) heater, still small tho

I have been using $99 cobra 2000wt invertors for 5+ years (truly only about 300 hrs a year guessing) never an issue, I have them sized at 1750watts which gives me a nominal 14 amps of power, they can surge to 2500wt for compressor kick ones
remember to size it to about 85% of your needs and you'll be good

we have them in every vehicle, hair driers, irons and crockpots are big users

look at your stuff "that makes heat" it will have a wattage on it, take that number and divide it by 120v and you can see what you need

[Zephod_beeblebrox2]

I just read a review of that traveller 3. Apparently it works but flattens batteries. Must be a power hog.

[taskswap]

If you want a 12V off-the-shelf heater the best units are the ones made to address "cold cabs" for the folks driving box trucks and older cars with bad heaters. They're self-contained ceramic heater units and cost around $50 on eBay. They're fused for higher power output and you can use an adapter or wire them directly:

Ceramic Heater Fan Portable 12V Hook Up Swivel Base Car Auto Truck Cold Garage | eBay

As noted above, there's a linear relationship with electric heaters between power draw and heat output - they're just converting one to the other. If it makes you warm, it will drain your battery. If it makes you warmer, it will drain it faster.

[Zephod_beeblebrox2]

I was looking At it more as a cooler

[nat_ster]

Originally Posted by Zephod_beeblebrox2

I was looking At it more as a cooler

In some cases, it takes more to cool than heat due to needing more parts to do the cooling process.

Heating is just a piece of resistance wire, and a fan.

Cooling needs all the parts in a window AC unit. That's a ton of parts = a ton of inefficiency.

Now with the introduction of variable speed DC compressor motors, the AC units are getting more efficient. However at the expense of high cost.

Nat

[Zephod_beeblebrox2]

The solid state heaters sound interesting.

[Zephod_beeblebrox2]

Err... I've been googled. Speech recognition does strange things. That should have been solid state coolers.