How much juice can I get from the dc outlets in the stro?

[pengyou]

With the engine idling and the air on, if I connect my desktop pc and lcd panel (about 400 watts) to a dc inverter, and also have a tv/vcr going (I think about 100 watts) - on another inverter will the stro put out enough continual electricity so that the battery is not drained - with the engine idling?

[peter]

Check to see what sized fuse covers the outlet in question. The recipe is volts x amps = watts. If your equipment pulls 100 watts at 12 volts, then 100 devided by 12 volts = 8.33 amps.

If you're pulling the previously-mentionned 500 watts, then you're up to 41.6 amps. Therefore, with just an 80 amp alternator and only the engine running (approx. 25 amps including fuel pump and on-board ecm), you should be ok. Add the heater/a/c & blower at full blast plus wipers, radio etc...., and you may just surpass the alternators' ability to keep the battery charged.

[pengyou]

Thanks! Any simple workarounds for this besides getting a generator?

[snapple]

Thanks! Any simple workarounds for this besides getting a generator?

You could setup a dual battery,and probably find you won't ever need to run everything at once. So you shouldn't have any concerns of having enough power.

[peter]

As well as a high-output alternator (or even adapt the bracketry for a 2nd alternator, it's been done before).

[astrozam]

You don't mention how long you want to do this for, is it for a road trip,over your lunch break ??? in addition to what Peter has mentioned and if you are wanting to do this for extended periods of time I would beef up the spindly power wire going to the dc socket and protect with the proper sized fuse, I see this as being more of a problem than wearing down you're batt.

[cd0156]

You guys are on the right track but overlooked one thing.. He is talking about wattage of his AC components running off of his inverter, and you are figuring current based on 12 volts DC...

The biggest thing to look at is the max current DRAW for the inverter. This is not the AC current capacity, which is usually the big number on the sticker, it is how many amps it draws from your 12 volt battery. As a general rule, if it came with a cig plug it is fine running off a cig plug, most are rated for around 15amp.. But you cannot overload the inverter either. Most of the basic ones I see with cig plugs say 300 watts @ 120VAC... This is a MAX rating... It usually means it is actually capable of about 175 Watts continuous. For example, a tube tv takes FAR more current to turn on than it does to stay on.
If it is more than a 175/300 you will want to run an 8awg wire to your battery, or if more than a 500/750 you will probably want a 4awg.. If you are talking about a 2000 watt rv style one then you need 1/0 cable..

The biggest thing is to make sure your inverter can handle your equipment, and you have the right size power cable for the DC input. DC creates far more heat than AC over distance and you can melt wires sometimes before you blow fuses.. Definately do NOT put a bigger fuse on the cig plug!!! That wire back there is a heavier guage than most plugs have, but it also runs really far to get back there!

[cd0156]

Peter I am disappointed in you... Being an hvac and a/c guy...
That would actually be 500w divided by 120vac = 4.166 amps draw from the inverter, which through the magic of induction does not neccessarily equate to the inverter drawing 41 amps from the vehicle..

[cd0156]

Ok... I am off... Law of conservation of energy and all that... Due to inefficiencies in the inverters, and power "lost" as heat, it may draw more than the 41amp DC... If it really is a 500 watt inverter I would run some 8awg... Usually around $0.90 foot at any car stereo shop...

[peter]

You're right Chris, I completely forgot about the loss at the inverter. I imagine 10% would be pretty well the minimum loss to expect. Which means you'd have to tack that on to the total load you're expecting to need.
As well, maximum curent draw has nothing to do with "peak" draw, which is what you get during the initial electrical surge at power-up. "Peak" may very well be 25-30% higher, but is totally useless as far as maximum safe amperage draw/wattage consumption