[tnast99]

Hey everybody.

I've got my 2004 Odyssey EX-L, with roughly 133k miles on it. Does anybody know how much current the vehicle uses under normal operation? I'm wondering because I've been turning mine into a utility vehicle of sorts, and would like to install an inverter in it for tools and such. I just don't want to install too big of an inverter (or at least use too much power for the alternator to handle on accident, and would rather the inverter take the hit instead).

Absolute worst case, I can save up for a while and get a higher capacity alternator if the stock one is too weak to power what I need.

Ideally I'd be at or above 1000 watts for my inverter, which should run most power tools.

 

[davedrivesody]

The power drawn by your inverter depends on the load connected to the inverter. The maximum power of the inverter itself only limits the load you can plug into it.

The stock alternator is rated for maximum 130A or 1560W at speed. Also, the alternator is electronically controlled. It won't go to full output unless the ELD (electronic load detector) sees the load of the inverter i.e. it won't if the inverter is connected directly to the battery.

The power used by the van depends on what's switched on, especially high power accessories such as seat heaters, AC, etc.

I wonder if a small generator might be more efficient and safer than pulling 1000W from the van's electrical system? That amount of load seems like it could stress the alternator and/or the battery.

Dave

 

[mwe2121]

I have a 800W modified signwave and a 300W pure signwave inverter installed in my 04 along with an additional 8 12v outlets. I routinely bring along a 700W microwave for the kids to use on trips and at baseball tournaments. Between the microwave running, kids school computers charging, wife's computer and iPad charging, phones and any other accessories we may bring along I am pulling over or close to 1000W. I also have a small coffee pot and a slow cooker that I sometimes bring with me and have used them in tandem with the slow cooker on the 300W inverter and the coffee pot/microwave running on the 800W inverter.

I haven't had any issues and am planning on upgrading my 800W inverter to a 1500W model next year. Make sure you get a good battery such as an optima yellow top, use large gauge wiring from the battery to the inverter. A link to a thread I made regarding my install.

 

[tnast99]

Thanks for the info, mwe2121. Right now I have a dual battery system so I can run some coms equipment without worrying about draining the starter battery and keep the engine off. From my little bit of experience the 35AH SLA I have as the secondary has a relatively high internal resistance (voltage drops to like 10.5 when the sliding doors are latching and engine is off), so I'm probably either going to add a capacitor to it so it can handle some short bursts, or maybe a smaller Optima battery just to help it out. I'm already using 0/1 and 4 gauge wire from the front to the rear for the system.

As far as inverter size goes, if it is possible to run that 1500w unit without upsetting anything, that'd probably be perfect for my use case- usually just charging some electronics, but sometimes running some more power hungry things (in my case, power tools and lighting equipment).

Dave, I have considered using a generator, but I'm not fond of the idea of lugging that around all the time when I'd only need that kind of power for a relatively short period of time (and in bursts). Granted if I needed more power or for a longer period of time for something, I'll bring a generator along instead of letting the engine just run.

I do have a voltmeter built into my custom center console, so that also helps as far as monitoring voltage as load increases. After that I think it becomes a matter of making the inverter work as though it's on ignition sense- I could probably use a (3rd) battery isolator for that, right?

 

[benjayman227]

I just don't want to install too big of an inverter (or at least use too much power for the alternator to handle on accident, and would rather the inverter take the hit instead).

I think you'd rather have the fuse take the hit, rather than either of those items. That kind of amperage is arc-welding territory. Every circuit has a "fuse", whether or not that's what you call it.

so I'm probably either going to add a capacitor to it so it can handle some short bursts,

What kind of short bursts? Energy stored by a cap goes as the square of the voltage, which at 12 volts isn't much. A 1-farad cap (huge) at 12 volts could power a 1000W load for ~70 milliseconds (by itself). The cap would help with impulse load smoothing (like the spikes you get when driving a huuuuge subwoofer) , but wouldn't really help the sliding-door scenario you offered.

 

[mwe2121]

I don't see why you couldn't use a 1500W inverter. Like benjayman227 stated just make sure you have an inline fuse.

 

[mwe2121]

The kids have run the microwave for 10-15 minuets continuously without the van being on. The low battery alarm starts peeping on the inverter before hand but the car still turned on.

 

[tnast99]

When I said "I'd rather the inverter take the hit" I was pretty much talking about whatever fuse it'd have, instead of melting something else despite being properly fused.

So I guess a capacitor may not be needed, and rather I should get some sort of lower resistance battery to help the 2nd one (such as an Optima yellow top) for those heavy drain loads, such as the doors or anything substantial on the inverter with the engine off. When I said bursts, I was indeed talking about stuff like the doors latching, locks, and then also the surges from power tools turning on, so I'll need to go the battery route for sure then.

1500 Watts seems like the limit that I'd push for now... But who knows what I might do with more time and money down the line...

Ben, you bringing up welding had me look at the power usage of my mig welder in hopes of being able to run it from the car as well... Guess that's one use case where'd I'd certainly pack a generator instead... 200 continuous amps is slightly above my comfort level right now - lol

 

[oldskewel]

If you're going to be pushing the limits, you might want to buy a clamp DC ammeter so you can get quantitative info to guide the evolution of your design. Pretty cheap (~$50 or less if you want to find a cheaper one). Very useful for things like this, debugging batteries, starters, parasitic draw, etc. You can observe time response as a load comes online. I have one that even has a bluetooth connection for a smartphone that basically gives it ~oscilloscope functionality (but at about a 5Hz sample rate).