Power question.

[Ric Burney]

Greetings all. First post to ST.
I have an issue concerning vehicle battery power that has me doing some head scratching.
This spring I will be chasing again for the first time in several years and doing so in a different vehicle (2001 mazda tribute). I am in the process of outfitting the vehicle with all of the necessary (and some not-so necessary) equipment.
Most of the 12 volt stuff (2m/444, GMRS, CB, scan and satellite radios) have already been installed.
I also have a 500 watt inverter for the 110 AC stuff (laptop, phone chargers, digital tv converter, etc.) but this has yet to be installed. The inverter will be mounted under one of the front seats with a fused 12AWG wire set to the vehicle battery teminals. A protected power strip will be included for all the 110v AC goodies to plug into.
Here is where I get a little fuzzy. I know that the vehicles alternator should have no trouble keeping the battery fully charged at highway speeds provided the current draw is normal (a/c, stereo, etc). My concern is if all the additional draw from the inverter and everything else may be pulling more than the charge being given to the battery.
I've been thinking of putting a 5 watt solar panel charger w/ controller in the mix by plugging it into an unused 12volt 'cigarette lighter' type power socket. It could stay in use indefinately. Someone else suggested just plugging in a regular trickle charger into the inverter, running a direct charge line back to the battery. This would charge the battery as long as the inverter was up and running.
All of my previous vehicles had only 12 volt equipment and a master switch between the equipment and the battery for down time.
I never had power issues with that setup before but now I'm worried that this vehicles charging system may not be enough with all the additional draw specifically the inverter.
I welcome any thoughts, ideas and suggestions anyone may have in this matter. Thanks in advance for your help.

 

[darnalljason]

Power

What Size alternator do you have??

You could also put in a second battery with an isolator and run the inverter off the spare battery with the isolator and the alternator can charge the main battery and when it isn't charging th emain it can charge the secondary and you could hook up a solar panel to the secondary battery as well


I have a 120 amp alternator on my vehicle and have no toruble running lights, siren, computer, inverter, camcorder, 2 way radio, stereo, headlights, ac

 

[Dennis Sherrod]

Ric. I run a 1500 watt inverter wired the way you are talking about.
Important: Be sure to put an inline fuse on the hot side close to the battery.
I have never had any issues running my battery down and I don't have any special sized alternator. I run a ton of stuff at once too. Most inverters now have a low battery voltage cut-off built into them. If you forget and leave stuff runing, it is suppose to turn your inverter off, saving the battery.
As I said, I have never run mine down. I have turned my equipment off, but have forgotten to turn the inverter off. It has run as much as almost 24 hours with the engine off and the car still cranked.

 

[Ric Burney]

What Size alternator do you have??

105 amp (original equipment and one of the hardest things to replace on Mazda).

You could also put in a second battery with an isolator and run the inverter off the spare battery with the isolator and the alternator can charge the main battery and when it isn't charging th emain it can charge the secondary and you could hook up a solar panel to the secondary battery as well

That thought crossed my mind as well. I thought of putting in a sealed battery box in the cargo area with a gas vent out to one of the wheel wells. This is a good possiblity as I will also be carrying a full size spare and having to re-configure the cargo area somewhat.

 

[Ric Burney]

Ric. I run a 1500 watt inverter wired the way you are talking about.
Important: Be sure to put an inline fuse on the hot side close to the battery.
I have never had any issues running my battery down and I don't have any special sized alternator. I run a ton of stuff at once too. Most inverters now have a low battery voltage cut-off built into them. If you forget and leave stuff runing, it is suppose to turn your inverter off, saving the battery.
As I said, I have never run mine down. I have turned my equipment off, but have forgotten to turn the inverter off. It has run as much as almost 24 hours with the engine off and the car still cranked.

I have an inline fuse about 2" away from the pos. terminal.
The inverter I bought has a continuous fan on it that hopefully will remind me to turn it off. I was also thinking of putting in a relay type master switch (under dash maybe) for down time.

 

[Rob Wadsworth]

A lot of CB'ers and Ham operators use deep cycle batteries, which are larger and have a greater reserve power. Hooking up a more powerful alternator would surely help too. Since I am going to use as little power as possible, I won't go with the alternator option; but I may have to go with the battery option. Calculating the overall battery load will be the real answer to the dilemma...

The wiring inside the vehicle isn't sufficient to handle the 50+ watts of a 2m/440 radio; so I will wire it directly to the battery. Not when you add up the entire load anyway. I think the B&D 400w inverter will run my laptop, GPS puck, and even charge my phone and camera battery just fine right out of the cigarette lighter plug. Even the cell phone amp isn't used at the same time either. Those alternators can get pretty expensive; but a deep-cycle battery isn't exactly cheap either (about $200).

 

[Graham Butler]

Ric. I run a 1500 watt inverter wired the way you are talking about.
Important: Be sure to put an inline fuse on the hot side close to the battery.

Actually, I would fuse both the hot and ground of EVERYTHING you have wired in your vehicle. When David Drummond's vehicle was stuck by lightning (the first time) the ONLY thing that saved his electrical system was because everything was double fused. About $30 in fuses and he was on his way.

Graham Butler

 

[John Erwin]

105 amp (original equipment and one of the hardest things to replace on Mazda).

That thought crossed my mind as well. I thought of putting in a sealed battery box in the cargo area with a gas vent out to one of the wheel wells. This is a good possiblity as I will also be carrying a full size spare and having to re-configure the cargo area somewhat.

Instead of trying to vent a conventional battery you can use a sealed AGM type battery which requires no vent, and is a lot safer. I currently use this type of setup. Your Alternator sounds like it should be up to the task. A lot of people think that a second battery is the answer to insufficient power but it really isn't; having an alternator that can output sufficient current is the way to go. The only reason I have a second battery at all is that I like to run some of my equipment with the engine off when sitting around; I would rather discharge the second battery than the main in these circumstances.

I don't recommend the comment regarding a trickle charger from the inverter back to the battery; such a configuration would be useless since the setup would actually consume more power than it supplies.

 

[Dan Robinson]

A Ford master mechanic told me that all of my chasing gear paled in comparison to what the typical aftermarket mega-stereo system amps pulled, and I shouldn't have to worry about putting too much strain on the battery/alternator. I've run 750watt inverters for almost 5 years (hardwired to the under-dash fuse panel) in two different vehicles with no major problems. The most power I've used in the car is four laptops, three camera battery chargers and three cell phone chargers for the entire 2006 chase trip. The only thing I run into every once in a while is forgetting to turn the inverter off after parking for the night, which drains the battery pretty fast.

 

[Ric Burney]

Thanks again to all for your insight. After doing a little further investigating I think I can get away with running some of the things on 12v with adapters. Using Anderson Powerpole stuff and lots of fused lines I think I can put together a couple of sets of cig. lighter sockets and get good results. Running #8 wire to a common bus then splitting to #12 for each device.
The ham radio was the main thing that pulls the most power and it now has it's own battery feed.
I will still keep the inverter in the mix but only for one or two items and only as needed. I've pared those down to under 40 amps total even if all the remaining devices are in use simultaneously.
This certainly has been an interesting undertaking. The last time I chased the biggest tech headache was where to plug in a cb and scanner.

 

[Cris Schroeder]

It sounds like you have gotten good advice. I run a 400W inverter wired directly to the battery, mostly for the laptop and a battery charger or two, so my setup is very similar to what you are using.

Your best bet would be to add up all the loads and see if you have the alternator capacity. I would be very surprised if you were pulling enough of a load to be an issue. Even if you ran the inverter at full load, you are pulling around 30A with it. Your radios won't pull much power in receive and you won't be transmitting continuously. You should be fine at highway speeds.

Something to keep in mind is that the alternator power drops significantly at idle so there is a good chance you'll be pulling power from the battery while parked on the side of the road. A high-capacity alternator usually hurts in this case, as the idle power ratings for them are generally lower.