Ask Slashdot: How To Add New Tech To Old Van? 212
First time accepted submitter Dslice_allstar writes "I have a '77 GMC Van that I would like to take into the 21st century with some good tech. I have several large LCD monitors, and I want to hook at least one up for watching movies and doing some mild PC gaming. I am concerned about power, i.e. using an inverter and not frying the computer every time the van starts/stops, and I'm worried about whether the alternator will support a computer/monitor setup as well as LEDs and the like. Would a UPC backup be a good idea? I would also like to be able to play music over the sound system, preferably off the computer. Should I be thinking mini ITX HTPC, or would a netbook better serve my purposes? How would you all pimp out an old conversion van?"
Power problem answered: (Score:4, Informative)
First, forget about connecting anything to the engine electrical subsystem. You've already identified the issue there, that being the risk of surging the equipment to death.
I would go with an isolated battery stack, a couple low-profile wind turbines and employing a substantial amount of roof area in collecting PV. This would easily accommodate the power requirements of a modern laptop (my Toshiba L755D draws less than 40W under load) and a late-model LCD panel (HP W1907v for example has a max load of 49W). Plenty of power there for an onboard computer, not including the sound system.
Blue Water Sailboats (Score:5, Informative)
Do some reading on the 12v systems of blue water sailboats. You'll find that they have a separate circuit for their running system/lights vs their navigational electronics/radar etc.
Generally they run the engine to charge the battery, and when that isn't possible, shore power or wind/solar. They will run the system/nav lights off of one 100ah (50ah real world use) deep cycle battery, and the other system will run off of 1-3 100ah deep cycle batteries, depending on size/budget. This is generally topped off by 1-2 400w solar panels (taking up the space of about a 4x8' sheet of plywood) and/or wind power. Wind power might be an issue in your mom's driveway though.
Also consider upgrading your alternator. Conversion vans typically come with a much higher rated alternator to deal with the additional loads the experience. Tapping in to the existing 12v system is asking for trouble, it's not designed for what you're going to ask of it.
Put in a marine alternator (Score:5, Informative)
The correct way (Score:5, Informative)
First is to do the math. Just like a bank account, there needs to be a balance. Just like the bank, you can store some savings.
Batteries are sized in Amp Hours when buying deep cycle batteries. Batteries that list cold cranking power are lower capacity and built for a momentary high current load. They are not designed for deep cycle use.
Look at your supply side. If you turn off the headlights, wipers, heater fan, defroster, air conditioner, all those unused loads are excess generation capacity for use, but there is a catch, while the engine is running and not at just an idle. Alternator capacity is reduced at an idle. Headlights are about 60 watts each. The heater fan is about 200 Watts, Rear Window Defogger, 60 Watts.
Volts X Amps in DC = Watts.
Shutting off the headlights is enough capacity to run a typical larger flatscreen monitor. Shutting off the AC/Heater fan is enough to run a PC, etc.
A larger inverter is quite efficient so don't assume a 1KW inverter will draw 80 Amps all the time. Advice is go larger on the inverter to deal with startup current many devices use. Forget the 75-300 Watt sizes and start with a 1KW or larger. Follow the installation instructions on wire size and length.
I have done two inverter installs in vehicles of mine. Both are 1KW in size. My Prius has a trunk mounted inverter that is used in place of a portable gas generator for many odd jobs including camping. I use LED and or CFL lamps (120V is much easier to find than 12 V) Laptop computers, musical instruments and PA amplifiers, flatscreen TV, and a vacuum cleaner. 12 volt car vacs just don't work nearly as well as a dirt devil hand vac.
My second install is in a 29 foot motorhome. I found the AC outlets are on 2 breakers. The driver side includes the kitchen and bathroom. I left that on the generator or shore power for use with hair dryers, coffee makers, waffle irons, and other power hogs. The other side of the motorhome is all on the inverter. This powers LED desk lamps, the flatscreen TV, and outlets for cell phone chargers, laptops, DVD player, etc. I put a 19 inch flat screen TV up front in place of the original tube set, this doubles as a rear view mirror with a backup camera. A flatscreen TV eliminates the need for a DTV converter box. It only draws 40 Watts.
On the energy side, the original motohome lights were power hogs. The 1187 bulbs draw 2.1 Amps each or about 25 watts. Using the inverter, I use 1.5 to 7 Watt LED lamps instead. The main dining area ceiling light has 2 bulbs, so the TV actually draws less than the original "Dome Light". With one or two LED lights on, I can run the TV all night on battery on the 2 deep cycle RV batteries. This saves lots of gas as I don't need a generator running burning 1/2 gallon of gas an hour just to run the TV and a few lights.
As mentioned in another post, a separate cabin battery is highly recommended. After running the PC and monitor all night, you will want a way to start the engine. Use a battery isolator so you charge both sets of batteries.
Re:Do it HAM style (Score:5, Informative)
Sorry, but this is wrong on many levels. An inverter isn't any harder, and most likely easier than going without because anything that would normally plug into the wall will.. Well... Just plug in and work.
Now the issue is you don't want to use just any old inverter as there are major differences between them. Get one with voltage stabilizing (does a good job of keeping a steady output voltage, just like the some home theater power centers do), and also make sure it's a pure sine wave. Pure sine waves run a bit more, but are much safer for sensitive electronics vs a non-pure wave system. The last one we did at the stop was a 2000watt RMS/4000 max pure sine wave that ran about $800-1000 (can't remember exact figure), but you can fine similar setups with less watts for a lot less money.
Also, use a good deep cycle or dual-purpose marine battery all the way around. Try to use the same battery in all locations, as using different batteries (different in style as in deep cycle vs a starting battery, or a smaller capacity vs larger capacities) can cause issues as one battery may fully charge before the other, but because of the load imbalance one may over charger or one may remain undercharged.
Also look into the after market audio areas for an alternator/generator. The same RV van I put the power inverter into above we also put a tsunami alternator which produced around 240amps at a fairly low rpm. We also used one of their heavy duty relays (500amp rated) to isolate the rear batteries from the one under the hood when the key was off so the main battery wouldn't drain and leave you stranded.
The setup used all home equipment (made a custom flip down mount for the 36" tv we put in), including the directv receiver and home theater system.
I've done it (Score:5, Informative)
1. your van likely got 12mpg city when it was brand new... What it gets now is probably a lot worse... so keep that in mind.
2. The alternator is likely already beefy. I'm not sure about your particular model but there are likely even higher amperage alternatives you can get. This will, of course, hurt your millage even further. The key here is to get the power consumed lower than the power produced by the alternator AT IDLE. You can literally drain your batter dead while idling in a parking lot otherwise.
3. for extended life while the engine in off, simply get more batteries. Preferably deep cycle. Get a HIGH amperage relay and put it in-between your primary (starter) battery and your extra batteries then hook the relay on-terminal to the "ON" part of your starter switch. The premise here is that when you start the van. All the batteries are in parralel, but when in ACC mode your equipment is only hooked up to the extra batteries. If you drain them dead, that's fine because the starter battery isn't connected.
4. There are 12volt power supplies (regulators) for computers made for cars. You do not need an inverter and I'd highly recommend against them as they are very inefficient.
5. Laptop diskdrives are designed to take shocks. When choosing drives, laptop drives are your first choice.
6. Por15 and Hurculiner are your best friend on old vehicles. Rip out the carpet, coat it in one or the other and put the carpet back in.
7. Metal vans are bad for wifi... you'll need an external antenna.
8. Don't over-do your stereo. It's dempting but really anything over 200 watts (even the sub) is just to annoy people outside the car.
9. When running your cable for power from your extra batteries, etc... Make sure you put fuses as close to the batteries as possible. If one of your cables rubs and contacts metal, your vans going to go up in flames if it's not properly fused.
10. The cables you use should be bought from a farm implement supplier. (Farm and Fleet, Fleet Farm, etc...) You can get rolls of battery cable the thickness of your index finger, for very cheap. The ridiculous stuff they sell like monster cable, etc... is totally worthless and costs a fortune.
Good luck!
Re:Power problem answered: (Score:5, Informative)
my van (a Mazda Bongo [bongofury.co.uk]) has a leisure battery (120Ah) that runs the electronics inside and has optional charging from the engine (if it is running - via Willington cable), solar panels (when out in the sticks) or through a campsite hookup electricity point common in EU campsites.
Whilst the solar panels only provide 26W or so at full sunlight; they do help extend the range of the leisure battery when camped out places. There's some new 80W panels [igmaynard.co.uk] that can bond to the roof [sunshinesolar.co.uk] (which is a rising roof in a Bongo) that I'm thinking of getting so I can run a better fridge. The nice thing about this is that if the leisure battery is drained; the engine will still start.
Whilst I do have an inverter for 240V, I try to use kit that supports 12V to save on transformer inefficiencies. Every Ah counts!