Convert cig lighter to DC plugs

If it's the same as in the current Prius the lighter circuit has a 10A fuse, so make sure you don't exceed this by connecting too many devices at the same time.

 

That would be quite an unusual choice for wiring circuits that are all between five and twenty volts. It's important to choose your material so the wire gauge is appropriate for the current you'll be carrying, the insulation is suitable for the intended voltages, and the stuff is easy to work with. You don't gain anything just by using wire engineered for voltages a thousand times higher, and it might be more fiddly to work with.

As ftl points out, the lighter socket is already fused at ten amps. That can give you two kinds of problem: (1) ten amps might be lower than the total of all the loads you want to attach, and (2) ten amps might be higher than the safe current-carrying capacity of some of the wiring to your smaller loads, presenting a fire hazard if that wiring gets pinched or damaged. (Usually, skinny-wired accessories that end in a cig lighter plug will include a smaller fuse built into the plug to further limit fault currents to what the wire can handle.)

An option you might consider would be a small distribution panel straight off the aux battery at the left side of the trunk. It's easy to buy tidy panels providing several separately-fused circuits, allowing you to fuse each one appropriately for the load it will be serving. This thread may give you some ideas; now that I know about the VCM-06, I would recommend it over the homebrew control circuit I used.

-Chap

 

As far as power consumption is concerned, 15A at 12V is equal to 36A at 5V. The above project is a mess...


Avi

 

My suggestion:

Get this Adapter and this cable.

Plug the adapter into one of your two power outlets and your 12V device into the other.

Read more here.

Avi

 

Device 1: 1 AMP, 5V => 5W
Device 2: 19.5V, 4.62 Amps => 90.1W
Device 3: 12V, 6A => 72W
Device 4: 8.4V 1.5A => 12.6W
Device 5: 5V, 1A => 5W
Total device power (excluding converter & inverter inefficiencies): 185 watts.

This circuit is overloaded.

Those 12V sockets are really intended for no more than 120 watts, though some devices appear to get away with 180-200 watts, at least for a while. Your devices are unlikely to all be pulling max power simultaneously and continuously, so you can get away with it for quite a while.

But at some point, the 15A fuse is likely to fail, due to too much use without adequate operating margin below its rated trip point. Can you hardwire a separate circuit, wired for and fused to 20 amps, and using more reliable connectors such as the Anderson connectors favored by the amateur radio folks?

 

Gluing the enclosures together and soldering to the contacts sounds like a dirty kludge, and won't let you change out devices easily.

Can the Roadmate 1700 be powered over USB, such as using a regular USB cord to your computer? If so, ditch its car adapter, and power it from the same 12V->USB adapter as the phone. Multi-outlet devices such as Avi pointed to are readily available providing 2, 3, or 4 USB outlets in a single 12V socket. Or use something like this USB converter ( DC DC Converter Module 12V to 5V Duble USB Output Power Adapter 3A 15W | eBay ) to skip the socket and wire direct to 12V.

Then, you are down to needing just two or three 12V sockets/converters and one or two direct connections. Something of this sort (Enercell 12VDC 3-Outlet Vehicle Power Adapter : Adapters | RadioShack.com) with provide the sockets and inline fuse holder to the battery (or Accessory 12V tap somewhere, to prevent draining the battery), though I don't see the current rating on this particular model.

I'm still browsing for other ideas on the 19.5 and 8.4V supplies. Pre-packaged devices wiring directly to 12V, skipping the socket, would be best. For converter devices with a wire between the plug and device body, just cut off the plug.

I don't endorse any specific products. The links above are to show the concepts, many similar products of varying quality exist.

 

If Toyota puts a 15 amp fuse on a circuit, that means all the wires Toyota supplied in the circuit have been sized to safely handle 15 amps. In case of an overload or short, the fuse will blow before those wires melt or ignite anything.

If you plug some gizmo of yours into that socket, and the gizmo's wiring cannot safely handle 15 amps, and that wiring becomes damaged/pinched in the seat rail/whatever, the 15 amp fuse might not blow before your wiring melts or ignites something. If you attach anything to a circuit that would not safely handle the maximum that circuit can deliver, it's up to you to supply a smaller fuse that will protect what you have attached. If you look at a lot of cig lighter powered accessories, you'll find there is usually a fuse contained in the lighter plug, small enough to protect the (often very skinny) accessory cord. If you're thinking of cutting off the fused lighter plugs and soldering wires together, including properly-sized fuses becomes your responsibility.

In other words, you can't only think about how much current the gizmo is intended to draw. Maybe it's only meant to draw half an amp, which means its cord might have really skinny wires that might only be safe for carrying an amp. The cig lighter plug on the end of that cord probably has a 1/2 or 1 amp fuse in it, so the skinny cord will be protected from unsafe currents even if some damage to the wiring or fault in the gizmo makes it draw more current than it was meant to. If you remove that plug and fuse and connect that skinny wiring to a circuit whose only fuse blows at 15 amps, you've asking for trouble.

You're really asking for trouble if you wire stuff directly to the battery without proper fusing. Nothing will stop that battery (even a dinky Prius battery) from delivering hundreds of amps into that wiring if a fault develops.

The other reason to be careful about attaching stuff to the battery directly is not so much a fire safety issue, but it could inconvenience you by draining the battery. The Prius battery doesn't store very much energy, so if any of your permanently connected gizmos draw any current while the car is off, you could find the battery drained when you come back. You might want to connect your stuff so it disconnects when the car is off. There's a product, the VCM-06, that's great for that purpose: it can tell when the car is in READY (voltage goes above 13) and turn on, and automatically turn off when the car is turned off.

The VCM-06 also contains its own, fuseless, self-resetting, current limit to 15 amps. If you are connecting loads with lower safe currents then it's still up to you to supply the smaller fuses they need. If you need to draw more than 15 amps, you can add a relay and use the VCM-06 to control it.

The link I supplied earlier can give some ideas on how this can be set up.

-Chap

 

The USB adapter is rated at 2.4A per port, the actual current flow will be determined by what you plug into it, including the type of cable. That is just the maximum it can provide. But, as fuzzy1 pointed out, the circuit would be overloaded.

 

This would work in theory. I would be concerned about the springs that push the tips out not having enough tension on them causing a poor connection inside the adapter.

 

...and I just realized this is in the Gen I forum and Gen Is only have one outlet.

 

... if the biggest risk of an improperly fused electrical circuit were just maybe having to replace the wire, insurance would be dirt cheap ....

-Chap