12v Power Into Main Cabin

[Benjamin Nead]

It's been a month of so since I last posted here: a busy time of the year for me.
Wow! I like the revamped look of the My i-MiEV Forum!

Anyway, here's why I'm posting today . . .

I'm contemplating the purchase of a small pure sign wave inverter: something I can plug into the car's cigarette lighter and run a small audio system with. I note that the i-MiEV's lighter receptacle (probably more properly called the accessory outlet these days) is rated 12V / 120W.

My proposed load, by coincidence, is a home stereo 2 channel power amplifier - an Adcom GFA-535 - which has a rated output of 60W per channel (120W total.) The speakers that the amp will be driving will be rather efficient and I don't plan to push the amplifier very hard. The music source for the amplifier will be battery powered: a tablet or laptop not plugged into the AC side of the inverter. So far, so good.

I've see one unit that looks pretty good and it's rated at 120W . . .

http://www.samlexamerica.com/products/ProductDetail.aspx?pid=546

The only thing that I don't like about this one is that it's got just a single 2 conductor receptacle.

But it's slightly larger sibling, rated at 150W, has a couple of 3 conductor receptacles . . .

http://www.samlexamerica.com/products/ProductDetail.aspx?pid=590

Either one of these inverters would work for my immediate purposes. The Adcom power amp has a non-grounded 2 conductor AC plug and, if I'm using the inverter to charge my laptop (I can't envision doing this at the same time that I'm running the power amp,) it's also possible to charge it via a 2 conductor plug. But I'm leaning towards the 150W unit with the 3 conductor plugs, as I'd like to have that flexibility for operating other devices with grounded plugs. The purchase price difference between the 2 inverters is negligible.

Question is: am I going to be compromising the accessory electrical system and/or 12V battery by plugging in an inverter that is rated 30W beyond the factory recommendations? Or, could I plug in just about any larger sized inverter (within reason) that exceeds the rating on the accessory plug, if I'm not going to running devices off of it that exceeds that 120W rating?

 

[mdbuilder]

The latter, it should not draw 150 watts unless something plugged in is consuming > say 125 or 130. Otherwise the thing would get hot enough to melt carpet

Also, there is a fuse yes? The fuse protects the wire and socket.

 

[PV1]

I wouldn't use the accessory port for anything above 50 watts. I've seen my fair share of melted ports.

I have a 750 watt inverter that has clips for directly connecting to the 12 volt battery.

For the PlayStation mounted in the back of the car (~11 watt draw), I have a 100 watt inverter hard-wired with a switch. It fits right under the front seat.

 

[JoeS]

Benjamin, I took the liberty of opening up a new Topic on this subject, as the other thread focused on the 12v battery itself, and brought those posts over here.

I agree with PV1 and would be hesitant to draw more than about five amps out of that accessory socket.

I have successfully run small inverters off the 12v accessory 'cigarette lighter' connector, powering little things like phone and iPad chargers and electric shavers. Kinda wasteful nowadays as everything seems to use a USB port for charging and plenty of direct 12v->USB dc-dc converters are now available.

For any serious work I externally connect a higher-power inverter directly to the 12v battery with my permanently-installed Anderson PowerPole connectors. I haven't tried bringing a 12v higher-power source into the cabin except for the trailer light wiring adapter.

For me, the figure of merit for an inverter is the quiescent (no-load) power draw of the device. I notice that the Samlex spec says less than 1/2A for the small unit but doesn't provide a number for the larger one.

Back to the OP question, for audio purposes I suspect the pure sine-wave inverter might be 'quieter' than a square wave inverter. Interesting to try both to see if there's a difference. Square-wave inverters have usually been cheaper for a given power output. I would go with the lower-power device simply to reduce the quiescent current.

 

[Benjamin Nead]

Thanks, all, for replies on this and, yes, making this a specific new topic is a good idea. My reply is late in coming, since the Forum's software didn't allow me to log on to reply until I reset my password (an artifact of the upgrade, perhaps.)

I've heard lots of bad things regarding the use of the cigarette/accessory port for higher amperage work, as different OEMs use slightly different sized ones. The lack of tolerances here can promote arcing. So, I'm inclined to run new dedicated wiring from the 12V battery terminals into the cabin and terminate inside with a better connector.

These people make "smart" battery chargers with proprietary connectors to interface. The wiring harness shown in the link is designed to integrates one of their chargers. Note the inline fuse . . .

https://no.co/gc008

NOCO also makes "gender bender" adapters to allow the same wiring harness to be used to run accessories or inverters. I might go this route, but I'm still open to suggestions , if there's something else out there that's clearly better.

And, yes, everything I've heard regarding inverters with a pure sign wave output is leading me in that direction.

More later . . .

 

[PV1]

Anderson Powerpole connectors are gender neutral and fairly common in the DIY EV world, and are available in several amperages correlating to color and physical size.

 

[JoeS]

Anderson Powerpole connectors are gender neutral and fairly common in the DIY EV world, and are available in several amperages correlating to color and physical size.

I can vouch for them as I've been using them for years and have hundreds in my garage, in my cars, and in my boat. Here's a well-organized source to show you what's available:
https://powerwerx.com/dc-power-products

 

[Benjamin Nead]

Thanks for the link to PowerWerx, PV1. I knew of the Anderson connectors (past adventures in the model airplane world and with the DYIers in our EV club,) but not where to get everything under one roof.

The i-MiEV's accessory battery is 32Ah at a nominal 12V, so that's around 384W. The 45W capable (PP45) Anderson connectors with 10 gauge wire and inline fuses (say 30A) should do the trick. So, unless I've left something out of the equation, I should be able to run a 300W inverter
safely off such a harness? . . .

http://www.samlexamerica.com/products/ProductDetail.aspx?pid=497

300W is massive overkill for the sort of current draw situations I envision encountering, but it's nice to have that sort of reserve power available in the field and not be running the inverter and/or accessory socket connector to the bleeding edge.

 

[JoeS]

Benjamin, a number of comments if I may -

INVERTER

Samlex makes a good product, but at $145 for 300W I would be very tempted to try a $25 (or less) no-name brand off eBay or your local bargain electronics store, to see if a square-wave would work in your application. 200W would be plenty, IMO.

ANDERSON POWERPOLES

Forget the 45A pins and go with the 30A pins with #12AWG wire. #10AWG and those 45A pins are difficult to crimp properly and even more difficult to insert into the shell. Your steady-state power draw should be well-below 30A. Did you try measuring your ac input power with a Kill-A-Watt, for example?

 

[PV1]

Actually, it was Joe that posted the link (I could spend a lot of time on that site :lol: ).

The car's DC-DC converter can provide up to 900 watts output, so you're not relying on the 12 volt battery to power the load unless the car is in ACC, but you'll want to be READY as the car cuts off accessory power after 10 minutes (and keep the 12v battery charged).

 

[JoeS]

Just to clarify, we've drifted off-topic as those power levels require a direct connection (via a fuse) to the 12v basttery. With inefficiencies, that 300W(ac) inverter means somewhere around 30A at 12v.

Once again, for the 12v accessory outlet, we're suggesting that the maximum steady-state current out of it should be somewhere around 5A, say 60W maximum.

Talking about PowerPoles and the accessory outlet ("cigarette lighter outlet"), I have one of these adapters and quite a few pigtail connectors which do the same thing and are much cheaper:
https://powerwerx.com/cigbuddy-cigarette-lighter-powerpole-adapter

 

[Benjamin Nead]

Just to clarify, we've drifted off-topic . . .

We have, Joe? The "topic" (which you already changed once) was, as far as I can see, safely running an AC device, such as an audio power amplifier, off of the vehicle's electrical system. A full discussion on this topic shouldn't be limited to just the accessory socket (ie: what used to be called the cigarette lighter back in the day.) Perhaps it's appropriate to - again - change the topic heading to reflect this? I'll leave that to you and PV1.

Here's a recap . . .

I inquired if running an 60 watt per channel stereo (combined total 120 watt) audio power amp from the accessory port, which is labeled to able to accommodate that exact wattage. I further inquired about two possible inverter choices. I was advised that, while the port is labeled such, the limitations of the interface meant that attempting to draw anything beyond around 5A would be risky.

It was then suggested that I might want to consider a separate tap from the 12V battery and terminate with Anderson connectors. I'm fine in pursuing this sort of modification and the talk turned to ("off topic?") the practical concerns of what gauge of wire to use and how this could accommodate a more powerful inverter that the 120 to 150W ones I originally envisioned.

Next, the conversation turned to the idea of running an far more powerful inverter, as it's been observed that the vehicle's traction battery is capable of supplying up to 900W when the car is turned on (ie: "Ready.") But, if I'm reading PV1 correctly, this is something that I could only do for 10 minute periods. That doesn't sound like something I'm particularly interested in trying.

I'm also questioning the value of the most recently linked item: the "cigarette lighter" plug with Anderson outputs. If the port itself is the compromising factor in safely accessing the 12V battery's fullest potential, it seems somewhat pointless to insist on passing through that port and onto a set of connectors that are more robust . The "a chain is only as strong as its weakest link" adage would seem to apply here.

So, yes, I suppose I'm wanting to focus on the "off topic" idea of, say, 12 gauge wire directly from the battery, inline fuses (or fuse,) the wires passing into the cabin and then terminating on 30A Anderson pins.

Questions I still have . . .

1) What's the procedure for attaching the wiring to the battery? What size lugs are on the i-MiEV's GS Yuasa's 12V/32Ah unit? Is it advisable to loosen the the bolts on the sides the the terminal clamps and inserting lugs through there? Or should I completely remove the terminal clamp/wire assemblies and slip larger lugs underneath there and reattach? From what I understand with any sort of modern computerized cars (i-MiEV included,) doing the latter would require a trip to the dealer to reset the dash warning light (if not something even more involved and expensive.)

2) Is it necessary to fuse both negative and positive wires? I'm assuming just the positive one would do the trick. With the above described battery/wiring scenario, is a 30A fuse (or fuses) recommended, or should it (they) be of a smaller value?

Final adage of this post "the only stupid question is the one that didn't get asked."

 

[JoeS]

Benjamin, point well made and I changed the title again. Don't forget, your original post was in the 12v battery thread rather than one about utilizing that 12v power.

To answer your questions:

1. Good practice (e.g., as required by marine wiring) says to place the fuse within 6" of the power source, in this case the battery. I attached my in-line fused wire directly to the battery terminal clamp using, if I remember correctly, a 5/16" lug (but since it's a 10mm nut then a 1/4" dia. terminal should fit the 6mm stud). No need to remove the large terminal: just take the nut off and slip the wire with its ring termination onto the stud and put the nut back on.

2. Only the (+) side needs to be fused. The fuse size should be appropriate to the wire size, wire length, and load that you plan on using. I have 30A on my #12AWG wire which is only about 8" long between the battery terminals and the Anderson connector. Here's a handy table I just found:
http://www.sunforceproducts.com/Sup...harge Controllers/WireGaugeSelectionTable.pdf
(their watts at 12v doesn't make sense)
Edit: here's a better link: http://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

Another Edit: if you don't want to make your own, here's a gold-plated ready-made harness with fuses in both the (+) and (-) legs: https://powerwerx.com/ring-terminal-powerpole-inline-fuses-10-gauge
You could then attach the wire going to the cabin to this Anderson connector (I would lower the fuse size to match your wire and load), thus giving you the ability to disconnect under the hood and use a different accessory (e.g., a battery charger) if needed.

 

[PV1]

I drifted off-topic myself, but after Joe's post, I went back and corrected it.

What I meant is that the car must be READY if you want to use the accessory port for more than 10 minutes at a time. You'll want it READY anyway so that the 12 volt battery doesn't go dead. With the car READY, you can use 12 volt power until both the main and 12 volt batteries go dead, which will take quite some time with a total load of 300 watts (accessory draw plus ~200 watts vampire from the car itself) drawing from the drive battery.

Leaving the key in ACC (car is off except for radio and accessory port) means that power drawn only comes from the 12 volt battery. The DC-DC converter isn't active. In READY, it is, so all power used actually comes from the high voltage drive battery.

 

[Benjamin Nead]

Splendid, guys. Much appreciated for all the info. I don't have a timeline on this project and it might not happen until after the new year. But now I have a good basic plan.

 

[Aerowhatt]

Splendid, guys. Much appreciated for all the info. I don't have a timeline on this project and it might not happen until after the new year. But now I have a good basic plan.

Alternately, I found that the best place for me to put an Inverter was in the little storage bay (rear passengers side cargo area). It was simple to connect the positive wire where the DC out on the cars charger unit (in the motor bay). By removing one of the child car seat attachment lugs I was able to have a bolt hole to run the positive cable up into the trunk and under the trunk mat to the passenger side cubby (without drilling). The inverter itself is a 300 watt pure sine wave unit which is mounted with SS zip ties (again no holes drilled in the car). The negative lead of the inverter is tied to a good existing ground (don't recall exactly where but it is very short). The hole that the pos wire comes through is sealed with a dab of silicone caulk and the wire is fused 3 inches from the cars charger DC out connection with a water resistant ATO fuse holder.

It works with or without the key.
Wire runs are short.
Full inverter power, Including surge, is available.
Tested the inverter and it will shut itself down leaving enough power in the battery to go to ready mode with the key!
This attachment point is a direct connection to the 12V battery in front.
when not in use the inverter is "stowed" out of site and out of the way.

Aerowhatt

 

[PV1]

Since it would now be on-topic, here are a couple of pictures of my inverter install (no, it's not a bomb :mrgreen: ):

https://www.dropbox.com/sh/hwp6neikv9grjj0/AADslA_4hcawMRLnC5wsLqZ7a?dl=0

Inside the box is a Black and Decker 100 watt direct plug-in inverter (no cord) with the plug removed and the connector soldered directly onto the board. There is also a step-down converter to drive the fan at a low speed. The noisy fan inside the inverter was removed, replaced by the large fan that moves 5 times more air and is almost silent. This inverter powers the Playstation 2 hidden in the rear compartment. Power was tapped from the radio's main feed (yellow wire). Likewise, it will run regardless of the key position, but I haven't tested its shutdown point. I control it with the red rocker switch I installed as part of my LED upgrade (used to control the red accent lights, but the dimmer is now used for that).

I only went the inverter route because it was cheaper than an isolated DC-DC converter for the PS2, and isolation is necessary because of disc motor noise on the head unit.

So, there are a few different options for getting auxiliary power in the cabin with higher amperage than the stock accessory port.