As an alternative I could survive with DC-DC that would survive through the car starting. I need to be able to output about 24W.
I've been struggling with the proper setup to provide 110v outlets (probably never draw more than 100 - 150 watts).
I've used inverters before but they shut down when the car battery's voltage drops during cranking.
I'm amicable to either using a lighter outlet or wiring it directly to battery.
I would consider putting a small UPS behind the inverter, but the UPS guys say that's a no-no even with a pure sine wave inverter. Most of the UPS are also pretty big and bulky...I'd like to keep the setup small so I could tuck it all under a front seat.
I've also considered the DC - DC options, but that would limit my flexibility with what could be plugged in.
This installation is going in a 2006 Honda Odyssey...and there's no room under the hood for a spare battery.
I'm not expecting to ever run the items very long while the car engine is off...I just don't want to have shut things down every time we stop for fuel or the bathroom.
Thanks for any help you can give me in advance.
As an alternative I could survive with DC-DC that would survive through the car starting. I need to be able to output about 24W.
Okay, I'm going to go with an inverter directly wired to the battery. Supposedly this will prevent it from shutting down when the car is started. Does anyone out there have an inverter brands they prefer? I'm considering Aims, Go Power or Samlex. Any good or bad stories on any of these brands? I'm going to go with a 300W inverter and manual shutdown.
They're amazing, and the only inverter I've seen that can reliably survive cranking, no matter how low the battery gets in the vehicle.
Their ProtWatt model inverters aren't bad either, but they only survive cranking if the battery is topped off.
The XPower ones don't survive cranking at all, they're your typical cheapie walmart $100 inverter.
I've also used the Go Power GP-SW2000, and it also survives as good as the prosine.
IMO the solution is a second battery.
[Technically this is a UPS system... providing uninterrupted power during an interruption event. (Though UPS is usually taken to mean AC-DC-AC, UPS does include DC-AC and even alternate DC sources.)]
Moving the inverter connection to the battery won't help - the voltage drop is at the battery, not from any internal wiring. (Starter-motor +12V is connected direct to the battery.)
Ergo, a dual battery system with the 2nd battery big enough to handle the inverter draw until the engine starts and charging takes over.
For 150W, a common 7AH 12V battery should be fine - they are usually the best bang for bucks for any battery around that size (eg, compare the ~$30 7AH to the 2x larger 15AH... $150??).
But a battery equivalent to your main battery may be worth consideration as a reserve in case your main dies (then it's really nice having dual batteries!! ).
Your main consideration is if it has to be an AGM battery if it's not mounted in the engine bay else a sealed but vented enclosure.
If engine-bay mounted, wet-cells are fine.
A 7AH battery will be an AGM anyhow (or cheaper and better than wets & gels - if they still exist).
It's then just the standard method of adding a dual battery with isolator - ie, main battery - through a nearby fuse - to the isolator - to the 2nd battery thru its nearby fuse.
And connecting the inverter to the 2nd battery.
The isolator should be automated so it only connects while charging.
I suggest using the alternator's charge-Light circuit (D+ or L) whereby you merely need a relay (see my posts elsewhere regarding the "UIBI" - google "UIBI" and maybe "oldspark"), but there are also voltage controlled or "smart" battery isolators (though more expensive and usually inferior in behavior except in chargelight-less situations such as marine and stator type alternators etc).
Your inverter should be powered direct from the battery via a relay anyhow (though 150W inverters are often ok from some cig-sockets etc).
Hence it's just a matter of installing the 2nd battery with isolator, then moving (or installing) the IGN +12V controlled inverter relay (with optional on-off or on-anytime switch) between the 2nd battery and the inverter.
More efficient than dc-dc conversion (ie, dc-ac-dc--dc-ac) which is better though less reliable than adding a UPS (dc-ac--ac-dc-ac) with its battery (maybe an expensive 15AH?).
In summary assuming an alternator with a chargeLight circuit (D+. L. etc):
- the 2nd battery (AGM?),
- 2 fuses and the battery interconnection wire,
- 1 relay.
- relay (#86) to alternator's D+/L circuit.
[ WARNING!: Older alternators handle 250mA relay-coil currents with ease, but some may not. Smaller relays else transistors or FETs to switch the relay(s) could be added for newer alternators, and RC filters for EMS controlled alternators. ]
If it's a 7AH battery a common 30A automotive relay is fine ($3?).
The fuses could then be 30A or lower, though I'd recommend auto-resetting circuit breakers which are cheap and common up to 50A ratings (with blade/ATS fuse versions up to 30A). [Nothing worse than having a momentary high battery or load inrush current that blows fuses thereby leaving the 2nd battery to discharge and lose the load!]
Skip this last block - it's extra incidental FYI for now - unless your inverter automatically reconnects a normal/high voltages:
Another consideration is to add a low-voltage cutout (aka Battery Protector) between the 2nd battery and the inverter to prevent flattening of the 2nd battery. But you have an inverter low volts cutout, and anyhow, at ~$20 for a 10A MW728 battery protector (which would control the inverter's relay if higher current is required) and with a ~$25 7AH battery, I was going to suggest a suck it an see approach.
One catch may be the inverter's low-volt cut-out - does it automatically reconnect if the voltage recovers? That could be an problem as batteries tend to recover voltage after disconnection and you can have annoying or damaging off-on-off-on situations. Note that LVCOs or LVSs (low voltage cut-outs or switches) usually disconnect at 11.2V or 10.6V or whatever, and reconnect at 12.5V or 12.6V or 13.2V etc and such "hunting" issues vary greatly with battery type, charge & resistance, and load combinations, as well as the LVS's reconnect voltage.
Some LVSs however don't automatically reconnect.
PS - My last inverter was a $60 600W (RMS!!) from Aldi. Though tested, I haven't yet used it in anger.
Actually I bought one ages ago, pulled it apart for a peek, and upgraded its cheap DC input terminals.
When next offered by Aldi, I bought TWO (slightly smaller) with the intent of selling the first.
I don't know if I'll ever use them, but I bought 2 for my usual spare and redundancy reasons.
I'll also sell my older 400W, 300W and other inverters bought at various sales.
I still tend to use my original 150W inverter if needed (it cost maybe $65 over 15 years ago?) which was originally the cheap and universal solution for AC devices (camera & phone chargers, shaver), but since then I picked up all the relevant dc-ac converters at sales etc.
Looking back, I laugh (and cry) at how long it took inverters to catch up with floating/isolated outputs (and dual-pole switching with AC bypasses) - but's that's just another of my FIGJAMs.
Last edited by OldSpark; 03-08-2012 at 05:48 PM. Reason: PS...
The problem with a 2nd battery is finding the space under the hood of an Odyssey to do so. What I really need is an inverter with a small backup battery that can handle the load for 30 seconds. I don't mind building something myself, but an integrated/manufactured unit could be compact and probably not require redundancies parts that would happen in a DIY project.
Ahh...well, it's never as much fun if you can just buy it off the shelf...is it?
There is one other very important factor I have to deal with...the Odyssey is my wife's car. She has put up with my dual-headrest monitor installation with video amp/comibiner attached to the bottom of her seat. But that doesn't require any interaction really on her part. I've got to figure out a way to make whatever power solution I come up with be a totally non-intrusive solution as well. The only time we'll ever really use the power (or the video monitors for that matter) is on the one or two long trips we take each year. On shorter trips we try to get our boys doing other activities (usually not involving weaponry).
I'm thinking right now I'm going to get a nice 150w inverter wire it to the battery (getting a new Optima Yellow Top) and test a bit. If that can survive ignition with a ~30w load I'll be happy...if not I'll be referring to your post some more for plan B.
As I'm sure you know that means I have about a 10% chance of Plan A working because it's almost never as easy as you'd want it to be.
I know this has nothing to do with this thread but I love oldspark's responses
dmcdlrn - THANKS!!
And if I may ask (without hijacking)...
Is that for their (brilliant?) simplicity? (Meaning technical simplicity and reliability - NOT necessarily my "simple & concise" (ha!) writing!)
... or occasional (subtle?) humor?
... or warnings?
... or pointing out what (might) not work?
... or thought provoking digressions & FYIs?
Oh - and cheap solutions?
FTR - I do battle between the KISS and my reply approaches. Unfortunately the "all of the above" ramblings still win...
POST EDIT - Sorry, it's not a deleted reply - its notification was very late, ad I missed its original posting. But FTR, this is how I started, then the rest....
Hey Ken - I got notification of a now seemingly deleted reply... (The disadvantage with notifications that contain the reply content - VERY incriminating! (and stored in my "FTR" folder - LOL!).)
end /POST EDIT
I'd suggest NOT buying THAT battery. (IMO wrong color anyhow.)
And if it's merely a 30W load (say a 4-8A input assuming 80% inverter efficiency and ~9V during cranking but excluding inverter overheads (idling current), a much smaller battery could do.
The Yuasa NP7-12 (7AH 12V) specifies a max draw of 40A, so a 1.2AH may do the trick.
But the battery - like the inverter - can be mounted anywhere.
What sort of 110VAC load is it? (If it's monitors, the usual solution is DC monitors - not AC with DC-AC conversion.)
Maybe a direct 12V supply exists, else a smaller inverter circuit can be used...
But if you were thinking of using a UPS, then why is mounting just a 7AH battery a problem? (It's smaller than a UPS and certainly smaller than their common 15AH battery!)
Also at such low power, big caps are a possibility, but they are bigger than the 7AH battery...
Last edited by OldSpark; 03-09-2012 at 02:15 AM. Reason: Post Edit:
OklSpark, it wasn't late, I'm on probation here cause I'm a roookie. My posts have to be reviewed by the local gendarmes before being made public.
My initial goal is to get a Western Digital Live Hub (1TB Media Streaming Device) to work in the car. It then feeds my rear-seat monitors. The good and bad part of the device for this application is, of course, the hard drive. Cutting off power abruptly to hard drives isn't generally the best thing for the poor, fragile souls and the shutdown/restart process on the device is much like that of a PC time-wise. The AC/DC power adapter on the device claims to be 24 watts (well 12v x 2 amps and then I did me some ciphering to figger it out). But, knowing me if there's an outlet available I'm gonna want to put something else in there sooner or later like a laptop or advanced weaponry for those high-traffic situations in the Northeast. So, I thought I would get a 150 watt or maybe even a 300 watt solution which could also handle a small UPS if that was the only way to keep the power to the WD Live constant.
I'm not at all excited about finding a place for the UPS, but there are some relatively small ones and they also would serve as the outlet receptacle. As for the car battery itself, it needs to be replaced and I've had pretty good luck with Optima's in the past, especially in my Toyota Prius. I thought the deep cycle capability of the yellow top would be what I would want for this application, but if there is something better suited please let me know.
Anyway, since you didn't ask, the reason I'm using the WD TV Live Hub over solutions I've used in the past like a Sony PSP is the ability for me to quickly transfer our online library from a media server to usability in the car. In the past, I would spend hours doing conversions of the full DVD formatted files to some form of compressed device and all too often there would be audio/video sync issues or other problems. Copying over the network is easy and allows me to not have to figure out what movies my kids are going to like in advance.
All will be wonderful if I can just find a way to power it without having to either go through the shutdown process and/or have it hard shutdown everytime we stop for gas or the bathroom on a trip. Laptops and just about every other device I can think of won't really care that much.
So, that's where I am....as I said earlier I was looking for the old off-the-shelf solution, but I don't see that happening...so I am where I am and my small, overworked brain has been trying to figure out the best solution ever since. Fortunately, I found this forum and some nice folks that know quite a bit more than I do about power in vehicles and how to make it usable for 110v devices.
I should probably do this whole story to the Beverly Hillbillies tune.