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I need 110 that work through ignition/cranking.

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  • I need 110 that work through ignition/cranking.

    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.


  • #2
    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.


    • #3
      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.


      • #4

        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.
        "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
        My Shop


        • #5
          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.

          Howz that?
          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, 06:48 PM. Reason: PS...


          • #6
            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 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.



            • #7
              I know this has nothing to do with this thread but I love oldspark's responses


              • #8
                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...


                • #9
                  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, 03:15 AM. Reason: Post Edit:


                  • #10
                    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 I said earlier I was looking for the old off-the-shelf solution, but I don't see that 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.


                    • #11
                      Originally posted by OldSpark View Post
                      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...
                      Pretty much all of the above. Specifically, you are always helpful and thorough, ask the right questions and offer a resolution based off of the information provided by the poster. To me that is a complete response. You think outside of the box it seems and are very knowledgeable specifically in electronics which is probably not the natural forte of most of the computer geeks on this forum. (GUILTY!)

                      Arguably a "negative point" for some but a + in my book is that I have to read your posts several times as they are laced with the subtle humor, digressions and FYIs you speak of as well as lingo, acronyms, strange formatting and symbols. The negative being that they might be "hard to read" but I think it is fun. Bring on the ramblings... if people don't want to read them, they don't have to.

                      Of course I also appreciate all of the times you have set me straight. Keep it up! You're an asset.


                      • #12
                        Thanks dmcdlrn.
                        So you like me burning others eh? ( ) [No, that's not the case - I was no different to them, and I've learned to stay clear of their expertise!! But I try to suggest the simpler & cheaper etc, or intervene when I thing it very likely something is wrong or won't work. Luckily many do the latter for me too. I don't think I ever get psst off or upset (though I might feel dumb else have that "ytf didn't I think of that!"...), instead I'm usually on a high for learning something new, or happy I was stopped. However there can be a wrong way to be told...]

                        But you met my suspicions, and I'm glad someone does see or likes all those things.
                        But how does it feel being alone on this forum...? (As in, that's a joke LOL - I'm NOT laughing at you. [Not like the others...])

                        The -ve is ok - I do write to be reread at intervals for interactive and greater understanding.
                        The real -ve is not being reread for that extra understanding, but worse (and unacceptable) is when my rambling is too long so people just give up. (Hence the odd humor, but that's missed in text, and when verbally delivered often "upsets" people - it interrupts their serious concentration...) FTR - even I have refused to reread some of my posts!
                        I know I should cut short, but I get bugged with un-thoroughness...

                        Then there is jargon etc. But IMO plain english expression is so ambiguous - even between family and neighbors. I just hope people ask just to be sure. Even techspeak is far from precise.
                        As to slang etc, I try to avoid that. But I learned years ago just how much I didn't think was slang. Bluddy Aussies - as the Poms complain, we just don't speak the Queens English (of course not you fkwits, we were colonized under a King!).

                        But thanks again. End of hijack.
                        Now to Ken's reply.

                        PS - I can still be wrong. And stupid. And even I still learn more & more. (What a pity I forget even quicker!!)


                        • #13
                          Ken - thanks for pointing out what should be obvious. (Probation = delay, but I guess I never clicked to the retro-posting in the original time slot. See how ignorant I can be?)

                          And oh yes, I too advise against disk & power interruptions (though flash drives seem worse). (FYI - I had a brief power outage last night. PC restarted (Pentium4 2.4G, Windoze 2000). I reopened firefox which logged me back in (to mp3car?) and had the last word I typed at the time of the outage! Man I love modern enhancements. And to think it's software, not hard- or firm-ware, yet it's still transparent... FTW!)

                          As to yellow tops, yes, they are deep cycle. But for cranking you want a red top. They should also dip less during cranking - though as I recall, their quoted ESR (internal resistance) was the same as the yellow equivalents. (Isn't that strange?)
                          But because you have had luck with Optimas, and because they tend to have a higher voltage than other batteries, cool. (Unless perhaps it was with old Optimas, and in a vehicle or whatever that is very different (mainly in electrical behavior) to the current,, present vehicle.)
                          If your ok with that (Optima), why not see how it goes? It should certainly be okay whilst new. If not, maybe another budget inverter has better low-voltage performance. And maybe a smaller inverter (50W?)?

                          The remaining stuff below is optional reading. First my approach (later some real ramble)....
                          I'd be tempted to open it up and see what voltage it really runs on...
                          IE - DC. Probably 5-12 or 15 or 24V etc. Then a dc-dc converter that handles low voltage inputs - some are amazing (IMO) handling down to 6V inputs! (People use to think I was crazy insisting on 8V to 16V designs.)
                          But opening it up voids the warranty (thereby almost guaranteeing smoke!).

                          And though good batteries may only dip to 11 or 10V during cranking, 9V is not uncommon. 8V is usually a sign of a near-death battery, unless perhaps in cold climates or if discharged.

                          Alas no internal DC specs on your link, but I was thinking - with its 100-240 VAC 50-60 Hz input, the inverter output need not be too stable. Hence maybe some cheap kit without a low voltage cutout.
                          At only 2A input, then a (12V x 2A = 24W, 24W/100V = 1/4A output; add margin -cum- inefficiency, a...) 110VAC 1/2A output inverter. Not too hard to find? (I recall simple 30W - 100W inverters though I have lost their links etc.)
                          But that's more for DIY constructors even if kits exist.
                          Maybe a 220VAC inverter? That halves the current output (1/4A - 250mA), but don't confuse that with commercial offerings - if they have a low voltage cutout, it will still halt during cranking.

                          And now for the real ramble, though I do like the bit in bold....
                          A cap? What was it? IF (1 Farad) = 100Watts for 1 second. That's ~3 seconds assuming 33W inverter output, but that assumes it discharges fully to 0V, and you can only discharge it from the initial battery voltage (~12.6V), less a 3A or probably a 5A diodes voltage drop (generally 0.7V or maybe 0.3V for a Schottky), hence cap discharge from ~12V or 12.3V to maybe 10.6V (wherever the inverter cuts out).
                          And I'd have to check formulas etc for that calc.. I think energy of a cap is V^2/C (VxV/C), so rough calc is initial energy ~12x12 = 144; 10.6B energy ~10.6 x 10.6 =~112; 144-112 = 32 hence 32/144 =~0.22 or 1/5th of the available energy. If all 1F energy is 3 secs for your ~33W input, then 3s x .22 = 0.66 seconds hold up time.
                          Sorry, I'm thinking aloud ... and probably wrong. (Is it VV/C or just V/C?) Besides, the discharge rate decay with time - it really requires a proper calculation...
                          But maybe as a ballpark it shows that a 1F cap might last almost or around 1 second. I'd probably assume 5 seconds if not 10 for cranking, so unless I'm way off, a big cap is needed.

                          [The astute may wonder how long a 1F cap will last on a 330W or 3,300W audio system. (60mS or 6mS? respectively?) Yeah - caps are really good for milli-seconds thumps!]

                          But your plugpack's 2A may also be an overestimate. A "standard" 1A may have been a tad small or didn't allow for start-up inrush or short peak draws. So maybe double the above times?
                          But 1F is almost as big as a 7AH battery.
                          A 1.2AH or 4AH is smaller than a 1F.
                          Nah, a battery is the better option. Even 1.2AH is the equivalent of at least hundreds even thousands of Farads.


                          • #14
                            I appreciate the suggestions and the time you took to make them. Finding information like what I've garnered here will save me hours and probably quite a few dollars in trial and error. Now, what I really need to do is convince some company to make an inverter/UPS to handle that start up situation. I'm surprised it hasn't happened yet considering the number of inverters on the market.
                            As for Optima I'm not in love with them, but I've had a good experience. The Toyota Prius is kind of a hackers dream, but despite having this huge traction battery the 12v battery is very small and when it starts to go all sorts of wonky things happen sporadically. Pretty much if you ever meet someone with a Prius having a problem ask them if they ever replaced their battery...if not they should. Other than a flat tire the 12v can pretty much cause everything from the radio, doors, backup camera and even occasionally the ignition not to work properly/sporadically.
                            Your calculations appear accurate, not that I'm an expert by any means. My wife looked over my shoulder and now believes her car is a goner.


                            • #15
                              I forgot to mention that a reduction starter-motor may be another consideration, though maybe your vehicle already has one?

                              Reductions use a smaller faster motor through gearing to crank the engine. I replaced my original 1960's Isuzu i-Mark/Gemini type standard starter with a reduction starter from later Isuzu 2.6L EFI Rodeo/Jackaroo/Trooper. My cranking Amperage hs nearly halved from ~240A to ~140A.
                              Modern reduction starters can be "in-line" and look the same as older non-reduction types, and are usually smaller (hence physical space is no issue).

                              Since a battery internal resistance's voltage drop is proportional to its current, nearly halving the starter motor current nearly halves the voltage dip during cranking. (Actually it's probably a better improvement since the chemical (or internal, theoretical, pre-ESR) battery probably has a higher voltage due to the lower current. But that's minor anyhow, assuming I am correct!)

                              An aged cranking battery will eventually dip lower, but the reduction-starter may be a consideration.
                              But its cost and fitting may be the excessive for a temporary? solution. (Though in my case, $45 from a wrecking/salvage yard, and 10 minutes to fit.) But there are other benefits....
                              And maybe other readers may get some ideas.

                              FYI - the other benefits I've has with my reduction starter - cranking out of bogs, clutchless cranking in first gear limping home with a failed clutch cable, cranking in 1st off the road when out of fuel, getting over excessively steep hills, etc.

                              What really blew me away however was its solid cranking at 5.2V with my defunct 8-year old 12V cranking battery.
                              [ Actually it was the engine starting that was the real mind blower - a later OEM reluctor/ignitor and IgCoil ignition... (Isuzu FWD iMark/Gemini).
                              But for any 12V ignition to fire a cold engine from 5.2V whilst cranking?! I was merely seeing how long my reduction starter would crank (at normal speed) on a maybe 1/20th original capacity, stuffed battery. Glad I was in neutral, and not in the engine! Strange how I never bothered building my cheap multi-input sequential splug CDI after that experience... ]

                              In fact now watching my 3-digit dash voltmeter hit 9.x Volts during cranking, I wonder if it would handle the original starter-motor?