Power inverter question

Status
Not open for further replies.
Joined
Oct 11, 2002
Messages
22,183
Location
Colorado Springs
I have a quick question for you electrical gurus, which I am not.

I can not buy a car charger cord for my cell phone, but I do have a cigarette lighter power inverter in which I could use the wall plug to keep my phone charged.

Do these power inverters draw a lot of electricity compared to using just the straight cell charger that plugs directly into the lighter outlet? I don't want to end up with a dead battery in the middle of nowhere!

Thanks.
 
Last edited:
Yes they do draw more power, But all the ones I've seen had a low battery shutoff. But it will more than likely still run down your battery.
 
Last edited:
Originally Posted By: Drew99GT
I have a quick question for you electrical gurus, which I am not.

I can not buy a car charger cord for my cell phone, but I do have a cigarette lighter power inverter in which I could use the wall plug to keep my phone charged.

Do these power inverters draw a lot of electricity compared to using just the straight cell charger that plugs directly into the lighter outlet? I don't want to end up with a dead battery in the middle of nowhere!

Thanks.


Other than efficiency and standby current draw, no, they don't draw too much power so long as you use it for low power AC units (e.g. laptops, portable DVD players, cell phone chargers, etc.)

If you plan on using one for just simple stuff such as portable electronic appliances such as DVD blayer, cell phone charger, etc. then get one that is rated between 60~125Watts max (standby current draw is way lower). Don't automatically assume that when it comes to AC inverter for cars, same holds true as to buying an SUV (bigger doesn't mean betta) for the standby current draw will becomes so significant that it may trip your fuse just as you plug it in to your cigarette lighter socket.

Lastly, anticipate about 75~85% conversion efficiency.

Q.
 
Mine is 75 watts so it sounds like I should be A-OK.

Would 75 watts be enough to power a video camera?
 
Last edited:
Originally Posted By: Drew99GT
Mine is 75 watts so it sounds like I should be A-OK.

Would 75 watts be enough to power a video camera?


Yes indeed! I use mine (Crrapytire's MortarMaster 75Watter) for recharging my Sony DV camcorder for many years, ditto with my portable 7" DVD player, older P-III laptop computer, etc.

Q.

p.s. I also have a 150Watt Mortarmaster and a 250Watt (fan-forced cooling) X-power for higher power requirements.
 
Originally Posted By: Quest
for the standby current draw will becomes so significant that it may trip your fuse just as you plug it in to your cigarette lighter socket


A couple of data points from actual inverters:

The Xantrex 400W power inverter I got from Costco (for $19) has a .3 amp no-ac-load current draw.

The Xantrex 1000W power inverter I also got from Costco (this was $39, a heck of a deal) also has a .3 amp no-ac-load current draw.

In a few hours I'll be able to tell you if one is more efficient than the other when powering a 90 watt load, as I'm timing how long it takes for each of those inverters to drain an 85 amp-hour deep cycle battery till it drops to the auto-cutoff voltage (10.5V on both models).

Quote:

Lastly, anticipate about 75~85% conversion efficiency.


Xantrex claims 90% and the run time figures I got on the 400W unit are right on, it ran a 90 watt load for almost exactly 10 hours from the 85 amp-hour battery before the low voltage cutoff shut it down. I didn't measure the current draw of the unit from the battery but given that the battery lasted 10 hours it was around 8.5 amps, 8.5 * 12 = 102 watts in, 90 watts out is about 90% efficiency....
 
Incidentally, I found that one of my deep cycle batteries was indeed bad as I suspected by load-testing it this way.

It passed the CCA test on a Midtronics conductance tester, but only powered the load for 4 hours, 39 minutes, less than half of the 10 hours it should have lasted.

I thought something was wrong with that battery for two reasons:

1)I was using it in a 24V series string and the charge voltage across this battery was always about .3V higher than the other battery.

2)One of the cells never needed water added to it. The water level dropped in all the other cells.
 
brian-

Mine based on CrrapyTire's MortarMaster 1750Watts invertor which is proportedly OEM'ed by Xantrex, but no further details other than the spec. sheet that came along with it.

These units are most suitable if you run it with 300Amp/hr deep cycle battery to drive things like ordinary fridge compressor, electric drill, etc., without overloading (motor starts usually takes a few times more current than it's running power consumption rating). Mine on standby mode draws close to 1amp, as opposed to my smaller units (biggest one I have is 250Watts which draws 300mA standby.plugging in one of these units to the cigarette lighter into my Mazda B6 block would spark and ditto when you clamp it onto the battery post (not with my 75Watter~250Watter) and that freaks me out whenever I do it (spark + lead acid battery = ka-boom!). also: I wouldn't do this with my fit.


boy I have to tell you how happy I am when I switched over from a really old tripplite 300Watts invertor (circa 1971, or maybe 73) which has a horrible efficiency rating of 65Watts approx. and that thing would melt your cigarette lighter in a heatbeat (currently sitting in my garage gathering moisture). Nowadays, switchers are so much more capable, high efficiency and cheap that there's no turning back anymore.

You may be right on the efficiency side for my memory told me that it's about 85% approx. back when I was testing one of the units (using pure resistive load on the AC side, and then measure the current and voltage on the primary side). Fan never kicks in though so I know that I'm not overloading the unit..

Lastly, there are some really inferior convertor products made by "victor" or "victory" or something like that. The component, design and construction quality was nothing short of terrifying and I wouldn't be surprised that it would burn down your car during extended run.


*grin*

Q.
 
Here's another dumb question: do cell phone batteries and video camera batteries (I guess they're all nicad?) develop a memory if you don't completely drain them and completely charge them, and operate them that way always?

I remember in my RC car days that those batteries would develop a bad memory and would last about a half as long if you didn't operate them like stated above.

Thanks
 
Ummm... currently, my on-going investigation has given me the following information:

(1)Nickel Metal Hydride batteries: still has some memory effect but can be restored to full capacity after a couple of full deep cycling (meaning complete drain and then full, slow recharge).

Using multi-stage computer controlled NiMH charger works best in maintaining performance and consistency in these battery types. There are some really terrible cheep battery chargers from Energizer and the likes that are nothing short of old-fashioned NiCd charger (current controlled) and they do not work very well in my case.Maha gets my vote on this one (so is the multi-stage, world voltage computer-controlled Sony 4xAA battery charger)

No 2 brands of NiMH batteries are created the same. There are some really ccrrrapty battery from China that will fail in about 100cycles (that incl. GP rechargeables, which has failed 2 times on my wifey's situation -for Canon S2). I would carefully pick the good ones that are still made in Japan (Energizer AA and Sanyo Eneloop are both Japanese made).

Do not fall for the "bigger is better" mentality when it comes to buying NiMH cells for I have experienced more 2500~2700mA/hr AA battery failures than anything else so far (and yet my Japanese made Panasonic 1800mA/hr, Sanyo Eneloop and Energizer 2200mA/hr have not failed so far).

(2) Li-ion batteries: this is a very complicated subject for the technology isn't fully mature yet, according to the industry.

Li-ion battery may hold the charge better initially and also comes with a much higher capacity vs size(or weight) in the rechargeable battery arena but they do not last very well: typically withing a couple of hundred cycles max. before they become so bad (charge so shallow) that they do not hold/receive charge properly anymore.

Thus the issue of laptop battery cells going bad in 1 yr or so.

Also: charging Li-ion battery requires computer multi-stage control and not just silly tempurature-monitored constant current run-of-da-mill, cheep chinese made miracle charger method. So far, most Japanese makers with extensive rechargeable battery background and technologies (e.g. National/Panasonic- Matsushita Industries, Sony, Sanyo, Toshiba, etc.) have the ability to develop a decent Li-ion battery charger that provides consistent performance.


http://www.batteryuniversity.com/print-partone-12.htm

Most chinese made Li-ion batteries, maybe due to poor manufacturing facilities or lack of technology, they tend to lead to a very short life (far shorter than that of the major manufacturers). Most likely due to ionisation layer contamination (been told that it's more like an intoxication than anything else) as recharge cycles go up. Once these batteries fail to hold their charge, they are considered "dead" and cannot be revived for reuse.

Hope that helps (based on my rather limited understanding on Li-ion battery)

Q.
 
Quote:
Nowadays, switchers are so much more capable, high efficiency and cheap that there's no turning back anymore.


I have a 1000W APC UPS and the transformer alone in that thing weighs more than the whole 1000W Xantrex inverter I have! The APC is also only about 70% efficient (running from battery. With no load, on AC power, it sucks down 30 watts. I guess that's not too bad but it could be better).

Quote:
plugging in one of these units to the cigarette lighter into my Mazda B6 block would spark and ditto when you clamp it onto the battery post (not with my 75Watter~250Watter) and that freaks me out whenever I do it (spark + lead acid battery = ka-boom!).


Many of them, like my Xantrex 1000W unit, have capacitors in the input section, and what you are likely seeing is the surge as these capacitors charge up. You can confirm this by disconnecting the unit from the battery and then touching the input leads together. If they spark--it has capacitor(s) in parallel with the battery input.

My 1000W APC UPS has capacitors in the input section as well, as I discovered one day when I had unplugged it and removed the battery and was startled by the spark generated when the battery input leads touched.

Originally Posted By: Quest

Lastly, there are some really inferior convertor products made by "victor" or "victory" or something like that.


Vector. I have a 400W one that for some reason started to go into fault mode whenever I try to power a desktop PC with it but powers 100W lightbulbs just fine.

Honestly I think I paid as much for that 400W Vector as I did for the Xantrex 1000W inverter.

By the way, the Xantrex 1000W powered a 90W load for 8 hours from an 85 amp-hour battery compared to 10 hours when I used the Xantrex 400W. I'm going to run these tests again, I'm not sure the battery was fully charged when I tested the Xantrex 1000W. (I have a Black and Decker "smart" charger but I have my doubts about how smart it really is...)
 
Status
Not open for further replies.
Back
Top