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StormyKnight · 15-11-2007, 02:40 PM

Plenty of people have had a look.....
My main use I think will be to run a fluro above the cooking table if its too far from the car. I already have a 300W invertor hard wired into the vehicle up the front for the laptop, & I had been looking at a portable power supply to run a fluro whilst cooking or eating.

With my calculations, a 12v 5AH battery will give around 4 hours continous for a 13W fluro.

I also noted that the same invertor as a separate unit was going for $41.

Whats your thoughts? Would you use such a thing?

Thumbs up

OR thumbs down :cry: ?

Cheers
Richard

MattWhite · 15-11-2007, 03:15 PM

You tell us in a few weeks!

I paid 70 for a waeco inverter on its own so can't be bad value. Have fun!

StormyKnight · 15-11-2007, 03:57 PM

Thanks Matt, I will.

One thing I have noticed so far is that the unit is very quite in operation if you can accept the fan noise. The unit I have in the car even with no load on, makes a definate switch-mode type noise which is a little annoying after a while. It has a fan, but its temperature controlled, whereas this unit, the fan is running all the time.

I have tested the inverter so far on a compact 240V fluro 11W & it is fine. No noise other than the fan could be heard.

I also tried a touch lamp because it had a 40W incandesant globe in it, however because touch lamps use zero-crossing circutry to dim the light, it wasn't happy with the output of the unit. It would only operate on the 1st setting & wouldn't switch brighter when touched. I concluded that the output of the inverter is either square-wave or modified square-wave & not pure-sine wave which is expected at this price bracket.

I have a few more tests to do, I will post the results & I've got to fix the upside down plug! Its the principle of the thing!

Cheers
Richard

MTpockets · 15-11-2007, 06:28 PM

My 600 watt inverter has some stupid alarm on it when it thinks the battery has been drained down to its minimum and gets annoying. Does yours try to warn you of flattening the battery?

Yota · 15-11-2007, 08:25 PM

Originally posted by StormyKnight

I concluded that the output of the inverter is either square-wave or modified square-wave & not pure-sine wave which is expected at this price bracket.

At that price it would most definently be square wave, do not even atempt to run anything that has a 240v motor, (eg electric shavers), as it will ruin it. Square wave inverters or really only good for things that run off plug pack or similar transformers, (eg rechargable shavers).

A pure sine wave inverter will set you back alot more money, but run any 240v appliance, I paid about $400 for a 150W.

StormyKnight · 15-11-2007, 09:24 PM

Originally posted by MTpockets

My 600 watt inverter has some stupid alarm on it when it thinks the battery has been drained down to its minimum and gets annoying. Does yours try to warn you of flattening the battery?

I don't know yet, but i suspect so. I haven't run it until the battery is flat, but when you turn the inverter switch off, there is a very quick beep that sounds like an alarm.

The unit is now on charge for 24hrs after I took it apart to have a look inside. After its charged I will check the output voltage from the unit over various loads.

StormyKnight · 15-11-2007, 10:00 PM

Ok, the covers come off....

6 normal philips head screws from the back allow the two halves to separate.

After unplugging the batteries, the back half contains the two 6V 5AH Sealed lead acid batteries wired in series to give 12V 5AH capacity.

This is the front half. Its considerably busier. The main board is the inverter board.

Ok, I had a quick look around basically to have a look at the "quality" of the workmanship. Well as you can guess the soldering was pretty average. Some of the insulation on the bigger high current cables showed signs of heat stress when they were soldered. The insulation wasn't broken just a little melted.

Another thing I noticed was the USB board. It wasn't sitting flat on its pegs. Note in the photo I had already taken the screws out, but this is the position it was screwed down to because the lower board is too tall for it to go any lower.

In addition, this board wasn't sitting square. You can see that the left side of the board is touching the yellow casing.

This meant that you could not fit a USB device into the connector from the front easily.

I tried to reduce the amount of solder on the board, but that didn't help enough, so I had to "reform" the casing with the soldering iron so that it would fit it such a position that a USB device could be inserted from the front.

Finally I wanted to turn the power plug round. Well it turns out it can't be turned around as the moulding will allow it to only go around the way it is. Possibly another reason for the bargin price :? .

After reassembly & retesting that all features still work, I decide to measure the plug pack as I was suspicious about the voltage since you can't provide a full charge to a 12V battery with only 12V being supplied.

As it turns out the charger is unregulated & runs at about 17VDC unloaded. The only thing between the charger & the batteries is a diode. The diode will stop the batteries discharging via the charger if the charger is still plugged in but turned off.

I now have the unit on charge for 24hrs.

I will test the output voltage over various loads over the weekend & I will also plug in my fluro light & test how long it runs for.

Cheers
Richard

Chippy · 15-11-2007, 10:30 PM

Top stuff Richard. What a great thorough report.

Looks like a great economical unit for lighter duties.
Looking forward to your testing to see if it can handle anything heavier.

Cheers
Chippy

MattWhite · 16-11-2007, 12:09 AM

HAHA Stormy! Your as bad as me, when I buy something I'm not going to just accept that it works and be done with it! I'm going to pull it apart and see how, why, what and when and how they've done it!! Love it, should be more of it!!
:lol:
Matt

MTpockets · 16-11-2007, 09:40 AM

I can't see it lasting very long. :cry:
5 amper hours is not long and with a wet cell 12 volt (or 2x6) if you take the charge down past 50% you start to damage the cells untill it gets charged again. In most batteries once is all it takes for damage to occur. If you were to drain it past 50% on a regular basis it wouldnt last very long.
I may be wrong and will stand corrected, but I had one simular from super sheep, and it died within 6 months, and after 4 uses camping. I only ran one 12 volt fluro from it.
Just my opinion guys :wink:

StormyKnight · 17-11-2007, 09:10 PM

Yep Les I took your information on board....& after some difficulty locating appropriate details, here we go...

We will start with the expected float life of a Sealed Lead Acid battery (SLA). The float life is the expected life if left on constant charge such as in an alarm backup battery installation.

Because an SLA battery has a fairly good self discharge rate (5% per month), if you were to top it up each month or so rather than continous float charging, that may extend the life even further.

However, unlike an alarm installation, we will probaly want to actually use the battery to supply power to some appliance. This is where the depth of discharge (DOD) comes into the life of the battery. The deeper that you discharge the battery on each use, the shorter the life. In this case its represented as recharge cycles.

Note that this graph is generic for lead Acid batteries & not necessarily (or likely) equivalent to the batteries in this product under review.

So lets say you wanted to limit the discarge to 50%? How would you know when it got there? Well there is a way. We can use the open circuit terminal voltage as a guide.

So from the graph, 50% is around 12.2V.

The only issue is you need to unplug any load & wait a minute or so for the voltage to stabilse before measuring before you will be able to deduce the charge % used.

So in my next post I will list the results from running an 8W 12V fluro using the power outlets over 6hrs continous use.

In addition, I wil be able to answer the question about the inverter low voltage beep & @ what voltage it comes on at!

Cheers

MTpockets · 18-11-2007, 08:19 AM

well done Richard :wink:

StormyKnight · 18-11-2007, 12:36 PM

Ok here are the 8 Watt fluro test results...

First this is a pic of the fluro unit itself.

I then hooked it up to one of the 12v power outlets of the unit & used a mutimeter to measure the battery voltages.

Below is the graph of the terminal voltages, both under load & open circuit. The open circuit figure is important if we are to determine the state of overall charge of the batteries.

As we can see there was a steady drop in both the open circuit & under load voltages.

Previously we had worked out that an open circuit voltage of around 12.2V would indicate a 50% drop in the total charge of the battery. From the graph we reached that point at 5 hours of continous use.

At 6hrs, the 12Volt open circuit voltage represents a remaining battery charge of only 35%. More importantly, if done regularily, it will shorten the number of possible recharges for the battery quite a bit.

I decided to stop the test at this point as I didn't want to unduly shorten the life of my batteries. The fluro however at this point was still running as strong as ever, so waiting for it to dim or stop working is not early enough warning of reaching 35% remaining charge.

Also with the battery at this point I decided to try the inverter unit in search of the so far elusive low battery warning beep.

I hooked up a 75W incandescent lamp to the inverter & turned it on whilst monitoring both the AC voltage output of the inverter & the DC voltage of the internal batteries.

Supprisingly the AC output was consistant to a figure I had measured when the batteries where near full - 210VAC. Now remember that the output from this unit is not pure-sine wave but more likely square wave or perhaps modified square wave, so my multmeter will not measure it 100% correctly as it is not a true-RMS meter. However, my research on the matter, has lead to my meter should read around 210V for this type of waveform inwhich a true RMS meter & most loads plugged in would read it as 240V.

Below is a graph showing the differences between the various output waveforms of inverters. Note that this is graph is for 120VAC but can be applied to 240VAC by replacing the 170V peak limit with 340V.

I now moved onto to measure the battery terminal volatge whilst under this load. It started around 10.8V & was slowly dropping. In perhaps 3 or so minutes, when it reached 10.3V, the low voltage alarm went off!

So I think the main thing with these type of batteries if you wish to extend there useful life, is to limit discharge amounts & to recharge them as soon as possible. It may also be prudent to hook up the device you intend to use on the battery pack & do a dry run. That way you will have some idea how long it will last depending on how discharged you want to take your batteries to.

plucker · 18-11-2007, 11:55 PM

champion effort Richard. :mrgreen: :wink:

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Portable 200W inverter & 12V rechargable power pack

Portable 200W inverter & 12V rechargable power pack

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