[Aroy]

Originally Posted by Guite

With multimeter probes on the plug going into the TV, voltage reading is 250 on mains power. Switch off MCB so that power comes from inverter + battery. Voltage reading fluctuates all throughout duration of reading. After about a minute inverter goes on over power mode (>100% load) and TV has to be turned off. When we try to restart TV on inverter power, voltage momentarily drops to about 170V. This is not consistent on every attempt, sometimes 180, sometimes 168, etc.

I also tried measuring current drawn by TV but power does not pass through multimeter. Connection is in series. Maybe multimeters cannot measure AC current?

This clearly shows that the Inverter is not able to "power" the TV. Forget the Voltages and currents, the clear fact is that at a given load the inverter gives up.

This has happened with my 800VA single battery inverter. In case the refrigerator is running when the power fails the inverter keeps it running, but if it stops and starts then the inverter gets overloaded.

What has happened in your case (in my opinion) is that the two battery setup had enough reserve power to start and run your TV, while the single battery model does not.

Please keep the following in mind
. The VA rating of inverter is the peak power it can output
. The current requirement, especially overload will not always be proportionate to the VA rating, as at higher current the battery capacity comes in
. For better efficiency higher voltage (hence multiple batteries) are better
. The battery ratings are for a 10 hour discharge. That is a 150AH hour battery is rated at 15A discharge over 10 hours. As current drawn increases, the capacity decreases - the actual capacity for current drawn is given in the battery manufacturer's site. Normally the capacity decreases to 70% at 5 hours and 50% for 1 hour.
http://www.exideindustrialbatteries....NVATubuler.pdf
http://www.exideindustrialbatteries....%20Tubular.pdf
http://www.way-india.com/pdf/LC-RD1217P.pdf

[aim120]

Originally Posted by Guite

Thanks for being with me on this.

It's a brand named Mastech which I bought from Ebay for Rs.895. I put the knob on 10A. However there is no separate section for AC current, only section for DC marked A with straight line and dot dot dot.


White slide makes no difference to the voltage reading and overload switch off. Whether on mains or inverter power, voltage reading at TV plug changes every second, ranging from single digit to 240V. It stabilises at 240 only on black slide and completely dark scene.

Another interesting point to note is that inverter does not indicate overload when supplying to desktop PC. Both PC and TV are more or less same load, not running concurrently.

Voltage reading at battery terminal is stable at 12.45V when power is drawn from it and supplying to TV. However I noticed something else, the battery cables are hot, though not scalding hot. Is this normal?

The battery wire getting warm is normal ,I hope its not too hot .
The single battery system has to transfer more current, around twice more amperes through the battery cable to get the same job done vs your 24v inverter.The fact that voltage of the battery is normal means that your battery are fine and its not the bottleneck.

Now all those measurements and info that you gave concludes that your inverter simply can't handle the load of the plasma.

The plasma manufactures only write the typical power consumption and not the max power consumption.What the size and model of your plasma.Your pc must consume lesser power.

Now your multimeter unfortunately doesn't have the ability to measure AC current.

[R2D2]

Originally Posted by Guite

Thanks for being with me on this.

It's a brand named Mastech which I bought from Ebay for Rs.895. I put the knob on 10A. However there is no separate section for AC current, only section for DC marked A with straight line and dot dot dot.

I guess this is your DMM?

http://www.ebay.in/itm/New-Genuine-O...item3a81ecf0dd

Ok, it DOES have an AC section. See attached JPG.

A 42" Panasonic plasma TV will pull up to 350W with a white slide i.e. about 550VA. I frankly feel your inverter unit cannot handle the load, which may be the reason why the voltage fluctuates. Get the battery and inverter checked.

Please do this without delay - I have had a fire hazard with a faulty inverter at home. The set went up in smoke and was very hot to touch. The inbuilt safety fuses didn't blow!

Luckily it was a holiday and being at home, I was able to disconnect the battery and AC input/output & switch it off. The inverter was repaired (new mother board) but I never trusted it after that.

[aim120]

It doesn't not have the capability to measure AC current.

If it was just 350watt it should handle the load but then again he is also using a PC which is another 120 to 350watt depending on cpu/gpu load.



@Guite
Best way to measure your inverters capability is to use incandescent bulbs which consume as per their specs or use a clamp meter to measure AC current ,if you call APC their technician should mostly have a clamp meter.

But did you by any chance gave the older 800va for repair or get did you get it replaced from APC ,chances are they could have put the 1000va circuity inside,since the 800va sinewave model was long stopped.

[Guite]

Originally Posted by R2D2

I guess this is your DMM?

Yes that's the one. As pointed out by aim120, it cannot measure AC current. I intend to get Metravi with more functionality.

Please do this without delay - I have had a fire hazard with a faulty inverter at home. The set went up in smoke and was very hot to touch. The inbuilt safety fuses didn't blow!.

Is this advise with respect to TV load or heated cable? Will the fact that it cannot carry the load of TV be that alarming?

Cable is in three segments and the middle part is thinner. I will try to replace with same size of cable as the thicker ones. Batteries are in the balcony and inverter indoor; the extension part is slightly thinner than cable factory attached to inverter and battery respectively.

Originally Posted by aim120

But did you by any chance gave the older 800va for repair or get did you get it replaced from APC ,chances are they could have put the 1000va circuity inside,since the 800va sinewave model was long stopped.

It was bought in the year 2008 and immediately failed. It was replaced under warranty with a refurbished piece. Your suspicion maybe true. Is there anyway to visually identify from the circuit board whether it was for 1000 VA?

[R2D2]

Originally Posted by Guite

Yes that's the one. As pointed out by aim120, it cannot measure AC current. I intend to get Metravi with more functionality.?

Do you wish to measure current (A) or voltage (V)? To measure current you will need to connect a meter in series in the circuit which is dangerous when you are dealing with high voltages. Please do not attempt this unless you know what you are doing and have the clamp lead set to make the appropriate connections. Or get a clamp meter.

Originally Posted by Guite

Is this advise with respect to TV load or heated cable? Will the fact that it cannot carry the load of TV be that alarming? ?
Cable is in three segments and the middle part is thinner. I will try to replace with same size of cable as the thicker ones. Batteries are in the balcony and inverter indoor; the extension part is slightly thinner than cable factory attached to inverter and battery respectively.

My advice is based on the following symptoms that you described:

• Fluctuating voltages under load
• It should support a plasma TV even as a solitary load at the very least. A 850 or 1000 VA (still confused which one it is) inverter can easily support this load.
• Battery cables heating up - that tells me the wires used in the battery to inverter connectivity are either faulty, or too thin. Battery wires are at least 8 AWG (US) or approx. 9-10 sq. mm in metric measure.

A wire feeling warm to the touch under load is acceptable but heating up is not. Remember heat cycles destroy plastic insulation and that in the long run is dangerous.

Either way, please get it checked by APC. There's no harm in doing so.

Originally Posted by Guite

It was bought in the year 2008 and immediately failed. It was replaced under warranty with a refurbished piece. Your suspicion maybe true. Is there anyway to visually identify from the circuit board whether it was for 1000 VA?

APC will generally replace it with one of equivalent range/capacity.

[aim120]

Well if you are buying another meter get a clamp meter from companies like Mastech or Uni-T.I have a mastech one which shows a TRMS reading.

The 800va sine wave model was stopped well before 2008 and you must have bought the remaining stocks.Well i do not know how to indentify it,but like i said if you have a resistive load like a 500watt of incandescent bulb load and connect only that to the inverter and see if it works fine .
Alternately use a clamp meter and measure the current

Originally Posted by R2D2

APC will generally replace it with one of equivalent range/capacity.

When i had my APC ups replaced by a refurbished one under AMC they had replaced the UPS with a lower wattage one despite the externals looking the same.

To my surprise the UPS used to shutdown after overload,I then measured the current using a clamp meter and it was showing that the UPS would only tolerate around 670watt where as it was advertised to handle 800watt.This told me that the circuit used inside was from a older model.

I raised this issue with their APC bangalore service head and it was replaced by another one and this could handle 800watt.So they told me that there was a goof up in their refurbished warehouse.

[R2D2]

@Guite - the more I think of it, I feel it would be better if you let a pro attend to your inverter problems. Reason is that if you are not aware of what to do and touch. It could be dangerous when dealing with mainline voltages (230 VAC). Batteries are not as docile as they seem to be.

Please don't take risks unless you are absolutely sure of what you are doing and have guidance from a knowledgeable person or professional.

Originally Posted by aim120

I raised this issue with their APC bangalore service head and it was replaced by another one and this could handle 800watt.So they told me that there was a goof up in their refurbished warehouse.

Unfortunately APC replaces all products with refurbs. You are really not aware of what PCB has been fitted inside their replacement unit.

When my 2.2 KVA Smart UPS had battery issues early last year (2012) I insisted they only replace batteries not the unit because I was aware of their policies. We as customers need to be aware of their rather surreptitious practices. They agreed. If you stand your ground they will do what you wish short of giving you a new unit. A new unit is given when the faulty one is less than a month old.

[Guite]

Originally Posted by R2D2

Please do not attempt this unless you know what you are doing.

Attached is the setup I made. I know it is a risky setup. I know the risks are take care accordingly. First of all I have a plug - socket pair connected by short cables. I remove the positive cable and screw in tight the probes as shown: red probe to plug (on LHS) and black probe to socket. This series connection allows current to flow through the meter. In theory I think its okay.

[*]Fluctuating voltages under load

Fluctuating voltage in also on mains power measured on the plug of TV power cable. However if I connect TV to UPS and measure voltage on UPS plug, voltage is stable- both on mains as well as inverter. Its strange.

[R2D2]

Originally Posted by Guite

Attached is the setup I made. I know it is a risky setup. I know the risks are take care accordingly. In theory I think its okay.

Ingenious Proper Indian "Jugaad" if you don't mind me calling it that. Yeah, it will work. LOL!

PS - just be careful about the Amps measuring capacity of your DMM. AFAIK it cannot measure AC amps, only DC amps.

Originally Posted by Guite

Fluctuating voltage in also on mains power measured on the plug of TV power cable. However if I connect TV to UPS and measure voltage on UPS plug, voltage is stable- both on mains as well as inverter. Its strange.

Do you have power supply issues from the electricity board?

[aim120]

Originally Posted by Guite

Fluctuating voltage in also on mains power measured on the plug of TV power cable. However if I connect TV to UPS and measure voltage on UPS plug, voltage is stable- both on mains as well as inverter. Its strange.

Is the inverter set in UPS mode or inverter mode.If its set to UPS mode the inverter will switch to battery mode when the AC mains voltage goes above and below a certain voltage ,despite it getting power from the mains.

AFAIK only UPS which are line interactive or On-line do active voltage regulation use a multi tap transformer.Your inverter is a OFF-line UPS which means it has no capability to do active voltage regulation.

[Guite]

Originally Posted by R2D2

Ingenious Proper Indian "Jugaad" if you don't mind me calling it that. Yeah, it will work. LOL!

Thank you . Voltage measurement is also done with this setup by screwing in both probes to live and neutral respectively of the socket.

PS - just be careful about the Amps measuring capacity of your DMM. AFAIK it cannot measure AC amps, only DC amps.

I know, AC current does not pass through DMM at all.

Do you have power supply issues from the electricity board?

Not at all. It appears to me that the fluctuating reading is triggered by the TV. Will get inverter checked for load capacity.

By the way, middle segment of battery cable is 6 sqmm. I will try to find 8 sqmm. The two connections between the three segments is bare copper strands intertwined together tightly and wrapped with insulation tape. Quite typical. I wonder whether the connections might be high point of resistance and hence source of heat generation.

Re aim120's query above which came in while I was typing my response:
inverter is set to inverter mode from the switch on rear panel.

[aim120]

Originally Posted by Guite

By the way, middle segment of battery cable is 6 sqmm. I will try to find 8 sqmm. The two connections between the three segments is bare copper strands intertwined together tightly and wrapped with insulation tape. Quite typical. I wonder whether the connections might be high point of resistance and hence source of heat generation.
l.

You just need to put another wire in parallel for eg you can add another 2mm wire,although it would look neat if you have just one thicker wire.
Also note a multi core/strand wire is better then single core/ strand type wire.

Your ups under full load is going to consume around 40A of DC current.So i would size up a wire which can take around 60A if you want it stay cool.

Use this calculator below to size up your wire depending on how much loss you want due to resistance and also the length of your wire.
http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

[drsingh]

I have a query for the battery gurus. I have purchased 8 lead acid batteries over the last year.for inverters.,cars and bikes.

I read up on battery maintenance. I want to know more about an"equilization" charge.how do i do it.i have an automatic charger that i use for my bike.will that do the job?

[Aroy]

Originally Posted by drsingh

I have a query for the battery gurus. I have purchased 8 lead acid batteries over the last year.for inverters.,cars and bikes.

I read up on battery maintenance. I want to know more about an"equilization" charge.how do i do it.i have an automatic charger that i use for my bike.will that do the job?

Here are some links which explain the equalizer charge
http://www.progressivedyn.com/battery_basics.html
http://batterytender.com/resources/battery-basics.htm/