Team-BHP - Inverter Batteries

Quote:

Originally Posted by ghodlur (Post 4647391)

1) The battery is not being charged, I assume this needs replacement as battery is more than 5 yrs old.
2) With the Microtek inverter unit, there is no indication of the mains On. According to the technician, for the indication to be ON the battery has to have some charge. Is this correct?

Battery age alone doesn't determine whether the battery is 'alive' or not. Turn off the power and connect a headlight bulb (at least 55 W). If the bulb lights up normally, your problem is elsewhere. But if there is no light, replace your battery.

Quote:

Originally Posted by Prowler (Post 4647430)

Thanks mate.
That light check was done by the technician, he said the battery life is done. During the last 6 monthly checks, he had observed heating of the battery and a bulge on one side. Because of that reason, the battery was disconnected.

I guess changing the battery will be the only option now. Any suggestions from experts?

Quote:

Originally Posted by ghodlur (Post 4647391)

A couple of issues with Inverter setup at my parents place.
1) The battery is not being charged, I assume this needs replacement as battery is more than 5 yrs old.
2) With the Microtek inverter unit, there is no indication of the mains On. According to the technician, for the indication to be ON the battery has to have some charge. Is this correct?

Hi Ghodlur,
On a normal Microtek invertor, running on mains power, there will be two green lights (steady) on the front panel.
In the event of a power failure, the invertor switches over to battery power and only one green light (steady) will show on the front panel. You will also usually get a high pitched whistling/screeching type of noise while on battery power.
Once the main power comes back on, the right hand side green light will start flashing to indicate battery is being charged. The left side green light stays on and steady.
Depending on how long the power was off and your battery condition, this light could stay flashing for up to 2 or 3 hours - or more.
In the event your power fails and your battery is old/dead/damaged, there will be an alarm (high pitched buzz), a red light will come on on your front panel and the invertor will shut down completely.
If the body of the battery is bulging, it's a bad sign. Usually means you have not kept it properly topped up with distilled water and the plates have buckled inside. Time to change the battery.
Hope this helps.
Regards,
SS

During the quarterly DW top up, I realised one of my 6.5 year old 200 AH Exide batteries is showing signs of aging. The presence of dark sludge (looks like used engine oil) floating on the electrolyte or coating the floats/vent caps is a sign of the +ve plate deteriorating and losing lead dioxide. The count down to replacement has begun. I hope they last me at least another 6-12 months. Frankly Exide inverter batteries are excellent but prices are up by about 30% compared to what I paid for the current set back in Apr 2013.

Quote:

Originally Posted by Thilak29 (Post 4678220)

Help!

This rainy season saw three burnouts among inverters (one standby and both Luminous branded). Are these devices highly prone to voltage surges? I have got the safety net of good earthing, fuse and MCBs and no other electric equipment took hit. I ponder what is wrong with inverter boards, will adding surge protector help?

It will surely help. Fuse/MCB will not protect against high voltage transients. A simple MOV (metal oxide varistor) wired in parallel before the inverter and fed through a MCB will save your electronics. But a full size Mains SPD will protect the entire house. We have been writing about them in this thread for a long time.

Quote:

Originally Posted by suzuki san (Post 4682299)

Does anyone know what the ratings C10 and C20 mean w.r.t. Inverter Batteries? I have been given to understand that C10 is industrial grade and gives better back up. Also more expensive. Can anyone confirm this?

Quote:

Originally Posted by Thad E Ginathom (Post 4682339)

I'm half guessing... But lead-acid batteries hate being fully discharged, which, in, say, a car, should never happen. Batteries made for inverters need to cope with occasional full discharge. Is the rating to do with this?

What the C10 and C20 means is the discharge rate i.e. 'X' Amps in 10 hours or 20 hour rate. So technically a C10 is better than a C20 because it can handle a faster discharge rate.

E.g. a 200 AH C20 battery can discharge 10 Amps/hour for 20 hours while a 200 AH C10 battery will handle 20A/hour for 10 hours. For home use C20 is fine.

And yes, batteries do not like to be completely discharged even deep discharge types can handle upto a max of 80% depth of discharge while with car batteries don't like anything less than 20%. Check the battery specs for the exact discharge rate C10/C20 and other technical characteristics including # of discharge cycles (life).

Quote:

Originally Posted by R2D2 (Post 4682385)

And yes, batteries do not like to be completely discharged even deep discharge types can handle upto a max of 80% depth of discharge while with car batteries don't like anything less than 20%. Check the battery specs for the exact discharge rate C10/C20 and other technical characteristics including # of discharge cycles (life).

Thanks R2D2,

Useful info indeed.

So how does one avoid complete discharging of a battery? If, for example, the power fails in the middle of the night and the inverter cuts in, how is one supposed to guess when the battery will get completely discharged? Right now with the new inverter I have bought, it does give me the "DTE" but this is not the case on most normal inverters. In the event that the battery does get fully discharged, what can one do to prevent damage to the battery?

Regards,
SS

Quote:

Originally Posted by suzuki san (Post 4682494)

So how does one avoid complete discharging of a battery? If, for example, the power fails in the middle of the night and the inverter cuts in, how is one supposed to guess when the battery will get completely discharged? Right now with the new inverter I have bought, it does give me the "DTE" but this is not the case on most normal inverters. In the event that the battery does get fully discharged, what can one do to prevent damage to the battery?

Normally an inverter will sound an alarm to indicate battery voltage is low (discharged) and should the load not be reduced or disconnected manually the inverter will automatically shut off the AC output to preserve the battery and its own circuitry. The voltage at which an inverter does an auto shut off varies from model to model so you need to check the instructions or ask the dealer.

That said, deep discharges are best avoided because they have a detrimental impact on the battery life. Even with tubular models try not to go below 50% SoC. Either reduce load in the home or buy a larger battery if your current models run down too soon. Our former 150 AH lasted us nearly 2 days when there was a blackout due to a damaged high voltage cable. Hence upgraded to 200 AH the next time, which I reckon will last me at least 2.5-3 days with minimal load.

To prevent lasting damage to batteries that are dead or have been drained below 80% SOC make sure they are charged back to 100% ASAP. Also remember the inverter takes quite a bit of power, to fully charge them again. And float charge also consumes power. My inverter is responsible for a hefty %age of my power bill. The more the # of batteries and the larger they are the more power your inverter consumes to charge and maintain them.

But TWO most important things for enhanced battery life are; adding distilled water in time AND checking charging voltage. Please ensure voltage is checked and water replenished regularly.

Quote:

Originally Posted by Thad E Ginathom (Post 4682394)

Thanks, R2D2. Zero out of ten for me because I answered the wrong question!

Not all marks lost Thad. You did score points.
All batteries are rated for 1C which means a 150Ah battery will be capable of delivering 150A for ~1 Hr. A 200Ah is capable of delivering 200A for 1 Hr.
However, the C rating specifies the safe discharge/charge rate for the battery.
So a C20 battery is safe to be discharged in 20 hours, and if you try to discharge it in 10 hours, the battery life will be affected. Try doing it 1 hour, your battery is permanently damaged.

The same goes for the charge rate. A 200Ah battery rated for C10 charging can be safely charged at 20Amps. C5 rated battery can be charged at 40A and you can get your battery charged in 5 hours. This doesn't mean that the battery cant be charged at a higher rate, but you do that at the risk of damaging the battery or its life.

The charge rate is more important for solar applications while discharge rate is important for UPS applications. In solar applications, You would ideally want a battery which can be fully charged in a days 5Hrs of sun light. So batteries with C5 charge rate is preferred for off grid solar applications.