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Old 27th April 2020, 20:17   #1441
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Default Re: Inverter Batteries

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Originally Posted by Thad E Ginathom View Post

I noticed that the sides of the battery have some very slight swelling. I'm guessing... this is bad news?
Many years ago we had a working solar power setup at home, it was mounted in a place that gets hot - under the roofing tiles and after a few years it had swollen up a bit and stopped working. Its either the heat from where it is at or the inverter is overcharging the battery, either ways its worth checking.
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Old 28th April 2020, 10:22   #1442
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Default Re: Inverter Batteries

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Originally Posted by Thad E Ginathom View Post

I noticed that the sides of the battery have some very slight swelling. I'm guessing... this is bad news?
The inverter display used to say >10 hours of backup duration for computer + a light and fan or two, now it says around 6 hours.
Your batteries have served for nearly 5 years - not bad considering the regular duty it had served in Madras conditions. A few years ago there was regular power cut in Madras lasting a couple of hours every day.
A Voltage check won't hurt. Over charging over a period of time can induce gassing - release of gases which in turn may cause warping of the case.

Don't take the inverter backup readout as Gospel truth. It is just a machine guess. Actual backup time will be far less than what it shows when the battery notches up years. The internal resistance rises as the battery ages. The electronics inside the inverter doesn't factor in that and so the calculation always goes awry.
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Old 28th April 2020, 23:35   #1443
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Default Re: Inverter Batteries

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Don't take the inverter backup readout as Gospel truth. It is just a machine guess. Actual backup time will be far less than what it shows when the battery notches up years. The internal resistance rises as the battery ages. The electronics inside the inverter doesn't factor in that and so the calculation always goes awry.
I was not thinking in actual hours, but wondering if a displayed reduction from from 10 to 6, fully charged, might indicate an approximate reduction of battery capacity to 60%?
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Old 29th April 2020, 12:16   #1444
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Default Re: Inverter Batteries

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I was not thinking in actual hours, but wondering if a displayed reduction from from 10 to 6, fully charged, might indicate an approximate reduction of battery capacity to 60%?
Yes - in theory. But unfortunately in practice, it may not be a 60 % capacity but far less.
I had a 3 KVA UPS fitted with 4 x 100 AH batteries. As we kept changing the batteries over a period of time, we realized that our actual load had come down in all these years (CRT monitors were replaced with LED monitors).
So I swapped out the 100 AH batteries with 36 AH batteries. I calculated that under the current standard load (about 900 VA) , instead of 24 hours, we should have at least 8 hours. But it just gave us 1 hour.
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Old 29th April 2020, 12:26   #1445
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Default Re: Inverter Batteries

Glad i came across this post. I am planning to buy an inverter for my house. Am looking help to purchase the right product with a backup of atleast 3-4 hrs.
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Old 29th April 2020, 12:31   #1446
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Default Re: Inverter Batteries

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Originally Posted by Prowler View Post
Yes - in theory. But unfortunately in practice, it may not be a 60 % capacity but far less.
I had a 3 KVA UPS fitted with 4 x 100 AH batteries. As we kept changing the batteries over a period of time, we realized that our actual load had come down in all these years (CRT monitors were replaced with LED monitors).
So I swapped out the 100 AH batteries with 36 AH batteries. I calculated that under the current standard load (about 900 VA) , instead of 24 hours, we should have at least 8 hours. But it just gave us 1 hour.
The batteries are normally rated for a 10 hour discharge duration. Higher discharge rates, that is shorter time requires derating. One hour will normally be derated by 50%. That apart hot weather also derates the capacity. To get an idea search the Exide site. They have the battery capacity curves both for discharge rates and temperature.
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Old 29th April 2020, 12:51   #1447
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Default Re: Inverter Batteries

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The batteries are normally rated for a 10 hour discharge duration. Higher discharge rates, that is shorter time requires derating. One hour will normally be derated by 50%.
Yes Aroy Sir. We had a conversation at that time about the UPS. That UPS failed in a dramatic fashion after serving for over a decade. We have a 'modern' 1KVA UPS now. Same 36AH batteries x3 now provide 2 hours backup time under similar load conditions. Like a motor, you need to run a UPS at nearly its load capacity for maximum efficiency.
Even the computer SMPS deliver maximum efficiency when they operate at their rated capacity.
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Old 29th April 2020, 13:08   #1448
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Default Re: Inverter Batteries

Need to buy a new Inverter and batteries. Unfortunately, they are not essential items :(

I was hoping to buy a inverter with solar panel input. But the VA ratings are lower for such ones. I guess I can buy a regular one and buy an adapter for solar panel input later ?
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Old 29th April 2020, 13:18   #1449
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Default Re: Inverter Batteries

What a coincidence, I found this thread at the right time.

Just today in the early hours, our inverter batteries are conked off. They are not charging any more. I was looking for suggestions like if topping it up with mineral water helps or not because distilled water is not available.

Any suggestions?
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Old 29th April 2020, 15:13   #1450
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Default Re: Inverter Batteries

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I was looking for suggestions like if topping it up with mineral water helps or not because distilled water is not available.

Any suggestions?
If your AC is clean, you can use the water from the condensation from the AC. Theoretically it is equivalent to the distilled water. But make sure that it has no sediments in it.
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Old 29th April 2020, 15:29   #1451
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Default Re: Inverter Batteries

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Originally Posted by RaceHorse View Post
What a coincidence, I found this thread at the right time.

Just today in the early hours, our inverter batteries are conked off. They are not charging any more. I was looking for suggestions like if topping it up with mineral water helps or not because distilled water is not available.

Any suggestions?
Not sure if topping water would help or not for that problem, it could be something with charging circuitry itself.

But certainly do not use mineral water. I saw in Youtube to make distilled water at home by some boiling method. No clue if that is really quick and worth it or not. The petrol pumps sell distilled water and they are open out there.
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Old 29th April 2020, 17:28   #1452
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Default Re: Inverter Batteries

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Originally Posted by RaceHorse View Post
What a coincidence, I found this thread at the right time. Just today in the early hours, our inverter batteries are conked off. They are not charging any more. I was looking for suggestions like if topping it up with mineral water helps or not because distilled water is not available.
Any suggestions?
As @Prowler said, you can use air conditioning condensate i.e. water dripping from ACs as they operate, provided the water is clean with no sediment or suspended particulate matter.

If distilled water is not available, use clean filtered drinking water (try to avoid bottled mineral water or bore-well/well water please!) from your water filter as a last resort. It will impact battery life but there's no choice during the lock down. Do not let the batteries run dry as that can be dangerous.

Topping off water is no guarantee batteries will recharge. They need to be tested as it could be an end-of-life case OR the inverter charging circuits could be faulty.
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Old 29th April 2020, 22:37   #1453
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Default Re: Inverter Batteries

As was drawn to my attention by a fellow member, distilled water for batteries is available --- from petrol bunks. I too was waiting for the battery shop to reopen, but didn't need to. But if your batteries are dead, no amount of water will do any good.

Experts: if a battery has died because of lack of water, am I right in thinking it will be too badly damaged to recover?
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Old 29th April 2020, 23:11   #1454
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Default Re: Inverter Batteries

^^ If a particular cell has water level below the plates and scaling has formed, it mostly will not recover. I am no battery expert, but a long time inverter user.

I use tall tubular batteries, Luminous brand currently, almost six years old. I always top up the distilled water myself once every four months. The water level always stays above the plates when I open. I buy the water from petrol stations only.

In general tall tubular batteries can be topped up once every six months, but there is always the risk of water going below the plates. The indicator floats are not always reliable, they may get struck. I never watch them anyway, because the battery is inside the cabinet.
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Old 30th April 2020, 10:45   #1455
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Default Re: Inverter Batteries

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Originally Posted by R2D2 View Post
Do not let the batteries run dry as that can be dangerous.

Topping off water is no guarantee batteries will recharge. They need to be tested as it could be an end-of-life case OR the inverter charging circuits could be faulty.
I realized the risk of running them dry, I checked the circuitry it is fine. Also, I found the inverter is providing a few minutes of backup but due to the load getting turned off quickly.

Not to take a further risk I turned off the UPS mode. I hope I can live without the backup for a few days. Now Inverter is one of the items added in the list of things to be repaired after lockdown.

Thanks for all the advice.
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