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I use Exide AGM VRLA batteries in my APC UPSes which have temperature sensitive charging.

These are similar to gel in the sense the electrolyte is trapped in an glass mat (hence called absorbed glass mat) while in a gel the electrolyte is in the form of a gel/slurry unlike normal flooded batteries which has eletrolyte in a liquid form.

The great advantage of AGM and gel is they're maintenance free. The flip side of the coin is gel or AGM VRLA batteries do not like high temps and must be kept in a narrow range of temps mostly between 27-35 C for longevity. Plus they are very sensitive to over charging and if loss of water should occur due to high temps and/or high charging voltage then the battery dies prematurely. You cannot top off gel cell or AGM batteries. They are sealed.

Now coming to my inverter. It is a Su-kam 1500 VA 24V dual battery system. I use 2 Exide Invatubular 200 AH batteries. These batteries have a life of 6-8 years if maintained and charged properly. My set of batteries is now in the 5th year of use.

If you live in an area where you see extreme temps and frequent power failures I'd suggest a flooded battery.

I think I'd opt for the Falcon. It has temp sensitive charging, which is important should you opt for a gel cell battery.

Thanks a lot for such a nice explanation!

Gel based is not an option for me...temp over here just breached 47!

Also, I think i'll continue with my old inverter, and will just pop in new batteries..money money shortage. In that sense, it would cost me 11000*2 = 22000 , minus 5000 for old battery.

Welcome.

If you are experiencing 47 C you should probably go with flooded tubular batteries.

This would be better than a single gel cell battery. Just make sure you have the battery installer or the inverter manufacturer check charging voltages. Also ensure you add only distilled water, never tap or even RO water.

Check the batteries every 2-3 months. More frequently if power failures of long durations are common. Most batteries come with floats that will indicate the need for a top up. You can buy distilled water from a petrol pump i.e. the same stuff used in automobile batteries. But do remember inverter batteries need several litres of water if the level is low. :) Keep sufficient stock and make sure to wear protective goggles when working on or near batteries.

I have this tall tubular 150 Ah battery. Apart from the water filling caps, there are also covers that are usually opened with a coin. Why are these present, when we have access to the water channels separately?

Is there anything that should be filled in after opening those covers with a coin?

Well, some inverter batteries come with screw on plugs that are removed and the floats installed in their place. At least my Exide Invatubulars did. They don't have coin slot plugs.

Do you have level indicator floats as well? If you don't then maybe you could buy them from your dealer. These floats are supplied with the battery. I wonder why your battery floats weren't delivered.

You can use either to fill water. Just be sure not to overfill. Stop when the floats indicate 'Full'.

Thanks.

Yes, this battery does have the level indicator floats. The water level is full.

I was just curious why they have the coil slot plugs, in addition to the level indicator plugs.

I can also add water to the battery by opening the coil slot plugs, rather than the level indicator floats. Is that right?

Need some help on one of my Inverter batteries. It is an Amazon tall tubular 150ah. The water in that never recedes. It is providing power backup and we rarely have a power loss these days in Chennai. I want to know if it is likely that the battery is faulty? It is about 3 years but this situation of no water reduction is there for past 18 months at least. On the other hand my Exide 150ah tubular is a water guzzler.

The coin slot plugs are to be opened to fill up distilled water whenever the level of the indicator floats goes down. As distilled water is poured in , the level of the indicator floats will rise.

If you do that, you could see the level indicator as you fill. Is this is a good idea?

Hmmm... ours does too, except the screw plugs are raised.

This is probably a quirk of the battery's case design. You can remove either the coin slotted vent plug or the floats to top up with distilled water. I personally find the floats easier to remove as they come off without the need for a coin.

What I do is add a little distilled water using my judgement based on prior fills OR look down into the vent hole (wearing protective goggles) to ensure I do not overfill. I prefer using the 'judgement method' as the fumes irritate my throat and I am bit wary of a battery with 20L of electrolyte exploding. Should that happen it won't leave a pretty sight behind. :)

So, when filling I place the float temporarily on top of the vent (without screwing it down) and check the level. When the float indicator is at about 3/4ths I stop filling. Once the float is screwed down tight the float rises to indicate full. If one has the patience then use the coin slot vent method for better control over how much DW is filled. My inverter batteries are topped up every 3 months on an average.

Thanks all, for the reminder. I see mine needs topping up --- after a year! One of the cells has dropped since I put a new inverter just a couple of months back.

When I used sulphuric acid in my jewellery hobby, a decade or three ago, the rule was always to add acid to to water, and never the other way around. But with a battery, we have to add water. I suppose the rule is for concentrated acid, where the heat produced by the mixture has a very nasty effect if one gets it wrong.

This safety precaution still holds true. Always add concentrated acid to water not the other way around.

The battery electrolyte is diluted acid in an approx. 35:65 sulphuric acid to water ratio. So one can add water without issues.

Wow, that strong! That is certainly something one would not want anywhere near eyes, and would feel the sting on the skin too. I've run to wash/neutralise with soap a few times. And I used to keep old clothes, as they would get small holes.

Last year I bought 220AH battery with brand named "Indo". It seems to be a local manufacturer in Pune. battery cost was 8.5k - 2k (for old battery) = 6.5k
I thought it was good deal hence went for it.

Initially, this battery used to give backup of 6-8 hours. Now suddenly backup reduced to less than 2 hours (load is same). I will try to get get it replaced under warranty.

Should I always go for known brands like Exide, or it's ok to buy such less-known brands batteries as well?

Would you prefer buying a car from one of the big names like Honda or Toyota etc OR a local maker like Sonalika?

Having had a bad experience with local batteries I will never ever buy them again. You get what you pay for. Stick to Exide tubular for inverter batteries. My current 200 AH battery set entered its 5th year of service in Apr 17. They're expected to last till 2020 or even beyond.

Yes, you need to wear safety goggles and old clothes. There's always a chance of acid induced damage. Even a drop burns a hole in clothing. It does give your skin a tingle. :)