[Sebring]

I think the times call for a wall mounted Inverter. Saves a lot of space. Does anyone have any experience with this?

[R2D2]

It has been a long hot summer in 2019. Frequent but short lived outages added to the work load. And this time the 200 AH batteries had to be topped up in 2 months instead of the normal 3 months during the same time of the year.

They are now 6 years and 2 months old & consuming water in nearly equal quantities in all cells. Sign of good battery health. They would have deteriorated over the years but I expect another 1-2 years out of them before it is time for a replacement. And yes, it will Exide Invatubular again. Colour me impressed.

[hondafanboy]

Does anyone know if APC UPS ( not inverter batteries) 1000br battery pack can be bought online?

[Gansan]

Originally Posted by Thad E Ginathom

That makes me wonder how often people top up their inverter batteries?

I don't rely on the float indicators, though they always indicate a full level. Mine is a Luminous inverter with a Luminous 150 AH tall tubular battery. Both were bought during July'14, and are 59 months old now. I check and top up water once every four months, winter or summer. One particular cell takes more than others, though plate level is never reached in any cell. Battery will take slightly less than one litre of distilled water during top ups, and the back up is still good. I hope it will last one more year at least.

[theredliner]

After hearing decent feedback about Exide inverters, I decided to look into them and came across 1450VA sine wave ones. They have two models. The older one is 12V. Newer one is 24V. The 24V one has some advantages like copper transformer, circuit breaker instead of fuse etc. (Exide Inverterz GQP)

The 24V one would cost much higher due to the need of two batteries. Is there any real advantage of 24V over 12V that warrants spending the extra money? Why are most inverter manufacturers moving towards 24V from 12V for 1000-1500 VA range?
Shall I consider saving the money by buying the older 12V model? TIA.

[Thad E Ginathom]

Whilst answering the previous post, can someone clear up one of my confusions on the 24/12 thing please?

Take two 150 amp hour, 12v batteries...

In parallel, they give 12v and 300 amp hours.
In series, they give 24 volts and... How many amp hours?

[gopalnayak]

Originally Posted by theredliner

Shall I consider saving the money by buying the older 12V model? TIA.

24V model is better. The 24V model would be much more efficient. With 12V, the current drawn from the battery would be substantially higher while delivering the load. There will be good amount of losses in the cable itself. In addition, the losses in the internal devices would also be higher.

Originally Posted by Thad E Ginathom

In parallel, they give 12v and 300 amp hours.
In series, they give 24 volts and... How many amp hours?

Two 12V 150Ah batteries in series => 24V 150Ah

[Thad E Ginathom]

Originally Posted by gopalnayak

Two 12V 150Ah batteries in series => 24V 150Ah

Thanks, somehow I thought so.

[Aroy]

Originally Posted by Thad E Ginathom

Whilst answering the previous post, can someone clear up one of my confusions on the 24/12 thing please?

Take two 150 amp hour, 12v batteries...

In parallel, they give 12v and 300 amp hours.
In series, they give 24 volts and... How many amp hours?

Ampere-Hour is based on the battery configuration. Assuming batteries of same AH then when connected in series the AH is same. When connected in parallel the AH is added up for each battery.

What is more important in storage is that both give the same capacity

12 x 300 = 3,600 WH
24 x 150 = 3,600 WH

It is advantageous to have batteries in series upto a 300V, as the current is less (hence loss in cables). Further during conversion from DC to AC, the voltage drop is more or less same irrespective of voltage, so you loose less power at higher voltages.

Of course for very large power banks; where battery capacity is limited; you have batteries connected in parallel for enhanced capacity and then each set is connected in series . This requires a sophisticated control mechanism for distributing charging/discharging current, as in case of one bad battery in parallel configuration can route excessive current through others.

[R2D2]

Originally Posted by Thad E Ginathom

Thanks, somehow I thought so.

The main advantage of using a higher voltage for e.g. 24 or 48 V instead of 12 is wires/cables can be thinner i.e. of lower cross sectional area or a in Americanese a higher AWG cable rating (in AWG, lower the rating thicker the wire and vice versa). Preventing power loss due to internal resistance and heating is a key concern which prevents fires. This is alleviated to a certain extent with >2 battery inverters.


PS - my APC 2200 VA Smart UPSes use a series connection. 2 x 12 V batteries in series to a string/pack and 2 of these packs in series to make 48 V DC. The cables interconnecting these batteries and packs are about 4 sq mm (I reckon) but are designed to take a load of up to 1900 W at full throttle.

[shipnil]

Originally Posted by R2D2

They are now 6 years and 2 months old & consuming water in nearly equal quantities in all cells. Sign of good battery health.

I regularly top up the cells with distilled water bought from battery stores. Do the batteries need any additional care or topping up of water is good enough?

Additionally, a question on capacity. I have 150 Ah battery. But in my area the power cuts are mostly lasting 30 minutes or so. During this time, my home mostly has 4 LED bulbs of 7 watt each and a couple of fans on. So does it make sense to buy a lower capacity battery, say 100 Ah, and save some money as and when my battery gives up? I feel we have rarely used the battery backup to full capacity.

[Aroy]

Originally Posted by shipnil

......

Additionally, a question on capacity. I have 150 Ah battery. But in my area the power cuts are mostly lasting 30 minutes or so. During this time, my home mostly has 4 LED bulbs of 7 watt each and a couple of fans on. So does it make sense to buy a lower capacity battery, say 100 Ah, and save some money as and when my battery gives up? I feel we have rarely used the battery backup to full capacity.

The battery AH rating is usually for 10 hour discharge rate. So if the rating is 150AH, then the rating applies to 15A per hour of 15*12 = 180VA. More than that you have to derate. Approximately you will have 1/2 the capacity (75AH) for a 2 to 3 hour discharge (~25A or 300VA). The exact figures are available at the battery manufacturer's site.

[Holyghost]

Originally Posted by theredliner

The 24V one would cost much higher due to the need of two batteries. Is there any real advantage of 24V over 12V that warrants spending the extra money? Why are most inverter manufacturers moving towards 24V from 12V for 1000-1500 VA range?
Shall I consider saving the money by buying the older 12V model? TIA.

Higher the voltage, lesser the Current (Ampere); which in turn benefit in the form of thinner cables, circuits and lesser losses in efficiency. When you switch from 12v to a 24v system, the current reduces by half and hence easier for the manufacturer to design the internal components which needs to handle only half the current.

As an end user, you are not going to benefit much by moving to 24V systems in 1KVA range systems except for a slightly higher efficiency and lesser thickness cable required on the batteries. For systems above 2Kva, the cable costs and efficiency figures will be more prominent for the end user and it will be extremely difficult to find 12V systems with such capacities. The cost and weight of components capable of handling 200A+ current on such 12V systems is very high.

[R2D2]

Originally Posted by shipnil

I regularly top up the cells with distilled water bought from battery stores. Do the batteries need any additional care or topping up of water is good enough?

No they don't. Actually batteries are quite trouble free as long as you top up regularly with water AND make sure the charging voltage and current are per manufacturer's requirements.

Additionally, a question on capacity. I have 150 Ah battery. But in my area the power cuts are mostly lasting 30 minutes or so. During this time, my home mostly has 4 LED bulbs of 7 watt each and a couple of fans on. So does it make sense to buy a lower capacity battery, say 100 Ah, and save some money as and when my battery gives up? I feel we have rarely used the battery backup to full capacity.

Sure from your description I feel you can downgrade. But then what happens if there's an extended outage? We do have unpredicatable supply utilities. It is like having extra fuel in your tank when going on a journey. No guarantee it will be required but then it caters for those unplanned situations.

Also, battery life is measured in # of charge and discharge cycles AND the depth of those discharge/charge cycles. The deeper the discharge the shorter the life. With tubular and deep discharge batteries it is advisable not to go to <50%. Point I am trying to make is the 150 AH parts will suffer a shallower discharge compared to the 100 AH parts, which in turn will contribute to better life span and lower water consumption.

[prithm]

Very happy to see that this thread is still kicking and alive (me too )

Summer is almost gone (well, atleast in most parts of India) and now comes another season of long power cuts during monsoon. Atleast those who still use overhead power lines.

I was wondering, if we don't use any of the appliances (say fans, tubelights since climate is already comfy), what will happen to the battery storage if UPS controller stays on for long powercuts with no appliance drawing anything from it, will the charge still hold good in batteries or will they subsequently discharge since the UPS is still on and monitoring the batteries ?

Is it OK if we turn off the UPS and turn them back on when we need them for real use (say after sunset and powercut is still ongoing) ?

This question has been bothering me for an answer ever since experiencing the punishment of Vardah in Chennai.