Feb 17, 2013 04:44 PM
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This time the project was to replace my inverter battery, it did really steal my solid time in researching what battery to buy, there are so many options and brands, had to literally revisit all the basics of lead acid battery.
I am sure you understand the pain, as any informed buyer, task is not going to be an easy one. My feeling was majority of people who deal in these inverters and batteries have only skin deep knowledge and at best you will be misguided or will be given with superficial explanation. For that matter most of battery manufacturers too looks like are hesitant in revealing all the technical information in their sites. Even though I always had my reservation to trust the Exide batteries, this time I have gone with it for one main reason that their website had plenty of technical info for battery maintenance, initial charging instructions and good amount of details for every battery catalog.
It made my decisions making somewhat simpler.
Now having used different brands/technologies of inverters and batteries for over a period of more than 13 years and with my recent study of so many battery related websites I thought why not I share my insight gained to my fellow members and all netizens for their benefit.
In this review I will share some specific details which one can use to ensure the battery is received in a condition which forms one of the major criteria for a battery to last for it's expected life and then how to maintain it thereon which forms the other factor in getting the full life.
My sincere thanks to all those websites and their original authors.
Here we go.
First the basics if you want to know https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery
The batteries specific gravity(SG) is the accurate way to measure the charge.
Buy batteries which have newest manufactured date.(If batteries sit idle in the stores without proper trickle charge post the Factory charging for months and months the sulphation takes place)
Insist the SG of every cell to be at company recommended levels while receiving it(it was mentioned as 1.250 for my Exide Inva tubular IT500) this ensures the intial filling and charging of the battery has been done which has an impact on battery life to a large extent.
My battery was delivered at 1.200 per cell and one cell was even less at 1.150 and my Whirlpool Elantra Sinewave Gold HUPS 800VA could not bring it to 1.250
(So had to boost charge the 150AH battery at around constant 5A for a weeks time using my old square wave inverter which for some reason I had not thrown so far, did change the voltage preset to charge indefinitely though, otherwise it would have also cut off at 14.5V)
Check the electrolyte level of all the cells are at the same level when receiving the battery
If there are variations such as more than 10% in the level indicator, ask the vendor to equalize the levels by using electrolyte from other cells where they are at higher level(Remember not to allow them to use distilled water for this initial leveling as adding more water to only one cell where some electrolyte loss has taken place either during transporation or on account of some other reason will result in lower electrolyte density(SG) and create problems in future such as mismatched charge levels across cells leaving one cell to under perform and eventually die etc.
Remember if one cell dies the entire battery will needs to be replaced.
Later when the battery is put on regular use one should always add distilled water to topup the cells and not allow the battery dealers to add electrolyte(Water+ Sulfuric Acid).
Read this section "Initial filling & charging(IFC)" at this link for more details https://exide4u.com/exide/JSP/masters/Batteryservicing/ser_tips.htm
Buy a battery hydrometer and check the SG level yourself at least once in 6 months(more frequently if the usage is high or you feel something is wrong in the backup time)
*When using the batteries over a period of time for many reasons and physical differences in the cells(Example amount of active material, small difference in structure, manufacturing, volume of electrolyte etc) the SG level may vary across the cells which if not addressed at least once in a year can cause the weak cells to call it a day making the whole battery unusable.
So this can be addressed by doing an equalization charge which is also called intended overcharge until all the cells gas freely and the SG level get equalized across cells.*
This is also important to prevent sulphation which is the number 1 cause to make a battery go dead.
More information follow this link https://marine-electronics.net/techarticle/battery_faq/b_faq.htm
Now comes the trickle charging current in ma(Milli Amps) I read somewhere unable to get the link
that it should be= 80+(C10 X 5)
C10 means 10% of the rated AH capacity, so if it is 150AH battery then C10 is 15.
so for my battery the trickle charge current should be= 80+(15 x 5)= 155ma
But my inverter was giving a 450ma which will unnecessarily cause the battery to bubble all the time and evaporate water sooner needing more frequent top up.
Trickle charging is a charge to ensure it just compensates the internal battery discharge / capacity loss if kept idle, so it is very tricky as the internal loss depends on so many factors like ambient temperature, purity/quality of electrolyte, purity of distilled water used to top up, alloy and purity of lead used etc.
So if you hear the battery bubble and gas all the time when not in either chrage mode or discharge mode the trickle charger is the culprit. There is nothing much you can do here rather than top up the water unless you are a geek like me who has put an MCB for the battery to disconnect it from inverter when not needed and has put a separate trickle charger which supplies just 150ma to the battery.
I have also connected the 12V from this battery directly to my WiFi ADSL router to ensure no disconnection in my internet during a power failure. So having the inverter isolated other times than of actual use will be of some help in protecting surges entering my modem.
Also I always keep my inverter in manual mode so that it doesn't waste the battery life cycle unnecessarily when no one at home or when backup during a power cut is not needed, little concerned about lead pollution and environmental impact you see.
Remember your battery power is always more expensive to your wallet and to environment as there are storage efficiencies and recycling overheads to be considered.
Now comes even more detailed clarity on SG of batteries when you are dealing with different types
ie Automotive / Flat Plate, Semi Tubular, Tubular, SMF / VRLA
The fully charged SG of different category of batteries vary so when maintaining them you need to consider those facts as well(of course based on your battery manufacturer recommendation)
Have a look at this
https://engineersedge.com/battery/specific_gravity_battery.htm
So as long as you take care of the above things irrespective of the battery brand and type you will get most out of it and will last year after year without having to runaround from UPS vendor to battery vendor to fix the issues, which in most cases they will never be able to with their inadequate knowledge, expertise, skills, willingness to solve or due to lack of backend support from their OEMs.
If time permits will share my understanding on different types of batteries to choose from for inverters based on our needs.
Happy buying!
