Mixing Old and New Lead Acid Batteries in Series

Hi,

I have an APC 1500 and it requires 24v setup.

I bought two new AGS 135 batteries but one of them had a dead cell just after 7-8 months use. and since then I have been just using them like that for about 4 months now.

So I am thinking of replacing the battery with the dead cell with a, say, AGS 100 battery, to make up for the loss of capacity in the working AGS 135 battery.

when my UPS shuts down after full discharge. The battery with dead cell has a terminal voltage of about 10.7 and the good battery has a terminal voltage of 12.7.

So i am guessing the Good battery still has some life left in it.

I know its a bad idea to mix old and new batteries, especially in Parallel setup. But I just wanna give it a shot.

So what do you guys think, is it worth it? any feedback from someone who has actually mixed old and new batteries in series?

its not a bad idea to mix old and new batteries as long as you know what you are doing

1 - if the cells of the battery are ok for the good battery, you can easily pair it with a 130AH AGS.. the 135 and 132/130 are different series of batteries. with different umber of plates. so the 132 would last you a long time on its own

2 - using apc you can easily get another 1 year easily with both or maybe upto 1.5years as well depending on the condition of the old good battery and your discharge cycles

3 - you could simply get the cell repaired of your bad battery for around 600rs and it should work fine for another 6-8 months easily.

[quote=“farhan_ds, post:2, topic:22413”]

its not a bad idea to mix old and new batteries as long as you know what you are doing

1 - if the cells of the battery are ok for the good battery, you can easily pair it with a 130AH AGS… the 135 and 132/130 are different series of batteries. with different umber of plates. so the 132 would last you a long time on its own

[/quote]

I am just doing this as an experiment so I don’t wanna risk too much by buying 130 or 132 capacity batteries. That’s why I was going for 100 AH battery, so it evens out with the current capacity of the 135 after about 1 year of use. which I assume would be around 80 to 100 AH.(given the usage in loadshedding conditions of Pakistan)

So tell me is there any danger in using 100 AH battery with 135 AH which has been used for 1 year?

[quote=“farhan_ds, post:2, topic:22413”]

3 - you could simply get the cell repaired of your bad battery for around 600rs and it should work fine for another 6-8 months easily.

[/quote]

Tell me more about this cell repairing thing.

Have you tried it personally?

Do you know anyone near Johar Town area who does such things reliably.

IIRC I have reviews of people saying that cell repairing aint worth it.

dont do experiment on battery ... n don mix old with new as it ll reduce ur backup times .........

[quote=“APC_UPS, post:4, topic:22413”]

dont do experiment on battery … n don mix old with new as it ll reduce ur backup times …

[/quote]

I would appreciate some logic with the answer.

please don’t use the regular UPS dealers talk of “don’t mix old new batteries”.

Kindly explain in my situation what would or can go wrong.

AssalamuAlaikum.

I wanted to ask a question to you guys that I've got a NS company's inverter just like that of Homage, it has two buttons on the back side. One with WIDE & NARROW and other with 10 AH & 20 AH, I'm confused what should I set on these two.

The battery is AGS GX200F. Inverter connected to a stabilizer.

Any help would be appreciated.

Thanks.

When battery get older its internal resistance/impedance increased, chemical properties changed so when a fresh battery added in old batteries it could nt be balanced with remaining old batteries in string and according to series resistance calculation every different value in string will get different charging voltage, hence could not be charged or discharged evenly, resulting reduced performance of whole battery bank. Therefore UPS manufacturers don't allow mixing of batteries. It is recommended practice that all batteries should be of the same brand and same model and preferably same batch/date of production because these variables also affect battery bank bank performance. In some warranty agreement cases (SLA) by OEM where a single battery failed in bank who passed less than 10 cycles and 90 days can be added / balanced with all other conditions in control.

Look mate ... the logic is simple. .. when u use old n new battery in series n specially when u r using apc not any other tom dick n harry typa ups thn its ovius dat if the new battery ll give u let say 2 hours runtime but due to the reason dat one of the battery is old thn it ll drastically effect its runtime. .. and again after three or four months when new battery ll be 3 to 4 months old n at tht time u replace that battery which was more older thn this one ... this ll again affect ur runtime cux one ll be new n other ll b months old ... this cycle ll remain bug u ... don mess with old battery cux its v v dangerous if u do it by urself and if u give it to a shopkeeper thn it ll b a risk to take .. after payin him sum 100 bucks u ll remain in crossroad tht how much longer ll it work ... so waste ov tym n money ...

[quote=“Abdul_Wasay, post:6, topic:22413”]

AssalamuAlaikum.

I wanted to ask a question to you guys that I’ve got a NS company’s inverter just like that of Homage, it has two buttons on the back side. One with WIDE & NARROW and other with 10 AH & 20 AH, I’m confused what should I set on these two.

The battery is AGS GX200F. Inverter connected to a stabilizer.

Any help would be appreciated.

Thanks.

[/quote]

If you are using any appliance-like desktop PC which turns off when the WAPDA goes off, turn the button to NARROW. Otherwise, you can keep it at WIDE.

I think the battery is of 200AH. According to the equation, you can set the button to 20A if you see the battery doesn’t recharge fully. But if the load the minimum you should set it to 10A for better battery life. At 20A, the battery is charged rapidly, and at 10A the battery is charged efficiently.

I dont think that it is recommended to use old batteris with new one.

AGS quality has nosedived in the last two years. I have three UPS with GX-135 batteries and all three have battery failure within 6 months. Buy any other brand but AGS.

1 Like

commonly used battery manufactured are 100-120-130-132-135-165 AH.. these are most comonly manufactured by all companies as their demand is highest.. as a result their quality also suffers the most.

185GX AGS is a big step up.. 200AH is also good. in AGS specifically 132 is much superior than 135 due to internal design of manufacturing.

[quote=“F11, post:11, topic:22413”]

AGS quality has nosedived in the last two years. I have three UPS with GX-135 batteries and all three have battery failure within 6 months. Buy any other brand but AGS.

[/quote]

agreed… my last AGS battery setup lasted about 2.5 years and still batteries didnt die… just their backup time was a bit reduced so i was forced to change them…

these new ones suck

Even AGS GX135 bought in January 2016 are having bad cells in just days of use.

my clients are usin this GX 135 model of AGS with APC UPSs for God knows how many years but thy had never ever complained abut its backup .......

[quote=“ShoukaT, post:, topic:”]

Hi,

I have an APC 1500 and it requires 24v setup.

I bought two new AGS 135 batteries but one of them had a dead cell just after 7-8 months use. and since then I have been just using them like that for about 4 months now.

So I am thinking of replacing the battery with the dead cell with a, say, AGS 100 battery, to make up for the loss of capacity in the working AGS 135 battery.

when my UPS shuts down after full discharge. The battery with dead cell has a terminal voltage of about 10.7 and the good battery has a terminal voltage of 12.7.

So i am guessing the Good battery still has some life left in it.

I know its a bad idea to mix old and new batteries, especially in Parallel setup. But I just wanna give it a shot.

So what do you guys think, is it worth it? any feedback from someone who has actually mixed old and new batteries in series?

[/quote]

.ASSALAM.O.ALEKUM.WA.REHMT.ULLAH

Yes you can mix up the batteries in series but keeping in mind that is not recommended to mix different capacity batteries or different ages or differently treated batteries.

But as APC is also not made to power the station pump or ceiling fans but we are using them like that way so Pakistan zindabad :)

Some advice or tips .

I know it’s an old thread and you have already bought the battery.

It is good to charge Both the batteries at fullest first and then leave them for 24 hours without Connecting with anything .

After 24 hours check the specific gravity from an inexpensive gadget named the hydroMeter , if the difference is more than 0.3 between different cells then balance them by adding or removing electrolyte to / from cell and pour into another Cell until you will see all the cells gravity is equals. Now you can connect them in your APC and use but the game is still remaining, once these batteries will be discharged and the APC shuts Off then again you need to check the specific gravity of all cells and again balance them. And then put them on charge.

If you have a solar charger then the above method will not work well because of some technicalities. But if you are using KESC or wapda ETC then it will work.

Have tested this method already.

Do update the results as it will be a hand on experience.

Sharing is everything.

NADEEM AHMED