Making larger battery packs is often required to extend backup time or increase voltage to make certain devices work. For example, if you own solar power system or Power inverter, you can connect several batteries to them to get more juice and more run time. Communication networks and small and large servers also use backup UPS which are circuited with often times large number of batteries or larger batteries. Different kind of packs are made depending upon needs and to cut maintenance costs.
Here, I have elaborately explained how to make Parallel, Series and Series-Parallel combined battery packs (battery banks). This guide is quite helpful for newbie users who want to learn how to connect lead acid batteries (Sealed, VRLA, MF, Gel, AGM, Wet or flooded) together while circuiting them with solar power systems, uninterruptible power supply (UPS) systems, power inverters or battery chargers. Additionally, I have also discussed some frequently asked questions related to the subject in FAQs section below. Note that Battery pack is also called as battery bank and AGM and gel batteries are also known as maintenance free or dry batteries in some regions.
Batteries in Parallel Connection (Parallel Battery Pack)
In this type of battery bank, batteries are connected from terminals to same terminals of other batteries that is positive terminal (+) of one battery is connected with positive (+) terminal of other battery and negative terminal (-) of one battery with negative terminal (-) of other battery. See the diagram below for more idea:
Batteries in Series Connection (Series Battery Pack)
Batteries are connected from terminal to terminal in a way that positive (+) terminal of one battery is connected with negative (-) terminal of other battery and negative terminal (-) of one battery is connected with positive terminal (+) of other battery. See the diagram for more idea:
Different Size Batteries in Parallel or Series Connections
In Parallel
(Criteria: If batteries are labeled as similar voltage but different capacity)
In Series
(Criteria: If batteries are labeled as similar voltage but different capacity)
Batteries In Series And Parallel Combination
In series-parallel batteries combination, one pack of batteries connected in series is joined in parallel with another pack of batteries connected in series. Therefore, the overall output voltage of series packs remains the same. But charge storage capacity is increased.
9 Batteries in Series Parallel Connection – Wiring Diagram
FAQs
1- Why batteries are connected in parallel?
Connecting batteries in parallel keeps the voltage of whole pack same but multiplies the storage capacity and energy in Ampere hour (Ah) and Watt hour (Wh).
2- Why batteries are connected in series?
Connecting batteries in series multiplies the voltage but keeps the capacity in Ampere hour (Ah) same. Energy in watt hour (Wh) increases. According to the common sense, overall charge storage capacity is also increased because there are more reservoirs available now to store charge.
3- Does connecting batteries in series or parallel increase capacity and backup?
Yes. As I mentioned above, it’s like now you have two or more reservoirs to store charge instead of one. The backup provided by the system will be increased. But you can not keep connecting batteries in series if a power device is designed to accept specific voltage. Connect them in parallel to increase backup or buy larger batteries instead.
4- Why is connecting different capacity batteries in parallel to each other is not recommended for the long term use?
Batteries with different capacity but same voltage can be connected in parallel but it is preferable not to do this. Because there are possibilities that different size batteries have slight voltage difference even though they are labelled as similar voltage on the label. This will lead to potential difference among connected batteries which means batteries with higher voltage will try to charge the battery with lower voltage which can result in heat up and destruction of that battery. Also, when different capacity batteries are connected in parallel to UPS or Power Inverter, charger of UPS might cause conflict and start behaving abnormally. To minimize such risks and troubles, buy similar capacity and voltage batteries of same brand made by the same company. Never mix different brands of batteries from the same or different manufacturers.
5- Why different capacity batteries should not be connected in series?
Never connect different capacity batteries in series to each other. If connected, smaller capacity battery will charge first but larger battery will still be empty. This will result in heating and over charging of smaller battery. In discharge mode, smaller battery will get empty first resulting in deep discharge of that battery. To make series battery bank, buy similar capacity and voltage batteries of same brand and company.
6- Can I mix old and new batteries in parallel and series?
A very bad idea to mix old and new batteries in parallel. Old batteries which have fairly worn out do not retain the voltage like new batteries. So, if old batteries are mixed with new batteries, this will shorten the life span of new batteries and damage old batteries too. But you may connect old and new batteries in series although I won’t recommend it either. Old battery may fail to attain cut off voltage which will result in overcharging and overheating of new and healthy battery as well.
7- Can I mix different types of lead acid batteries?
No. Never do it. Each lead acid battery type including VRLA, AGM, Gel, Wet or flooded has got different charge rate and different maximum and minimum tolerable voltages. Mixing them means damaging them and wasting your money.
8- Why large battery packs are made?
Series battery pack is made to multiply the voltage. This helps in decreasing the size of transformer which is used to step up the voltage. Machines which require high voltage direct current (HVDC) to operate request for the series battery pack. Parallel battery pack just increases the back up.
Safety: High capacity batteries should be handled with care. Never short circuit them as short circuiting can cause fire and explosion of batteries. Must connect batteries correctly with UPS, inverter or solar power system. Wrong connection can damage the unit.
Also Read:
How to Connect Batteries in Parallel with Power Inverter or UPS [Wiring Diagrams]
How to Connect Batteries in Series with Inverter or UPS [Wiring Diagrams]
R. N. Karmaker
Hello, dear;
Normally 3phase IN / 3phase OUT UPS’s require more batteries than Single Phase UPS’s. For Example, SERVO-MATIK UPS demand 720VDC (12VDC * 60 nos battery).
User must consult manufacturer’s published specification of the particulars UPS.
harshit
hello
i have 4 12volt batteries connected in parallel.so is this possible to without removing batteries from parallel connection i can find voltage of one battery
Talal A.
No. You need to remove the terminals. Just remove positive terminal and you can check single battery voltage.
3leducation
If a single lithium h battery has a continuous current rating of 80 amps what would happen to the continuous current and max current ratings of the new resultant battery where 6 of these are connected in series to have volts and another 6 are added in parallel to have a total of 480 ah?
Talal A.
In series voltage will multiple but current remains the same. In parallel voltage remains the same but current multiplies. That’s the scientific explanation. Now in real world whether you connect the batteries in series or parallel, capacity of pack multiplies.
In real world:
[6×80=480A series] + [6×80=480A parallel] = 960A. You got 960 amperes available to draw from the battery pack.
sachin kanse
is it possible to connect 12v ups with two similar 12 voltage 7.1 amp batteries?
if possible then what should i do 1.go by parallel or 2.series
Talal A.
Parallel.
http://benignblog.com/connect-batteries-in-parallel-with-power-inverter-ups
20 Words
Can I use two batteries of different capacity to power an inverter? If yes, will there be any effect?
Talal A.
In what combination, parallel or series?
pratap chandra sahu
I have 4 inverters and 8 batteries I use them differently I want to use all of the single input and single output can u help me with that
Talal A.
you con not join output of inverters together. That will cause potential difference and damage them.
Prashant Pandey
Hello Sir,
I am using 650va inverter and i have 2 12 v 200Ah battery, while my maintenance person is saying i should use 3 12v 65 Ah batteries (which i don’t want to purchase) otherwise it will damage the ups. Please suggest a suitable measure.
Regards
Talal A.
Is it 12 V inverter?
Connecting batteries in parallel will keep the voltage same no matter how much large batteries you use. But charger may fail to charge large batteries completely if charging current is low.
Tukuna kumar mishra
Hi sir, 12 v battery 30 nos bank in series connection for ups , 1amp 12v load for one battery , result battery voltage down, no charge what is the problem?
Talal A.
Sorry. Couldn’t understand your question. Could you please elaborate it?
OLS
hi, i want to get an inverter.
is it advisable to use a 800va with 200am battery?
can i add one more battery later?
will the 800va charge 2 x 200ah/12v bateries?
or i should just go for 150ah x 2?
what is the difference between 1400va and 800va?
Talal A.
Use single battery with this unless your inverter supports higher charging current (20A or more)
On Inverter with higher VA, you can run more devices.
Ragaven
hi, can i connect 2x12v batteries in parallel to a 12v inverter with 1100VA, am only looking to increase backup time of running 300 – 400 watt maximum, one battery is exide and one is sukam both are tall tubular batteries with 150 ah, sukam battery was bought on 2015 and exide was on 2016, will there be any complication due to time difference if i connect them in parallel to the inverter?
Ragaven N
Hi, i know how to connect in parallel with the inverter, i just want to know is it advisable to connect two batteries in parallel with 12v 1100va inverter? One battery is 1 year older than the other…
Talal A.
What’s the charging current of your inverter?
Talal A.
It is not recommended to mix old and new batteries especially in parallel. Often older battery lose voltage faster which will result in newer battery with higher voltage charge that older battery draining newer one. And if brands are different, they could also have different standby voltages.
Ragaven
oh….i see , what if i put an arduino controlled relay in between two batteries such that if one battery drains completely and relay closes contact and start using the secondary battery?
Talal A.
I don’t think it will work. Or if it worked it won’t handle very high current that is drawn from the batteries.
CHIRANJIT BISWAS
HOW TO CHECK 6 KVA UPS BATTERY BANK???
WHEN POWER IS GONE NO ALARM IS SHOWING ALSO NO BACK UP IS GIVEN BY THE UPS. HOW TO CHECK EACH BATTERY????
Talal A.
Check each terminal. Clean them and clamp them firmly. Check the battery cables too.
CHIRANJIT BISWAS
Thank You … It’s Done.
jayesh thakidiyil
Sir 3.5 kva ups 3 nos 200 ah battery. while charging battery getting very hot pls solution
Talal A.
How old are your batteries?
Hari Kodi
I have 3 kV 72 volt AC 230 volt input ups, which use 7 ah 6 battery,
Can I use 5 no of 7 ah battery and one 150ah battery,
I need more backup, can I change as I asked?
Please confirm.
Talal A.
NO.
You can not connect large and small capacity batteries in series.
Wale
I have a 30kva 3phase inform online ups(pyramid pps 330), which currently use 40Ah 12v battery.
I want to increase the back up time.
Would it be safe and effective to use a 200AH 12v battery.
How should it be connected?
Talal A.
How many batteries are already connected to it? The specs say it got 30 pieces of 12 volt batteries. You can connect 200 Ah battery in parallel. But I won’t recommend mixing old and new batteries.
AMJAD
CAN I REPAIR BATTERY 12V 100AH USED FOR UPS SYSTEM 400KVA
THE BATTERY OLD ABOUT 8 YEARS
Talal A.
Yes and No. You can use epsom salt to desulfate and recover its capacity. The success is not guaranteed because your battery is too old.
Dharani Dhara patra
Sir,I have 12 v inverter. i want to do series connection.
Talal A.
Buy 6 2V batteries then.
Imma
Good day sir, I have 4 200A 12vbatteries connected parallel to 800va 12v inverter. Is there any undercharging implication on the batteries? Thanks for the anticipated swift respons
Talal A.
What’s the charger current rating?
Imma
The charging current is 10A
Talal A.
It’s not adequate. At least 20 A is recommended.
Praveen
In ups battery bank why we take mid point having 54 batteries
hamza
24 volt UPS how to connect single battery 12 volt please answer me fast
Talal A.
you can’t connect 12v battery to 24v UPS.
Sam
Sir I have 4 12v 200ah batteries, 3.5kva inverter and 4 250w solar panels. How will I connect the solar panels to charge the batteries when there is no light.
Talal A.
Is it solar inverter? Solar inverter got the built-in charge controller. But if it is an ordinary inverter, you will need to connect panels with a solar charge controller and then connect that controller with batteries.
Avdhoot narote
Sir I have 12 v 40 ah battery.
Can I use this battery with inverter?
Talal A.
Yes. But backup time will be short.
JAMES
I have 12pcs of 12v battery of 200ah, of two different make but same volt and amp, 7pcs and 5pcs of battery,
whats is the best connection should i apply,
Talal A.
It depends upon your voltage requirement.
Best method for making large battery packs is to use similar batteries of same make. Often batteries from different makers have got different capacity despite the fact they have mentioned the capacity on battery but actual capacity could vary. So, this could cause problems when you have to connect batteries in series.
John Kilday
Hi All,
I was hoping somebody could help please. I’m looking at doing a large battery bank in parallel 20 x 55ah and wondering what the best way is to wire them up so I’m using them all efficiently, also what wire size should I use, cheers Jk
Talal A.
Buy 6 or 4 AWG (gauge) battery cables to connect batteries. These cables will have connectors so you can easily connect them with battery posts. You can buy them at Amazon, Ebay or your local hardware store.
John Kilday
Thanks Talal, any ideas on best way to connect them in parallel. I’ve heard a few different methods but not sure how for so many batteries. Should I go positive out on one end and negative the other end? Cheers
Talal A.
Since you wish to connect 20 batteries, just connect them from terminal to terminal, (+) terminal of one battery with (+) terminal of other battery and (-) terminal of one battery with (-) terminal of other battery. Do this for all batteries and connect your last battery terminals with your device. 20 batteries with 55 AH will add up to 1100 Amperes in total. So if you wish to draw high current better go for 3/0 (000) or 4/0 (0000) AWG cables. It’s safe to use thick cables in this scenario.
Other way is to connect all your 20 batteries directly with your device. That will cause mess of wires but in this case you can use thinner cables like 4 or 6 AWG.
erhes
when the Ups is on AC power the output is 220 Volts (Thats ok) but
when i disconnect AC power output drops to 170 Volts.
Talal A.
Some inverters (or UPS) are designed that way. When no load is connected, backup voltage stays below 200. Once you connect a load, it starts rising. 170v is too low. Contact the service center to confirm if it is normal for your UPS.
kamran
Dear Sir!
I have dc invertor having 24vdc input i have connected two 12v-165ah batteries in series but the batteries backup time is too low while the batteries are just one year old.
Now i want to connect 4 batteries having 100ah what connection will be the best to get maximum backup time, maximum charging,
will series parallel connection be the best or parallel series connection will be the best
which one i prefer first ?
Talal A.
You need to make two series battery packs to maintain 24V.
Connect 2 batteries in series and connect them to inverter.
Connect next 2 batteries in series and connect them to inverter.
Bittu
I have two inverter battery 155 Ah and 160Ah with 850 w ups . How to use both battery
Talal A.
You can connect them only in parallel. If your UPS supports single battery, you can connect them both in parallel with UPS. Do not connect in series.
Bilal
Sir
How much amp current required for four batteries of 190ah in series to full charge batteries
Talal A.
10-25 ampere should be fine.
smith
can i connect two 12V batteries to a 12V inverter in parallel
will there be any change in power or will it damage the equipments
and the brands are different how will it affect if the ah is changed and the V remains constant
do i get the reply in my mail
Talal A.
You can connect two batteries in parallel from different brands. Not a very good idea but still works. Make sure both of them are new. Do not mix old and new batteries.
jan
can i connect two 12v batteries 200 amp to my 1000 watt homage ups?
Talal A.
What’s the battery voltage requirement?
Sufi
I have four 12 v 150 ah batteries attached to 3 kv ups. Recently my ups broke down. I have a spare 850 va inverter. Can I connect to the existing 4 battery setup or should I disconnect any batteries.
Talal A.
I suspect that 850va inverter requires 12v battery input. Connect 4 batteries in parallel and connect them to that inverter.
Paramjit Singh
I have three 12V 28AH sealed lead acid batteries. Can I use them in parallel (84AH) with my 12V inverter?
Are they safe to use? ?
Talal A.
Yes.
M Aslam
Hi,my 24v ups it gives too much power the speed of the fans get very fast
and I cannot adjust the speed and my Phone Chargers burn out is there anything I can use to control the voltage thanks
Talal A.
check the voltage of UPS when it’s running on batteries. If it’s too high than normal, stop using this ups before you burn more things. Return it or show it to technician and get its voltage adjusted if possible.
Okumu kenedy
Hello sir
I have inverter rated 240vdc input, 415vac output,and 12v 100ah battery 40 pcs, can you sketch for me how to connect the battery bank in both series and parallel to get the correct voltage and maximum backup.
Talal A.
connect 20 batteries in series.
Connect another 20 batteries in series.
Now you got 2 battery bank with 240V each.
Connect these two banks in parallel to maintain 240V. Connect them with inverter.
Dheeraj
Can I use two battery in parallel one should be charged with electric power other through solar ..Is it possible?
Talal A.
then what’s the advantage of solar if you still have to charge battery with electric power?
Din Dayal
Hello sir
can I Attach 150ah and 80ah battery together for use with 1200 Watt inverter.
Talal A.
you can connect in parallel only.
Bruce
Hello, I have 4 – 12v batteries which currently are connected to an inverter to produce 110vdc. (12vdc X 110vac). I now need 220vac but the inverter I have requires 48vdc for input power. Can I hook both inverters to the same battery bank and operate the inverters at the same time (assuming proper battery sizing)?
Talal A.
your inverter with 110 vac output requires 12v battery input?
raju
Can you suggest me what should be the dead battery voltage? and can we check amp remaining? if an old solar battery voltage reading is 12.9v after 3 day same battery voltage reading is 12.3
Means what? Is volt ok and how can we measure amp storage in battery bank
Talal A.
Dead battery voltage varies from battery to battery. Can’t standardize it.
In Lead acid batteries, you can’t measure exact charge of battery. But you can measure approx charge left by looking at battery voltage when load is connected.
raju
If inverter rating is 30 amp can it charge 150*2 12 volt battery. I think battery should be charged in 10 hours. If we connect 2 150 amp battery in parallel, I think inverter or solar can’t provide 30 amp continuously, if provided 30 amp for 10 hours battery will be full charge. when we use inverter total 35 % power loss in dc to ac conversion. 10 % battery cut off mean 150 amp total where 150*12volt=1800 -35%= 1170whr will be available to use means if battery is fully charged we can use 100 watt ac load for 10/11 hours. it’s ok or not.
Talal A.
Yes.
But to get maximum juice out of solar panels, you will need to face them towards direct sunlight. Noon is the peak time for maximum power generation with solar panels.
Besides you won’t get 30 amp all day long. Clouds, fog and other factors also affect the power generation.
raju
What will be be the voltage of full charge battery 13.4v or 14.3v
Talal A.
Depends upon the cut of voltage of charger.
If isolated from system, voltage of fully charged battery will drop to 12 – 12.9 V
raju
What is voc isc imax pmax vmax when we connect 4 solar panel how it is important tell me ? If 100 watt panel rated voc 21.89, isc(a) 5.60, imax(a) 5.33 ,pmax(w) 101.31, vmax(v) 18.98
2 charge controller pwm isc 5.60*4 panel=22.42*1.25=28.03*1.25=35.03 means 40 amp will work
sharon
APC 600VA ups backup time 10-15min 7ah battery can i use large Ah batteryfor more backup time(48ah or 100ah external)
Talal A.
Yes
Rene Wyers
Hi Raju. I have a bank of 18 x190 amp hour batteries can u explain how to draw the power from them would it be ok to connect positive terminal at one end of bank to inverter and negative terminal at the other end of bank to negative terminal to inverter or do u have a better idea. Regards Rene.
Talal A.
What’s the battery requirements of your inverter? I mean how much battery voltage it requires to operate.
See the specifications before connecting anything.
raju
Can I go for bigger inverter or 1 more battery in parallel or whatever because I need to run that application in summer 12 hours and winter 7 hours.
Talal A.
You can connect batteries in parallel to increase backup but I won’t recommend mixing new and old batteries.
raju
I am using 12 volt 200 amp solar battery on 400 watt solar panel 20 amp controller 300 watt inverter. problem is battery back up is very low. load 60watt cfl battery backup 6 hours .how to increase battery back up.
Talal A.
Charge your battery fully and then check how much backup you actually get. If it is the same, then your battery is weak.
Lancy
Hi,
How many batteries can be connected in order to get 6 hours backup for power load of 4000W??
Talal A.
if you use 200Ah 12V batteries then 10-12 batteries are required.
Zulfikar Ansari
Hi,
I have purchased ups (rating 80Ah to 200Ah) range 12v.
And two 12v batteries 220Ah each. Now I want to know that, is it possible to use both batteries in single ups in parallel or series, I have doubt that series connection will increase battery voltage while ups having 12v range mentioned, parallel connection will increase Ah (220+220) while range is only 200Ah.
Kindly help me
Talal A.
connect in parallel.
Check the charger current rating. If charging current is too low, two batteries would charge slowly. You should have gone for 24 V UPS.
MAHESH SHARMA
please send me your views
MAHESH SHARMA
sir
i want to know can i connect 2 batteries 12v with 650va inverter in parallel battery pack
.mahesh
[mod edit: personal contact details removed]
Talal A.
Yes you can. You will need extra pair of cables. Make sure they are of high quality and can tolerate the load.
Connect batteries in parallel to each other.
Connect the pack to inverter.
Colin Cleary
I have 2 x 150Ah AGM Battiers ,Connected in my caravan to a solar Panel , I Charged by 240 Amp Solar Panel on roof of van & also a connection to my Truck Motor to alternator up market 180 ,I want to add 2 x 200 AH AGM Battiers new to the system is this possible? I believe not recommend is this so.
I believe I should purchase 2 x 150 Ah battiers as I will have no advanatage by adding 2 X 200 AH AGM .I also have 3 x 200Ah in my truck & 240 Watt solar Panel on a separate system also connected to alternator,The reason for requiring extra power in caravan is when parked for 3 days in bad weather( no Sun) I have to recharge by generator or Truck alternator. Please note I have a 1000 Inverter in Truck & a 4000 Inverter in Caravan. I believe I require more AH to run caravan Inverter .
Note all items in Caravan Micro wave Elect Jug ,Elect Toaster,Elect Ice machine & Water ,Elect Milk shake mixer Elect food Mixer, Gas Fridge & Waco 40 Liter battery & Elect Fridge, 240 volt Computer ,Printer & scanner,,12 volt Tv
In Truck 40 Liter Battery Fridge Evacool 1000amp Inverter Computer ,Rev Camera.GPS, Dash Cam , Blue tooth Hands free Phone Connecter, Computer Laptop
Talal A.
you can add larger pack of batteries in parallel with a smaller pack. (as long as voltage remains the same)
But the best way is to go for equal capacity batteries.
Tudor
Hello,
I have a PV system 3.2kw with backup 4x12v 150Ah batteries (48v in series). I need more energy for the night and I know that the best it is to add another series with 4 batteries with the same capacity and producer. But it is too expensive. Can I add only 2 batteries? And how to connect them to have more energy additional energy and my system to load them with no problem?
Thank you in advance.
Talal A.
You may buy 4 equal capacity smaller batteries (12V each), connect them in series and then connect the pack to the main system. Although I won’t recommend it but you may go for it if you need more backup.
Tudor
Thank you
olivia
I need to install a 10 KVA 3 phase in/ 3 phase out online UPS. How many 12 V, 26 Ah batteries i will require and how will i connect?
Talal A.
Depends on specifications of UPS. You can see the requirement in specs.