Serial and Parallel Battery Configurations
Battery packs achieve the desired operating voltage by connecting several cells in series, with each cell adding to the total terminal voltage. Parallel connection attains higher capacity for increased current handling, as each cell adds to the total current handling. Some packs may have a combination of serial and parallel connections. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh. Such a configuration is called 4S2P, meaning 4 cells are in series and 2 in parallel. Insulating foil between the cells prevents the conductive metallic skin from causing an electrical short. The foil also shields against heat transfer should one cell get hot.
Most battery chemistries allow serial and parallel configuration. It is important to use the same battery type with equal capacity throughout and never mix different makes and sizes. A weaker cell causes an imbalance. This is especially critical in a serial configuration and a battery is only as strong as the weakest link.
Imagine a chain with strong and weak links. This chain can pull a small weight but when the tension rises, the weakest link will break. The same happens when connecting cells with different capacities in a battery. The weak cells may not quit immediately but get exhausted more quickly than the strong ones when in continued use. On charge, the low cells fill up before the strong ones and get hot; on discharge the weak are empty before the strong ones and they are getting stressed.
Single Cell Applications
The single-cell design is the simplest battery pack. A typical example of this configuration is the cellular phone battery with a 3.6V lithium-ion cell. Other uses of a single cell are wall clocks, which typically use a 1.5V alkaline cell, as well as wristwatches and memory backup.
The nominal cell voltage of nickel is 1.2V. There is no difference between the 1.2V and 1.25V cell; the marking is simply preference. Whereas consumer batteries use 1.2V/cell as the nominal rating, industrial, aviation and military batteries adhere to the original 1.25V. The alkaline delivers 1.5V, silver-oxide 1.6V, lead acid 2V, primary lithium 3V, Li-phosphate 3.3V and regular lithium-ion 3.6V. Li-manganese and other lithium-based systems sometimes use 3.7V. This has nothing to do with electrochemistry and these batteries can serve as 3.6V cells. Manufacturers like to use a higher voltage because low internal resistance causes less of a voltage drop with a load. Read more: Confusion with Voltages
Serial Connection
Portable equipment needing higher voltages use battery packs with two or more cells connected in series. Figure 3-8 shows a battery pack with four 1.2V nickel-based cells in series to produce 4.8V. In comparison, a four-cell lead acid string with 2V/cell will generate 8V, and four Li-ion with 3.6V/cell will give 14.40V. If you need an odd voltage of, say, 9.5 volts, you can connect five lead acid, eight NiMH/NiCd), or three Li-ion in series. The end battery voltage does not need to be exact as long as it is higher than what the device specifies. A 12V supply should work; most battery-operated devices can tolerate some over-voltage.
Figure 1: Serial connection of four NiCd or NiMH cells
Adding cells in a string increases the voltage; the current remains the same.
Courtesy of Cadex
A higher voltage has the advantage of keeping the conductor size small. Medium-priced cordless power tools run on 12V and 18V batteries; high-end power tools use 24V and 36V. The car industry talked about increasing the starter battery from 12V (14V) to 36V, better known as 42V, by placing 18 lead acid cells in series. Logistics of changing the electrical components and arcing problems on mechanical switches derailed the move. Early hybrid cars run on 148V batteries; newer models have batteries with 450–500V. Such a high-voltage battery requires 400 nickel-based cells in series. Li-ion cuts the cell count by three.
High-voltage batteries require careful cell matching, especially when drawing heavy loads or when operating in cold temperatures. With so many cells in series, the possibility of one failing is real. One open cell would break the circuit and a shorted one would lower the overall voltage.
Cell matching has always been a challenge when replacing a faulty cell in an aging pack. A new cell has a higher capacity than the others, causing an imbalance. Welded construction adds to the complexity of repair and for these reasons, battery packs are commonly replaced as a unit when one cell fails. High-voltage hybrid batteries, in which a full replacement would be prohibitive, divide the pack into blocks, each consisting of a specific number of cells. If one cell fails, the affected block is replaced.
Figure 2 illustrates a battery pack in which “cell 3” produces only 0.6V instead of the full 1.2V. With depressed operating voltage, this battery reaches the end-of-discharge point sooner than a normal pack and the runtime will be severely shortened. The remaining three cells are unable to deliver their stored energy when the equipment cuts off due to low voltage. The cause of cell failure can be a partial short cell that consumes its own charge from within through elevated self-discharge, or a dry-out in which the cell has lost electrolyte by a leak or through inappropriate usage.
Figure 2: Serial connection with one faulty cell
Faulty “cell 3” lowers the overall voltage from 4.8V to 4.2V, causing the equipment to cut off prematurely. The remaining good cells can no longer deliver the energy.
Courtesy of Cadex
Parallel Connection
If higher currents are needed and larger cells with increased ampere-hour (Ah) ratings are not available or the design has constraints, one or more cells are connected in parallel. Most chemistries allow parallel configurations with little side effect. Figure 3 illustrates four cells connected in parallel. The voltage of the illustrated pack remains at 1.2V, but the current handling and runtime are increased fourfold.
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Figure 3: Parallel connection of four cells With parallel cells, the current handling and runtime increases while voltage stays the same. Courtesy of Cadex |
A high-resistance cell, or one that is open, is less critical in a parallel circuit than in serial configuration, however, a weak cell reduces the total load capability. It’s like an engine that fires on only three cylinders instead of all four. An electrical short, on the other hand, could be devastating because the faulty cell would drain energy from the other cells, causing a fire hazard. Most so-called shorts are of mild nature and manifest themselves in elevated self-discharge. Figure 4 illustrates a parallel configuration with one faulty cell.
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Figure 4: Parallel/connection with one faulty cell A weak cell will not affect the voltage but will provide a low runtime due to reduced current handling. A shorted cell could cause excessive heat and become a fire hazard. Courtesy of Cadex |
Serial/Parallel Connection
The serial/parallel configuration shown in Figure 5 allows superior design flexibility and achieves the wanted voltage and current ratings with a standard cell size. The total power is the product of voltage times current, and the four 1.2V/1000mAh cells produce 4.8Wh. Serial/parallel connections are common with lithium-ion, especially for laptop batteries, and the built-in protection circuit must monitor each cell individually. Integrated circuits (ICs) designed for various cell combinations simplify the pack design.
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Figure 5: Serial/ parallel connection of four cells This configuration provides maximum design flexibility. Courtesy of Cadex |
Simple Guidelines for Using Household Primary Batteries
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Keep the battery contacts clean. A four-cell configuration has eight contacts (cell to holder and holder to next cell); each contact adds resistance.
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Never mix batteries; replace all cells when weak. The overall performance is only as good as the weakest link in the chain.
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Observe polarity. A reversed cell subtracts rather than adds to the cell voltage.
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Remove batteries from the equipment when no longer in use to prevent leakage and corrosion. While spent alkaline normally do not leak, spent carbon-zinc discharge corrosive acid that can destroy the device.
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Don’t store loose cells in a metal box. Place individual cells in small plastic bags to prevent an electrical short. Don’t carry loose cells in your pockets.
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Keep batteries away from small children. If swallowed, the current flow of the battery can ulcerate the stomach wall.The battery can also rupture and cause poisoning.
- Do not recharge non-rechargeable batteries; hydrogen buildup can lead to an explosion. Perform experimental charging only under supervision.
Simple Guidelines for Using Household Secondary Batteries
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Observe polarity when charging a secondary cell. Reversed polarity can cause an electrical short that can lead to heat and fire if left unattended.
- Remove fully discharged batteries from the charger. A consumer charger may not apply the optimal trickle charge and the cell could be stressed with overcharge.
Comments
I wish there was a way to quickly identify a bad cell from a laptop battery pack. Often it is only 1 bad cell causing a laptop battery to only charge to 80% or 85% or whatever. Sadly they are always spot-welded together in parallel groups of 2 or 3 forcing you to destroy the nickel sheets holding them together if you want to find the faulty cell.
Dear Sir.,
I wonder you can help me in the below query.
Given a DC circuit with two 5-volts batteries and two resistors ,1 and 2 ohms respectiverly
araanged in series’ in which the 1 ohm resistance is connected between the two batteries. What is the total resistance and emf of the araangements
Thanls
Larry
I have a hunting shack that I power with a 12v deep cycle battery. Would it help conserve power if I have a disconnect switch at the battery to stop leakage from wires when I turn the lights off at night? Is it better to drain one deep cycle first than hook the next one up or hook both up at same time?
Thanks
Mike
Aamir - The voltage would be the lower of the two, as current would flow from the battery with the higher potential to the one with the lower potential. This would in fact “charge” the second battery. For this reason if you are using non-rechargeable batteries it is important to replace all cells at once.
Mike - If the only thing connected to the batteries is the lights, then opening the contacts of the light switch opens your electrical circuit. At that point there’s no current flow and therefore no drain on the battery. If there are other things wired in there that stay on all the time then a disconnect is a good idea. But sounds like you’re okay with tjust the switch.
As for the one battery at a time or both at the same time, my answer to Aamir may help… If the two batteries are fully charged and at the exact same voltage, then there’s no difference. But if one’s a little lower than the other then some energy will be wasted while the batteries equalize. It’s not much but if you’re trying to squeeze everything out of the cells as you can, it’s something to think about.
In my mind your answer comes down to a matter of convenience vs knowledge… If it’s a pain to wire these in then do it once and get it over with. If not then I’d do it one at a time this way once the first battery’s dead you know you’re on the second battery. Think of it as a primitive fuel gauge.
I have my car battery, which is reading only 10V. Can I supplement this with another battery of 2V (of same rating) in series with this 10V battery, and continue using it? Is it feasiblible for a moving vehicle? and If it is possible , please suggest any specific measures to be followed.
no you can not. you will blow the battery up. charge the battery with a 20 amp car charger and read it then if it still reads 10 volts, get a new battery. but the car should be able to start with voults above 10v. so ide say to charge it first.
@jason: you can spot if you have a bad cell. voltage meter on the 2 ending terminals on the battery. one on the left terminal, one on the right. you can only spot IF you have a bad cell battery.
best site
I have a question for you. If i have a 24v system with 4 12v batteies ( series and then in parralel to get 24 v) with a load of 18watts. will it be worth wile to run 4 12 v batteries in parralel to get more amp hours out of the system? the load can handle voltage from 12-60 volts.
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Hi I am an Iranian student project I made for my university needs to build a car battery charger circuit (car) Vjryan output voltage display on the LCD please help me I can just fast Khvbtan Batshkr site today 22/12 / 2010 is my email najafkhanirasoul@yahoo.com Those who are on this site to me they have requested. D John Please anyone who can help you love
I have a small radio transmitter that sends brief pulses twice a second. It’s in a limited access space. It currently runs on a 300 mah, 3v lithium primary coin cell which gives a lifespan of two years. I need to up the lifespan to 5 years minimum, but I don’t have room to put in a thicker coin cell, nor go to a cylindrical battery. But I do have room to add more 300 mah primary cells. Theoretically I can put three of the 300mah, 3v coin cells in parallel, and achieve over 5 years of battery life by doing so. Is there any reason that wouldn’t work or any other factor I should take into account?
I’m thinking of putting three 6 volt baterys together will i be abole to get 12 volt.If not what can i do to get more running time from my battery bank.
if two batteries are connected in parallel and they have different voltage ,so which one voltage will be shown on multimeter
Can 2 deep cell batteries (12v) of different amperage (say 100 and 80) be connected in parallel and charged with a solar panel in a camper? If your answer is no, what is the rational of why not?
Great Site,
I will be building a 12v battery pack, I have 20 new matched Powerizer 4500 NiMH cells.
I was thinking I would place 10 in series and then 10 in parallel to produce a battery system with 12v and 45,000 mAh.
Is my math correct? Ten 4500 mAh in parallel would be 1.2 v 45,000 mAh, but if I add the second set of 10 in series, would I also add the 4,500 mAh from that set to total 49,500 mAh?
Many Thanks
What about the coverning formulas. I thik for series it should be like nV=I(R+n.r)/n and for Parallel nV=I(R+n/r). Is this orret
if we are connected battries in parallel,the life time is some of two r one.
This site is the best place to be. Thnx
Is it possible to connect 6 12 volt batteries so as to deliver 48 volts output? Can you have two sets of two in parrallel, then connect these parrallel connected ones in series with the other two and thus get 48 volts total, or will this wreck the charging and discharging rates of the two standalone ones?
@Kolin
No, that’s not right at all.
20 batteries @ 1.2V and 4.5 A
To get to 12 V you need 10 in series giving 12 V @ 4.5A
Do this twice and place the two sets of 12 in parallel, you get 12V @ 9A.
You overall battery capacity Wh, can not exceed the sum of the individual pieces.
20 batteries @ 1.2 V and 4.5A = 5.4 Wh per cell or 108 Wh total.
The same above, 12V @ 9A = 108 Wh.
I was wondering if anyone could clarify this. If you had a 10v battery in parallel with a 5v battery. what would be the voltage of the circuit.
Can i connect 12V and 24V ups with two 12V batteries connected in series, as we do get 12 volts and 24 volts when two batteries are connected in series.
There is a mistake at the end of this article. It says
“Remove fully discharged batteries from the charger. A consumer charger may not apply the optimal trickle charge and the cell could be stressed with overcharge.”
I think this is meant to say “Remove fully CHARGED batteries from the charger….”
this is a good site. very informative.
sir
Its equivalent ckt
if i’ve four cells in serie connection, how is it possible to measure the voltage or monitor each voltages where there are no the same grounded point?
Hi, can two 12vdc batteries of different Ah, (110ah / 50ah), be connected in parallel for increased Ah capacity (160). To be charged by 100W Solar PV panel via 15A solar charger regulator for leisure use, ie caravan. Many thanks, Lance.
Any one can help me to configure a battery bank for solar power system. With 2V each battery what is best way to get required 8500AH. I mean number of battery and each battery AH ?
If I have 2 RV deep cycle 12V batteries in parallel, can I place a charger on one of them, and get adequate charging on both?
how i get 12v dc using 3.7v li-on cells.what will be the connection.
Can I use 4 rechargeable batteries and i non-rechargeable one in a 5 battery recorder?
Hey, just wanted to say thanks! Great information. I’m glad I found this site.
I have two 12v deep cycle batteries in parrell. Doe one drain before the other or do they both drain equally?
I just want to know if what happens if one cell(Battery) in placement is reversed in series and parallel?
we want to buy 400 Battery 1.25V , 5A/H ,NI/CAD , Dimentions : 35mm . 35mm . 82 mm
I have 8 12v deep cycle batteries to be connected to an 24V inverter. I know that I need to connect 2 together (+ -) to get 24V. What would be the correct way to connect these 4 cells to the inverter.
I have 3 12v X 16aH batteries i want to connect? Since i want to increase the wattage and amperage, can i connect these 3 batteries by series and parallel?
can i add eight 7volt lithium batteries of cameras to get 56V?? what be the result?? is it risky to try that? i need a 50v source for my project… pelase help..
There should be a disclaimer warning that this article is overly simplified and does not account for many problems that can occur in the field. Some of the statements are wrong if taken literally. “On charge, the low cells fill up before the strong ones” is not true if the low cells have high internal resistance. “most battery-operated devices can tolerate some over-voltage” needs to be more clearly defined - while a few tenths of a volt might not matter, tens of volts could fry things. “A higher voltage has the advantage of keeping the conductor size small” is misapplied: for a particular power output, higher voltages allow smaller current flows which in turn allow smaller conductors (ignoring start-up surges and increasing current draw as batteries lose voltage as they deplete). “Parallel/connection with one faulty cell A weak cell will not affect the voltage” actually the weak cell can draw enough current from the good cells to lower the overall voltage of the connection. “The serial/parallel configuration shown in Figure 5 allows superior design flexibility” but also increases complexities of battery management and system troubleshooting immensely.
The article then jumps to tips about household batteries without explaining the difference between primary and secondary batteries, nor this section’s relevance to the previous discussion.
I realize that you are attempting to present technical information to a lay audience, but please be careful. The confusion shown in the comments proves that this article hasn’t achieved its goals.
all cells will drop performances after certain cycles of charging and discharging. If you use cells from same produciton lot, it is likely that no particular one single cell will break down while others still working in very good condition, however, It is also likely that each cell will drop performance slightly different as time gone.
As a result:
1. one cell totally fail while others still working properly seldome happen;
2.. it is certain that each cell will have slightly different capacity after certain time.
As a result, in series will give better engineering result than in parallel.
I would like to know just how volitile the lithium polymer battery is and how can i process the use of this kind of battery. thanks Virian
Our bike shop has taken apart many 24, 36, and 48 volt lithium batteries used for electric bikes looking for bad cells so we know how the round cells are spot welded to metal strips. I have seen a new type of lithium cell that is flat (not round) with the two contacts sticking up on top. How are these flat cells physically connected together? I think we may be able to assemble batteries with these flat cells that will save space.
Lynn: You would connect them in the same way (spot weld tags onto the contacts)
I hope this helps
I run 2 interstate 4d deep cycle batteries in parrallel, via, power invertor to power machinery in my work van. recently the power invertor as well as the batteries, crapped out, i tested the batteries and they were shot. the power invertor was sparking and smoking, so i replaced that. It’s a 2500 watt invertor. replaced one battery so far, the other is on order. however the alarm on the invertor goes off immediatley and i’m unable to run machinery. is keeping the old battery connected in parrallel with the brand new one causing this? i went for six years, no problems then the batteries died(which i expected) the invertor crapped out and now i can’t seem to get it running again.
I need to run 4 twelve volt batteries in parallel. is there a way to connect a battery charger and charge all the batteries at once without disconnecting them?
I am interested in this “4S2P, meaning 4 cells are in series and 2 in parallel.” mentioned in the beginning of the article.
This is my understanding, please help me fill in the blanks though.
(A) if I run 4x1.2v 1800 mah in series I get 4.8v 1800 mah.
(B) if I run 2x1.2v 1800 mah in series I get 2.4v 1800 mah.
(C) if I run (A) and (B) in parallel I will get 3600 mah, and I hope 4.8v (?)
This idea of doubling the output time without having to double the number of batteries is compelling.
Will this be a safe configuration for Ni-MH AA’s? would I need some “insulating foil”? How would this portion work?
I really enjoyed the article, and am looking forward to hearing a response to my query.
Thanks.
I have 800 kva APC ups, what type of rating batteries to be conected and how many nos of batteries to obtain full load, please give formula to calculation .
What will be the electromotive force forTwo battery cells 1.5V each connected in parallel to one cell 1.5V.
Thanx.
Learning about primary cells atm and they say never to connect cells of different types, why is that and does that rule comply with secondary cells???
Dear sir ,
I have 1 no of 12 V battery and two solar panel its rating is 17V +17 V . please let me know the connections? sires or parallel connection is use full?
sir there are two batteries one is 5v second is 10v . when we use parellel combination of batteries and connect with a network then it shows inregular circuit why?
I constructed a 12v battery charger bt is getting heat too much. What is the problems?
Ok, here’s one for you. I need to wire 6 12volt batteries together to get 24volts and triple amps (3 bats. parallelled twice then seriesed together). Easy enough, however, I also need to be able to wire a 12 volt starter to the same system. Anyone got a clue? I’ve tried the manufacturer’s web site (Tronair ground power units) to no avail. I’ve called and left messages and no calls back. I’ve tried several configurations, no luck. Anyone?
lawrence have you tried taking a measurement with a voltmeter off of the positive and negative terminals of one battery while all the batteries are hooked together? your setup should be like figure 5 of this page but instead of two batteries down your setup has three down and two across. right?
I have 12V 12AH battery only one.
I want to get 2V 72AH output to load.
Please advise properly connection for it.
Running an approximately 3HP winch Motor off a 12V Deep Cycle Marine Battery. The winch is being used in a way that it runs for 40 seconds, off for a bit then runs again. We use a rapid battery charger hooked to a portable electric generator. Having problems occasionally where the batteries lose there charge and motors start to overheat. Would I be better to run 2 12V Deep Cycle Marine Batteries in parallel? Are there any drawbacks to doing this? Thanks
how does the contact points of
batteries connected in series add to the resistant of the circuit.
Can any one clarify my doubt. If the UPS DC Input is +192 -0- -192, Current at both +ve and Negative limb should be equal or need not. Suppose if we provide Current sensor to measure the discharging Current Do we need to put the sensor in both arm seperately or not?
I recently purchased a lot of rc helicopters . 12 of them actually . My friends and I are in the process of weekly helicopter wars . Although we can only fly 3 at once it is a lot of fun ! Problem is , I am eating up ‘AA’ batteries like crazy . My question is : What is the ac to dc equivalent of 6 AA in series ? I would like to cut out the AAs altogether and use one of my many adapters connected to the + and - terminals on the charger/remote with out damaging the charger/remote and/or the 3.7v 70mAh in the helicopter itself . Any help would save me midnight runs to the drug store to buy AAs . The clerks must think I’m a Smurf !!
Hi Charlie:
I would highly recommend trying AA Ni-MH LSD (low self-discharge) rechargeable batteries. I like the Sanyo Eneloop batteries a lot. They are rated for 1500 recharge cycles (that’s a lot of flights!). I think you might see as much as 4x more flight time as well based on my tests of compact photo flashes. I can’t say for sure if you will get the same performance, but it is definitely worth a try.
Keep in mind that they are heavier than most Alkalines, which may be an issue. You can check the specs on various websites.
All the best,
Andrew Darlow
Editor, The Imaging Buffet
http://www.imagingbuffet.com
I do night work in the oil field and am trying to build a battery powered light that I can attach to equipment from job site to job site, and charge while in the truck. A 12-18V, 6W LED will serve my purpose. I will have AA batteries connected in series to supply approximately 12V. My question is in regards to charging. Can I simply connect the 12V battery pack in parallel to charge the batteries or will the amperage get too high and cause the batteries to explode? Could I avoid such circumstances by making a battery pack to supply a higher voltage, such as an 18V Li ION or NiMH battery pack. They would never reach an over-voltage during charge, but would they still be subjected to too high an amperage? I realize that they would never reach a full charge, but since it is simply a light that requires 12V I don’t think that would matter would it?
Hi Bill:
I personally would just buy AA or AAA LSD NiMH batteries (Eneloop brand are my favorite, though there are others), and a 12v or 120v plug-in charger for them to recharge (they need about 3-5 hours to recharge - avoid 30 min and 1-2 hr chargers since they will limit the life of the batteries).
Then charge them in sets and put 4 AA’s or 3 AAA’s in a flashlight (depending on model) like this one from Harbor Freight (you can buy 3-4 of them and have a huge amt. of light). The light is very bright.
http://www.harborfreight.com/3-1-2-half-inch-21-led-flashlight-98503.html
or this one sold on Amazon.com that takes 3 D cells:
http://www.amazon.com/AMAZING-95-LED-Aluminum-Flashlight/dp/B000Z7GCRS/
or this lantern:
http://www.amazon.com/Rayovac-SE3DLN-Sportsman-300-Lumen-Lantern/dp/B0018S4XIS/
You can get convertors from D’s that use AA’s:
http://www.amazon.com/Sanyo-Eneloop-Spacer-Pack-Packaging/dp/B003EJ1QL6
Rechargeable D cells have about 5-10 times the capacity (mAh) of AA’s, so check the est. run time with alkalines and divide by about 5-10 to determine how many hours you will get from them.
Hope that helps,
Andrew
Andrew Darlow
Editor, The Imaging Buffet
http://www.imagingbuffet.com
In Figure 5: Serial/Parallel connection of four cells.
Is there an Advantage/Limitation to connecting the Cells in the middle as well?
For instance if there was a weak Cell in Figure 5, would it make any difference if the was a connector in the middle?
I need to charge a separate battery on my motorcycle for nightly use in a campground to power my cpap machine. It would be discharged nightly and needs to be recharged daily thru the motorcycle charging system. Should i connect Series or parallel ? Thx
I have a question about running multiple 12V batteries in parallel. They are all the same type, brand, voltage, and amperage. 12V @400a If I had 10 of them in parallel that would give me 12V @ 4000a. Since this is DC current what gauge wire is appropriate between each of the battery posts?
Any other useful information is very welcome. Oh, and these are gel-cell PureLead batteries.
What causes the battery voltage to rise when you hoo batteries up in series? Does it change the lines of electricity (electric field)?
HI guys! I have a battery that is totally screwed! It’s a 4CGR18650A2-MSL as seen here - http://www.batteries-laptop.co.uk/batteries.php?productcode=951
I’m considering doing a rebuild but i’m confused about the voltage per cell. Everywhere seems to have 3.7v cells but if it’s only a 14.8V battery, surely i only need 1.2v cells each?
Which way do i go? Where do i turn? What would you suggest i do if i was to do a rebuild?!!
As you may have guessed, i’m a bit new to all of this so any assistance you can provide me is really welcome and i’m thankful for it 
Many thanks in advance, Steve
if two batteries are connected in parallel and they have different voltage ,so which one voltage will be shown on AVO meter, and merits and demerits