Charging a battery from multiple sources?

Replies

• 

  Abhishek Rawal

  Car batteries explodes if overcharged.
  But Li-ion batteries don't as most of Li-ion batteries consists of controller chip that stops Li-ion to overcharge.
  If there is no controller chip embedded then overcharging of Li-ion battery can result in explosion.
  
  My question : Can we overclock batteries ? 😉
• 

  Kaustubh Katdare

  I like the sound of 'over-clocking batteries'. If I'm not mistaken, the Li-Ion batteries typically used in most of the gadgets these days have over-charge protection. But we've had news of mobile phones exploding. Wondering if it's the failure of the charge protection circuits.
• 

  arunchary

  here i am working on the same concept designing solar to battery from over charging protection circuit, so i considered with lm358 circuit as follows.
• 

  Jeffrey Arulraj

  zaveri

  Can a battery be charged by more than one source, such as a couple of generators or solar panels ?
  
  what happens if a battery is overcharged ?
  
  does it explode ?

  Source become void if the net voltage given by them is lesser than the Working voltage of the Battery
  
  For eg you can never charge a 12 V battery with a 12 V input voltage
  
  But the nuber of sources are not an issue at all if the effective voltage is more than the threshold voltage of the battery you can charge it
• 

  zaveri

  jeffrey samuel

  Source become void if the net voltage given by them is lesser than the Working voltage of the Battery
  
  For eg you can never charge a 12 V battery with a 12 V input voltage
  
  But the nuber of sources are not an issue at all if the effective voltage is more than the threshold voltage of the battery you can charge it

  thanx buddy.
  
  the system of a battery and its charging sources, i think so, is analogous to a water tank.
  
  the battery is like the water tank, and has a particular capacity.
  
  the charging source are like the sources of water.
  
  now if there are two or more sources of water, the only net result is that the tank gets filled faster, but under any case the tank will not hold more amount of water than, its capacity.
  
  the same thing goes for a battery, and it cannot hold more charge than its capacity.
  
  right ?
• 

  lal

  Well, there is something to note there. More sources or more voltage and so more charging current doesn't mean faster charging. It means battery is going to fail soon. For every battery, there is a fixed maximum safe charging current. If this rating is exceeded, it means the life of battery is shortened. The charging current varies for different batteries like 1/100th of the Ah rating or may be 1/50 or 1/10. So more sources isnt a feasible way to charge the battery fast. The charging circuit should be designed to limit the charging current and the voltage.
  
  In case of lead acid batteries, once the battery is fully charged the charging circuit employs something called 'trickle charging' to keep it full. It is applying periodic current pulses at the battery terminals to keep the charge full.
  
  The best thing about Li-po or Li-ion are that we can charge them anytime without waiting to get them fully discharged but still have long life. Actually, tests show that the life is increased if Li-po cells are recharged when they are discharged to 60% or higher of full capacity. In case of Ni-cad cells, it is recommended only to recharge once the battery is discharged fully. Else the life will be reduced. By the way, Life is the number of charge cycles possible with a battery.
• 

  Jeffrey Arulraj

  lal

  Well, there is something to note there. More sources or more voltage and so more charging current doesn't mean faster charging. It means battery is going to fail soon. For every battery, there is a fixed maximum safe charging current. If this rating is exceeded, it means the life of battery is shortened. The charging current varies for different batteries like 1/100th of the Ah rating or may be 1/50 or 1/10. So more sources isnt a feasible way to charge the battery fast. The charging circuit should be designed to limit the charging current and the voltage.
  
  In case of lead acid batteries, once the battery is fully charged the charging circuit employs something called 'trickle charging' to keep it full. It is applying periodic current pulses at the battery terminals to keep the charge full.
  
  The best thing about Li-po or Li-ion are that we can charge them anytime without waiting to get them fully discharged but still have long life. Actually, tests show that the life is increased if Li-po cells are recharged when they are discharged to 60% or higher of full capacity. In case of Ni-cad cells, it is recommended only to recharge once the battery is discharged fully. Else the life will be reduced. By the way, Life is the number of charge cycles possible with a battery.

  Yeah that must always be considered friend But we are not going to be so unwise to use a direct coupling of source and battery We prefer to bypass the battery by a near short ckt to limit the current in the actual Ckt this prevents high current from entering the battery and issue is solved
• 

  Jeffrey Arulraj

  zaveri

  thanx buddy.
  
  the system of a battery and its charging sources, i think so, is analogous to a water tank.
  
  the battery is like the water tank, and has a particular capacity.
  
  the charging source are like the sources of water.
  
  now if there are two or more sources of water, the only net result is that the tank gets filled faster, but under any case the tank will not hold more amount of water than, its capacity.
  
  the same thing goes for a battery, and it cannot hold more charge than its capacity.
  
  right ?

  More or else same but keep a tag over what #-Link-Snipped-# says cause very high Ah rating is not good for any battery
• 

  Ramani Aswath

  zaveri

  Can a battery be charged by more than one source, such as a couple of generators or solar panels ? what happens if a battery is overcharged ?

  Even a discharged battery has some voltage left. It also has an internal resistance. Such a battery can be recharged only if the supply voltage is above the battery voltage at the time of charging. Normally charging is done with a constant current till full charge. After this only a maintenance current/voltage is applied.
  It does not matter about what are how many sources are used, so long as the charging current flows. If more than one source is connected simultaneously, what is implied is that these are in parallel and may have some conflict among themselves.
  
  Overcharging
  What happens in charging is that electrical energy is converted to chemical energy given by the relationship that one Faraday of charge produces one gram equivalent of the reactants. A rechargeable battery works on reversible chemical reactions. When a battery is fully discharged, all the original chemicals will have reacted to form the lower energy level chemicals. At the end of full recharge, these are reconverted into the original chemicals, which can again react to release electrical energy.
  
  When a battery is overcharged the excess charge goes to generate oxygen and Hydrogen gas at the electrodes inside the case. If enough is produced in a sealed case one can have an explosion.
• 

  lal

  Thats good, to employ protective measures. By the way my reply was mostly intended to the tank analogy. The tank may fill faster with many sources, but battery would fail.
  
  One of the biggest enemies of battery is the temperature. If the charging current is too high the battery temperatures rises leading to a shorter life span. This is true while loading the battery too. If the cells are loaded too much for long time, the temperature will rise.
  
  The charging current is limited to block the high temeprature rise. And the value of current is decreased further as the charging progresses.
• 

  Jeffrey Arulraj

  #-Link-Snipped-# and #-Link-Snipped-# true But I had this question in mind
  
  Why does it take more time to charge with lesser the charging current though the voltage is sufficiently high
• 

  Ramani Aswath

  The capacity of a battery is in amp hours. One Faraday is 96,500 Coulombs, which is 26.81 amp hrs.
  The voltage is only a driving force to push Coulombs into the battery.
  What is important for charging time is the rate of passage of Coulombs into the battery. That is Coulombs/sec = (amp.sec.)/sec = amps.
  So, lesser the amps longer the time for the same total Coulombs.
• 

  dossdss

  if i want to charge a 12v lead acid battery (1.2Ah) with linear regulated power supply (30v,2A), i keep voltage to be around 13.4v and current knob at middle position.. so should i use any current protection ckt in between and yes how should i design it ?
• 

  dossdss

  can any one plz help ?
  i am reading about this fact but not able to find the solution.