Solving the charging problem for hybrids

Replies

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  Ramani Aswath

  The issue is power transfer. The time taken to put in X amphrs charge will be independent of whether it is one large battery of X capacity or 20 batteries of x/20 capacity for a given type of battery.
  There have been concepts describing changing a power pack at outlets. The problem has to do with life of batteries. If I pull in to a charging station with a brand new power pack needing to be charged, I may not be too keen on geeting a charged pack at the end of its life. This concept was proposed for power packs based on primary cells, which cannot be recharged. The chemicals can be recycled off line.
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  Gurjap

  Interesting argument about the charging time. This kinda crossed my mind too, and forgive me for being naive, but if we were to simply upgrade the voltage and amperage being applied to a battery, wouldn't that decrease the time require to charge it to a specified kwh rating?
  
  Also, an array of discrete batteries makes sense in another way: if a single battery malfunctions or is otherwise damaged, it would be easier to replace. Also, I believe (can't cite sources right now) lithium ion batteries last longer if they are discharged completely and then charged, as compared to charging them halfway depleted. Having an array would make it easy to discharge one cell completely, and then another, and so on.. And ensure better overall battery life.
• 

  lal

  Also, I believe (can't cite sources right now) lithium ion batteries last longer if they are discharged completely and then charged, as compared to charging them halfway depleted.

  Actually it is the NiCd cell that lasts longer if charged and discharged as you mentioned. Lithium batteries would provide a longer life if they are charged within 50% of their total capacity.
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  Gurjap

  I do believe you are right about that. Looks like recycling chemicals after, say, a hundred charges might just be our best bet.
  
  So, what other ideas on solving this problem?
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  Gurjap

  Following up on this thread: I did some research on charging batteries (Lead Acid ones, specifically) and as it turns out, you can't just ramp up the supply current while charging and hence reduce the time. It looks like doing that will only charge the electrolyte that is closest to the electrode and leave the rest as it is.
  
  So I am thinking, and forgive me if this sounds retarded to the electric experts, why not use some acid resistant pump to swirl around the acid while charging the battery? Would this reduce charging time?
• 

  Ramani Aswath

  It looks like doing that will only charge the electrolyte that is closest to the electrode and leave the rest as it is.

  Electrolyte cannot hold any charge. In a rechargeable battery a reversible reaction takes place. During discharge the reaction goes to a thermodynamically less energetic state. The heat of reaction is released as current through the external circuit. During charging the reverse reaction reproducing the original high energy state reactants takes place consuming theoretically the same amount of energy as released during discharge. In reality efficiency is less than 100% and so some energy is lost.
  
  If too high a charging current is used usually some other irreversible reaction also takes place, leading to products that do not revert. In lead acid batteries sulphation takes place. The lead sulphate cannot take part in the electrochemical reaction
  
  I am afraid that swirling the electrolyte around will not help much.
  There will be some benefit because the ions in the acid have to move by diffusion, which will be accelerated by the pumping action. If I can hazard a guess, the energy spent on the pump may not be recovered by the benefit accrued.
• 

  Gurjap

  A.V.Ramani

  Electrolyte cannot hold any charge. In a rechargeable battery a reversible reaction takes place. During discharge the reaction goes to a thermodynamically less energetic state. The heat of reaction is released as current through the external circuit. During charging the reverse reaction reproducing the original high energy state reactants takes place consuming theoretically the same amount of energy as released during discharge. In reality efficiency is less than 100% and so some energy is lost.

  Of course, I meant 'charge' in the general sense. Correcting my own words, only the electrolyte that is nearest to the electrodes would transform into a high energy state while charging at a high current rate.
  
  As for the energy loss, I suppose it cannot be helped.
  
  

  I am afraid that swirling the electrolyte around will not help much.
  There will be some benefit because the ions in the acid have to move by diffusion, which will be accelerated by the pumping action. If I can hazard a guess, the energy spent on the pump may not be recovered by the benefit accrued.

  Good point about the energy efficiency. But maybe if the battery were to be large enough, or/and it were to use a gel electrolyte ..?
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  oprime

  #-Link-Snipped-# Check out this website - #-Link-Snipped-#
  This company swaps out depleted battery packs with fully charged batteries.
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  Kaustubh Katdare

  oprime

  #-Link-Snipped-# Check out this website - #-Link-Snipped-#
  This company swaps out depleted battery packs with fully charged batteries.

  BetterPlace is doing an excellent job and I think the technology they have've developed has a great chance of being adopted in a smaller sized country. Israel is very small in size and it's possible for the company to setup the battery changing station throughout the roads. But not an ideal solution in bigger countries - as the cost of setting up stations would be huge.
  
  PS: Just got nostalgic about my visit to Better Place -
  
  

  Kaustubh Katdare

  Photos from the "Better Place" - the 100% electric car company -
  
  
  
  
  That's me, getting ready to accelerate!
  
  
  
  
  
  What do you think, folks? 😁

• 

  Gurjap

  A.V.Ramani

  I can hazard a guess, the energy spent on the pump may not be recovered by the benefit accrued.

  It just came to my mind: we are not hunting down efficiency while charging from an outlet, we are trying to reduce the charging time!
• 

  Gurjap

  oprime

  #-Link-Snipped-# Check out this website - #-Link-Snipped-#
  This company swaps out depleted battery packs with fully charged batteries.

  Thank you for this reference. I did check it out.
• 

  Gurjap

  @kasturbh what was your overall "feel" of the company and its Oscar? How did the car handle? How was its noise, its acceleration? Did it have regenerative braking? How was the "feel" of the regen brakes?
  
  Aw man, I have a thousand questions. 😛
• 

  Kaustubh Katdare

  Gurjap

  @kasturbh what was your overall "feel" of the company and its Oscar? How did the car handle? How was its noise, its acceleration? Did it have regenerative braking? How was the "feel" of the regen brakes?
  
  Aw man, I have a thousand questions. 😛

  The company is definitely doing a great job. I had never driven any electric car earlier so it was a pleasing experience for me. The car is of course totally noiseless and you won't know whether the car is on or not if the dashboard lights don't tell you.
  
  The acceleration was beyond impressive and it's expected because they've really amazing electric motors producing high torque. I couldn't get the technical details of the drive system though.
  
  The car performed well on turns and since we drove the car on the test track, we had to follow speed limits 😁. The braking system was second to none. Overall I'd say the car would score above any IC engine any day.
  
  However, I think electric cars may not make it to India in sooner future. The distances we cover and the networks of charging station would prove to be a very costly affair. It's a great ride in the city though.
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  Gurjap

  You're a lucky guy. Mind me asking hiw you ended up in Israel in the first place? 😀
• 

  Kaustubh Katdare

  Gurjap

  You're a lucky guy. Mind me asking hiw you ended up in Israel in the first place? 😀

  #-Link-Snipped-#