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Lead acid battery technology

06/14/2008 3:10 PM

Despite over 100 years of use there still seems to be a mystery surrounding lead acid battery technology. What factors will prevent a new battery from absorbing the full 100% output of a smart charger. AGM are advertised as being able to absorb current at a rate even faster than flooded wet cells. YetI have repeatedly seen instances where the depleted battery cannot accept even the C/4 rate. Why?

Cabling and connectors are up to spec if not over sized. Not all batteries exhibit this but many do. Manufacturers deny any knowledge of the issue, preffering to blame other causes.

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#1

Re: Lead acid battery technology

06/14/2008 3:34 PM

Hi elnav,

I don't know how it is now but back around '73 I worked in a machine shop in Tucson. Our main product was repair parts for F16s. Remember when they kept losing the wings? We made the struts to fix that. Well anyway, we got a job into the shop to build new plate molds for lead acid bateries. I dont remember what company it was for but the problem they were having was with bubbles in the lead (or plate material I should say). I don't know what came of it because the gas crunch and various other circumstances closed the business. Also the F16 contract was done. Perhaps they are still struggling with thier plate technology.

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#2
In reply to #1

Re: Lead acid battery technology

06/14/2008 3:48 PM

Could be. Although 35 plus years later should have seen marked improvement in that area. Bubbles in the plate mush as they are formed would reduce storing capacity but I do not see how that would necessarily affect acceptance rate.

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#3

Re: Lead acid battery technology

06/14/2008 3:55 PM

I remember in the late 60's my Dad was working on some military stuff that used lead acid batteries and ended up going to the battery manufacturer to help sort out more conssitent plate manufacture...
I never heard the full story 'cos a) I wasn't that interested at the time b) It was classified.... it was probably all tied up with alien technology, magnets and hydrogen gas production

Del

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#4
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Re: Lead acid battery technology

06/14/2008 9:17 PM

Must be alien technology. I specified AGM batteries for a project. So what does the chinese ship yard install. Gel!! Evidently they don't understand the difference. To add insult to injury they stole the electrical design ( drawings are marked "copyright") and used it on another vessel. Now that owner is asking me to trouble shoot the mess and figure out why the system doesn't work as intended. I notified the other owner who had paid me for the design and he is going to insist on contractual compliance.

AGM have extremely high acceptance rate. you can charge them at C3 or even C1 although not too often. Gel have a much lower acceptance rate so consequently require much longer recharge time. Not only does that involve running the genset for much longer intervals but wastes fuel. The 9kW genset is driving a 3kW charger so it is undeutilized and the extended run time under light load is harmful to the engine.

What amazes me is that most people in the industry don't even understand the workings of the batteries and the associated chemistry. When you ask the suppliers for details they say they don't know. Like you said, it must be alien technology

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#5
In reply to #4

Re: Lead acid battery technology

06/15/2008 9:06 AM

That is typical Chinese business.

It is best to supply them with drawings with several failures in them and go and make the corrections yourself each time, do not let them see the final corrections.

Or not let your drawings go out of your hands without a contract specifying everything down to the last pin, so you can sue them in a Chinese court if needed AND WIN!!!

What is not in the contract WILL be used to your personal disadvantage.....they are well known in this area......give them your hand and you will find your arm missing, if it is not contractually forbidden....thats Business in Bejing!!

Look at the Chinese copies of Mercedes and even the Hummer......down to the last nut and bolt!!!

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#6

Re: Lead acid battery technology

06/15/2008 1:43 PM

ok i have to ask is anyone following the new batteries from firefly.com ?

these look ok but wonder if they have the idea down of still testing

Richard

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#7
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Re: Lead acid battery technology

06/15/2008 2:07 PM

I am, but am not willing to commit a design yet to these. If they fail to perform as promised what do you do when you have to switch to more conventional designs.

In most cases the weight and volume would be so much greater that it would be impossible to install the same capacity using conventional technology.

We are however giving some consideration to using the Firefly batteries on a pure electric 30 foot boat design.

BTW Richard; someone approached me about an inverter product that sound similar to yours. He claimed the inverters are made back east by a hutterite or mennonite group. They offer 2.5 5.0 8.0 and 12.0 kW capacity as an inverter only function in a portable cart containing North star batteries. Any connection?.

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#9
In reply to #7

Re: Lead acid battery technology

06/15/2008 3:06 PM

Elnav,

Do you have a website for your company. It sounds like you're into some pretty interesting stuff.

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#8
In reply to #6

Re: Lead acid battery technology

06/15/2008 3:03 PM

Magnacoaster,

Do you have the website (other than Firefly.com). For some reason I'm not able to get it to come up.

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#10
In reply to #8

Re: Lead acid battery technology

06/15/2008 3:11 PM

seems i did not check it right

http://www.fireflyenergy.com/

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#11

Re: Lead acid battery technology

06/15/2008 4:31 PM

try here; www.windsun.com/batteries/battery_FAQ.htm

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#12

Re: Lead acid battery technology

06/18/2008 2:24 AM

Lead Acid battery has PbO2 in positive plate and Spongy Pb in negative plate when in charged condition. They both become PbSO4 upon discharge. So the electrical enrgy is converted to chemical enrgy. There some evolution of gas also.( which is a loss)

AGM is separator between the plates : There are other varities like PE .But the effect of Separator in loss of efficiency in charging is not much compared to Alloys used for the Grids. The charge acceptance varies a lot with types of alloy.

Next comes the Chemistry. In a new battery when you put the acid there is exothermic reaction. So enrgy input gets converted to some heat.( so some loss here) As you continue charging , Initially the charging proceeds well , then a back emf developes so the Charging voltage has to go up to overcome this back emf , so that charging current flows. Say intially if you measure the voltage between the plates in a cell , you will get around 2.5 Volts , but after nearly 50 % charge the charging voltage is going up accross plates to 2.90 Volts or so . This is for the new battery charging. Now as the charge proceeds , you will find that to have complete charge some Dissociation of water is inevitable and bubbles coming out. So this consumes additional energy. For a AGM batterry majority of this Oxygen and Hydrogen produced gets recombined to Water , so one does not have to top up. And batteries are sealed with a safety valve , which can release the gases if the recombination is not full. So the AGM is for preventing water loss.

let us discuss about charging /current time. Basically lead acid battery charging is more effcient in terms of the active material getting reconverted if the duration is long. This long duration requirement is the major obstacle of using Lead acid batteries in Hybrid cars. The Charging process is much slower than Ni- MH or Lithium -ion. But cost/unit wise it scores over al others overall.

Lastly if it is not a new battery and a flooded battery, the acid can slowly stratify ( a property of Sulphuric acid) and one can get much lower capacity progressively.

The above is a simple explanation of the Lead acid battery Charging efficiency. There are many aspects in charging eg temperature/active material content/bonding of activematerial with grids/inturrupted charging/Pulse charging etc etc. And it is not mystry anymore than what it was 2/3 decades back.

Now Chinese.- Well have we been able to prevent copying ?. NO. They copy well and make it much cheaper. (But they can copy only as of now and can't improve upon.) So for non chinese this is a huge threat( there have been many "copy countries" - dont forget Japanese who were original masters then Koreans and Taiwanese ) . Indians too, now but with some chages in design and improvements. Why we talk about Chinese ?, because we are mostly affected by the Volume of the products /large scale availability. Now many western makers are sourcing mechanical portion from China and getting electronics added up at their own country and selling at a parllel cheaper price along with the original fully made equipment.One has to survive !!

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Andy Germany (1); Anonymous Poster (1); chakraborty ranabir (1); Del the cat (1); elnav (3); Magnacoaster (2); Shadetree (3)

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