How long should a battery last?

Give it up mate, I understand and agree with your arguments, just good sound logic and 'O' level physics is all one needs.

If that Ploughman geezer said 2+2=5 you could try all day to persuade him otherwise and you'd fail. I'm afraid he has the mind of an immature teenager at times.

Julian.

No - I was specifically asking about your charging point, so don't try and confuse things with some overall picture. . You've been making such broad claims I simply want them explained. You haven't quite claimed it makes a superb cup of tea - but that wouldn't surprise me.

No alternator has a fixed voltage output.

OK then. This should be interesting. Please show the calculation which determines the charging rate from the internal resistance of the battery and a fixed voltage output from an alternator. Including the result...

Oh dear. ;-)

You think car electrics comprise of pure DC? And niggle about the number of zeros?

I'm not the one making the claims.

When I see your calculations for 'your' charging system a comment might be appropriate.

Right. You certainly seem good at insults.

Batteries technology has more to do with chemistry than physics.

Thanks for adding something useful to the debate.

Err you dont understand how zenner diodes and alternators work then either do you. I cant be bothered any longer you are truly clueless.

Its rather well known even to school kids, At least the less dim ones its called OHMS LAW!

You truly are absolutely clueless. An alternators ac output is simply rectified and controled in voltage to whatever voltage the the value of the zenner chosen was. Recently that is around 14.4 volts.

As far as starting and charging are concerned for all intents anp purposes its as close to DC as matters. There may be a tiny amount of noise from the alternator but its of no consequence here at all.

I dont make claims unless it can be supported by fact and figures. I leave that to you with your clueless physics and knowledge.

Clueless.

Not at all. All based on the facts as seen on this thread. You are doing it to yourself.

I found you a nice simple page...

Although I doubt you will understand that either. Charging at 14.4 over your flat batteries 12.xx with the batteries internal resistance being the thing that controls the amps that flow and the energy wasted as heat.. Ohms law is what charges your battery and determines the current that flows into your battery.. Even 12 year olds can understand that.

Dave's not wrong though - you're too busy blustering to see his points. However it's all a bit angels-on-pinny.

The main point is the one which you almost tried to agree with - that even if they are as great as you describe, these posh batteries aren't necessary or cost-effective for the vast majority of car users. Except you can't quite bring yourself to say it.

There is the other bit you conveniently ignored which is that Dave did say he'd met Optimas in a professional capacity, and they'd not performed any better than others....

No I completely agree. I took issue with the "con" statement and all the special "dave" versions of physics! And the fact that he claims (without understanding any of the electrical parameters) that they are not better when they clearly and provably are.

Its free choice. I wouldnt use anything other than optima or hawker AGMs because they are better and I can afford to. Actually I cant afford not to like a great many others... But I'm not forcing anyone to use them.

Because he doesent understand what they are good at. Low internal resistance is extremely important for heavy starting duty but pretty irrelivant for what he was doing where something like a high capacity for size and weight with huge 1000 cycle capability and huge price advantage was what he really needed.

EG a Elecsol battery or similar would have been better here. S*it at starting but ideal for what he needed. But since he doesent understand things too well as evidenced by this thread he chose very unwisely. He didnt need huge currents and high USABLE capacity. He only needed small currents and more capacity.

The point being that he does not understand still that the actual usable capacity of a battery, the ACCESSIBLE power, depends on load (amps) and internal resistance. Wheras if your load is low as his was an optima is totally wased. Bigger capacity cheaper batteries in the same case size are available. The fact he bought optimas to do that job simply proves he doesent understand much about batteries.

Thanks for confirming you're all mouth and trousers.

I was asking for the calcs so even you would see where you'd gone wrong.

No - I wanted to see *your* calculations. Not another website. You claim to be such an expert it shouldn't take you a moment - and after all you've posted screeds on the subject.

It just says the same as I did but has "pictures". Thought you may get it a bit easier.

I dont need to calculate anything because its pretty obvious to anyone with a clue I am not wrong.