The battery thread...some facts please

to many battery's was the first reply i gave to a member here asking for an at first sight interesting see trough drawing of a formule 1 offshore racer
got this request these drawings had to be used for a maritime presentation on electric propulsion showing the technology to the whole nautical world and we all could benefit from that
a F1 offshore racer drawing with solarcells on deck and fuell cells below. the solarcells came of easy but contact insisted on having some for dashboard licht
than i realised hydrogen tanks dont fit well in a F1 boat and dont deliver the 2x1200hp it wants, i had qeustions like what unknown to me tech was collected

it would have been a joy drawing lichtning strikes over a F1 victory boat but "whats the problem?" was the reply i got in my mail
after saying this asked pic needed more than a thousend words to draw. contact fell silent, checked and it wasnt a kid, well allrite with me
but an electric F1 victory boat kept naggin and later checked on solid oxide fuel cells but that technology is even less ready than electric propulsion
i have to learn, buy a deep charge, blew a gel but anyone here with some more bright ideas for an F1 offshore technology demonstrator? granted, its a great idea

 

Leaving a battery in a discharged state is known to damage the battery. It is particularly true for lead-acid batteries (where lead sulphate crystals form if discharged state) and for Lithium-based batteries (which will experience 60% and more capacity loss if held discharged for prolonged periods of time). The only exception I know of are NiCd batteries, which have to be fully discharged before re-charging, to avoid the so-called "memory effect".

 

" batteries seem to be a major hybrid stumbling block."

Right, little change in 120 years , even with decades and billions of R&D blown.

Makes those 200,000rpm flywheels look better and better.

At least they don't die an expen$ive early death when unused!

FF

 

Know that but I expect the Volt has a system which keeps the propulsion battery from being unintenitionally fully, 100% discharged.

I'd still like to a reference. For those outside the US the Volt has become a topic of disparaging comments in the US during the current political season..

 

Guess the problems might arise, even with a similar safety system, if the car is left parked for a long time with drained batteries.
The problem, however, in this case sounds more academical then real. If someone spends $39.000 to buy a car like that, I guess it is very probable that he will be instructed about it's limitations, will take care of it and will follow the charging instructions. Not an absolute rule, though...

 

Nicad memory is a myth. There is some truth to it but not as stated or commonly believed.

-Tom

 

Tom I don't know what do you intend as "commonly believed". This site explains very well the problem and the (partial) cure: http://batteryuniversity.com/learn/article/memory_myth_or_fact

 

what needs to be done is use lead/acid bats as keel-bulb ballest or at least

dagger-board ballast.

Sure, it will an another maintenance issue and require a whole new breed of seals, but I've got infinite faith in design, mechanical and construction getting cheaper and better maybe 1/20 as fast as computers, which is still a lot.

Have a fat dagger board able to have the bats changed out from the top with just enough of a seal to prevent splashes from getting in.

A bunch of bats in a bulb keel would require much better seal of course, and only be accessible during haul outs.

Fill any extra space in the battery compartment with cut to fit lead sheets.

If I was MacGregor I'd replace the 300lbs of lead in the bow with 6 big marine bats. They would function as ballast same if dead, AND in emergency you could toss them overboard.

Sure, batteries don't have near energy storage needed for boats to go anywhere, but with a solar panel and typical weekend use, a hybrid keelboat could get out and in the marina without firing up the engine.

Plus, lots of little low cost household appliances could be used instead of super expensive specialized boat gear.

What is the density of your typical lead/acid marine battery VS solid lead?

 

Lead is 11.34 g/ml

-Tom

 

Yes, you can do it for either VERY large boats, where you have the space and displacement to play with, (E.g. the old diesel-electric subs); or very small boats with limited range. What you can't do is to go fast for a long time. You just can't store enough energy.

I like the idea of a "hot-swappable powerpack" though. You'd just need a crane to get it in and out. However, if it became a standard then it would fix all the charging and longevity problems. Just pay for each recharge used, and that cost pays for a new pack when needed.

The NiCAD "memory effect" is not a myth. It's very measurable. Discharge tests show significantly less power from charging a partially discharged cell than charging a fully discharged (to 1.1V) cell. That's why for control-critical applications it's good to give the cells a few full cycles occasionally. NiMH has pretty much replaced NiCAD, though, so we shouldn't have to worry about that too much.

Tim B.

 

If battery tech hasn't improved, how do my camera, my phone, and my laptop run 5x longer on a charge than in the year 2000? And charge faster to boot?

 

1st Agree with BPL - there has been huge improvements with lithium based batteries. Powertools anyone? modern cordless drills are amazing compared to previous generation.

But still the price/weight/number of cycles doesn't make them viable for many applications.

 

It's still two bits of metal and an electrolyte. It's just that the electrolyte changed. And the metal. In fact, it's not even metal. So yeah, a modern Li-Ion/Li-Poly battery bears a passing resemblance to a voltaic pile because it does the same job; only much, much better.

Tim B.

 

Cordless drill is a prime example. My first cordless drill had a battery pack twice as heavy. I had to change and charge it so much the clips broke off one. It always got tired before I did. It took hours to charge up. The drill bit would turn slower and slower until I set it aside and waited for the second battery to green light. Huge improvement now

 

What does it mean when a 12 volt battery is now 9.5 volt. Can I still use it as 9v battery or is it going to zero soon?