electic kW / diesel kW

Diesel powered trucks are equipped with deep cycle batteries. I've used and sold a lot of used ones from the vehicles I've salvaged and I've bought them new when I had to. Over the years I have known many people that have bought them new for solar applications and quickly destroyed them because either their protector failed to shut down before they were too deeply discharged or their solar system couldn't deliver high enough charges.

The original poster's original question addresses the fact that there is a lot of confusion out there as a result of the multiple ways in which outputs and capacities are described. I believe unscrupulous retailers and manufacturers are deliberately creating the confusion so that they can market inadequate products to the gullible. I am reminded of a light roof top boat with a battery powered electric trolling motor my father bought many years ago for hunting. He and his friend proudly cruised across a lake with it to previously inaccessable areas.On the way back there was a heavy wind and they couldn't get 20 feet from the shore with it. Unwilling to leave his new thousand dollar toy behind they jumped into the swampy water and towed it across the swampy edges of the lake. Several hours later they came home frozen and covered in mud. Over the years since them I've met at least a dozen other hunters that have shared his experience.

I do believe that there are alternative technologies out there that could significantly reduce fuel waste but there are also a lot of totally useless products in the marketplace that are being grosslly over rated by retailers as well. I have acquired a lot of them over the years.

 

There are plenty of sites explaining battery behavior. A true deep cycle battery cannot be used to start engines.

But I looked at the Exide website and see many types for North America that are sold as dual purpose. The "deep cycle" label justifies a higher price, nothing else. So your above statement applies to these products as well.

In my opinion, only Exide Orbital and Megacycle are true deep cycle batteries. You'll never find these in a truck.

 

There are major differences between conventional auto batteries and deep cycle diesel batteries.I've handled thousands of them and seen many of them after they have been broken open. Some car batteries have only a thin filament printed upon a plastic insert. Others have tissue thin plates that crumple as easily as tin foil. Deep cycle diesel battery plates appear to be 10 to 40 times thicker than what I see coming out of the average car.When I take automotive batteries in for scrap to my chosen broker I get between $6.00 and $30.00 each for them. The broker tells me he sometimes loses money on the six dollar minimum per battery he pays but his margin on the heavier batteries more than compensates for losses on light weight batteries. The value of the scrap battery is in the lead.

There are major differences between deep cycle diesel batteries and the average car battery. Whether the term deep cycle is a misnomer or not I don't know but I do know there is a very substantial difference between the two.When I find broken open deep cycle marine batteries they seem to have the same heavy plates as the deep cycle diesel batteries.I can't visually recognize alloy differences but apart from that they look and weigh the same.

 

Yep, Q, you're probably right about that. There is a lot of junk out there, mixed in with a few really well-engineered gems, and it becomes hard to pick the wheat from the chaff.

It's also probably worth noting that good engineering (for a particular purpose) plus misguided marketing usually results in perceived sh*tty engineering. The trolling motor is a perfect example- it's perfect for what it's meant to do (pull an 18' sport boat along at 0.8 knots for an hour or two) but is easily mis-marketed into disaster (as in Q's story above).

 

Maybe people should buy batteries by weight or by density.

 

"Maybe people should buy batteries by weight or by density."

The best is to purchase the batts FOR the Service needed

Starting batts excel at creating loads of amps , with small voltage drop for a few seconds. Discharge starts below 60% full and you have FOREVER decreased their service life and capacity.

Deep Cycle , golf cart or industrial fork lift batts can be regularly discharged 50% of their 20 hour rate .

BUT they should be recharged soon.

Batts MUST be recharged to 100% full, (either style) or they will loose capacity and service life.
This is always a slow process for the last 15% to get pushed in.

FF

 

Thats true, there are significant differences beween a ordinary starter battery (what you name "auto battery") and a deep cycle battery. (diesel batteries are not on the market).

But you have not seen a single one of the latter in any truck you are referring to! No matter how many thousands of them you have seen or replaced, they ALL have been simple starter batteries (most probably of different quality), not deep cycle! A deep cycle does not fit to start your truck (and a starter battery does not bear with your hotel load).
Therefore your "deep cycle diesel" battery is either a marketing gag or just phantasy.

To get a better idea about the topic you might like to have a look here:
http://www.victronenergy.com/support-and-downloads/white-papers/
download "energy unlimited" and enjoy a good read.

Regards
Richard

 

forklift batteries

These are true deep cycle batteries. Not too hard to get 10kw out of one of these packs for an extended time. Will weigh a couple of tons but not expensive second hand (like EBay). I understand the (home) solar community is using these because of cycle life and their low second hand cost. Cost seems to be under $0.10 US. Proven, but heavy technology. Also, they do release hydrogen - be careful.

 

Deep cycle batts will indeed start a diesel . The difference is the plate surface area.

The D-C have few quite thick plates to handle the cycling so their surface area is limited.

However as house batts there are usually a number of batts , so the combined surface areas is similar.

It may take 6 deep cycle batts to have the plate area of two start batts , but folks with trucks or boats that LIVE off the house set have them anyway

For years we operated with NO starts , hust a big house set with no problems.Startibng a 6-71 with the house at 50% or less.

Today it could be more difficult as the engines with electronic injection MUST have great voltage to operate.

On trucks its (2) Series 31 that is usually chosen.

The simpelest way to decide what the Mfg thought the batts were for is to read the rating.
If its CCA (cold crank amps) its a start batt ,
If the rating is a "20 hour rate" its a deep cycle.

Deep Cycle Batteries
www.trojanbattery.com or www.dcbattery.com/rolls.html


Or from the charger site,

2.3.3. The flat-plate automotive battery (flooded) This is the battery used in cars. Not suitable for frequent deep discharging as it has thin plates with a large surface area – designed purely for short-term high discharge currents (engine starting). Nevertheless flat-plate heavy-duty truck starter batteries are often employed as house batteries in smaller boats.

2.3.4. The flat-plate semi-traction battery (flooded) This battery has thicker plates and better separators between the plates to help prevent buckling of the plates and shedding of the active material under cyclic use. It can be used for light duty cycling and is often referred to as a ‘leisure’ duty battery.

2.3.5. The traction or deep-cycle battery (wet) This is either a thick-plate or a tubular-plate battery. Used for example in forklift trucks, it is discharged down to 60-80% every day and then recharged overnight – day after day. This is what is referred to as cyclic duty. The deep-cycle battery must be charged, at least from time to time, at a relatively high voltage. How high depends on chemical and constructive details and on the charging time available.

FF

 

Your replacement for a 40 kW diesel would be (more or less) a 40 kW electric engine. Fortunately, for the electric engine salesmen, physics do not apply to their engines. But physics might apply to yours!

 

Mr Know It All, you are under the incorrect information.

Electric engines are so much more efficient than IC, especially regarding torque, that comparison of horsepower ratings have little relevance.

For example, on "Lean Green Machines" TV show, a worked modern V8 RangRover 4x4 couldn't accelerate over 100m or handle a rough track climb as fast as an old Land Rover with a 20HP rated electric motor! Suck on that comparison and over 250 HP in a modern suspension 4x4 is beaten in torque challenges by 20HP of electric motor. The Range Rover did beat the Land Rover 'just' in the twisting track and rock climb race and the articulation challenge, where its modern suspension and handling made a huge difference.

HP and Torque are different values. Efficiency and relevance to the task is the reality. Electroic boats turn large high pitch props that an IC (diesel or petrol) would stall trying to get turning. These props have much less 'slipage' or cavitation in water and are quantum amounts more efficient.

You need to learn more about motors used to drive Electric Vehicles on land or water, then you will not be so classicly misinformed...

 

For example, on "Lean Green Machines" TV show, a workled modern V8 RangRover 4x4 couldn't accelerate over 100m or handle a rough track climb as fast as an old Land Rover with a 20HP rated motor!

IF its an old gas motor the "hp" rating has no reality , it was a con for the TAX MAN.

FF

 

I give up on you guys. You are fixated on your misapprehension that "Gas is good, electric -bad!. Grunt, grunt!"

Trying to reason with you about the benefits of electic drives is hopeless. The fact that modern cruise liners, with their tight budgets, use diesels only to make electricity for the ship and their MORE EFFICIENT electric pod motors is lost on you..

Just remember that the world isn't flat anymore either!!

 

That statement is wrong, sorry.

Cruise ships have a very high Hotel load which makes it sensible to go DE, nothing else.

Regards
Richard

 

Who is Misinformed?

I almost never do rough track climbs with my boat and must admit I don't know if an electric motor would propel it better in that situation.

I like sailing and hate the diesel engine in my boat. It is noisy, smelly, need a lot of maintenance, etc. Some electric motors are maintenance free. The problem is that I cannot buy reasonably priced batteries and my extension cord is only 100 feet long. So I end up with an IC anyhow. Connecting the IC directly to a propeller (via a gearbox), is the best solution for me, since it requires the least maintenance.

Despite that I want to replace my engine with an electric motor, I don't resort to wishful thinking.

I think you don't understand what torque and horsepower is. They are DIRECTLY related, i.e., if you know the torque at a certain RMP, you can calculate how much power the engine is producing at that RPM.

The props you are referring to is only a bit more efficient. Also very large props don't fit on many sailboats. A gasoline or diesel engine have no problem turning them. It is only a matter of gearing.

I will also try to explain WHY an electric motor can accelerate so well. Since the torque (at the RPM) x RPM is the power, if the V8 is not allowed to reach high RPM, it will not produce high power. The electric motor may reach it's 20 HP at low RPMs and hence the average power over the competition might be equal for the V8 and the electric motor. If the V8 had a different gearbox (such as CVT), it could run at an RPM where it produces more power. You must remember that there are many other factors affecting speed as well, traction, weight, etc....

In my boat, my diesel is allowed to reach the RPM at which it produces the maximum power. I need (but very seldom) the maximum power in certain situations and if I replaced my diesel, I have to buy an electric motor with the same MAXIMUM power.


Efficiency and torque have no direct relation. Efficiency is how well you convert energy, such as the energy in diesel to movement, or energy in batteries to movement.

If you read my post thoroughly, you will understand why "high torque" is more important for cars than for boats.