Beware Charging Dual Battery in D4.

no the intent of that post wasnt to post the vehicle OEM spec for the SOC of the battery but more to point out that the newer batteries do the same "work" at a much lower SOC than an older battery.

Ca/Ca batteries have been around for about 10 years now the information should be out there but as the calcium batteries werent widely used outside of heavy industrial and exotic use for the first 5 years or so while the battery tech cheapend up

I've always maintained that you shouldn't discharge a lead acid battery (regardless of if its open, closed, sealed, calcium, SLA GEL, AGM or other) below about 60% soc to get maximum life and reliability out of the battery.

if you take the voltage at various stages of dischage from an old school flooded cell and a newer calcium "sealed" battery you might find it looks something like this (and yes these are made up numbers just to emphasize the point but the pattern is similar to in real life)

old school V, soc %, New school battery V , plain english as to what the expected fail point is

12V, 100%, 12V
11.5V, 90%, 11.9V
11V, 80%, 11.8v
10.5V, 70%, 11.6v, at this point if you had a new engle/wayco set to its most conservative setting it would turn off on your old school battery you might still be able to start an electronic car or a diesel
10V, 60%, 11.3v, at this point an older battery does not have the ability to power up the ECU if its cutout voltage is set to 10.5V it may crank the engine over but it wont start you probably wouldnt get a diesel to start
9.5V, 50%, 11V, on an old school battery an engle/wayco on its most agressive power use setting will have shut down and your ability to start an old school high compression petrol engine is questionableand is now at the point where its going to fall off of the voltage curve with additional loss of SOC dropping the voltage at an exponential rate.
8.5V, 40%, 10.6V the old school battery will struggle to start a low compression petrol
7V, 30%, 10.2V, the old battery will struggle with anything resembling a decent load (think headlights and parklights not startermotor) and the newer battery is now below the cut out voltage for you ECU but should still crank the engine over well enough for a start if the ECU didnt cut you off. The new battery is now going to start dropping voltage at an exponential rate with loss of SOC.
5v, 20%, 9.5V your old school battery is basically useless unless you have 2 of the same and can remove them and wire them up in series to get your start. The newer battery probably wont start a diesel but should still be able to start a petrol engine providing the ECU lets it or its old school
3v, 10%, 8v, the newer battery wont start much but will still give you your lights.

If you plot it out on a graph youd notice.

the older batteries voltage drop is linear for longer than the newer styles battery but the voltage drop rate is steeper. The newer battery is not completely linier but it stays above the older school batteries curve.

lets substitute SOC for battery health..

the old battery still falls off faster than the new battery BUT.. its ability falls off in the linear section of discharge before it hits its exponential drop. The newer battery is starting into exponential discharge and is well into the curve before it fails as a battery.

I know its not entirely accurate but for 8 oclock on saturday morning with no coffee its the best Im going to do.

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Originally Posted by Graeme

They didn't put a big enough one in the D4s for the showroom floor, with so many of them with a flat battery from people opening the doors for a squiz.

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....and the same could apply to camping - people getting in and out of the car for various reasons. Having the battery half flat on top of this sounds risky.

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Originally Posted by drivesafe

So Wilbur, what your saying is that 10% difference between what I use, 50% and the 60% that Dave has quoted is a huge difference but 40% lower than your claim of needing a fully charged battery to start a vehicle is not that much different.

Mate, as previously posted, you wouldn’t know what the truth was if it jumped shook your hand.

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But surely there must be some reason why Land Rover spec such a large (expensive) battery? If half the capacity was adequate in all foreseeable situations, surely they would save the money and weight and fit a smaller battery?

First of Wilbur, the LR battery is NOT an expensive battery, it is in fact quite a moderately priced battery.

An Optima of half the size and twice the price will do the same job.

Next, again stating that a 10% difference is worse that a 40% difference is nothing but out and out dishonesty.

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Originally Posted by drivesafe

First of Wilbur, the LR battery is NOT an expensive battery, it is in fact quite a moderately priced battery.

An Optima of half the size and twice the price will do the same job.

Next, again stating that a 10% difference is worse that a 40% difference is nothing but out and out dishonesty.

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But even so, surely a battery half the size would be cheaper? Why would they put in a battery twice the size it needs to be?

Not sure what you mean by 10% and 40%?

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Originally Posted by Wilbur

But even so, surely a battery half the size would be cheaper? Why would they put in a battery twice the size it needs to be?

Not sure what you mean by 10% and 40%?

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I would suggest the primary reason for choice of battery size would be to be adequate for 98% of normal customers or suchlike, ie to reduce warranty claims to an acceptable level. Most new vehicles get used daily but enough get used 1-2 times a week for this to figure in engineers calculations of battery size. This is how manufacturing works, to optimise production for lowest cost overall.

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Originally Posted by Wilbur

But even so, surely a battery half the size would be cheaper? Why would they put in a battery twice the size it needs to be?

Not sure what you mean by 10% and 40%?

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the reason they put such a large battery in is simple..

its a requirement for the electrical system to operate the vehicle for a given period of time following Alternator failure. ((Duh hows the battery supposed to help you in an emergancy if its dead?)

its also a requirement for the battery to be able to start the car reliably from a lower state of charge.

sure a battery thats just about big enough will start a vehicle from a fully cahrged condition but wont do it from say 80% charged.

you can start a td5 from a motorbike battery if you want to... try running a td5 for 30 minutes with the alternator disconnected from the same motorbike battery.

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Originally Posted by Wilbur

But surely there must be some reason why Land Rover spec such a large (expensive) battery? If half the capacity was adequate in all foreseeable situations, surely they would save the money and weight and fit a smaller battery?

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At -40C, very few batteries seem large enough, particularly when you are on the Tundra; it is dark all the time in the winter, and no go means you probably freeze to death in less than 3 hours if not properly dressed. Also my Land Rover is not by any means the only LR3 around here - there are many to the north in the land of the midnight sun and that means dark 24 hours per day and cold for five months a year, and then 24 hours of daylight for about 2 months solid and still cold.

I installed a second battery, the same CaCa as the main starting battery, using the Traxide system, not because I have a fridge to run, (that we get free here), but because I do not wish to look like the contents of the icebox.

Here in the Great White North, there is no such thing as too large a battery or battery's. It was the physically large battery and the provision for a second that most impressed me when I was looking for a new vehicle. This is the reason all Ford, Chev, and Dodge pickups here also have provision for a second battery, and most of the true field work trucks are ordered that way - nothing special so to say, just what is needed for the job - that and when in the field, we sometimes do not turn them off - some not all winter, (the diesels), and they remain running when being fuelled. I might also add the the LR3 has a very good heater and yes, my 3 to date, has always started so I guess the conditions were foreseeable by Land Rover.

I attached a typical picture of the North in the late spring; can't take a picture in the winter.

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Originally Posted by bbyer

not because I have a fridge to run, (that we get free here)

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:lol2: :lol2: :lol2: :lol2:

Also we do not need a fridge to carry around treats for the polar bears either. Just peering under a hood can make you the treat. They are not herbivores and like their meat fresh, mostly seals, but they are not fussy.

Even the small one in the picture below when standing towers over an LR3. Gaining entry into anything smaller than a Kenworth is pretty easy so one does not want to be just parked anywhere.

This one is a small one, but it is hard to tell as there is nothing to scale against, very scenic background however, but not much to hide behind. The paws will give you a feel however; they can be contrasted against a typical roo's paws. Also we do not install bear bars here as it is sort of futile.

It is also difficult to find a picture of a big polar bear; you see them from a helicopter, but on the ground, for some reason, pictures are rare.

Big bears, yes, but too big a battery, have not seen one yet.