Member Since: 16 Sep 2007
Location: UK
Posts: 6019
Robbie wrote:
I'm sure you have noted the hydrogen vent to the wheel arch on the D4 battery already.
It's important to differentiate between hydrogen which naturally occurs in charging and is relatively harmless in the concentration that occurs during charging and hydrogen sulphide caused by over charging.
Hydrogen is lighter than air so won't drain, hydrogen sulfide is heavier than air.
Normal concentrations of hydrogen produced by normal charging in a area the size of the D3 cabin is unlikely to be a issue in my opinion.
I would be more worried about it coming loose or tipping over. Keep it in a battery box well secured.
In the Jaguar XF the battery (well batteries with stop start) is under the floor of the boot, which in the estate is in the passenger cabin. It has a vent and you could do something similar in a battery box in the D4 to the outside if you are worried.
Last edited by countrywide on 7th Jun 2015 8:58 am. Edited 1 time in total
7th Jun 2015 7:26 am
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26701
Thanks Chaps. All I want is a cold beer whilst watching Le Mans! I do not see the need to charge the batteries whilst travelling. I have had the fridge in the car, and the batteries are secured in the boot, and have been running it for 2 days now, and they are still showing over 12v.
I think for future reference for anyone reading this thread, who potentially might copy my idea on a more permanent basis, then there is some very good advice regarding using proper, made for the job equipment.
I do note the potential risk to existing aux power circuits if I were to start the engine whilst a battery was connected via the 12v aux socket in the boot, as this does become live as soon as the car wakes up, and would be connected during cranking.
On my F Type Jaguar, the main battery is in the boot, behind the passenger. There is a pipe connected that vents to the exterior of the car. On my batteries in the D4, they all have a connection for such a pipe, so I have put some plastic pipe on, and via a couple of T pieces and an extension, I have stuffed it down the side of the boot trim, and out through the vent behind the tail light.
Anything for a cold beer and a bacon butty
7th Jun 2015 8:09 am
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Gareth and the ruling factor in such setups as your were proposing, is the thickness of ( read very thin ) wire used in the cigarette power socket circuit ( this is common to all makes of vehicles ).
The point is, no matter what state of charge your batteries were in, the voltage drop that would occur in this thin wire, IN EITHER DIRECTION, caused by the charging or discharging, would at the very most, restrict the current to doing no more than blow the fuse for that circuit.
As to venting to the battery to the outside atmosphere, well that is your choice but it is not a problem if you, or anyone else chooses not to waste their time and money to do something that will be of no real benefit or gain in safety.
There were 25 million VW Beetles with the battery sitting in the cab under the rear seat. None of there batteries were seal or vented to the outside atmosphere and the cab of a VW Beetle is a fraction of the size of the cab in a D3 or D4, and no one ever had a problem.
To many people read one thing in one article and then something else in another and then put 2 and 2 together and end up with 17.
I would not bother trying to charge a battery via the cig power socket in the first place but anyone could safely maintain fully charged batteries, as Gareth had asked about originally.
As for gassing, well a lead acid battery has a defined total amount of gas that it can produce, and once the water in the electrolyte is cooked off, there is no additional hydrogen produced.
The IEEE has a calculation available that allows anyone to calculate the safe cubic area required to make a battery safe from explosion and as the ratio of hydrogen to atmosphere required to allow the hydrogen to reach an explosive level is 4.1%, so international safety standards limit the maximum safe acceptable level of only 2%.
A good few years back, I used the calculation to workout the safe tolerable amount of battery capacity I could locate in the cab of my L322 RR and I could mount three 100Ah batteries in the rear cargo area of the cab, and if an event occurred and the three battery released their total hydrogen available, this still would not reach the international safety standards limit of 2%.
As to hydrogen sulphide gas being released. Well you would have to be totally devoid of any sense of smell not to notice even a very small amount of this being produced, and even this would only occur once the battery was totally cooked out.
Nice to have a little info but people need to know the whole picture before making erroneous statements of something being dangerous when it is not.
The only thing required when carrying ( and charging ) batteries in the cab of a vehicle, which Gareth had already stated was done, is to make sure the battery is well secured ( and should be in a plastic battery box ).
Thats all that is required.2008 TDV8 RR Lux + 2009 D4 2.7
7th Jun 2015 10:16 am
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi again Gareth, and as much for my own curiosity as for supplying you with exact info, I tested a wiring setup similar to your D4’s rear power socket setup.
While wiring size to some of the socket in a D4 is 1.5mm2, the rear power socket is supplied with 2.5mm2, and is about 6m from the cranking battery to the socket.
I used 4m of 2.5mm2 wire for the test setup to get worse case results, meaning you would not get as high a current draw as my test would produce.
I used 270Ah of battery capacity ( 2 x 105Ah + 1 x 60Ah ) and I deliberately discharged the batteries down to 12.5v ( 90% SoC ) ( fully charged batteries have a voltage of 12.7v ) before conducting the test. Again, this was done to get worse results than you would have achieved.
I placed a load at the end of 4m cable and increased to load until the voltage at that end of the cable was down to 12.0v ( your D4 will not drop below 12.2v ).
And Note, the 12.2v operation in your D4 will only be for a very short part of your drive, if it even occurs, so your rear mounted batteries would only be partially discharged but would then be topped up again.
The lower voltage level was chosen to compensate for a low auxiliary battery voltage.
Even so, with a voltage difference of 0.5v, the current draw was just over 6 amps.
I did not both emulating the voltage drop that would occur while starting the motor as this is over such a short period of time, no matter how low the voltage got down to at the cranking battery, because of the long thin wire length to the rear batteries, you would still not have blown the fuse.
Next and this is far more likely to blow your cig socket fuse, if it was going to blow, I then reversed the setup and applied a 15v charge voltage at the other end of the 4m cable, to simulate an alternator voltage, when it was at it’s highest.
The charge current started at 21 amps and over the next two minutes rapidly dropped to 13 amps.
And remember, my battery capacity was larger than yours and was at a lower state of charge.
So once again, Gareth contrary to all the other claims of gloom and doom, Bodsy got it right in the first place.
One more point I have already raised. Alternators do not cook batteries and contrary to claims DC/DC devices are a safer way to charge batteries, battery chargers and DC/DC devices are renowned for faulty operations that result in batteries being cook and many DC/DC devices are so pathetic at charging batteries that they often have info printed in their installation manuals demanding that you do not power a fridge off a battery while the battery is being charged by the specific DC/DC device.
Having a fridge connected to the same battery as a DC/DC device, can cause the DC/DC device to go to full charge every time the fridge cycles on or off, and if the battery is already fully charged, many DC/DC devices will over charge the battery on a long drive.2008 TDV8 RR Lux + 2009 D4 2.7
8th Jun 2015 2:42 am
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Robbie wrote:
I'm simplifying things a bit but when batteries are in parallel they settle at a common voltage and share the load. When you look at the wiring on the main battery you see 50.0D wiring and 400 amp fuse to cater for the initial 120 amps or so drawn when the ignition is switched on with more on cranking. If a second battery is on this circuit it will try to join in.
If the second battery is on a switched ignition or on an 'engine running' command it may avoid the start but will participate in all other power demands. If it can take a charge it will try to draw the amps it needs. When the BMS drops the alternator output to zero it will try to share the power demands. When the BMS ghosts the battery voltage it will now try to do this with an unexpected battery attached. When the BMS applies the learned discharge and charging rate of the battery it will have some new challenges. When the BMS deliberately decays the state of charge the vehicle will draw from both batteries. When the BMS triggers the high charge rate with overrun / energy recovery charging this will be dumped into both batteries. Consider the amperage in and out of the battery system in these modes.
Hi Robbie and think you misunderstand a few things about how the BMS achieves it’s cranking battery analyse.
When they changed the way the D4’s BMS worked, I had to do a hell of a lot of R&D to see if my dual battery systems would effect the operation in any way and they do, but not in any harmful way.
First off, the only current monitoring the BMS is capable of carrying out, is the current passing through the negative lead of the cranking battery. So any current coming from any other battery connected to the D4’s electrical system is NOT monitored.
As such, whether the additional battery is in the rear cargo area and connected to the Cig socket, like Gareth intended, or if the additional battery is in the engine bay or it is a battery or two in a caravan or if it is a collective of three or four additional batteries mounted in different locations, none of these additional batteries will have any effect on the accuracy of the test, they will simply cause the discharging of the cranking battery to take a longer period from fully charge to the desired voltage level.
This in it self is actually going the help prolong the life span of the cranking battery.
The reason for this is because of the way the BMS uses the D4’s own electrical needs to provide the “DUMMY†load used to discharge the cranking battery.
Now these are purely example figures but will explain in simple terms how it all works. If the D4’s own current requirements were at say 30 amp and you only had a single cranking battery in the D4, it would take roughly 1 hour to draw the cranking battery down to 12.2v or about 70 to 75% of it’s total capacity or about 25 amperes of the ( this is factoring in Peukerts Exponent, based on the high constant current draw being place on the cranking battery ).
No lead acid battery likes continual long periods of high current discharging. It simply errors their life span.
Now add a 55Ah Optima D34, which is probably the most common auxiliary battery used in D4s, and the discharge time now increases to about 90 minute.
While the total power needed to be used by the D4 to get the voltage down to 12.2v is now around 40 amperes, only the same 25 amperes will be draw from the cranking battery. So the end result for the BMS test is exactly the same cranking battery discharge, but it has taken longer.
But because the average current load place on the cranking battery is about 1/3 less, this will help extend the cranking battery’s life span.
NOTE, the actual D4 “DUMMY†current load in normal operation, is more likely to be somewhere between 40 and 50 amps.
Now lets look at your suggestion of using a DC/DC device.
With the cranking battery being the only source of power during a BMS test, the battery will be discharged down to 12.2v much quicker than normal because the DC/DC device will add around 25+ amps to the load being applied to the cranking battery and this time the additional load will be part of the load measured by the BMS.
While the additional current will not effect the results of the test, the much higher load placed on the battery while the discharge cycle of the test is being carried out, will most certainly help to shorten the cranking battery’s life span.
All the testing I have done shows that my dual battery systems, because of the unique way they work, not only has no effect on the operation of the BMS but helps to extend the operating life span of the cranking battery.
And with Land Rovers equipped with STOP/START gear, my system help spread the continual starting loads over the cranking battery and the auxiliary battery and again, this will again help to extend the life span of the cranking battery.
So based on extensive testing, sorry Robbie but your suggestion that Gareth’s battery setup would have had some form of detrimental effect on the operation of the BMS, where the exact opposite is the case, and your statement that a DC/DC device is the only safe way to charge his batteries, is also the exact opposite.
Robbie wrote:
When considering placement, restraint and gassing in the context of standard mounting of a battery in a rear, front or cabin mounting location consider if the manufactures and regulators manage the issues with dedicated restraints, safety connections and hydrogen vents routed to the outside air. I'm sure you have noted the hydrogen vent to the wheel arch on the D4 battery already.
One more point. The reason the battery compartment of a D4 and for that matter, in a D3 and the original RRS, is vented is because the battery compartment is so small and the amount of atmosphere surrounding the cranking battery is so limited that it would be very easy, if the battery gassed, for the ratio of hydrogen to atmosphere would get to and quickly exceed the 4.1% needed to be able to be dangerous.
Where as the cabin area of the D4 is so large that it is IMPOSSIBLE for hydrogen escaping from a battery, being able to get anywhere near the 2% safe level limit let alone getting anywhere near a dangerous level.2008 TDV8 RR Lux + 2009 D4 2.7
8th Jun 2015 3:50 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Tim,
You are typing loads, most of it to me. I'm not going to be drawn into whatever hole you have dug for yourself. The idea of using underrated wires as a form of current limiter is pretty odd in any circumstance, but in bundled looms it is sheer folly. There is no magic power in the thinner gauge wire, its just adding resistance and with resistance comes heat. We have to calculate for both the wire and the bundle hence the calculations in the SAE RP.
Reliance on fuses when you deliberately exceed the circuit specification is not a great idea either. Things can melt without fuses blowing and there have been quite a few examples with this on the D3, especially with 7-pin tow electrics. We have to consider failure states too.
You are recommending stuff that is way outside of automotive / maritime / aviation recognised standards and practices. Experiment as much as you like but don't propose it to others. It's not that long back that you viewed hydrogen risks with such fear that you suggested connecting even a spark-free battery charger to an uncovered and safety vented D3 battery would be suicidal(!).
As I fear you must have banged your head somewhere along the line I will cease and desist. I suggest you do the same.
Regards,
RobbieLand Rover - Turning Drivers into Mechanics Since 1948
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Robbie, you obviously have no idea what you are talking about.
As clearly demonstrated, Gareth’s original suggestion would not have posed any form of danger as he could not have caused an overload in the circuit in the first place and for you to suggest that that my test proved the opposite simply means Land Rover are using the wrong size fuses for that cabling situation.
I don’t think so.
As to the connection of a battery charger to a cranking battery, if you had any real idea of the danger posed by a battery that may have just been over discharged and need to be recharged. This is the very time when there is a real possibility of the being a gas build up and the potential of a spark being triggered as you connected the battery chargers leads to the battery causing an explosion.
Or are you suggesting that Gareth is going to be climbing into the back of his D4 while he is driving down the road, to connect or disconnect wiring on his battery, because this is the only way there could be a spark generated, and even then, as the ratio of hydrogen to atmosphere is way to low for a gas ignition to occur, nothing would have occurred.
If you want to keep trying to use unrelated situations to try to make up for your misinformation, carry on. At least other will be getting the correct info.
To prove the point, there are plenty of recorded instances where people have connected battery charger leads to a flat battery and have been harmed because the battery exploded. Now can you post up a single event where a battery has exploded in the rear of a vehicle while the vehicle was being driven.
And last but not least, Marine and Aviation standards are completely different to those use in the automotive industry, as I suspect you already know and are just trying to muddy the water.
As for genuine info about the safety requirements relating to hydrogen, I’ll stick with the information provided by the internationally recognised experts, the IEEE ( Institute of Electrical and Electronics Engineers ).
Robbie, I thought you did have a real knowledge of this stuff, hay, even I can be wrong sometimes.2008 TDV8 RR Lux + 2009 D4 2.7
8th Jun 2015 5:39 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26701
Right chaps, cold beer has been achieved. Suffice to say that most of the scientific argument is waaay over my head, and I am more concerned about the 3 gassing who will be sharing my steed, after a long weekend of cheese burgers and (cold) beer!
8th Jun 2015 7:09 pm
boyd
Member Since: 26 Mar 2014
Location: Brackley
Posts: 217
Not to open old wounds but found a couple of pictures of my auxiliary battery box so thought I'd share.....
Click image to enlarge
And this is where is sits in the truck, kept in place by the front passenger seat.
Click image to enlarge
Works perfectly with the Engel MT45 ilo of the 2nd row middle seat :thumbsup:
Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated
19th Jul 2015 6:39 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Very neat. Is that a Ctek DC to DC charger in there?
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 15 May 2013
Location: Chester
Posts: 7633
That's my plan, when I get round to doing it. My ctek d250s is sat in the garage, but after I get chance to install my dual battery, the ctek will be next
23rd Jul 2015 3:33 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
I've played with a few and they are a good bit of kit.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
tayaste wrote:
That's my plan, when I get round to doing it. My ctek d250s is sat in the garage, but after I get chance to install my dual battery, the ctek will be next
Hi tayaste, but any DC/DC device used in a D4 is a complete waste of money and at the end of a days drive, is more likely to leave your auxiliary/house batteries in a lower state of charge than what the D4’s alternator can do by itself.
DC/DC devices have their place but if any vehicle, not just a Land Rover, is wired up properly, you will have a far superior battery charing in a shorter drive time.
BTW, to be able to run a DC/DC device properly, you have to run decent cable to it anyway.
So why not just run decent cable in the first place and do away with something that quite simply “chokes†the battery’s ability to charge properly, particularly if the battery is low when you state your drive.
Again sorry but small DC/DC device in a vehicle setup are nothing more than an advertising con job.
We have D4 owners over here, who tow caravans and have an auxiliary battery in the D4 and two or three house batteries in their caravans and have no problem charging them straight from the D4's alternator.2008 TDV8 RR Lux + 2009 D4 2.7
23rd Jul 2015 10:08 pm
boyd
Member Since: 26 Mar 2014
Location: Brackley
Posts: 217
You really are irritatingly opinionated aren't you...
As I change my cars every 9 months and I shouldn't really modify them in that time anyway, this is the most appropriate solution for my circumstances. It also carries the benefit of being able to move it along with my fridge into the back of the NAS 90 on off roading weekends.
23rd Jul 2015 10:54 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Well I liked it.
Land Rover - Turning Drivers into Mechanics Since 1948
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who will be sharing my steed, after a long weekend of cheese burgers and (cold) beer!
