Hi Chris,

We may be talking past one another, since your concern is float voltage, and mine is peak charging voltage when cold. There are references to the charging system in multiple documents. It might help if you post a snip of the specific section of a specific manual you are referring to.

At the link below is a good discussion of the various issues engineers must grapple with in devising a battery charging strategy. The article states that balancing all of the necessary compromises is akin to "dancing on the head of a pin."

Battery University: Charging Lead Acid

A key bit of data in this article is that the maximum recommended charging voltage for lead-acid batteries is 2.45 volts per cell, or 14.7 volts for a typical six-cell battery. As the Jaguar documentation states, under certain circumstances, the X350 charging system can reach levels a full half volt higher than that. A battery subjected to excessive charging voltage may develop corrosion and exhibit excessive gassing and water evaporation (according to the article). The higher-than-normal peak charging voltages in the X350 seem to exceed the limits of the operating envelope of standard flooded lead-acid and absorbed glass mat batteries, and seem to be a point of valid concern.

The article also states that "the recommended float voltage of most flooded lead acid batteries is 2.25 to 2.27V/cell," or 13.5 to 13.62 volts for a six-cell battery.

Cheers,

Don

 

Its all very interesting. I never attempted to measure the "floating " voltage on my XJ. I did change the battery before I sold it, a made in Germany doped full flood battery, to my 2012 XF and I have installed continuous voltage monitor ( along with ECT and Engine oil Temp ). Typical data shows start up voltage in the 14.5v range and the "float" voltage range 13.9-14.2 . The only variation I have seen is when the Battery Monitoring Module does things--- in one observation the voltage was reduced to 11.5V and then brought up slowly to 14.1 over about 100kms of highway driving.

 

OK, actual figures *at battery* from startup (X358, 19degC ambient, "calcium" battery installed, idling)
-0-5 minutes. 14.4v to 14.5v
-At 5 minutes. Suddenly drops to 13.4v decreasing to ~12.7v (apparently not charging at this time).

After 15 minutes gets bored, puts headlights on.
-Switches back to 14.7v (!). It might stay there for all I know if there's a significant current draw.
-Switches headlights off. Measures 5 minutes until it drops back to the "2nd stage".
-Stops engine. Puts car cover back on. Checks multimeter against another one.
----------
Regarding AGM. Depending on internet source, an AGM battery might go up to 14.9v (sources vary). But lets take a C-Tek charger which many people use, it states 14.7v for it's AGM setting.

Exact figures can vary, notably with temperature. For example, there are higher figures when the temperature is down to 0, or -10 (or -20C for 15.3v). If you insist on living in those temperatures you need a snow-cat not an XJ!!! (I spent a year in Antarctica, but God thought I might be too dangerous with a multimeter at the time)

My figures suggest that the brouhaha over using AGM might be exaggerated. Happy for others to post their figures. Cheers

*** the fact that it drops back after a short time, is very important.

 

Question: Why not lithium ion?

I have ebikes and I commission Paul Lynch at em3ev.com in Shanghai to make me lithium ion batteries. For a 36v he adds an extra row to give me 41V. Why can't owners commission 14v lithium ion batteries with sufficient amp/hours? I know nothing about batteries except that they work, and on Jaguars the computers are not as tolerant of lower voltage than pre-digital cars like my 1982 G wagon.

 

My understanding of lithium ion is lots of energy, low on power (compared to normal starting batteries). So you could park it a long time and still have proper voltage but you may not have enough power to supply cranking. Also they do not accept charges at low temperatures.

 

Lithium Ion: Very expensive, really does require an accurate Li-Ion charger, and depending on it's safety electronics you can kill a Li-Ion with just a single complete discharge.
Plus you need a big tank of water to dunk the car in if it catches fire :-)

 

https://antigravitybatteries.com/pro...tive/ag-h8-rs/

They are very expensive however do have that nice re-start capability. We use them in the RX7 world to save weight, typically 20-30lb, however no idea on longevity in a more daily driven car.

 

Does anyone have any charging data on these new "Enhanced" flooded batteries? https://www.stryten.com/enhanced-vs-advanced/

https://www.batterysystems.net/exide...group-h8-l5-49

 

I couldn't really find useful charging specs on the Exide Marathon (above post). "Technical specs" tend to be limited to AmpHrs, weight, dimensions, and of course how damn good Exide is!

For EFB in general, I looked up CTek Stop-Start charger: (EFB is primarily for Stop Start, but doesn't matter if yours isn't)
CT5 START/STOP UK CTEK Consumer
...where the max voltage is given at 14.55v

And whilst distracted I came across this from Yuasa
Silver Calcium Batteries for Ford Vehicles - Yuasa
They pooh-pooh silver calcium, possibly because they Don't Make One!!! (has a mention of several voltages)
On another page of that website, they describe other batteries including EFB.

If you are at all concerned about overcharging, I would suggest putting a multimeter on your actual example, both max charge voltage and whether it switches back to a floating voltage after a time.
As far as I'm concerned, the Exide Marathon looks fine in the X350, but that's just my opinion. (my opinion is "damn near anything", because of the drop to a float voltage after x minutes)

And just as I was ready to sleep well, my Mercedes has an EFB battery and it sits at 15.1v continuously (i.e. no drop to float voltage)! Fortunately, because it's a factory certified vehicle, my role is limited to watching if it blows up within 2 years.

 

Has anyone looked at the Exide Sprinter Max at Home Depot? It seems to meet the requirements that have been posted here.

https://www.homedepot.com/p/Exide-SP...-49/308488577?

Greg

 

All I found was that the Sprinter uses "calcium plates".
"LifeGrid™ Technology are calcium/lead alloy punched-grid plates"
Other than that I'm thoroughly sick of reading Exide marketing blurb.