Modern cars can have current pull when parked. I put my modern cars on battery maintainers when not driven enough. For example, Ferrari recommends battery maintainer if car not used within 72 hours (and usage does not count if only driven 10 miles since battery recharge is not done well in short drives). I use CTEK products.

 

How come we are talking cars that are not Rangerover’s

 

The CTEK is a good unit, and I would buy one. You got your money's worth on the Cayenne battery lol...Anytime you have a car left for an extended period without starting it and letting the engine run, a charger will definitely keep the battery healthy.

 

I've never had to do this except for an old Boxster, but all vacations used to be 3 weeks or less in the past. Now these long trips have become an annual feature.

 

If it is a 2020 or later (not older, but in years, 2020-2025 MY), the Lithium battery management system would kill batteries and force replacement before the actual battery died. I don't know your year Cayenne, however that is a known problem/issue. I put ours on a Li-Ion tender from CTEK and it never missed a beat - although that was after the dealer replaced it under warranty.

I don't know whether the Rover has a Li-Ion battery or not, however worth a check and then the CTEK battery tender is a great brand to use.

Side note: the Cayenne battery was one of several items (water pump, bubbling leather dash, HVAC evaporator) that were replaced under warranty and scared us to death. The Cayenne is gone and the P550E is in the garage now.

 

If it is a 2020 or later (not older, but in years, 2020-2025 MY), the Lithium battery management system would kill batteries and force replacement before the actual battery died. I don't know your year Cayenne, however that is a known problem/issue. I put ours on a Li-Ion tender from CTEK and it never missed a beat - although that was after the dealer replaced it under warranty.

I don't know whether the Rover has a Li-Ion battery or not, however worth a check and then the CTEK battery tender is a great brand to use.

Side note: the Cayenne battery was one of several items (water pump, bubbling leather dash, HVAC evaporator) that were replaced under warranty and scared us to death. The Cayenne is gone and the P550E is in the garage now.

The Rover has a LI-Ion battery, just like the Cayenne. Our 2020 Cayenne was delivered in April 2020, and has just under 50,000 miles on it. Zero issues so far.
We have been going out on a 6 week trip every year for the last three years. The last two were not a problem, this time the Cayenne battery fataled.

 

Excellent, great to hear! I would get that CTEK tender you referenced then and you should be just fine!

 

PHXATC, what model do you use on your Cayenne?

 

if you know your going to be gone for a long while more than a week,
I suggest , disconnect the battery after waiting for the specified time for the other electronics to shut down.

When you get back connect the battery the car will start right up.

NOTE follow the advice for recharging the battery every so many months .

NOTE a battery maintainer is not a charger,
giving the battery a 6 amp charge for 4 hours every few months will keep it topped off.

NOTE unless the battery system requires different parameters for keeping the battery charged,
or recharging RTFQ in the manual please.

 

One week? That seems extreme.

 

You need to read the manual well.

We are NOT permitted to use ANY CTEK charger on the Audis we have (48V mild hybrid batteries like on the RR). The issue is these CTEK chargers have desulphation modes on them.

Generally speaking P0 MHEV vehicles like the RR and the Audi A8L that I have FORBID any charge voltage above 14.8V. Desulphation = > 14.8V which can blow the DC DC converter and ruin your 48V/12V subsystems.

Read the manual!

 

This charger DOES NOT have a desulphation mode as per the manufacturer. It’s specifically designed for Lithium batteries. Lead acid battery chargers have this mode.

Don’t confuse the hybrid battery with the starter battery. The starter battery can be lead acid or Li Ion, and manufacturers are moving to the latter because of size and weight. This also locks in their customer to a proprietary battery when replacement time comes around.

 

I don't understand what you're trying to do. The 12V and 48V subsystems are linked with a DC DC converter. Unless RR does something different, you are NOT supposed to ever charge/touch the 48V battery. The regular lead acid 12V battery is what you're supposed to 'charge' and the DC DC converter upvoltages to 48V to charges that. The DC DC converter is what is not allowing anything > 14.8V. That's why i'm lost.

This LiFePO4 charger - why are you using this? To charge the 48V battery directly?!

 

CTEK offers charging solutions according to type of battery, intended use, and application country, see www.ctek.com and choose local website under the "globe" tab upper right.

In the US I use CTEK for several vehicles.

Specifically for my 2025 Range Rover LWB with the 3.0 engine and MHEV, the owner manual says in several places, e.g. page 470 "If the vehicle is not being used regularly, make sure that the 12V battery remains connected, and in a sufficiently charged state using a battery charger compatible with Li-ion LiFePO4 batteries, during the storage period. A battery charger must not be permanently connected to the vehicle unless specifically designed for the purpose."

I use a CTEK "LITHIUM US" for my 2025 RR LWB 3.0 MHEV. I use other CTEK models on other types of batteries on different cars.

 

CTEK offers charging solutions according to type of battery, intended use, and application country, see www.ctek.com and choose local website under the "globe" tab upper right.

In the US I use CTEK for several vehicles.

Specifically for my 2025 Range Rover LWB with the 3.0 engine and MHEV, the owner manual says in several places, e.g. page 470 "If the vehicle is not being used regularly, make sure that the 12V battery remains connected, and in a sufficiently charged state using a battery charger compatible with Li-ion LiFePO4 batteries, during the storage period. A battery charger must not be permanently connected to the vehicle unless specifically designed for the purpose."

I use a CTEK "LITHIUM US" for my 2025 RR LWB 3.0 MHEV. I use other CTEK models on other types of batteries on different cars.

Interesting! Very cool - thanks for sharing! Is the 12V battery lead acid or lithium ion on the RR?

 

In addition to the example above showing page 470 indicates lithium battery, page 470 shows vehicle battery decal image which shows Li-ion and is the same image as the decal seen when opening the hood (bonnet) on the vehicle.

 

So why are you looking into using a LiFePO4 battery charger? Just get a 5amp battery tender charger and be done with it. It's what I used on my A8L. I think you're overthinking it...

Interesting! Very cool - thanks for sharing! Is the 12V battery lead acid or lithium ion on the RR?

Lithium.

 

Earlier this year we were away for almost 6 weeks. When we came back, our Cayenne was dead. Jumping the car started it, but the battery would not hold a charge even after driving it around for 30-40 minutes. A few months earlier, we had the car serviced and the dealer had said that the battery was ok but would need to be replaced in the next 1-2 years. The battery was a few months beyond five years when it failed (i.e. well outside the 4 year warranty period). Long story short, we got the battery replaced for $$$ and all is well.

I'm getting ready to buy two battery chargers for the two cars, because this sort extended away situation is going to happen periodically. I should get this?

CTEK 56-926 Lithium US | Fully Automatic Lithium Ion Phosphate LiFePO4 Battery Charger | 5.0Ah - 60Ah | Maintenance Charging up to 120Ah

Thanks for the advice.

The owner’s manual says not to charge above 13.6v. CTEK does not offer such a charger; I spoke with two of their technical support people at length. I bought the above but am not using because it because I am concerned to damage the electrical systems.

I asked my Range Rover dealer what they use and was told


TRACTION

BSU2-125/B

BATTERY SUPPORT UNIT


+ DC O/P -

Traction Charger Co Ltd

Model No: BSU2-125/B - US

I/P: 110-120VAC 60Hz 12 AMPS

O/P: 13.8V -75A

Made in UK

Refer to operating manual before use

Se référer au mode d'emploi avant utilisation

Serial No.

S15023/004

FUSE T15AH 250V

The sales person for Traction chargers info:
TRACTION

ED

GIACOMUCCI

NATIONAL

SALES MANAGER

MAIN: 610-605-3634

EMAIL: sales@tractionchargers.com

WEB: tractionchargers.com

TRACTION CHARGERS, LLC

*they seem like complicated highly advanced chargers and I recall cost around 1,100usd. I have opted to not use a charger, but if anyone finds a solution that works please share.

 

The owner’s manual says not to charge above 13.6v. CTEK does not offer such a charger; I spoke with two of their technical support people at length. I bought the above but am not using because it because I am concerned to damage the electrical systems.

I asked my Range Rover dealer what they use and was told


TRACTION

BSU2-125/B

BATTERY SUPPORT UNIT


+ DC O/P -

Traction Charger Co Ltd

Model No: BSU2-125/B - US

I/P: 110-120VAC 60Hz 12 AMPS

O/P: 13.8V -75A

Made in UK

Refer to operating manual before use

Se référer au mode d'emploi avant utilisation

Serial No.

S15023/004

FUSE T15AH 250V

The sales person for Traction chargers info:
TRACTION

ED

GIACOMUCCI

NATIONAL

SALES MANAGER

MAIN: 610-605-3634

EMAIL: sales@tractionchargers.com

WEB: tractionchargers.com

TRACTION CHARGERS, LLC

*they seem like complicated highly advanced chargers and I recall cost around 1,100usd. I have opted to not use a charger, but if anyone finds a solution that works please share.

I went and looked at this device - it's indeed highly advanced and seems to be designed for commercial use on showroom floors of car dealers and such. A bit of an overkill for home use and certainly very expensive.

 

The New Range Rover manual has this for battery care

If the vehicle is not being used regularly, make sure that the 12V battery remains connected, and in a sufficiently charged state using a battery charger compatible with Li-ion batteries, during the storage period. A battery charger must not be permanently connected to the vehicle, unless specifically designed for the purpose.

This page has additional information on battery charging:

Make sure to use the correct type and rating of battery charger compatible with a 12V Lithium-ion (Li-ion) battery. Using an unsuitable charger may damage the battery or potentially result in damage to the vehicle. Refer to the label near the vehicle's positive jump start terminal. If in any doubt consult a retailer/authorized repairer or a qualified person.

This page has this image which implies that the charger should provide a voltage of less than 13.6V.

The CTEK Chargers I bought (fortunately not opened yet) have a charging voltage of 13.8/14.4V so I have to conclude that the CTEK charger isn't suitable for maintaining the Range Rover lithium battery.

 

One may find the technical specifications on many of the Lithium battery maintainers available today in the US. All of the ones I checked have maximum voltage listings above 13.6 V, typically around 14.4 V maximum. They all say they are for LiFePO4 batteries.

Specific to CTEK, one may watch a CTEK video "Which CTEK Charger Do I Need? | North America"

Other battery maintainer manufacturers have similar information available online to help with choices.

Traction Charger products seem aimed at high usage, quick utility large fleet operations, such as a dealer service center. My needs are served by a product which costs one tenth as much.

 

Here is a photo of my battery maintainer around seven hours after connecting to my 2025, the six cylinder engine with lithium 12 V battery. One may see the steps finished in yellow lights with the last sequential light green in the "battery" symbol, green circular power light, and error light off. Dealer service advisor thought several lithium-rated battery maintainers were fine, including the one pictured. Other people may have different experiences, I'm just reporting my own.

 

Yes you are correct. I’ve returned the CTEJ chargers I bought because they deliver a slightly higher voltage than what JLR specifies.