Discovery Sport Forum banner

Maintenance charging battery

43K views 81 replies 34 participants last post by  Bushellj 
#1 ·
I have just bought a CTEK MXS 5.0 battery charger and intend to use it following a weak battery start engine warning when opening the tailgate. I have some queries before using the charger:
1. My LR dealer said to just expose the battery by taking off the cover (being careful not to drop the fixings into the engine compartment). Then to connect the charger to the battery terminals. However the CTEK instructions say that the charger should be connected to the positive terminal and to the vehicle chassis. Which is correct as I don't want to damage the electronics?
2. What is an AGM battery and is this type installed in the DS or is it just a normal battery?
Any advice would be appreciated.
 
#2 ·
Connect the negative direct to the battery if easier, or connect the to the chassis if you are certain its a zero resistance connection.
The AGM battery is installed in the DS, the CTEK should be changed to 'AGM' via the mode button on the charger and it will give a higher voltage charge supply (14.7v instead of 14.4v in some stages of the charge).
Have not read of a CTEK damaging vehicle electronics, I charge via my towball socket with a CTEK 10 amp a little way away from the battery but it does the job OK.
 
#4 ·
I know I should have RTFM. I now have read page 266 of the Owner's Manual and it says under the heading "Charging the vehicle battery" that "If the vehicle's battery should require charging, the battery must be removed from the vehicle".
I am now confused as elsewhere in the manual that special tools are required to refit the battery after removal. Battery removal and refit should be carried out only by qualified personnel.
However, I only want to maintain the battery when the car is left in my garage for the days/weeks I am away and hence why I invested in the CTEK charger. I do not want to remove the battery every time I do this but also I do not want to do anything that will damage the electronics.
 
#5 ·
In reply to your second question an AGM (Absorbed Glass May) battery is a special type of lead acid battery in which the electrolyte is stored in glass fiber mats between the plates. They are always sealed and need no topping.

As far as charging is concerned I always connected my CTEC charger to the battery plus and negative stud in the engine compartment and never had any problems. Same applies for my GLC.

Hope this helps.
 
#6 ·
Hi

I have the Ctex charger and I wired the adapter directly to the battery and ran the wires to a more convenient location. Now when I use the charger it is just a matter of popping the hood/bonnet and connecting. The charger is not high output so gassing is not a problem and I leave the battery cover on.
In a shop they would be using a much higher voltage and therefor higher amps and it may be advisable to disconnect the battery,, but removing the battery is not necessary.
After setting the charger once to AGM it will remember the next time and start in AGM mode.

Your dealer gave you the best advise and the other warnings are there to protect against people who should never even open their hood/bonnet :lol:
 
#7 ·
Is it OK to leave the cover to the battery compartment off when driving the DS? As it is a real faff to keep taking it off every time I want to connect the maintenance charger when it is in the garage.
 
#8 ·
I am not a professional and am not advising anyone to go against written instructions but here is my experience:

I have been using chargers on Land Rovers of many types over many years. When completely flat i used to take the battery out. For trickle charging i would connect direct to the battery.

In recent years i have used Ctek chargers, of various types, through a permanently live cigarette lighter socket. My vehicles have been left connected for months at a time whilst I've been away. I have not had a flat battery for years.

I now have a Ctek MXS 5.0 and as illustrated in another thread have fitted a connector to the towing electrical socket under the boot floor. I believe the 5 amps the Ctek puts out should be no problem through this connection.

I did this because of access to the bonnet in my garage, hassle of removing and refitting the battery cover and fear of upsetting the battery management software which is connected directly to the battery.

A permanently live cig socket in the boot would be ideal but i don't know how to do it.

As i say just sharing my experience. Like many things with modern vehicles these things are not as simple as they used to be!
 
G
#9 ·
Just to add to this, if you have a towbar fitted you can connect a Ctek directly to the towbar electrics socket via an adaptor which can be purchased from the RRS/Disco3 forum
https://www.disco3.co.uk/shop/connectors-and-adapters-c8.html

In fact, I have one somewhere from my RRS days (7pin) which I can dig out if anyone is interested
 
#10 ·
Lofty1 said:
Is it OK to leave the cover to the battery compartment off when driving the DS? As it is a real faff to keep taking it off every time I want to connect the maintenance charger when it is in the garage.
Hi
I have been using a CTEK CT5 "stop start" charger on my DS for over a year and an older CTEK model in my 2001 Jag XKR for over a decade (on continuously throughout the winter lay up) with no issues at all. In both cases I have used the CTEK comfort lead directly wired to the battery + and - terminals. I run the CTEK cables through a short length of black plastic flexible conduit secured with a zip tie just as it exits the battery compartment. All I need to do is then plug in the CTEK flying lead to the connector and I'm good to go. No need to leave the battery cover off. In the case of the XKR even after a 6 month winter layup it invariably fires up first time with no electric/ECU/memory issues.

Steve
 
#11 ·
There is lots of foam around the exit in my battery box so just ran the wires using the foam as protection. The lead has a fuse so even if it shorts out because of poor installations it will not harm the car.

Keep the cover on ,,keeps debris off the battery. But then for years batteries had no cover.
 
#12 ·
Just wanted to add a few clarifications to the information already on this thread...

1. There is no problem charging the DS battery in-situ with the small charging current used by a CTEK 5 charger. LR are just playing safe suggesting you remove the battery, and it's not an easy process, and requires some things re-setting on replacement so is a PITA.

2. No I wouldn't drive around with the battery cover off. AGM batteries are more sensitive to heat than wet cells, and can be cooked much more easily by the heat in the engine bay. That's why in the DS they are effectively in a separate compartment that has the air going to the internal air vents flowing over them. If you leave the cover off you are exposing them directly to the heat from the engine bay, and incidentally sucking in hot engine bay air to your ventilation system.

3. There is a sensitive bit of electronics called the BMS, attached directly to the negative terminal of the battery. This measures the flow of current in and out of the battery and provides this information to the car's ECU so it can calculate what state of charge the battery is at. If you connect the charger, or anything else for that matter like an accessory, direct to the battery negative post you are bypassing the BMS so it's calculation of battery state of charge will be inaccurate. That's one reason for connecting to the chassis ground point instead, or at very least to the non-battery side of the BMS. Second reason is that any voltage surges (sparks!) can easily damage the sensitive BMS. Not such a problem with the CTEK chargers because they are well protected, but other chargers and especially jump cables for jump starting can cause voltage spikes as you attach them which can damage the BMS. That's why it's safest as a general rule to only connect things to the chassis ground point on modern cars, not the negative battery terminal.

4. While it's OK to attach a charger at other points in the system, rather than direct to the battery, there can be issues. The accessory sockets/cigarette lighters on the DS are disconnected by a relay after a certain time the car is inactive, so are no use for charging. You need an always live direct connection. The trailer socket has such a wire, but it's a long way away from the battery and connected by a small gauge wire (2.5mm2), and there will be voltage drop as a result (the voltage at the end of the wire is not the same as what is put into it, the difference being lost as heat along the length of the wire). Why is this an issue - well the CTEK is quite a sophisticated charger and it relies on knowing the exact voltage of the battery at any point in time to decide on it's charging regime. If it's not sensing voltage accurately due to voltage drop it will not charge optimally. Also, it uses temperature compensated charging, ie. reduces the charging voltage if the battery is getting hot to avoid damaging it - especially important with AGM, as already mentioned above. If the charger is at the back of the car it won't be measuring accurately what the temperature of the battery is.

5. So, bringing all this together, the optimum solution is to connect charger by shortest and most direct route possible to the battery positive, and the chassis ground point (just behind the battery). Which is how I've wired mine and brought the socket out right next to the battery box so I don't have to take the lid off....

Hood Motor vehicle Automotive tire Automotive design Trunk
 

Attachments

#82 ·
Thank for an accurate and informative post on connecting Battery Chargers. So many of the other posts here are just wrong and ignore the fact that nearly all modern cars have a BMS (Battery Management System) and you must absolutely NOT attach the charger to the negative terminal !!

Our previous car (BMW) had a specific “socket” under the bonnet specifically for attaching a charger - even though the battery was in the boot of the car - but this was on a massive cable carrying the main current to the engine and Stop/Start motor.
 
#14 ·
In these troubled times I'll not be using the DS much, certainly won't be towing our caravan. So, I've bought myself a CTek smart charger to help keep the battery in reasonably good condition. I'm going to wire in the connection plug so I won't need to take the cover off each time it gets charged. I'll do it pretty much in the manner that Mamil describes. However, after carefully surveying the job I noticed that next to the main chassis earthing point, which is where the wire from the negative terminal is bolted to the bulkhead (in the corner under the plastic trim) there is an unused threaded hole, M8x1.25. This will make a good earth for the CTek negative wire. Has anyone else noticed this hole?
By utilising this hole one can wire the CTek plug in without disconnecting any of the terminals. For the positive side I will put a clamping device on the battery terminal connector whilst I release the nut to then install the CTek positive wire. The wires will lead out as in Mamil's picture.
 
#15 ·
Agree with everything 'Mamil' says for optimum charging.
I charge via my towing socket with my CTEK, during the winter I was only interested in topping up the battery due to short journeys, and I felt that the once fortnightly and approx 4 hours before 'float' appeared on my charger was sufficient.
It was not optimum charging, but was enough to put something back into the battery which the system appreciated, its all I wanted really and it worked.
 
#16 ·
#17 ·
Unclemort54 said:
In these troubled times I'll not be using the DS much, certainly won't be towing our caravan. So, I've bought myself a CTek smart charger to help keep the battery in reasonably good condition. I'm going to wire in the connection plug so I won't need to take the cover off each time it gets charged. I'll do it pretty much in the manner that Mamil describes. However, after carefully surveying the job I noticed that next to the main chassis earthing point, which is where the wire from the negative terminal is bolted to the bulkhead (in the corner under the plastic trim) there is an unused threaded hole, M8x1.25. This will make a good earth for the CTek negative wire. Has anyone else noticed this hole?
By utilising this hole one can wire the CTek plug in without disconnecting any of the terminals. For the positive side I will put a clamping device on the battery terminal connector whilst I release the nut to then install the CTek positive wire. The wires will lead out as in Mamil's picture.
I too have wired my CTEK in the way Mamil describes. However, the second smaller chassis earthing point was already occupied with a smaller gauge black wire terminating there so I added the ctek negative lead and tightened. We're all good now.

I especially like Mamils trick of using the captive dust cap on the CTEK direct connect lead to attach it to the bulkhead so it is retained and wont rattle or flap about. Just need to dig out my Dymo for a label now...
BB
 
#18 ·
On my MY20, there is a negative terminal distribution plate about 10mm above the battery -ve clamp. It is difficult to make out whether the gap accounts for the BMS transducer. However, as there are a number of connections taken from this plate, I assume that it is at the same potential as the chassis and therefore a safe connection for the CTEK comfort connector -ve. Photo attached.
Your comments would be appreciated.
PS The photo confirms the AGM battery type.
 

Attachments

#19 ·
I think the BMS is under the -ve distribution plate on the -ve battery terminal. The photos below show what I have done. The secondary earth (left hand of the three terminals) is the one BobbyBox (above) refers to. I think using this makes a neat job of it although I decided to utilise the spare threaded hole (right hand of the three terminals in the photo).
Hope these help.

Automotive tire Hood Automotive lighting Motor vehicle Bumper


Land vehicle Vehicle Car Hood Motor vehicle


Tire Automotive tire Hood Motor vehicle Vehicle
 

Attachments

#20 ·
Thanks for this info.
Had the CTEK on the DS from this morning (not used for a week), so have just switched off, repositioned the charger earth clip and switched back on (soon went back up to light 4 where it had got to before)
 
#21 ·
Thanks UncleMort54 for the confirmation. At least I now have the option for a permanent -ve connection for the CTEK which will obviate the need to remove the battery cover. Ironically the +ve terminal is not as convenient as the arrangement shown in your photo, so I will resort to using the clamp nut.
 
#22 ·
:cry: just had to put the Ctex on the VW Polo MY10, as had to jump start it after being called by son with flat battery at local Tesco's, he couldn't understand it, but he had sent his girlfriend in to do all of the shopping while he stayed with the ignition switched on playing the radio and charging his fone! Shows how long the weekly shop now is. :roll:
 
#23 ·
Does anyone know if it's OK to use the reconditioning cycle on the Ctek charger on an AGM battery? I note that on Ctek's the reconditioning uses the 'normal cycle and not the AGM.
Maybe one can initially use the AGM and when charged switch to recon. The AGM charges at a slightly higher voltage.
Views and knowledge appropriated.
 
#24 ·
I used the AGM reconditioning with my CTEK . Do not know if it helped but I assume it did not hurt.

Prior to using the ctek I would get the low battery warning occassionaly but now with the ctek directly wired to the battery terminals have never had it in over a year. Put on charge once a month in winter and if doing lots of short trips in summer with the a/c on full once a month as well.

With the ctek directly wired there is no change of sparking and accompanying problems.
 
#25 ·
:cool: I have used the AGM once when first got the unit, instructions recommend once a year, just use normal charge since when needed, no battery warnings yet.
 
#26 ·
I bought a ctek 5 last week and charged the battery using the crocodile clips. All good and I'm now going to attach the comfort connectors.

From what I can gather using the secondary earth for the -ve comfort cable would be fine? Photo below from a previous post.

Anyone confirm?

Thanks.
 

Attachments

Top