12V battery flat

[booty]

HONDA JAZZ HATCHBACK 1.5 I-MMD Hybrid EX 5dr eCVT (20-) new 28/5/2021. Telematics unit was activated on 8/6/2021. Car left in garage since that date, went to start on 17/6/2021 battery flat. What current is drawn from the battery while the car is left locked?

[Kremmen]

Was the battery fully charged ?

Often the dealer just gives them a basic charge and it does take some weeks of discharge/charge to get it up to par.

Without that charge I could see a 2 week sit taking enough out of it to refuse to start.

If you can, get a CTEK and keep it charging till the CTEK goes green.

[nowster]

How much distance had it done before you garaged it?

The telematics unit is unlikely to be the culprit. It's more likely that one of the interior lights was left on.

Incidentally, the manual recommends driving the car for a minimum of 30 minutes every three months to top up the high voltage battery.

[John Ratsey]

Incidentally, the manual recommends driving the car for a minimum of 30 minutes every three months to top up the high voltage battery.

I think it's more a case of making sure that the charge doesn't get too low. Unless one has a convenient big hill to drive down the battery doesn't go above 70% in normal usage. However, I think Honda is being cautious as the self-discharge of Lithium batteries is very low and I believe that the the battery is isolated when the car is switched off. It's the baby 12V lead-acid battery which is both vulnerable to self-discharge and meets any residual power demands. I believe that the telemetry system goes into sleep mode after a day or two to minimise the power drain.

I agree that the culprit could be a light. Check the boot light as if this is left on then it won't be obvious (tip: put an LED bulb which is not only brighter but also uses less power - I'm surprised that Honda didn't fit one as standard rather than offer it as an expensive option given it's cost is a few pennies). However, I've thought of a possible scenario. If there's no phone signal in the garage could the telemetry unit have been frantically trying to connect with the server without success to report the vehicle location etc when the engine was turned off?

My Crosstar spent two months of being parked either side of Christmas and I topped up the 12V battery with a charger every couple of weeks as I noticed that it was dropping to about 11.8V and I'd prefer, for the sake of battery longevity, for it to not sit with a low state of charge.

[Bristol_Crosstar]

Incidentally, the manual recommends driving the car for a minimum of 30 minutes every three months to top up the high voltage battery.

I think it's more a case of making sure that the charge doesn't get too low. Unless one has a convenient big hill to drive down the battery doesn't go above 70% in normal usage. However, I think Honda is being cautious as the self-discharge of Lithium batteries is very low and I believe that the the battery is isolated when the car is switched off. It's the baby 12V lead-acid battery which is both vulnerable to self-discharge and meets any residual power demands. I believe that the telemetry system goes into sleep mode after a day or two to minimise the power drain.

I agree that the culprit could be a light. Check the boot light as if this is left on then it won't be obvious (tip: put an LED bulb which is not only brighter but also uses less power - I'm surprised that Honda didn't fit one as standard rather than offer it as an expensive option given it's cost is a few pennies). However, I've thought of a possible scenario. If there's no phone signal in the garage could the telemetry unit have been frantically trying to connect with the server without success to report the vehicle location etc when the engine was turned off?

My Crosstar spent two months of being parked either side of Christmas and I topped up the 12V battery with a charger every couple of weeks as I noticed that it was dropping to about 11.8V and I'd prefer, for the sake of battery longevity, for it to not sit with a low state of charge.

I have a 2A trickle charger which I used to use on my Mk 2 without disconnecting the battery. Did you disconnect it before charging up the Crosstar?

[John Ratsey]

I have a 2A trickle charger which I used to use on my Mk 2 without disconnecting the battery. Did you disconnect it before charging up the Crosstar?

No - I leave the 12V battery connected. The charger is the previous version of one of these https://www.amazon.co.uk/gp/product/B07B9CFV7V . There's something strange about the battery charactistics as, when the battery is down to 11.8V according to my voltmeter (cross-checked previously against the voltage according to an OBDII reader) the charger will switch from charging to full after a few minutes (but I leave it connected for a few hours). I saw the same behaviour on my HR-V.

One point to note is that the -ve charger clip should be connected to the earth strap end of the Intelligent Battery Sensor and not directly to the -ve terminal so that the car knows that the battery is being charged.

[nowster]

The manual suggests that the battery should be disconnected from the car if it's being charged. That might explain the strange results when trying to float charge it.

[Expatman]

The manual suggests that the battery should be disconnected from the car if it's being charged. That might explain the strange results when trying to float charge it.

That's generally because Honda don't know what charger you will be using. Smart chargers like the Ctec detect the battery, condition and environment and charge the battery safely without having to disconnect it.

[Kremmen]

I've sort of hardwired my CTEK so I don't have to faff with crocodile clips. I have a plug under the bonnet and the CTEK has a plug. Takes seconds to connect.


However, we had a discussion on Civinfo and the conclusion we came to was to connect the positive to the battery but the negative to the car body, not the battery negative.

The reason for this was so the 'car' can calculate/recognise the charge for the stop/start. With the charger connected to battery negative stop/start did not recognise a full battery so turned it off.

[Bristol_Crosstar]

HONDA JAZZ HATCHBACK 1.5 I-MMD Hybrid EX 5dr eCVT (20-) new 28/5/2021. Telematics unit was activated on 8/6/2021. Car left in garage since that date, went to start on 17/6/2021 battery flat. What current is drawn from the battery while the car is left locked?

If the car was ok before the telematics was activated it could be a factor. As I garage mine at home I don't lock the car to save a bit of energy (I switch the remote off once inside the house).

[Expatman]

I've sort of hardwired my CTEK so I don't have to faff with crocodile clips. I have a plug under the bonnet and the CTEK has a plug. Takes seconds to connect.


However, we had a discussion on Civinfo and the conclusion we came to was to connect the positive to the battery but the negative to the car body, not the battery negative.

The reason for this was so the 'car' can calculate/recognise the charge for the stop/start. With the charger connected to battery negative stop/start did not recognise a full battery so turned it off.

To be fair all modern cars advise connecting a battery charger to the car body rather than the battery terminal.

[booty]

Hi Everybody and thank you for your replies. In answer to your replies:
The car was purchased on the 28th May 2021.The Telematics unit was not activated at the PDI check.
I am unsure how fully or not the battery was charged by the dealer when I took delivery. It as had a few runs out (180 miles) plus a 25 mile round trip to the dealer for the telematic setup on 8th June 2021.
I am unsure if I locked the car in the garage or it self locked after I left it, I only know it was locked when I came to use it on the 17th June and I opened the drivers door by using the key.
The garage is attached to the house and dark, no interior lights were left on, I am unsure about the boot light but after climbing through the car I could not see any boot light switch. I think it comes on if the hatch is opened.
I have been out all day today and not able to chase the dealer except by email which they have not replied to as yet.
I do have a CTEK charger but was reluctant to do anything myself as the car is not a month old yet.
I felt Honda assist should be called out to register the problem but would prefer a new fully charged battery to be fitted rather than a fast charge to my existing battery. After consideration I did connect my CTEK with the battery in situ, Red to positive and Black to chassis earth but after 2 lights light up on the charger the horn kept sounding so I removed the CTEK. As the car was left with the alarm set I think it's Honda Assist in the morning.
I did check the battery voltage with a Fluke multimeter this morning which read 2.44V and this evening 2.33V, a loss of 0.11V in 16 hours.
Hope its not too much of a novel.  Thanks for reading it.

[Kremmen]

Having the horn sound when a CTEK is connected is a worry as that's what I will be doing regularly being a low mileage driver now.

[booty]

After checking the manual regarding the battery going flat after the alarm had been set I went through the procedure to clear the alarm. I locked the car manually with the key, reconnected the Ctek charger to the battery but not to the mains, closed the bonnet and switched on the mains power to the ctek, when the alarm sounded I cleared it with the key fob. The Ctek has been changing all night, waiting for level 5 to complete at the moment. If the charging process completes I intend to monitor the battery voltage for a few days and recreate the situation.
I an lucky to have a camper van which I can use while the Jazz stands.
Hopefully I may hear from Honda but not impressed by their  Aftersales so far.

[culzean]

Got these for our motorbikes and cars.

The fused lead bolts onto battery ( or with start stop the negative lead will go to earth point on body ),  the SAE plug is accessible by pulling out of grille ( cable tied to grille ) and the batteries can be easily charged without unlocking the car.  The 'external charging' can come in useful if the battery ever goes completely flat and central locking ( or rather unlocking ) does not work....  On a motorbike it means no need to remove the saddle,  and I also fitted a digital voltmeter to handlebars and use the SAE charging plug to plug that straight onto the battery,  which cuts out any voltage drop in bikes wiring.


https://www.amazon.co.uk/gp/product/B01N7CEV00/

https://www.amazon.co.uk/KUNCAN-Extension-Battery-Disconnect-Connectors/dp/B01MZZGHNK/

https://www.amazon.co.uk/KUNCAN-Motorcycle-Extension-Disconnect-Connection/dp/B01N7CHYCF/