Hi,

Just wondering,

Correct method to jump start a flat battery,if you can’t open bonnet, as passenger door won’t open with no power, and bonnet release won’t work with passenger door shut.

I did it by forcing the lever, which broke it off.

Any suggestions welcome.

 

2 hours ago, CalstockCarsTaxi said:

Just wondering,

Correct method to jump start a flat battery,if you can’t open bonnet, as passenger door won’t open with no power, and bonnet release won’t work with passenger door shut.

I did it by forcing the lever, which broke it off.

Any suggestions welcome.

 

I would just connect a battery charger to the cigarette lighter socket...although this does require patience, but you might find that the car will start after just one or two hours even with a slow 3.5A battery charger, ie. the battery doesn't need to be anywhere near full for the car to be able to start...perhaps just 20% of a full charge.

 

Something like this would be helpful, but zip tie the red positive lead connector away from the black negative lead connector...or it's easy to short circuit and blow the fuse.

 

I'm not a fan of fast charging because it is very easy to damage the battery cells with these, and much prefer a 3.5A battery charger that switches down to a trickle charge of about 0.2A when the battery is almost full.

 

If the cigarette lighter socket is fused with a 10A fuse, you wouldn't be able to use more than a 10A battery charger.

 

Another tip is to connect a multimeter to the below wires when you have a battery charger connected and charging. This lets you see the charging voltage rise, and also lets you see when the trickle charging is still charging. However, with the car's 12V battery still connected to the car there's probably no need to trickle charge as the normal 3.5A charge will charge the 12V battery to about 80%...which is enough to let the car's own charging system take over. On the Bosch C10 battery charger, the trickle charging stops when the charging voltage hits about 14.95V. A similar thing happens when the normal 3.5A charge switches to trickle charger. I noticed that the normal 3.5A charger switches over to trickle charge at different voltages depending on battery chemistry. The normal SLA (Sealed Lead Acid) battery switched over to trickle charge at a lower voltage compared to the AGM battery. It was about 13.6V for the SLA battery, but the AGM battery didn't switch over to trickle charger until a much higher 14.95V.

 

Car 12V cigarette lighter power supply

https://www.ebay.co.uk/itm/175764521528

 

I use this Bosch C10 12V 3.5A battery charger, but I do use it in conjunction with a multimeter to keep an eye on the voltage while the battery is being charged. For example, a LED tells you when the normal 3.5A charge has finished but there's no LED to tell you when the 0.2A trickle charge has finished...you can tell with a multimeter connected because the voltage starts to slowly drop when the trickle charging has finished.

 

Car 12V Bosch C10 3.5A battery charger

https://www.amazon.co.uk/Bosch-Battery-Charger-Trickle-Function/dp/B0CJTZWZCN/ref=sr_1_5

 

Edited 17 September, 20241 yr by Carlston

Thank you Carlston,

much appreciated.

Edited 18 September, 20241 yr by CalstockCarsTaxi
Misspelling

Not sure if I should have started a new topic but had a rather narrow escape last Friday when setting off on a long journey, hopefully this saves someone else from a similar fate!

Superb had sat in the drive for probably a couple of weeks hardly being used and the weather has obviously been quite cold...

Car was loaded, all ready to go.

Pushed the start button and... not a lot happened!

Was our day out about to be ruined?

No!

Enter my latest hero...

https://www.amazon.co.uk/27000MAh-Compressor-UTRAI-Flashlight-Powerbank/dp/B0F4C96KZG?ref_=ast_sto_dp

I bought this a year or so back to replace my previous portable compressor (which was 12v cable powered and died) for topping up the tyres occasionally. I didn't really have much need (or so I thought) for the jump starter or the other features such as power bank, flashlight etc but the fact that it was battery powered and had these extra features was a pleasant upgrade at the time and fitted with my mantra of being prepared for anything you can reasonably foresee.

And I was exceedingly glad I had it (and that it was charged!)

Straight out of the boot, bonnet up and connected up in seconds.

Pushed the starter button and bingo - started like a new battery!

On our way with only a minute or so of delay - VERY relieved!

Not exactly putting a plug in for any particular product as I guess there are quite a few out there that do a similar job (there are smaller and cheaper ones available I believe). This just happens to be the product I have.