CTek or standard trickle charger?

[enuff_zed]

On Wednesday bigwinn is going to come over and reflash the DME on my recalcitrant 3.0i.
I know I need to make sure we don't drain the battery so will be hooking it up first.
Question for those more knowledgeable than me:
Can I use my CTek to do this or is it better to borrow a standard battery charger.
The way the CTek works is black magic to me and I'm not certain whether it would do the job correctly?

 

[Usel]

I don't think it will work.
I am currently at work and tested a CTEK, with a muliti-meter, and when on and not connected it reads 0 volts.
An old 50 amp sealy battery charger, which will charge a flat battery, when turned on and not connected will read 9 volts.
A Ctek won't charge a flat battery.

 

[enuff_zed]

I don't think it will work.
I am currently at work and tested a CTEK, with a muliti-meter, and when on and not connected it reads 0 volts.
An old 50 amp sealy battery charger, which will charge a flat battery, when turned on and not connected will read 9 volts.
A Ctek won't charge a flat battery.

Thanks,
To be precise, the battery is fully charged now, but I want to maintain it like that.
I do have access to a standard battery charger too.

 

[Usel]

Thanks,
To be precise, the battery is fully charged now, but I want to maintain it like that.
I do have access to a standard battery charger too.

As soon as the battery is removed the ctek will sense that and stop charging.

 

[enuff_zed]

Thanks,
To be precise, the battery is fully charged now, but I want to maintain it like that.
I do have access to a standard battery charger too.

As soon as the battery is removed the ctek will sense that and stop charging.

We're not removing the battery.
We are doing a reflash of the DME which requires the ignition to remain on for quite a while. Losing power halfway through could be disastrous.
I do also have access to one from a friend.
Does this look a better bet?

 

[Liam22]

Top tip: Disconnect the fuel pump during flashing. This is the main draw - you'll hear it!

Trickle charger will only send 2-4A which is a lot less than the fuel pump. A slave battery will be enough.

 

[Pondrew]

For the job you want it for, the only difference between a 'smart charger' (ctek) and a 'standard' charger will be the current it can put into the battery.
Your ctek will probably be 5 amp (most common one) so while you draw current from the battery it will charge it at 5 amp at around 15v.
It's only when the battery is at, or near, full charge that the 'monitoring' circuitry comes into play on a smart charger and starts to drop the voltage.
I presume the battery on an E85 is around 70amp/hours(?). If you use your ctek it can replenish that battery at 5 amp/hours. A higher current charger will replenish it at whatever current it is rated at.
I think it will be absolutely fine unless your flash takes all day and draws a lot of current, which is unlikely.
As far as I am aware it is voltage drops in the 'system' that software updates don't like and you will be maintaining the voltage well with a 5 amp charger connected.

Disclaimer: Not my fault if you do the above and it crashes!

 

[Pondrew]

Does this look a better bet?

That's a 5 amp charger, no bigger than your ctek (presuming you have an MXS 5 or bigger).

 

[enuff_zed]

[ref]Liam22[/ref], excellent advice! How? Pull a fuse?
[ref]Pondrew[/ref], thanks for that explanation. Looks like my mate's one is 4Ah, so the CTek 5.0 will be better?
[ref]Usel[/ref], do you concur?

 

[Usel]

I have a 10amp smart charger you can borrow. Its a Streetwize master charger.
I think your Ctek will do the job though.

 

[enuff_zed]

I have a 10amp smart charger you can borrow. Its a Streetwize master charger.
I think your Ctek will do the job though.

Thank you. I'll see what I can dig up and maybe come back to you.
Seems the fuel pump is the thing to consider.

 

[Pondrew]

Pondrew, thanks for that explanation. Looks like my mate's one is 4Ah, so the CTek 5.0 will be better?

Says 5 amp on the top right of the box! So exactly the same as your ctek.

Does the fuel pump run continuously with only ignition on. or just 'pump up' to pressure and stop?

 

[enuff_zed]

Appreciate the instant supply of so much help chaps. Thank you.

 

[enuff_zed]

Says 5 amp on the top right of the box! So exactly the same as your ctek.

Oh yeah, I was looking at the wrong bit.

 

[Liam22]

[ref]Liam22[/ref], excellent advice! How? Pull a fuse?

I disconnected the fuel pump controller that sits inside the car (above the tank, behind driver). There will be a fuse, but I don't know which one.

FWIW, my Lithium battery was able to run the fuel pump for about an hour. So a well-charged battery should be fine on its own if you disconnect the fuel pump during flashing.

Mine gave up *during* the flashing which was worrying, but it flashed a second time without bother.

 

[enuff_zed]

[ref]Liam22[/ref], excellent advice! How? Pull a fuse?

I disconnected the fuel pump controller that sits inside the car (above the tank, behind driver). There will be a fuse, but I don't know which one.

FWIW, my Lithium battery was able to run the fuel pump for about an hour. So a well-charged battery should be fine on its own if you disconnect the fuel pump during flashing.

Mine gave up *during* the flashing which was worrying, but it flashed a second time without bother.

Thanks Liam, roadster not coupe so possible a slightly different layout.
I'll rummage for the fuse I think.

 

[B21]

I'm suprised that the E85 LPFP runs continually..if the engine is not running and rail pressure is built up why run?

It certainly doesn't do it on the E89 but I don't know much about E85s.

FWIW the CETK and there OE badged versions aren't great at keeping a car battery topped up for the exericse you are about to do..I found that out myself..

A less sophisticated one like your picture or a Lidl charger on a fully charged battery will be better.

If you are reflashing the ECU remember to switch of the heating and audio controls too..

Also usually with DME flashing avoid opening / closing doors or touching any other controls..some peope say you should put the drivers seat belt into position.

Do you know how long the projected flash time is?

 

[enuff_zed]

I'm suprised that the E85 LPFP runs continually..if the engine is not running and rail pressure is built up why run?

It certainly doesn't do it on the E89 but I don't know much about E85s.

FWIW the CETK and there OE badged versions aren't great at keeping a car battery topped up for the exericse you are about to do..I found that out myself..

A less sophisticated one like your picture or a Lidl charger on a fully charged battery will be better.

If you are reflashing the ECU remember to switch of the heating and audio controls too..

Also usually with DME flashing avoid opening / closing doors or touching any other controls..some peope say you should put the drivers seat belt into position.

Do you know how long the projected flash time is?

No idea on time.
I'm relying on bigwinn for this.
Thanks for the rest of the inputs Peter, I'll make a long list!!!

 

[B21]

I'm suprised that the E85 LPFP runs continually..if the engine is not running and rail pressure is built up why run?

It certainly doesn't do it on the E89 but I don't know much about E85s.

FWIW the CETK and there OE badged versions aren't great at keeping a car battery topped up for the exericse you are about to do..I found that out myself..

A less sophisticated one like your picture or a Lidl charger on a fully charged battery will be better.

If you are reflashing the ECU remember to switch of the heating and audio controls too..

Also usually with DME flashing avoid opening / closing doors or touching any other controls..some peope say you should put the drivers seat belt into position.

Do you know how long the projected flash time is?

No idea on time.
I'm relying on bigwinn for this.
Thanks for the rest of the inputs Peter, I'll make a long list!!!

Belt n braces if you can manage it is a second fully charged battery ..jumpered.

Unless the process is exceedingly slow then you should be fine..just don't get tempted if the first attempt aborts to retry without being recharged...corrupted DME will ruin your day..

 

[Liam22]

I'm suprised that the E85 LPFP runs continually..if the engine is not running and rail pressure is built up why run?

Because there's no signal from the DME. It has power, but as soon as the DME flash is erased it starts running at full duty.

I've always flashed mine with door open and with a ton of ancillaries deleted. No seat belts, no airbags, etc.