Leaving battery on charge

[Simon Bags]

Morning everyone. I'm going to be out of the Country for 5 weeks or so soon and I was wondering if rather than letting the battery go flat and having to charge it on my return, I can leave it on charge whilst I'm away? It's quite a modern charger so would assume it would be safe?

Cheers, Simon.

[Shnozz]

Just buy a ctek or another brand of pulse charger that’s designed for the purpose.

[NDA]

As above, a CTEK battery charger is what you need. I have two cars that are on SORN over the winter months and don't get used or started for at least 5 months - they are both on one of these each:

https://www.amazon.co.uk/CTEK-Battery-Automatic-Te...

Well worth getting.

[eltax91]

Yep. If your charger is a maintainer, then it’s designed for just this purpose.

I’ve got 2 ctek doing this job and the midl @ Lidl ctek rip off attached to the mower in the shed

[Simon Bags]

I've just had a look, it's a 12v intelligent pulse charger.

[Shnozz]

Simon Bags said:

I've just had a look, it's a 12v intelligent pulse charger.

Should be fine then. I’ve got a cheap brand pulse charger but must admit I then wussed out using it for this winter on the Exige and bought a ctek for brand recognition but it’s probably the same thing underneath….

[944 Man]

Lidl’s own brand chargers are excellent. They’re red now, but inside they’re the same as the grey original. I Have two (a grey original and a red replacement after I wore out the original grey through 10yrs constant use) and I usually use them instead of the C-Tek that I also own.

[anonymous-user]

I had my C43 sat untouched for 5-months over winter hooked up to a NOCO Genius charger. No side effects at all, she fired up effortlessly.

[119]

C-Tek without doubt.

[Griffith4ever]

Any 12v trickle charger will do. Don't get obsessed with "pulse charging". All that is is the desulphation mode that just about any charger does, just with a new name :-) and your battery should never need that mode unless you run it very low and leave it there. Desulphation (pulsing at a higher voltage) mode is specifically for battery repair. I have just read up and seemingly Ctek have reinvented "pulse" mode as their "advanced" float charging because otherwise you might "overcharge" your battery - an utter load of nonsense. Just about every charger get your battery to full and simply keeps it there. NOT damaging it. Still, of you have £90 you want to burn.

Charging Lead acids (that includes AGM) is a really simple "technology". Ctek don't do it any differently, or "better" than everyone else has been doing it for ever. They are just a "premium brand". The Lidl/Aldi chargers charge in exactly the same way, though someone here who' spent £90 on a Ctek will try and tell you different. They have a bulk phase, where they charge at full power, then sometimes, absorption, where they reduce the rate to bring the battery close to full, then float, which is a constant low current top off voltage to "maintain" the battery (Lead acids lose charge naturally over time (unlike lithiums)).. I see that Ctek have somehow managed to squeeze out 8 phases of charging now - clever stuff seeing as 3 stage chargers have been doing the job perfectly for ever and a day. Agin, I've just inspected this and "stages" 1,2,6 are what all chargers do as part of the process, and 8 is what all cahrgers do during float. They've just made names and inserted them to make their kit look "premium".

If you go away for long periods it worth checking that your charger will resume its charge after a power outage. MOST cheap ones don't. They require you to press ther start button. This renders them usless is you have even a brief power cut when away for months.

I use this for when we are away for 3 months at time :

https://www.amazon.co.uk/dp/B0BH8XMRWH?ref_=ppx_hz...

I have checked / tested and it resumes after a power interruption.

If you have a lithium / LifePo4, then you need a slightly different charger that crucially won't go over 15v, and consequently won't ever try and "pulse" charge.

Edited by Griffith4ever on Monday 14th April 07:53

[Simon_GH]

If in any doubt just fit a timer to the plug socket and charge for 24 hours every week.

[119]

Griffith4ever said:

Any 12v trickle charger will do. Don't get obsessed with "pulse charging". All that is is the desulphation mode that just about any charger does, just with a new name :-) and your battery should never need that mode unless you run it very low and leave it there. Desulphation (pulsing at a higher voltage) mode is specifically for battery repair. I have just read up and seemingly Ctek have reinvented "pulse" mode as their "advanced" float charging because otherwise you might "overcharge" your battery - an utter load of nonsense. Just about every charger get your battery to full and simply keeps it there. NOT damaging it. Still, of you have £90 you want to burn.

Charging Lead acids (that includes AGM) is a really simple "technology". Ctek don't do it any differently, or "better" than everyone else has been doing it for ever. They are just a "premium brand". The Lidl/Aldi chargers charge in exactly the same way, though someone here who' spent £90 on a Ctek will try and tell you different. They have a bulk phase, where they charge at full power, then sometimes, absorption, where they reduce the rate to bring the battery close to full, then float, which is a constant low current top off voltage to "maintain" the battery (Lead acids lose charge naturally over time (unlike lithiums)).

If you go away for long periods it worth checking that your charger will resume its charge after a power outage. MOST cheap ones don't. They require you to press ther start button. This renders them usless is you have even a brief power cut when away for months.

I use this for when we are away for 3 months at time :

https://www.amazon.co.uk/dp/B0BH8XMRWH?ref_=ppx_hz...

I have checked / tested and it resumes after a power interruption.

If you have a lithium / LifePo4, then you need a slightly different charger that crucially won't go over 15v, and consequently won't ever try and "pulse" charge.

Edited by Griffith4ever on Monday 14th April 07:46

The C-Tek isn't just a charger though is it.

[david.h]

I use a simple small light powered panel (about 10 years old!) plugged into the car power socket
All you need is a window ! Trickles at about 1.5 amps.

[Smint]

Lost an almost new Varta battery some years ago when the CTEK it was connected to died during one winter, neither my spare old school charger nor the Lidl spare would revive it.

Bought a NOCO Genius 10 few years ago, a decent bit of kit, couple of weeks ago one of the family cars had been stood for weeks, battery flat and the owner's charger wouldn't revive it, nor would the Genius on normal charge mode, but a day on 'repair' mode saw it up and running again and the sight glass top of the battery showing green once more.
Wasn't aware of Genius chargers back when the CTEK died ruining the Varta battery, would have been interesting to see if the current (hoho) charger would have revived it.

[Leins]

Smint said:

Lost an almost new Varta battery some years ago when the CTEK it was connected to died during one winter, neither my spare old school charger nor the Lidl spare would revive it.

I had the same, albeit my CTEK was 10 years old at that stage. I still use them though, but now my cars are in the garage rather than external storage I can keep a better eye on them


One word of warning - worth keeping a post-it note in your dash to remind you to unplug before driving. I found out the hard way!

[vikingaero]

Disconnecting the battery terminal is free...

[shtu]

119 said:

The C-Tek isn't just a charger though is it.

No. It's a way of life.

As above, lead-acid batteries haven't changed much in ever. (yes, EFB and AGM are slightly different, but it's hardly revolutionary)

The CTEK chargers are perfectly good, but they are very much a triumph of marketing. The most well-known competitors in the UK are likely the LIDL\ALDI own brands, and they're perfectly good too. There's many many others out there, all of much the same basic design.

CTEK have 8 stages of charging? Ring have Spinal Tapped them - https://shop.ringautomotive.com/rsc901-1a-smart-ba... for when you need your battery charging to be one more chargey.

If you want a lot of off-the-shelf accessories to build your own Personalised Battery Optimisation Solution, then CTEK have more of that sort of thing, but the same can be created for any other charger with a few cheap connectors and a bit of wire. Or, looks like Ring throw that stuff in for free.

[swisstoni]

I’ve been let down by battery maintainers a couple of times over the years and in cars with difficult to reach batteries that really is a pain.

So I have a habit of switching them off/on sometimes on cars that have been sitting for months.
It’s surprising how different the picture can be whem you do that.
From a green OK light to a few stages of remedial work needed just because you flipped the switch.

[sherman]

Five weeks.
Unless you have a parasitic drain on the battery.
Do nothing and a decent run when you get back will be fine.

[Shnozz]

vikingaero said:

Disconnecting the battery terminal is free...

I do that on some of my vehicles due to the absence of an electricity supply. On modern tech cars it seems to give rise to various issues. Even on my old school cars I then have to reset the clocks, central locking etc. Not really an issue but nonetheless would be nice if it could be avoided.

I do feel in buying a ctek I have been lured in by the marketing of what is effectively the same as a £20 product, but the risks of attaching something from the electrics to a car battery and leaving it unchecked for months on end made me edgy enough to think the extra £100 was worth it to allay such fears! (and I kept a security camera pointing at the car albeit not sure what I could have done anyway other than watch Rome burn if there had been a fault...).