Motorhome - CTEK - differing voltages

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Mon 5 Dec 2022 07:17
Motorhome - CTEK - differing voltages - Will deBeast

I have a bluetooth battery monitor on the starter battery in my motorhome. When the battery looks a little low, I put a CTEK on it.

I noticed that the float charging voltage on my CTEK was a little high - 13.95v. Verified with my multimeter.

So I borrowed a CTEK from my friend and tried that - his one has a float voltage of 13.45v.

Both are nominally 13.6v. I'm not really surprised that there's a bit of variation, but thought they might be a little closer.

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Mon 5 Dec 2022 07:35
Motorhome - CTEK - differing voltages - RT

Could that be the difference between an AGM batter and a conventional lead-acid type?

For a conventional lead-acid, including EFB, the maximum float voltage should be 13.8v.

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Mon 5 Dec 2022 07:38
Motorhome - CTEK - differing voltages - Will deBeast

Both were set identically. Non AGM. The 13.95v felt a little too high to me. I'm much happier with 13.45v.

Edited by Will deBeast on 05/12/2022 at 07:39

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Mon 5 Dec 2022 07:51
Motorhome - CTEK - differing voltages - elekie&a/c doctor
Can’t see .5 volt making much difference. You could lose that voltage with bad connections at the croc clips . Are both the chargers identical models ?
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Mon 5 Dec 2022 08:05
Motorhome - CTEK - differing voltages - Will deBeast

I hardwired to the battery, so just plug the charger in.

They aren't the same model. One has a max charge rate of 3.8A, the other is 5A.

I don't think either charge voltage is 'wrong' - just there is a tolerance that CTEK don't specify.

From my (very) limited sample, it appears likely that the float voltage is 13.6v +/- at least .35v.

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Mon 5 Dec 2022 12:01
Motorhome - CTEK - differing voltages - focussed

Possibly buy a proper charger as opposed to a chinese made Ctek?

www.12voltplanet.co.uk/durite-automatic-battery-ch...l

Absorption charge voltage 14.7 Float voltage 13.8

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Mon 5 Dec 2022 14:21
Motorhome - CTEK - differing voltages - Cris_on_the_gas

So logically the higher current rated charger will have a higher output voltage on no load.

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