Charging leisure batt when in use

[itchyfeet]

Any reason why I should not use the leisure and charge it with an intellegent charger at the same time?

[CJH]

Good question - motivated I guess by the definition of 'intelligent'. I've always assumed it's safe to do so. If the load is light it won't make a difference. If the load is heavy enough to reduce the battery voltage, then I think this would be the signal to the charger to increase its output. The extra output would cover the additional draw. I guess it depends how long the charger takes to adjust its output - if the heavy load is removed while the charger thinks the battery is depleted, how long would it take to reduce its output?

Interested to hear from those that know, rather than my wild guess.

[itchyfeet]

I suspect the intellegence varies ( just like us lot ) from one to another, it goes through some sort of routine as I can see the voltages vary during the charge cycle so I wonder if it would get confused or not, may just depend on the charger.

[CJH]

I suspect the intellegence varies ( just like us lot ) from one to another, it goes through some sort of routine as I can see the voltages vary during the charge cycle so I wonder if it would get confused or not, may just depend on the charger.

Yes, I have a cheap smart charger from Lidl/Aldi, and I can see that turning off the charging current occasionally for a few seconds at a time - I suppose that's to see how far and how fast the voltage drops to determine the state of charge. My expensive CTEK charger hardwired in the van doesn't do that as far as I can tell. I have no idea how that one knows the state of charge. Current? Resistance?

[ghost123uk]

I am going to say I reckon it will be just fine.

I have been doing pretty much that with my "poor man's Sterling" set-up for a while now with no ill effects. I run my Stereo head unit, amp and a few other odds and ends off my leisure battery, which is charging from an intelligent charger (whilst driving).

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For those reading this who don't know, my leisure battery is charged via a 12A "smart" charger, which is powered by a 500W inverter, which is fed via the output from the split charge relay (which no longer feeds the leisure battery). This way my 2 batteries are never connected in parallel and my leisure is always kept "just right" (with the help of a Low Voltage Disconnect). I have been using this set-up for a few months now and I am very pleased with it's performance.

[windydubber]

I've just wired in my new ctek charger and intend to leave it permanently hooked up! I'll report back if I'm burnt alive in my van overnight!

[LeeME3]

Essentially solar panels via a solar charge controller do exactly this....!

[itchyfeet]

Solar chargers are designed to do this, as are alternators, are intellegent chargers designed to do this is really the question? I know it works as I'm doing it now but wondering if there are any possible or known problems.

Also are they designed to be permanently connected when no mains attached, Battery drain possible do you think? May have to measure current on mine to check it, not sure you can assume they will all be the same.

[AdrianC]

Solar chargers are designed to do this, as are alternators, are intellegent chargers designed to do this is really the question? I know it works as I'm doing it now but wondering if there are any possible or known problems.

No, no problem at all. The charger doesn't know whether the current is going to the battery or being used or what. It just periodically checks how the battery voltage is responding and decides whether to continue to charge or go to maintenance.

Also are they designed to be permanently connected when no mains attached, Battery drain possible do you think? May have to measure current on mine to check it, not sure you can assume they will all be the same.

I don't know about others, but CTek quote a (very low) reverse power consumption figure for precisely that situation. A lot of chargers are installed in boats/motorhomes/caravans where the battery is permanently connected, but the mains might not be.

[lloydy]

I've been charging mine while using it for years, I was under the assumption that everyone did. As it's what happens when you plug into a EHU, also a lot of the intelligent chargers also work as a power pack.

[greasemonkey]

I always heard using a battery on charge is ok, but you shouldn't put a charger on a battery with the engine running, as the current flow from the alternator could damage the charger, but as you say not sure on modern smart chargers.

[Oldiebut goodie]

My charger has an engine start feature - it is an 80A rms output so it is capable of being used with the alternator running. (I don't know if anyone would be quick enough to disconnect the charger immediately upon the engine starting )

[itchyfeet]

Checked current draw with mains disconnected and no load and it was zero
Checked current draw when it showed fully charged and at 13.3v ish trickle charge with an lamp on and it was the current of the lamp, so I wonder what happens when current draw exceeds what the charger can do?

probably worrying about nothing but worth discussing I think.

[nicq]

Checked current draw with mains disconnected and no load and it was zero
Checked current draw when it showed fully charged and at 13.3v ish trickle charge with an lamp on and it was the current of the lamp, so I wonder what happens when current draw exceeds what the charger can do?

probably worrying about nothing but worth discussing I think.

The same as when you have a flat bat, it will charge to the max it is can charge at.

[CovKid]

I went in a different direction with this when I was fortunate enough to be given a 17amp 240v to 12v supply. I don't use hookup much but if I did I can switch from leisure to this supply source and I suppose I could wire that so it switched on a leisure charger when the battery wasn't in use. The only downside of charging the leisure while its being used is some electronic items tend to be sensitive to it in terms of hum/buzzing. A case of trying it I think.