Can a use a 12volt battery while its charging from a Smart Charger?

Submitted: Sunday, Jan 06, 2013 at 04:52
ThreadID: 99821 Views:7673 Replies:6 FollowUps:9
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Hi All,
I havent been able to find an answer to this question. My wife is about to take delivery of a new horse float this week, and it has a 12volt water pump and 4 x 12 volt lights as well as a 12volt/240volt waeco camping fridge. (also has a seperate 240 volt wiring setup for powerpoints etc)

The float has been wired up with an Anderson plug (prefer not to use - as the wife will be sure to flatten the car batteries at some point in a remote location!), but also has the wiring in it ready to wire the 12 volt side up to a 12volt battery.

I hope to install a 100amp battery and a smart charger. My question is - is it ok if she is away for a weekend and camping and has access to power, to use the 12 volt devices (like a light or pump etc) while the smart charger is connected and turned on?

I was planning to permntly install the charger and permanenty connect to the battery, so when ever she is plugged into power, the battery chargers, but I also need to insure she can use the battery/lights/pump etc while it is charging.

Is this possible? Anyone recommend a suitable charger?

Thanks
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Reply By: Work2Travel - Sunday, Jan 06, 2013 at 07:18

Sunday, Jan 06, 2013 at 07:18
Hi Zebu, yes it is perfectly fine to use power from your 12volt battery while they are being charged. I do the same thing with my set up.
AnswerID: 501798

Reply By: Bushranger1 - Sunday, Jan 06, 2013 at 07:48

Sunday, Jan 06, 2013 at 07:48
G'day,
No problem. I asked the same question here a couple of years ago & got plenty of replies saying it was ok.
Been running my Engel fridge while charging the deep cycle battery from a generator & smart charger ever since. Only thing I notice is that sometimes the smart charger cranks up the charge rate for a short time when the fridge comes on but it has not done any harm to the battery

Cheers
Stu
AnswerID: 501799

Follow Up By: Member - Rod N (QLD) - Sunday, Jan 06, 2013 at 07:54

Sunday, Jan 06, 2013 at 07:54
Yes you can, but read your instruction manual. You need to select a different setting on the charger, something like 'supply'. This will prevent over charging of the battery when loads are applied. As noted in Stus post a load will crank up the charge and if prolonged will overcharge the battery, shortening its life.
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Follow Up By: Bushranger1 - Sunday, Jan 06, 2013 at 08:35

Sunday, Jan 06, 2013 at 08:35
Good point Rod.
It was suggested I do this at the time but I have never bothered to do this. I notice that the charge rate only increases for a short time when the fridge kicks in then it settles back down again.

Everything is still working fine so I guess that as the battery does not always get charged with the fridge running then no damage has been done.
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Follow Up By: Allan B (Member, SunCoast) - Sunday, Jan 06, 2013 at 09:42

Sunday, Jan 06, 2013 at 09:42
.
It is quite OK to run the fridge from the battery whilst a multi-stage charger is operating. The increase in 'charge rate' when the fridge cuts-in is simply the additional current being supplied to the fridge and this current is not passing through the battery. It is similar to a car battery being charged by the alternator whilst having the headlights etc operating.


There is no need to set the charger to 'Supply" which causes it to output at a constant voltage of typically 13.6v. This setting is intended for using the charger to directly power appliances without a battery in circuit. Whilst using this mode will not necessarily harm the battery you lose the advantages of the charger's control algorithm and may overcharge the battery.


My Troopy's two aux batteries are charged by Redarc DC-DC chargers with load connected. This works fine and has the specific approval of Redarc's engineering department.


Cheers
Allan

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Follow Up By: Bushranger1 - Sunday, Jan 06, 2013 at 10:56

Sunday, Jan 06, 2013 at 10:56
Thanks Alan.
Then I can just keep running the system as I have been for the past 2 years then. Battery is still working well.
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Reply By: daz (SA) - Sunday, Jan 06, 2013 at 08:10

Sunday, Jan 06, 2013 at 08:10
Hi there Zebu.
Yes you can use your 12 volt lights etc whilst the battery is being charged. Caravans are set up to do this with solar or 240v. Why not install a battery isolator in your vehicle such as a Redarc for around $175 ? that way you can safely use your Andersen plug & know the vehicle battery is safe from discharge should the plug be left connected. There are plenty of good 3 stage battery chargers, I use a projecta 25 amp which I find vg, For battery I would not go past a AGM, I use Fullrivers which the 105 amp is around $350
Daz
AnswerID: 501802

Reply By: Zebu - Sunday, Jan 06, 2013 at 08:59

Sunday, Jan 06, 2013 at 08:59
Hi All, Thanks for the feedback.

Yes i might also put an isolator in the vehicle, anyone recommend a good charging unit - I am guessing around 10amp would be ideal for a 100amp battery? Which would be about a 10hr charge time - or is that over killl?
AnswerID: 501804

Follow Up By: Bushranger1 - Sunday, Jan 06, 2013 at 09:07

Sunday, Jan 06, 2013 at 09:07
I reckon that would be a good size charger as they say that 10% of battery capacity is a good way to spec a charger.

Do not run your battery down to flat or you will ruin it. 50% is as far down as I would go so this equates to 5 hrs recharge. Well roughly speaking as the charger will ramp down as the battery approaches full charge anyway.
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Follow Up By: Bushranger1 - Sunday, Jan 06, 2013 at 09:14

Sunday, Jan 06, 2013 at 09:14
One more thing. Keep the battery fully charged when your not using it.
My friend bought a brand new battery for his van then stuck the van in the shed for 8 months. When he went on holiday the battery would not hold charge because it had been flat for so long. Battery ruined & not covered by warranty.
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Follow Up By: Member - ACD 1 - Sunday, Jan 06, 2013 at 12:56

Sunday, Jan 06, 2013 at 12:56
Hi Zebu

K.I.S.S. - What about installing a heavy duty relay.

Ignition on - relay on - battery gets charged.

Ignition off - relay off - wife doesn't get stranded!

Not fancy, but it works and a hell of a lot cheaper.

I am sure some may disagree - but it worked for me for years

Cheers

Anthony
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Work - a 40 hour interuption to my weekend!
Too many places - too little time

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Follow Up By: Member - ACD 1 - Sunday, Jan 06, 2013 at 12:59

Sunday, Jan 06, 2013 at 12:59
Sorry,

Should also have stated this is for charging the batteries whilst driving.

Cheers

Anthony
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Work - a 40 hour interuption to my weekend!
Too many places - too little time

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Reply By: Patrol22 - Sunday, Jan 06, 2013 at 10:02

Sunday, Jan 06, 2013 at 10:02
I have installed a CTEK 7500 (240 Volt to 12 Volt smart charger) and a Projecta DC20 12 Volt to 12 Volt charger in my campertrailer. The Projecta looks after the battery (200AH deep cycle) when I'm travelling and the CTEK is used when I have access to 240 volt mains supply. Been using this set up now for about 4 years and still going strong. I also have another Projecta in my ute that looks after the 2x110AH aux batteries. All aux batteries are downstream of a Redarc isolator which prevents any drain on the cranking battery.
AnswerID: 501811

Reply By: Zebu - Thursday, Jan 10, 2013 at 19:09

Thursday, Jan 10, 2013 at 19:09
Picked the trailer up yesterday - one more question before I start this project.

All the wiring came in place in the trailer, ready to drop a battery and charger in. Also has and anderson plug installed from the factory - which just runs the two wires from the anderson plug at the hitch, internally and the wires are waiting to be comnnected to a battery that will be fitted in the trailer.

My Question is - can I wire the two wires from the anderson plug direct to the battery? (the vehicle will have an isolator near the vehicles batteries)

Is there any risk to the vehicle battery, if the trailer and car are connected togeather via the anderson plugs and the battery charger is turned on.??

Apprecaite any thoughts.

Zane
AnswerID: 502163

Follow Up By: Bushranger1 - Friday, Jan 11, 2013 at 05:54

Friday, Jan 11, 2013 at 05:54
G'Day Zane,
I had a setup like that when I owned a camper trailer & used to charge the Camper battery from the 240v charger with everything connected without a problem.
I had a diode style of isolator but I shouldn't think it an issue with other styles of isolators.

Cheers
Stu
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