Can you charge a battery while using it?

Submitted: Sunday, Jan 20, 2008 at 23:52
ThreadID: 53731 Views:2449 Replies:4 FollowUps:7
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Hi all,

Every few days I am charging my camper battery (100amp/hr Gel), either via genny or 240V. I have a Projecta 3 stage charger. While it is charging is it OK to still be using it for the likes of lighting inside the camper? I vaguley remember hearing it's not a good thing to do so but does anyone know the answer? Just in case I have been using a portable 17amp/hr battery for the lights while the main one is charging.

Cheers,

Mark.
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Reply By: Member - Barnesy (SA) - Sunday, Jan 20, 2008 at 23:54

Sunday, Jan 20, 2008 at 23:54
Yes. I run the fridge off of the second battery continuously, even when the isolator is charging it whils driving.

Barnesy
AnswerID: 282820

Reply By: Member - Doug T (FNQ) - Monday, Jan 21, 2008 at 00:00

Monday, Jan 21, 2008 at 00:00
You charge the main car battery while it's being used....???

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AnswerID: 282824

Follow Up By: Member - Barnesy (SA) - Monday, Jan 21, 2008 at 00:03

Monday, Jan 21, 2008 at 00:03
The 100 amp/hour gel battery is a deep cycle which would be his second battery. He is asking if he can recharge the deep cycle with his genny whilst still running the lights off of the battery.
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Follow Up By: Member - Mark H (VIC) - Monday, Jan 21, 2008 at 00:08

Monday, Jan 21, 2008 at 00:08
Yeah good point but my main worry is when it goes into the 'bulk' phase of the charge, I think it would be OK when it's in float mode, which I imagine is similar to the main car battery when driving. Like I said, I can remember someone saying it's not good, can't remember the reason so that's why I'm throwing it to this forum.

Cheers,

Mark.
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FollowupID: 547318

Follow Up By: Member - Mark H (VIC) - Monday, Jan 21, 2008 at 00:11

Monday, Jan 21, 2008 at 00:11
Exactly Barnesy, Doug's response is certainly a good point though.

Cheers,

Mark.
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FollowupID: 547319

Follow Up By: fisho64 - Monday, Jan 21, 2008 at 00:29

Monday, Jan 21, 2008 at 00:29
the only reason why it may have a downside is that while charging, you will receive a higher voltage at your appliance, probably around 14.5 volts.
This wont affect any but the most fragile item on a 12 volt system, but I cant think of any that it might.
Of course you must be charging at a higher rate than you are drawing or it wont be charging anyway.
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FollowupID: 547322

Follow Up By: Nav 8 - Monday, Jan 21, 2008 at 00:49

Monday, Jan 21, 2008 at 00:49
No probs at all, Most 12v electrical appliances can take up to about 16 volts and as has been stated your charge rate is around 14.5. The Amps or current input into the battery is not an issue so yes you can use the battery while it is being charged... Nav.
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FollowupID: 547327

Follow Up By: Redeye - Monday, Jan 21, 2008 at 07:02

Monday, Jan 21, 2008 at 07:02
A Gel cell should not be charged above 13.5 volts if possible as it will shorten the life of the battery. The charger should be set to Gel and Hot if these options are available.

Yes it is OK to charge the battery when using it. I have my battery on float all the time at home and run the camping fridge as a beer fridge.

Redeye
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FollowupID: 547337

Follow Up By: bv - Monday, Jan 21, 2008 at 15:20

Monday, Jan 21, 2008 at 15:20
As other have said, yes you can. Just make sure your charger is up to it, otherwise it is going to be working overtime playing catchup.

BruceV
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FollowupID: 547406

Reply By: Member - Mike DID - Monday, Jan 21, 2008 at 19:25

Monday, Jan 21, 2008 at 19:25
3-stage chargers decide when to drop back to float voltage (around 13.6) to avoid overcharging, by detecting when the current drawn by the battery drops to around 1 amp.

If you have a load connected then the current will never drop low enough and the charger will stay at the Absorption voltage (around 14.4).

This won't hurt for a short time, but can cook your battery. Feel the battery to see if it's getting warm - if so, disconnect the charger for a while. If it's an AGM, put your ear up to it and listen bubbling. If it's a wetcell, remove the caps and look for bubbling.
AnswerID: 282945

Reply By: Member - Mark H (VIC) - Monday, Jan 21, 2008 at 20:51

Monday, Jan 21, 2008 at 20:51
Thanks everyone, your advice is appreciated.

Mark.
AnswerID: 282971

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