Trickle Charge on Second Battery.

Submitted: Monday, Jan 01, 2007 at 13:09
ThreadID: 40757 Views:2534 Replies:7 FollowUps:2
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Hi all,

Another question on second batteries. Does it do any harm to have a trickle charge on the second battery for a long period, (at least 2 weeks). And do you have to disconnect it from the main battery?

JD
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Reply By: Derek from Affordable Batteries & Radiators - Monday, Jan 01, 2007 at 15:30

Monday, Jan 01, 2007 at 15:30
Hi TL

It would depend on the quality of the charger.

2 years on a good charger is OK.

Regards

Derek.
AnswerID: 212732

Reply By: Member - Norm C (QLD) - Monday, Jan 01, 2007 at 16:36

Monday, Jan 01, 2007 at 16:36
As Derek said.

Also, if your second battery is isolated from the main battery (which it normally would be), it is already 'disconnected'.

If you have a good multi stage charger, you will be doing the battery a favour.
AnswerID: 212741

Reply By: Mike Harding - Monday, Jan 01, 2007 at 17:43

Monday, Jan 01, 2007 at 17:43
The best way to treat a lead acid battery is to keep it on "float charge" during it's unused periods. For 12V batteries this requires a constant voltage charger which will maintain a voltage of 13V7 +/- 0V1 which is not a difficult thing to do and should be available quite cheaply. Beware of "trickle" chargers - "trickle" is, technically, a meaningless term - look for float charging at 13V7. This is how systems such as fire panels and intruder alarm systems maintain their back up batteries over long periods.

Mike Harding
AnswerID: 212751

Reply By: Mainey (WA) - Tuesday, Jan 02, 2007 at 13:10

Tuesday, Jan 02, 2007 at 13:10
Treading Lightly you have posted;

"Does it do any harm to have a trickle charge on the second battery for a long period, (at least 2 weeks). And do you have to disconnect it from the main battery? "

Do you not drive the vehicle for the 2 weeks you have mentioned ???

As replied to above, the two batteries will be 'disconected' if you use a "battery Isolator" as they are only 'connected' when the engine is running.
AnswerID: 212850

Reply By: BUGGER ME - Tuesday, Jan 02, 2007 at 23:32

Tuesday, Jan 02, 2007 at 23:32
hi treading lightly

don't keep on trickle charge for long periods' if just sitting in your yard will distroy your battery' only start charging with a trickle charger a couple of day's before going away. my 3 amp trickle charger has a safety cut off when fully charged and goes to float so does not over charge.

regards, bugger me
AnswerID: 212949

Reply By: Treading Lightly - Wednesday, Jan 03, 2007 at 16:55

Wednesday, Jan 03, 2007 at 16:55
Thanks guys for all the input I will give the second battery a charge for a couple of days before the depature.

JD
AnswerID: 213053

Reply By: disco1942 - Wednesday, Jan 03, 2007 at 21:45

Wednesday, Jan 03, 2007 at 21:45
JD

What are you going to trickle charge your battery with? If you are going to use a quality 3 or 4 stage charger ($250 + ) then you may leave it on for as long as you like (providing you have it programmed for your type of battery.) If it is a cheapy chain store type you can boil the water out of your battery and it is best not to even try to fully charge your battery - use the charger to bring the terminal voltage up to 14.5V before you travel and let your alternator finish the job.

PeterD
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AnswerID: 213095

Follow Up By: Treading Lightly - Thursday, Jan 04, 2007 at 07:40

Thursday, Jan 04, 2007 at 07:40
Thanks for info. What would the max volts be if the battery was fully charged by a charger and would that be the same as the alternator.

JD
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Follow Up By: disco1942 - Thursday, Jan 04, 2007 at 10:52

Thursday, Jan 04, 2007 at 10:52
JD

A fully charged battery after standing without charge or load for 12 hours would be 12.6 to 12.9 V depending on the type of battery. You will have to go to the manufacturer or supplier to find out the exact chart of voltages.

If you go to www.uuhome.de/william.darden/ and click on Temperature Compensated Battery State-of-Charge (SoC) Table two different types of battery have been used as examples. You will also note that temperature is a big determinant in battery terminal voltage.

PeterD

ps don't forget the 12 hour resting time
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