Battery charging

Submitted: Sunday, May 02, 2010 at 16:41

ThreadID: 78170 Views:3513 Replies:4 FollowUps:5

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Battery Power

In this article we explain why you might need an additional power source independent of the starting battery installed into your vehicle and we look in detail at types of batteries,

Rick and Kerrie

Hi everyone,

We are new members, we have been following the forum for several months and this is our first post, we recently bought some gear including a 100ah AGM battery and a CTEK XS7000 charger. This battery will be used to power the Engel fridge when camping, when not camping do we leave the battery connected to the charger full time or charge for a period and then disconnect for a time.

Thanks for your help Rick

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Reply By: Wilko - Sunday, May 02, 2010 at 16:58

Sunday, May 02, 2010 at 16:58

Hi Rick and Kerrie,

I leave mine (Ctek M100) connected 24/7, Thats what it was designed for.

Cheers Wilko

p.s. the M100 is a 7amp marine charger almost the sameas the XS7000.

AnswerID: 415117

Reply By:- Sunday, May 02, 2010 at 17:02

Sunday, May 02, 2010 at 17:02

Gidday Rick,

when I bought my set-up - same as yours except a 120 ah agm - they just told me to charge it up once a month when its not in use for long periods. At the time I thought - once a month - I will be camping more often than that, so no worries.

Well, it didn't work out that I get camping as often as I hoped, so I now charge the battery once a month! I just put it on for about 48 hours, once a month. I've had it for about 18 months now - so far so good.

Check the charging voltage for your battery (mine is written on it) - from memory, mine prefers 14.7 volts, so I use the higher charging setting on the ctek 7000 - I think its called snowflake.

Cheers!

AnswerID: 415118

Reply By: Allan B, Sunshine Coast, - Sunday, May 02, 2010 at 17:09

Sunday, May 02, 2010 at 17:09

Hi Rick, welcome aboard to you and Kerrie.

Lead-acid batteries, including the AGM type, will self-discharge over a period of time and if left in a discharged state for an extended period will permanently harm the battery.

The best maintenance is to leave the battery connected to a float charger full time and your CTEK will do this nicely. If you prefer, the battery can be connected to the CTEK say once per few weeks and left on charge for at lest 24 hours.

Cheers
Allan

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AnswerID: 415121

Follow Up By: Sand Man (SA) - Sunday, May 02, 2010 at 18:03

Sunday, May 02, 2010 at 18:03

Allan,

I don't believe you are fully correct mate.

AGM batteries have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries.

I have left my Thumper battery pack (AGM cells) for a few months in the shed and when I have dragged it out and checked the voltage, it has shown 12.7 volts or so, which is almost fully charged.

Having said that, there is no problem in leaving a smart charger connected providing it has a float charge setting.

Bill.

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Follow Up By: Allan B, Sunshine Coast, - Sunday, May 02, 2010 at 18:31

Sunday, May 02, 2010 at 18:31

Yes Bill, agreed that AGM have less self-discharge characteristic than flooded cells but it still does occur and more so as they age. So it is still good practice to keep them charged-up.

Cheers
Allan

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Follow Up By: Ianw - Sunday, May 02, 2010 at 18:51

Sunday, May 02, 2010 at 18:51

The specs on Vision AGM batteries states that they should be charged every 3 months, but MUST be charged every 6 months.

Also for every 10deg C over 25C in storage, design life is halved !!

Ian

FollowupID: 685306

Follow Up By: Secret Mens Business - Sunday, May 02, 2010 at 21:06

Sunday, May 02, 2010 at 21:06

My experience with AGM's shows that charging batteries every 3-4 mths is fine. Off course I am assuming the battery was at full capacity before sitting for that period. The discharge of these batteries is minimal, unlike Wett Cells. I am into my 5th year with a whole range of Fullriver AGM batteries and all is perfect.

FollowupID: 685326

Follow Up By: Rick and Kerrie - Monday, May 03, 2010 at 07:05

Monday, May 03, 2010 at 07:05

Thanks for the advice,

It seems I can do either without damaging the battery, I think I will charge and disconnect as it doesn,t seem right to me to leave on charge when not being used.
But maybe I'm old fashioned.

Cheers Rick

FollowupID: 685354

Reply By: Member - Phil G (SA) - Wednesday, May 05, 2010 at 17:56

Wednesday, May 05, 2010 at 17:56

I also have a 100Ah AGM and the same Ctek charger. Like Sandman says, the self-discharge is very, very low.Mine goes on the Ctek every 2-4 weeks. I have an ammeter in the Ctek leads so I know what's going on, and it takes very little charge. Leaving it hooked up is unnecessary.

AnswerID: 415535