Smartchargers

Submitted: Tuesday, Feb 15, 2011 at 17:17
ThreadID: 84384 Views:2548 Replies:5 FollowUps:7
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I use a 120a/h deep cycle battery from which runs a 12 volt fridge(2.7a average) and 3 led lamps(rated@0.23a). I am just wondering what size charger smartcharger would be recommended, to get a good recovery time of the battery and give it a good life when running the fridge at same time as charging the floating battery????
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Reply By: kevmac....(WA) - Tuesday, Feb 15, 2011 at 17:24

Tuesday, Feb 15, 2011 at 17:24
Over the weekend was using a 6 amp 3 stage charger to keep fridge going, but came to being either the gennie running or the battery on......thinking maybe running 2 of 6hr max periods with the gen and the battery for the rest
AnswerID: 445541

Reply By: Gronk - Tuesday, Feb 15, 2011 at 17:43

Tuesday, Feb 15, 2011 at 17:43
Any good 3 stage charger between 5 & 15A will do just fine..
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Reply By: ABR - SIDEWINDER - Tuesday, Feb 15, 2011 at 18:12

Tuesday, Feb 15, 2011 at 18:12
Hi Kev

As mentioned a small is charger is fine. Check your battery specs but rule of thumb is 10% of the battery capacity so 12 or 15 amp will do.

Try get one with power supply mode so you don't over charge the battery when the fridge is running for extended periods in summer.

The 15A Ctek or 15A ABR unit will be fine.

Regards

Derek from ABR
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Reply By: Battery Value Pty Ltd - Tuesday, Feb 15, 2011 at 18:37

Tuesday, Feb 15, 2011 at 18:37
Hello kevmac,

...maybe running 2 of 6hr max periods with the gen....

So you're planning on running the gen for 1/3 of the time while the fridge draws 2.7A for 3/3 of the time, or around 64Ah per day.

At first sight it looks like the gen/charger needs to supply at least 3 times 2.7A equals 8.1A during its daily run time of 8 hours.

But there's more to it:
because the battery will allow this current only for about 80% percent of the time the remainder needs to be supplied during the following absorption and float charging stages.
Let's look at the numbers:

The 80% state of charge will be reached after 64Ah*0.8/8.1A equals 6.3 hours of charging, leaving only 1.7 hours for absorption and float stages. This isn't quite enough to fully recharge the battery.

To overcome this problem, select a charger which offers 25~30A during the bulk charging stage.

Now, the 80% state of charge will be reached after 64Ah*0.8/25A equals 2 hours of charging, leaving 6 hours for the absorption and float stages.
This outcome is a lot better for your battery's health because it'll get almost fully charged on a daily basis.

Hope this explains it?

More information about 25A high quality chargers can be found in my profile.


cheers, Peter
AnswerID: 445554

Follow Up By: kevmac....(WA) - Tuesday, Feb 15, 2011 at 18:43

Tuesday, Feb 15, 2011 at 18:43
ok Thanks for that will check u out when i get home.......shhhhhhhhhh!!
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Follow Up By: Gronk - Tuesday, Feb 15, 2011 at 22:20

Tuesday, Feb 15, 2011 at 22:20
So, you're advising 25-30A charger for a 120A/H battery ???
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Follow Up By: kevmac....(WA) - Tuesday, Feb 15, 2011 at 23:30

Tuesday, Feb 15, 2011 at 23:30
dropped into my local auto one store on way home from work and he showed me a Projecta 6 stage(it says) 15 amp charger so wondering if that would be a good half way point between what i have been using and what our commercial member was suggesting (25 - 30 amp)???...... he quoted that could quite easily leave battery on float all year round and it would give as it is required...........
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Follow Up By: Battery Value Pty Ltd - Wednesday, Feb 16, 2011 at 08:23

Wednesday, Feb 16, 2011 at 08:23
Hello kevmac,

why settle for 50 if you can get 100% for similar money?
Did you take the additional gennie run times into account if you take the smaller charger?
Please note that not the number of "stages" above 3, are important when looking at a charger, it's mainly the amount of juice you can squeeze out of them....

@ Gronk,

yes that's right, a typical AGM battery is able to absorb/accept a max charging current of around C/4.

cheers, Peter
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Follow Up By: hawks_tasssie - Wednesday, Feb 16, 2011 at 21:41

Wednesday, Feb 16, 2011 at 21:41
Hi Gents,

I have a battery shop down here sunny Hobart. I with agree 100% with Peter. Using the correct charger will save you money in the long term. Having such a draw on your battery means it is really important you charge it properly. CTEK 25amp would be ideal.


Regards,

Matthew Millington
96 Clarence St, Bellerive Tas Ph 03 62448377
www.easternshorebatteries.com.au

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Follow Up By: kevmac....(WA) - Thursday, Feb 24, 2011 at 17:27

Thursday, Feb 24, 2011 at 17:27
I would like to be able to go the C Tec but at moment i am immediately ruled by finance. Once I retire may be able to invest more heavily in my travelling.
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Reply By: kevmac....(WA) - Wednesday, Feb 23, 2011 at 18:21

Wednesday, Feb 23, 2011 at 18:21
After much ado about nothing, finally decided upon a Calibre 20amp multi stage charger(currently have Calibre 6 amp) was normally priced at $199, but went in at right time and have on order at a special price of $159. At least if something goes wrong with it, i will be able to go to local store and slam it on counter and abuse them face to face(hahaha).
Oncee I have it installed and trialled , I will let you all know how it goes. Thanks again for your advice and help.
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Follow Up By: Member - Graham H (QLD) - Thursday, Feb 24, 2011 at 09:42

Thursday, Feb 24, 2011 at 09:42
If something does go wrong with it you may well have to take the battery back

and try to slam it on a counter as well

Why buy cheap when for a bit more you can have peace of mind with a CTEK.

Not a lot of Supercrap stores in parts of the country either.

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