CTEK charging a Ritar AGM?

Submitted: Thursday, Jan 14, 2010 at 19:26
ThreadID: 75204 Views:6892 Replies:1 FollowUps:7
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I have a Ritar RA12-120S (12V120AH/C10HR) AGM battery (http://www.ritarpower.com/upload/pdf/2009103111253617252827.pdf). Can I charge it with a CTEK Multi XS 7000 battery charger?

The reason I ask is it states on the manual "For lead-acid batteries 14-225Ah".
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Reply By:- Thursday, Jan 14, 2010 at 19:44

Thursday, Jan 14, 2010 at 19:44
AGM, spiral wound lead, calcium, gel, VRLA, sealed lead acid, flooded, wet, all these acronyms pertain to 'lead acid', thus yes, you can use this charger on your AGM battery.

Best regards, batterymeister
AnswerID: 399419

Follow Up By: ryangus - Thursday, Jan 14, 2010 at 20:20

Thursday, Jan 14, 2010 at 20:20
Thanks mate. I assume I should use the following mode:

"Mode 14.7 V - This setting is recommended for a battery at
temperatures < 5 degrees C. It is also recommended for many AGM
batteries like Optima, Maxxima and Odysseys. Consult your battery
manufacturer when in doubt."

Is this correct?
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Follow Up By:- Thursday, Jan 14, 2010 at 20:50

Thursday, Jan 14, 2010 at 20:50
Yes, use the 14.7V setting for boost charging your AGM battery. Make sure the battery temperature is around 25 degrees, if it's warmer than that, use a slightly lower voltage setting i.e. 14.4V.

Because your charger only can deliver 7A max, there is a chance that it'll miss the boost/float change over condition (rule of thumb: charge current =<10% of max charge current or =<0.7A), especially if the battery isn't new, and/or the temperature is elevated.
Keep an eye on the charging time and voltage to gain an understanding if and when this switch over from 14.7V to 13.6V occurs. If it doesn't, after say 5 hours of sitting on 14.7V and/or your battery gets more than hand warm during charging, select the next lowest boost charge setting and watch out for this change over to happen again.

Best regards, batterymeister
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FollowupID: 668402

Follow Up By: ryangus - Thursday, Jan 14, 2010 at 23:11

Thursday, Jan 14, 2010 at 23:11
Using the 14.7 setting, the CTEK is showing as still charging after about 4-5 hours. The battery is not warm to touch whatsoever.

According to the volt meter I have attached to the battery, it's showing about 13.06V - I assumed it shouldn't go much higher than 12.8, as that's what the battery was at when I bought it. The battery was at 12.26 before I started charging.

Is this normal?
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FollowupID: 668427

Follow Up By:- Thursday, Jan 14, 2010 at 23:41

Thursday, Jan 14, 2010 at 23:41
Yes, this is normal.
The battery voltage during charging is always higher by up to 2 Volts compared to 'open circuit'.
This is because the charging current 'pushes up' the terminal voltage due to the battery's internal resistance and other electro-chemical effects.

From the time the maximum of 14.7V has been reached, it shouldn't take longer than a few hours for the charger to reduce the boost voltage to the float voltage (around 13.6V).
As I mentioned before, it's important to verify the charger actually does switch over to the lower voltage.

Looking at your charging voltages, it'll take the 7A charger at least another 5 to 7 hours to fully charge your battery (which was pretty much empty when you started the charging process).
So by tomorrow lunch time, I guess you should see the battery sitting on 13.6V float and the charger will signal 'charging finished' or similar.

Best regards, batterymeister
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FollowupID: 668430

Follow Up By: ryangus - Thursday, Jan 14, 2010 at 23:53

Thursday, Jan 14, 2010 at 23:53
Thanks mate - I'll keep an eye on it.
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FollowupID: 668435

Follow Up By: ryangus - Friday, Jan 15, 2010 at 22:44

Friday, Jan 15, 2010 at 22:44
Thank you all for your advice.

One more thing. I have a small portable 12V 7Ah external battery for my hunting spotlight. Would it be safe to use the CTEK on that also, and if so, what setting?
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FollowupID: 668605

Follow Up By:- Friday, Jan 15, 2010 at 22:55

Friday, Jan 15, 2010 at 22:55
no worries ryangus,

I wouldn't use the 7A charger on a 7Ah battery as it's recommended to have the max charge rate below 25 to 30% of Ah rating, or 2A in this case.
There are inexpensive 12V plugpack chargers available from Jaycar etc.

best regards, batterymeister
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FollowupID: 668609

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