Deep cycle battery charger

Submitted: Tuesday, Apr 12, 2016 at 08:09
ThreadID: 132098 Views:2182 Replies:8 FollowUps:8
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Hi everyone, needing advice, I am currently rebuilding my camper for some remote travelling.
I have currently 100a/h of batteries (3of Agm) in series that charge via solar. Questions are

Can I charge them with a normal battery charger I use on my car?

Thank you
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Reply By: Athol W1 - Tuesday, Apr 12, 2016 at 08:36

Tuesday, Apr 12, 2016 at 08:36
Larsy
Are you sure that the batteries are in series, as this will give you a voltage that is the sum of all 3 batteries (ie 3 x 12 = 36 volts), whereas in parallel will only give the voltage of each of the batteries but the capacity of the 3 combined (ie 12 volts but 3 x 100 = 300ah).

Should your normal battery charger that you use for your car be a good quality multi stage charger of recent manufacture with the correct voltage output for the combination of the batteries then it would be suitable for charging AGM style batteries.

Hope this helps.
Athol
AnswerID: 598531

Reply By: Member - Phil G (SA) - Tuesday, Apr 12, 2016 at 08:52

Tuesday, Apr 12, 2016 at 08:52
You will need a beefy charger - 15A minimum and preferably 25A or more to do 3 AGMs in parallel.

If you are remote travelling I expect there will be times when you might arrive at a powered site with empty batteries and you will need all the amps you can get.

I'm sure you'd have solar panels as part of your system.
AnswerID: 598534

Reply By: Member - larsy - Tuesday, Apr 12, 2016 at 09:03

Tuesday, Apr 12, 2016 at 09:03
Hi,

Thanks for the quick replies!!

Sorry, they are parallel, yes are also charged via solar.

So a multistage charger, of 25amps would be suitable for backup?
I will go shopping and find a good one.

Any recommendations of decent brands to look for?

Thanks again.
AnswerID: 598536

Follow Up By: CSeaJay - Tuesday, Apr 12, 2016 at 10:31

Tuesday, Apr 12, 2016 at 10:31
Get yourself a CTek and forget about all your charging worries.
CJ
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Reply By: Sigmund - Tuesday, Apr 12, 2016 at 09:46

Tuesday, Apr 12, 2016 at 09:46
The advice I got on this is that the charger should be connected to one pole on the first battery and the other pole on the last.

Maybe I can jump in with a related question ....

I use a Powertech smart charger from Jaycar for bulk and float charging. When this is connected it defaults to a mode marked by a snowflake and the manual says this is recommended for two batteries in parallel which is in fact what's there.

However, in this mode it's putting in pulses of over 15v. My understanding is that this is high for AGMs. Would it be doing any damage?
AnswerID: 598540

Follow Up By: Nomadic Navara - Thursday, Apr 14, 2016 at 17:36

Thursday, Apr 14, 2016 at 17:36
What are these pulses you are referring to? If they are like those described in this article then they will be beneficial.
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Follow Up By: Sigmund - Thursday, Apr 14, 2016 at 17:58

Thursday, Apr 14, 2016 at 17:58
Thanks NN. I read that Rivers piece.

By pulses I mean this: when the charger is connected I'm looking at the voltmeter that's fitted to the CT, and it sits on c. 13.8 volts for about 10 seconds and then goes up to just over 15v for a second, drops back and repeats.

I've just hooked it up to get the times more accurately and it wouldn't do it!

So it according to Rivers it shouldn't be needed with AGMs. Question is whether it does damage.

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Follow Up By: Nomadic Navara - Thursday, Apr 14, 2016 at 22:32

Thursday, Apr 14, 2016 at 22:32
Sigmund, without knowing exactly the model number of your charger I can't assist you much. Please supply it.

"voltmeter that's fitted to the CT" What is this CT you are referring to?
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Follow Up By: Sigmund - Thursday, Apr 14, 2016 at 22:52

Thursday, Apr 14, 2016 at 22:52
CT = camper trailer Peter.

This is the charger model: Click

Thanks.
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Follow Up By: Nomadic Navara - Thursday, Apr 14, 2016 at 23:56

Thursday, Apr 14, 2016 at 23:56
Here are the details of a similar model of charger. Note the first stage of the charging:

"1. Diagnosis and Recovery - As soon as charging instruction is given to the charger, the unique diagnostic function automatically checks status of battery (detects voltage). If a deeply discharged battery's voltage is over 4.5 ± 0.10 (for 12V battery) or 16V±0.32V (for 24V battery), charger begins pulse charging with 5.0A high current and 1.5A low current to recover it, which terminates when voltage reaches to 10.5V±0.25V (for 12V battery) or 21V±0.42V (for 24V battery) at the beginning of the process, the charger skips pulse charging and it switches over to pre-selected charging mode. If within 7 hours voltage of battery does not rises to 10.5V±0.25V (for 12V battery) or 21V±0.42V (for 24V battery), charging process is terminated and battery is treated as bad battery."

I think you observed the first stage of charging. You have now brought the battery up to a charge level where the charger now slips through the first stage very quickly. That's why you are not seeing that pulsing first stage.
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Follow Up By: Sigmund - Friday, Apr 15, 2016 at 05:07

Friday, Apr 15, 2016 at 05:07
Thanks. Perhaps that's it.

The SoC was around 12.5 v when the charger was hooked up. (Analogue meter with 0.2 gradations). Will run it again and see if the pulsing is temporary.
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Reply By: Athol W1 - Tuesday, Apr 12, 2016 at 20:02

Tuesday, Apr 12, 2016 at 20:02
Larsy

I am currently using a 35a Projecta multi stage unit (with 350ah of battery to charge), I have previously used Ctec 25a (with300ah of battery) , both of which did the job with no issues, there is also units available from Redarc, all of which are generally considered to be quality manufacturers so price and availability could be the influencing factor.
Regards
Athol
AnswerID: 598566

Reply By: Member - larsy - Thursday, Apr 14, 2016 at 11:14

Thursday, Apr 14, 2016 at 11:14
Hi again!

Next question?

Can I charge my deep cycles via 240vlt charger, whilst the solar regulator is connected? Or does it need to be disconnected?

Thank u
AnswerID: 598632

Follow Up By: Nomadic Navara - Thursday, Apr 14, 2016 at 17:31

Thursday, Apr 14, 2016 at 17:31
If the total combined charging current of the two chargers does not exceed 80 A or so then it will be OK to parallel the chargers
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Reply By: Member - Balvenie Pastoral - Thursday, Apr 14, 2016 at 11:56

Thursday, Apr 14, 2016 at 11:56
Follow the "Ctek" advice..... end of story !
I bought an Optima OD34 Yellow top in June 2004. The CTek XS800 (its been superseded now) is continually connected to the battery when not in the Car and maintains the battery, which is still going strong. Its the best hundred odd dollars I've ever spent. Good luck
AnswerID: 598635

Reply By: Member - Peter H41 - Thursday, Apr 14, 2016 at 14:53

Thursday, Apr 14, 2016 at 14:53
Just out or curiosity what sort of solar panel have you got hooked up to you deep cycle Battery?

I was looking at getting a deep cycle battery for my land cruiser and hooking it up to charge via solar as I am a big fan of the solar energy concept
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