Battery Charger for AGM

Submitted: Sunday, Nov 05, 2006 at 17:31
ThreadID: 39177 Views:14325 Replies:7 FollowUps:11
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Hi All,
I have spent about 6 hours this morning reading archives about battery chargers but need some clarification.
I have just purchased an AGM deep Cycle battery as my auxilliary and have a normal NZ70 cranking battery in the Cruiser.
I have a small Arlec 4 amp battery charger which I use occasionally to top up my batteries.
In archives, it appears that I need a new battery charger for the AGM.
Is that so? As I don't use the car much now except when we go away and a quick run on weekends, it needs a top up more regularly.
Do you install a charger in the car and just plug it in when not used. Is there a charger that you can install that will charge both different types of batteries?
I have read about a Xantrex TC10 that is fitted to Kimberly Campers. Is this the sort of thing I need?
Thanks for advise,
Steve
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Reply By: Grungle - Sunday, Nov 05, 2006 at 18:43

Sunday, Nov 05, 2006 at 18:43
Hi Steve,

For starters AGM's do not like heat so be wary of under bonnet temps (if fitted there). Secondly I would suggest getting a spec sheet from the manufacturer of your AGM to see what they suggest as the optimal charging voltages. The charging voltages for AGM's vary a little from manufacturer to manufacturer but on average they are lower than those for wet cell batteries which is what your Arlec would be setup for. Compare these to the charger you have and if they are different by a large amount (say 0.2V) then I would suggest buying a charger that is capable of charging AGM's.

I have not listed specific volatges BTW as each manufacturer will list what they believe to be the best for their battery.

Regards
David
AnswerID: 203204

Follow Up By: Alloy c/t - Sunday, Nov 05, 2006 at 19:46

Sunday, Nov 05, 2006 at 19:46
Dont like heat ? please explain then how my Fullriver AGMs under the bonnet of the landcruiser turbo diesel survive ,, AGMs were origanaly designed for military and space use , that AGMs cant stand heat is just a load of bovine droppings ,, any normally operating vehicle alternator WILL suffice to recharge an AGM ,, any voltage from 13.8 thru to 15.0 will suffice.
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FollowupID: 462793

Follow Up By: Grungle - Sunday, Nov 05, 2006 at 21:09

Sunday, Nov 05, 2006 at 21:09
Alloy c/t - what sort of a response is that?

Why do people like you contribute (if you can call it that) if it is not constructive?

I had a Dynasty AGM swell so bad that it was almost impossible to remove from the battery tray (10 inches from the turbo) yet the other 4 in the camper are still going strong today.

It is obvious you know nothing about your AGM if you think it can be happily charged at 15V at 50°C (I checked the Fullriver spec sheet which tells you the charge rate). Yes AGM's were designed for the military but mainly because you can orientate them in any plane but also because you can put a bullet through them and they will still perform. You probably didn't know either that they shouldn't be paralleled with convential wet cell batteries due to the fact that they have different internal resistance and thus different voltage requirements.

As stated to Steve, I suggested getting the spec sheet to see what it states. Would you like me to send you one for yours?

Regards
David

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FollowupID: 462827

Follow Up By: Alloy c/t - Sunday, Nov 05, 2006 at 21:22

Sunday, Nov 05, 2006 at 21:22
My response shows that you know jack about AGMs in practice , following and believing the spec sheet on batteries is like believing a nissan 3lt patrol is a better vehicle than a 4.2. ,, who in their right mind would put any battery 10 inches from a turbo ,gel ,agm ,or wet cell ?? ,I run 3 x AGM HGL Fullriver under the bonnet of the 80series factory turbo ,never a problem in the last 36 mths ,use your spec sheet for its main purpose ,remember to burn it when finished.
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FollowupID: 462835

Follow Up By: Member - Phantom (WA) - Sunday, Nov 05, 2006 at 21:53

Sunday, Nov 05, 2006 at 21:53
I have downloaded the spec shhet for my DC96-12 and it says the initial charging voltage is 14.5-14.9V, that is very different from my Arlec which charges at 12.0v?? That is far greater than the o.2v.
Steve
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FollowupID: 462841

Follow Up By: Member - Mike DID - Monday, Nov 06, 2006 at 18:25

Monday, Nov 06, 2006 at 18:25
Military Spec AGM batteries have metal cases to allow any excess heat to be conducted away to prevent thermal runaway.

AGMs are more prone to themal runaway than Gel or Wetcell because the electrolyte is not in ocntact with the outer case - unlike Gel or wetcell.

If your charge voltage is low enough and your Alternator is temperature compensated, you will not have a problem thermal runaway. If not, your AGM may die.
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FollowupID: 462965

Reply By: Mainey (WA) - Sunday, Nov 05, 2006 at 21:22

Sunday, Nov 05, 2006 at 21:22
Steve, you say ""you have purchased an AGM deep Cycle battery as your auxiliary and have a normal NZ70 cranking battery in the Cruiser. You have a small Arlec 4 amp battery charger which you use occasionally to top up batteries. You don't use the car much now, except when you go away, and a quick run on weekends, does it need a top up more regularly""

First question is; do you have a battery regulator and also dual battery isolator system that's suitable for the two different types of batteries!!!

Unless you are running your fridge 24/7 in your vehicle you are not going to have any problems with any AGM Aux battery that only gets charged by the vehicle alternator once a fortnight or so as the drain on any decent AGM's is the lowest around, definitely far less than a NZ70 Cranking battery, so if either battery is going to go flat due to self drainage it will be your Cranking battery!!

Remember your alternator is regulated to deliver far more power than the 4 a/h available from your battery charger, which is ok to use if you want to make sure the boat battery is fully charged during the winter months when it's not used.
AnswerID: 203247

Follow Up By: Member - Phantom (WA) - Sunday, Nov 05, 2006 at 21:45

Sunday, Nov 05, 2006 at 21:45
C'mon boys,
I guess it is comments like those above that confirm that wading through 6 hours of archives ends up in total confusion. There are so many varied products, experiences, applications and expectations that no one person will ever be be correct all the time.
Mainey, I originally had the Cruiser set up by an auto leccy that ran both batteries, charged the cranking battery first, then the aux but then both batteries were the same. I have only just changed over to the AGM. Are you indicating that my current set-up may not be appropriate? No, I don't run the fridge unless we are going away, and yes, I recently had to jump start the car cos it would'nt go. My cranking batery is fairly new, just needed a run.

Steve
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FollowupID: 462840

Follow Up By: Mainey (WA) - Sunday, Nov 05, 2006 at 23:11

Sunday, Nov 05, 2006 at 23:11
Steve,
You say "I recently had to jump start the car cos it would'nt go.
My cranking batery is fairly new, just needed a run"

Can I suggest there is a problem if you run the vehicle only weekends and your 'as new' NZ70 Cranking battery won't hold enough charge to start the vehicle!!

No Steve, I'm not saying your charging set-up is inadequate - you implied that, because you had the flat battery.
If I had a battery that would not hold a charge for a fortnight I would be getting it back to a qualified person for expert advice, because when the warranty is 'out' it's your problem, not the retailers or the auto leccy's.

Maybe the battery is not being fully charged - for any number of reasons, making it a charging problem and not a battery problem.

Have it checked while still under warranty, because either the battery is faulty or possibly the charging system is faulty/inadequate.

If any 'as new' battery won't hold sufficient charge for a week or realistically even a fortnight it's a problem you don't need.
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FollowupID: 462858

Reply By: Aston - Sunday, Nov 05, 2006 at 22:37

Sunday, Nov 05, 2006 at 22:37
Steve,
Can i suggest that you have a look at this site for a charger that will cater for batteries of different types.
I have just purchased one of the MC121045 which is computer controlled.
If you read the info you will soon see why charging batteries has become a science.

Click on this
link text

Hope this is more help
Cheers Aston
AnswerID: 203262

Follow Up By: Mainey (WA) - Monday, Nov 06, 2006 at 15:02

Monday, Nov 06, 2006 at 15:02
MC121045C..... 4500mA battery charger
12v Cranking battery - maximum 650 cca
12v Deep Cycle battery - maximum 80 a/h

Above are technical specs of battery charger mentioned,
note; it's NOT recommended for Cranking batteries over 650 cca.
Large diesel cranking batteries are often >700 cca's
Most effective Deep Cycle batteries are well in excess of 80 a/h

By comparison the "AC1000" is 6200mA which is ~40% more power and is therefore rated by the manufacturer as suitable for up to 800 cca batteries and 100 a/h DC's
However it will only charge to 14.2v so the final 'boost' charge is not available.
I believe the AC1000 is only about $100 and fully automatic.

Option (1)
If you NEED in excess of 14.2v and your alternator IS REGULATED to about 14.2v you will need a higher rated charger like the MC121045C

BUT...
what happens when you install the battery charged on the 'expensive' charger at about 15v into your vehicle, the battery will never be fully charged ever ever ever again, till you again recharge it with the 'expensive' charger as the vehicle alternator/regulator won't be able to maintain the higher required charge!!!
IF, as we have said above, the alternator IS regulated to only about 14.2v

Option (2)
The most probable scenario.

The vehicle alternator/regulator WILL charge in excess of 14.2v
therefore;
You can use the 6200mA (10a) battery charger to get the initial 14.2v charge back into the battery and install the battery into the vehicle, it WILL start the vehicle and the alternator/regulator WILL fully recharge it....when driven.
Note; the caps are there only for emphasis - not screaming L0L
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FollowupID: 462928

Reply By: Member - Peter R (QLD) - Monday, Nov 06, 2006 at 08:46

Monday, Nov 06, 2006 at 08:46
Steve,
I have a Full River AGM and charge it with a C-tek 7000, also charge my boat battery (ordinary marine type) with it.

Charger can be set to required voltage for either the AGM or your normal charging battery,(The charging voltage can be set to 13.6v,14.4v,14.7v or 16 v. with selection made by pressing a "mode" button)
For AGM the setting used is 14.7v.
For the marine battery I use 14.4v
I use the AGM to run Waeco , and when i am home I simply recharge through the Ctek.
The beauty of the charger is that it can be connected full time without doing any damage .

Pedro
AnswerID: 203295

Follow Up By: Des Lexic - Monday, Nov 06, 2006 at 12:07

Monday, Nov 06, 2006 at 12:07
Pedro,
I was having a discussion with a 12 volt specialist shop on the weekend regarding charging of my AGM and normal wet cell cranking battery and they informed me that I should never use a Arlec type charger on the AGM battery but they highly recomend the C-tek type smart charger as they considered them to be the best available. They had other battery chargers there but their opinion was that the C-tek is the best current technology.
I currently use a Protector 1600 battery maintainer which is grosly undersized for what I expect it to do but the car is only used on weekends too so the trickle charge is sufficient to top the batteries up.
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FollowupID: 462899

Reply By: rolande- Monday, Nov 06, 2006 at 12:51

Monday, Nov 06, 2006 at 12:51
G'Day Steve,
Xantrex or C-Tek chargers will work fine. C-Tek reasonably priced as well so long as you don't buy a high amp model. For the price of the AGM I would spend the extra and upgrade to one of these chargers
Regards
Rolande
AnswerID: 203317

Reply By: Derek from Affordable Batteries & Radiators - Monday, Nov 06, 2006 at 22:51

Monday, Nov 06, 2006 at 22:51
Hi Phantom

You shoud be quite confused by now.

Give me a ring or email me if you like and I will help you if I can.

Regards Derek.
AnswerID: 203448

Follow Up By: Leroy - Wednesday, Nov 08, 2006 at 15:23

Wednesday, Nov 08, 2006 at 15:23
Derek,

Please tell us your solution online as it's an often asked question.

Leroy
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FollowupID: 463334

Follow Up By: Derek from Affordable Batteries & Radiators - Wednesday, Nov 08, 2006 at 18:16

Wednesday, Nov 08, 2006 at 18:16
Hi Leroy

There are too many variables.

It would require another battery article.

Maybe time to write one on chargers.

AGM's require higher charge rates and good quality chargers. 4amps is too low.

Regards Derek.
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FollowupID: 463397

Reply By: porl - Wednesday, Nov 08, 2006 at 15:15

Wednesday, Nov 08, 2006 at 15:15
You've gotta the specs on you AGM, I have an old optima AGM and it says don't charge over 14.2v, but I have noticed on some new AGM's, eg Fullriver, their specs say okay to charge at up to 14.8v.

Some battery chargers have a button to select type of battery, like one i had that died after 8 months.

My new charger says it will charge at up to 14.8v (but no switch) which is fine for the fullriver AGM but not fine for my optima.

Just a bit of shopping round i guess.
AnswerID: 203709

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