AGM Batteries

Submitted: Tuesday, May 18, 2004 at 19:25
ThreadID: 12990 Views:5785 Replies:5 FollowUps:9
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I've been doing a lot of research on sealed batteries that can be safely installed inside a vehicle to use in a dual battery installation.

Looked at Odyssey/Optima, but at around $400 for a 55 A/H Batt they seem expensive and don't offer a lot of power/time.

Have since found out about Lifeline (USA made) AGM 100 A/H for $400 and Remco 100 A/H $300 (Chinese) from Battery World. Also Fullriver (Chinese) 90 A/H from Fridge and Solar, QLD for $275.

Advice on AGM's is that will accept a bulk charge and go from very low charge to full from an alternator in 2-3 hours, wheras a standard deep cycle will only charge at around 5A/H and will only ever achieve 80% capacity from an alternator (they need proper charging from an expensive 3 stage charger to get full). Also AGM's will tolerate being fully flattened many more times than a standard deep cycle.

Have been told that Winnebago Aust use Remco's; if true it is a fair recommendation.

100 A/H capacity and the ability to quick charge from the alternator seems to suit my needs well.

Has anyone used these?

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Reply By: TassieDave - Tuesday, May 18, 2004 at 20:56

Tuesday, May 18, 2004 at 20:56
G'day Jimbo
I use a 55ah optima yellow top in our camper and find it great. Had it for about 2 years now and have had it dead flat (lights left on in camper for months) quite a few times and have put it in the cruiser as the only battery and recharged it full within 30-40 minutes. They seem to accept charge as fast as you give it to them. I will be buying the new 75ah optima when my cruiser's battery gives out.
AnswerID: 59158

Follow Up By: Graham & Ann - Wednesday, May 19, 2004 at 22:19

Wednesday, May 19, 2004 at 22:19
Jimbo like TassieDave we have yellow top Optima 55ah in our van, for 18 months now, runs the lights etc 5 days no problems, haven't been unconnect for the car longer than that. Qucick to top up the charge and the battery can replace our car battery as its same external size, and the optima yellow tops are deigned to work as starting batteries as well as deep cycle, unlike most deep cycle. New 75ah should fit in crusiers etc.. Ok they cost a few $$$ but theya re maintanice free, can be left for months without loosing charge etc. Saves us having to fit 2nd battery in vehcile and they CAN be carried inside vehicle (even on their side)
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Reply By: Eric Experience. - Tuesday, May 18, 2004 at 22:20

Tuesday, May 18, 2004 at 22:20
Sorry to prick your ballon but no battery is safe to use inside a vehicle, the sealed ones will hold in the hydrogen until it gets up a little pressure then it lets it out all at once, if you charge it slowly the hydrogen can migrate around the cell and be absorbed to a certian extent but if you charge it fast it will vent out in a concentrated form which is much worse than a normal open cell. Just place it outside and be safe. Eric.
AnswerID: 59184

Follow Up By: Jimbo - Thursday, May 20, 2004 at 18:05

Thursday, May 20, 2004 at 18:05

The battery experts assure me they are safe inside a vehicle.

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Follow Up By: Eric Experience. - Thursday, May 20, 2004 at 22:17

Thursday, May 20, 2004 at 22:17
Of coarse the salesman will say that, but you can not defy the laws of chemistry. There are some good books on batteries and they all warn that the sealed batteries can only reabsorb the hydrogen at the lowest charge rate. good luck, Eric.
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Follow Up By: Andrew - Friday, May 21, 2004 at 16:16

Friday, May 21, 2004 at 16:16
Hi Guys

I hear what you say, however there are some new vehicle models (Nissans and Benz) supplied with sealed batteries mounted in the vehicle either in the boot or under the seat.
Perhaps alternators charge slowly enough for the Hydrogen to dissipate as you suggest.


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Follow Up By: Eric Experience. - Friday, May 21, 2004 at 23:02

Friday, May 21, 2004 at 23:02
The box contianing these batteries wil be vented outside. The vehicle could not get registration compliance without a vent. All batteries sold in Aus have to have a warning sticker on them saying that they must be charged in a ventilated space. all batteries including the ones mentioned have a vent to allow the hydrogen to escape. As I say if you understand the chemistry you will know this is true. Eric.
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Follow Up By: Jimbo - Saturday, May 22, 2004 at 11:06

Saturday, May 22, 2004 at 11:06

Have a look at this site.,%20or%20Absorbed%20Glass%20Mat%20Batteries

Whilst AGM's do emit some hydrogen it is quantities so small so as not to be dangerous. Quotes it being below the 4% US aircraft regulations.

Your opinion please.


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Follow Up By: Eric Experience. - Saturday, May 22, 2004 at 22:25

Saturday, May 22, 2004 at 22:25
The amount of hydrogen is proportional to the charge rate, as mentioned before if the rate is low you are OK. But the original question was relating to a 1hour charge which is very fast, I.E. 10x the normal rate. The regulations on aircraft require a complete change of air in the fusalarge every 30 seconds this is done to prevent the build up of fumes. So the battery could not put out 4% of the volume of the fusalage in 30 seconds, see how easy it is to play with figures to make a sale. The bottom line on this question is realy about air flow, if you drive with the windows down there will be no problem but if you are driving on a cold day with the windows closed and fast charging you battery you may have an explosion.The risk may be small but if it happens you may end up with ruptured ear drums and lose of hearing. Its the drivers choice. Eric.
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Follow Up By: Jimbo - Sunday, May 23, 2004 at 15:51

Sunday, May 23, 2004 at 15:51

Thanks for your valuable advice. There is something new to learn everyday and I am now in a much better position to decide than I was two weeks ago.


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Reply By: Ross - Wednesday, May 19, 2004 at 11:34

Wednesday, May 19, 2004 at 11:34
I use AGM's in my boat for everything from starting to long slow loads. Have had them for around 3 yrs. General expectation is around 10 yr life. I get mine from a crowd called Power Dive in Brisbane--they have a web site and they deliver to Sydney for $20. Their prices are very good. In a lot of boats it is compulsory to have sealed batteries and these are far better than gel as their physical size is compatible with normal lead/acid and the charging regime is the same.
AnswerID: 59231

Reply By: Rosscoe - Wednesday, May 19, 2004 at 15:35

Wednesday, May 19, 2004 at 15:35
I think I read somewhere that you can't or at least it is not recommended to use a mixture of AGM and Lead Aciod Batteries on the same charging regime. Anybody know if that's right?
AnswerID: 59275

Follow Up By: TassieDave - Thursday, May 20, 2004 at 15:53

Thursday, May 20, 2004 at 15:53
Yes that is correct, you can't parallel a normal lead acid and a AGM, they must be charged separately. Not sure why this is. There is a lot of info at . Oneday I hope all of my batteries will be AGM's.
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Reply By: Paul1 - Sunday, May 23, 2004 at 20:22

Sunday, May 23, 2004 at 20:22
I came to the same decision as you regarding AGM batteries. The battery installed in the car and removable is a more suitable option than installing a dual bat system.

I have read all of these comments and will chase them up with Fridge and Solar. If AGM batteries are vented, to allow the emmission of gases, how can they be installed on their sides???? Surely the contents would leak.

If it is the case that they are unsafe in the car then there is a lot of false advertising going on. Have you followed this up ??

AnswerID: 59824

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