AGM Battery charging

[Robmac]

My daughter has asked me to charge her AGM battery for her.

I have a Paco 20,000MA charger, and in the instructions it says "For charging 12V lead/acid batteries only", so you would have thought - question answered, it can't do the job or may ruin the battery.

However, I have heard conflicting answers to this question, some say it will be fine as it's a 7 stage charger and shouldn't be too heavy for an AGM, others say don't risk it, which I'm inclined to agree with.

has anybody got any experience with charging AGM batteries? Thanks in advance.

 

[HandyAndy]

you can charge it on the charger you have but once it gets to float if it's left there then that's when this charger may damage the battery.

 

[Richard n Ann]

They charge to 14,400mv same as lead acid batteries but long term float voltage is very slightly lower at 13,500mv. But that shouldn't be an issue for one charge ? ?

 

[pappajohn]

Just charge it, if it knackers it you won't be asked again.

 

[Gaston aires]

Uses smart charger. I have and it works great.
Phil

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[Robmac]

I decided to give it a go. The problem now is that it won't even get to stage 1 of the charging cycle.

I suspect that the battery is completely flat ie. below 2V. The manual states that if this is the case, I can hook up a 2nd battery to raise the voltage and disconnect it when the cycle starts.

Would this be a case of using jump leads pos to pos and neg to neg, and would it be ok to hook up a lead/acid to an AGM in this way?

 

[HandyAndy]

I would open the bonnet of your car and start the thing up and then connect the dead battery with jump leads as you specify... pozzy to pozzy, neg to neg then leave it running ten mins, that should bring it back to life if it's not buggered..

 

[autorouter]

Technically, AGM batteries use lead-acid battery chemistry. The main difference between AGM and conventional 'flooded' lead-acid is that the acid is soaked into a glass fibre mat between the plates. (AGM - Absorbed Glass Mat). That means there is no actual liquid to swill around and possibly spill or leak if the battery case is damaged.

When charging, they should ideally be held at the absorption voltage of about 14.4 volts for an extra period of time, maybe an hour or two, to cram in the last bit of charge.

Maybe it will suffer long-term, but a few standard charges are not going to damage anything.

 

[Robmac]

...When charging, they should ideally be held at the absorption voltage of about 14.4 volts for an extra period of time, maybe an hour or two, to cram in the last bit of charge.

Maybe it will suffer long-term, but a few standard charges are not going to damage anything.

Yes, my charger holds the charge at 14.4V for about 4 hours. Unfortunately that is step 4 and it won't even go to step 1 of the cycle.

I have tried hooking it up to another leisure battery to give it some oomph and as HandyAndy suggested tried to get some voltage into it by hooking it up to the car with the engine running, alas to no avail.

I'm suspecting that this battery is well and truly stuffed and will need replacing.

Thanks for all the suggestions everybody.

 

[Scotsblood]

I'm suspecting that this battery is well and truly stuffed and will need replacing.

I would think the term is well and truly "ferked"!
Remember this when forking out for a replacement!
AGM Batteries

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[Robmac]

I would think the term is well and truly "ferked"!
Remember this when forking out for a replacement!
AGM Batteries

It's my daughters' battery and I think she is going to replace it with a standard lead/acid battery.

She didn't really want to do this because it is a nice compact size and fits neatly under the front seat of her T5, she will have to have new brackets put in to take a larger battery.

her split charging system needs looking at anyway, apparently it was not wired in properly so the battery was never charging from the alternator, but my son is going to reinstall it for her at the weekend.

 

[TheCaller]

You will get a variety of opinions as to how much it is a concern, but not everyone would be comfortable fitting an open vented battery inside the passenger compartment.

 

[autorouter]

You will get a variety of opinions as to how much it is a concern, but not everyone would be comfortable fitting an open vented battery inside the passenger compartment.

An alternative to AGM is Gel. Again, it's lead-acid chemistry, but the acid is absorbed in a silica gel between the plates, instead of a glass fibre mat. Again, no liquid acid to spill and leak if the case is damaged.

Gel seem to have a better reputation on this forum, but still need a special charging profile, similar to AGMs. Hopefully, you may be able to get a Gel battery of the same size.

 

[StephDeLux]

An alternative to AGM is Gel. Again, it's lead-acid chemistry, but the acid is absorbed in a silica gel between the plates, instead of a glass fibre mat. Again, no liquid acid to spill and leak if the case is damaged.

Gel seem to have a better reputation on this forum, but still need a special charging profile, similar to AGMs. Hopefully, you may be able to get a Gel battery of the same size.

Sorry, but no. Gel batteries can be fully recharged with a tension of 14.4V applied continuously. 14.4V is delivered by the alternator, allowing full recharge while driving.

AGM requires a very different charging profile and needs between 14.7 and 14.8V to be properly recharged. That tension is never delivered by an alternator, leading to problems when relying on battery charging while driving.

Gel batteries are much more reliable than AGM precisely because they have a simpler charging profile.