AGM BAttery noise when charging

thanks. charger says its and 8 stage and only settings available to me are supply mode and normal charge cycling. Dont think i can alter it for different battery types.

The noise is constant and coming from the battery rather than the charger. It is difficult to describe, a little like quiet trickling water. It is stil charging at 14.8v, but has only been a couple of hours, so ill check later. The charger is fully automatic and has no setting other than normal charge or supply mode, so dont think i can change it for gel or other battery type.
The AGM is a first start. www.firststartbatteries.com.au

Thanks very much for your help. I'll check it out later and see what noises and voltages it's producing.

If you have any loads connected to the battery while you're charging it, the charger will never drop back to the lower Float Voltage and you'll cook your battery eventually.

I can only imagine one way, an AGM could produce noise... by gases venting through the (with moisture covered on inside) overpressure relief valve(s).

I'm with Mike DID on that one, who suggested to turn off all connected loads while charging in order not to interfere with the charge algorithm/routine.

And I'm also with Maîneÿ on having the battery load tested to see if its still holding 100% of its rated charge of 120Ah - and get this documented.

You could also try and load test it yourself by hooking it up to a heavy load. I test all my batteries with a 660W (55A) load over 30 minutes which discharges them to 50%. Taking voltage measurements at the battery terminals every minute and plotting them along the time axis of the discharge curve diagram (manufacturer supplied), I get a pretty good idea of the battery's health/quality.

If you'd like to take a closer look at how such a load test result of a new and healthy quality AGM might look like, go to www.batteryvalue.com.au

I'd do the following:
Since the batt has been sitting on charge now for a while it should be fully charged. Give it a light discharge by running the fridge/DVD player for half an hour off it. And while the load is still drawing current, measure the voltage across the battery terminals. A healthy 120Ah AGM should still hold the voltage around 13 V then.
If it fails this simple test, it's either not 100% charged or already been damaged (or it was already a dud when you bought it).
If it passes this light load test, give it the heavy treatment as described above.

Good luck with it all!

Chaps, the thing I leave on permanently is the ERPS anti rust system (but lets not argue about that!!). From memory it draws about 30-40 milliamps - we measured 60milliamps total from car and ERPS, when car stopped and nothing else on. Is that likely to stop a ctek charger going to float? Or, is there a particular draw that stops a charger going to float? cheers

As a general rule, 3-stage chargers will drop to float voltage when the current drops to 0.1 of its rated output - i.e 1 amp for a 10 amp charger.

. . . that's 1 amp of total current from the charger - could be 0.9 amp into the battery and 0.1 amp into the load.
.

See Lex M's post below, he says the 25Amp ctek drops to a reduced absorption voltage after the bulk charge current has tapered off to around 3A (if I've understood this correctly!) And subsequently reduces to the float voltage which isn't increased unless there is a higher draw than 7A.

The important thing to note here is that the ctek makes up its mind on the charge voltage by monitoring charge currents in the range of several Amps.
Thus, light loads like the one you're talking about won't have much of an influence on the charge algorithm which is mainly determined by the battery's 'thirst' for charge current.

Unless, your charger is lower rated. Then lower load currents become more significant in the charger's decision making process.
But we're still talking chickenfeed in case of your rust preventer's 60 milliamps.

No worries there!

@ Mike DID

hmmmm, this has me thinking.....

If a high rated AGM (100Ah plus) is bulk charged by a smallish (3A?) three stage charger which only switches to float mode after the current has dropped to 0.3A, it will never do so because at 14.7V, the charge current of a phat AGM is certainly higher than that, especially under elevated temperature conditions.

This could result in serious overcharge, if left on permanently!
This is probably why the better chargers are charge time limited (like the olden day ones lol!)

First start. Australian company, but not sure where their batteries come from. Rang them and they said that 14.8v shouldnt be an issue.

Most manufacturers specify 25% of the Ah rating as the Maximum charging current - i.e. 25 amps for a 100 AH battery.

The MINIMUM charger size is usually recommended as 10%, so the battery will be charged in reasonable time.

Ian,
So what do you believe is the reason battery has made no noise this time ?

Maîneÿ . . .

Not sure mate. Not sure what the reason was in the first place. Rang first start which seem to be aust company, not sure where their batteries come from and the seemed to think that noise would not be an issue as opposed to a hiss or crackle.
So it has me beat.

They are low recombination immitation AGM batteries more than likely from Asia.

They claim a charge acceptance of 14.4-15V and state should accept 30A at 25oC.

Be careful when charging them in Summer at 14.8V as they are a battery generally designed for a standby application.

The site gives missleading information claiming that AGM can charge 5 times faster than flooded wet cell but Im sure that the actual battery specs for your battery do not reflect that aspect.

They are using reasonable quality AGM specs to promote an inferior battery.

Ian