Charging AGM batteries.

[1LE]

So, let's say I've got an AGM battery that's been sitting around all Winter and I'd like to top it off before use this year. What's the procedure? Can I use a regular lead acid battery charger? Is it a problem if the charger has automatic desulfation (which they all seem to now)?

[kdo58]

mine has a switch for agm, it charges at a lower voltage.

[92xjunker]

A normal charger will work, just unplug it after full charge. Lithium batteries can't take desulfation

[TRPUT]

A normal charger will work, just unplug it after full charge. Lithium batteries can't take desulfation

It's not Lithium - it's AGM - which is effectively just a better lead acid battery.

A "battery tender" type charger or <2 amp charger is best as small batteries in general don't like being cooked with high amps. However, you will probably find it needs very little "topping up" as AGM batteries have very slow self-discharge.

[92xjunker]

I just stated that so he would know. My agm required a different charger than a standard one, it did say you could charge it with one just disconnect when fully charged.

[TRPUT]

I just stated that so he would know.

It's a mute point anyway ... my AGM just doesn't need charging.

[1LE]

Thanks! Sounds like regular charger is OK, just make sure charge current is in the right range for the size of the battery and keep an eye on it so it can be unhooked when fully charged.

The exact battery in question is a motorcycle size, but is actually set aside so I can run my ham radios "off the grid". Haven't had to charge it yet because I haven't done much with it. However, I want to top it off and make it part of a small kit I can take to local events. I'm a volunteer with a group that provides communications for local races (marathon, triathlon, etc). I'd like to get a kit that'll be small enough to transport via the Kat, but still have enough punch to let me operate from the far reaches of the cycling courses. With a motorcycle size I expect to only discharge down to about 80% on the longer events, so it'll need charging, but I won't be doing anything like a deep discharge.

[92xjunker]

A lithium iron battery would yield longer use and is 1/10th the weight.

[1LE]

A lithium iron battery would yield longer use and is 1/10th the weight.

Yeah, I'm planning on using this AGM battery since it should be "good enough" and is essentially "free". I'm pretty much only doing "free" projects these days since the wife is still out of work. Nearing 1 year, unemployment about to run out. Still not a job lead in sight.

Long backstory for those bored today: My rally car was in the shop having new intercooler piping built and the old flooded lead acid battery in it failed. To get it home I bought one of the lightweight AGM batteries at the shop. 9 months later that battery goes up in (almost literally) smoke, I could smell it cooking off and it was extremely hot. 1 year warranty, but the manufacturer was giving me a hassle about it so I bought another cheap flooded lead acid for the car. Finally got my replacement AGM battery yesterday after months of waiting, but don't really *need* it and don't really trust it quite enough to use it in the car (especially since the cheap-o flooded lead acid I dropped in turned out to be incredible). Considered selling it, but if I don't trust it enough to put in a car, I don't feel right selling it to somebody else either... Just so happens that the old monster dry cell I used to use (transported via car) for field radio work died a couple years back... Seemed like an opportunity to use this AGM battery, get my portable station back together while reworking things to be portable enough to transport via motorcycle and not spend any money doing it.

[91_gsx600F katana]

A lithium iron battery would yield longer use and is 1/10th the weight.

Yup and they don't need to be tended at all for a yr of storage. Not to mention they offer quicker starts and increased cranking amps and lots of other goodies. Got my 2nd shoria lithium ion battery a few weeks ago from GsxfJim.

[rschlegel]

Yup and they don't need to be tended at all for a yr of storage. Not to mention they offer quicker starts and increased cranking amps and lots of other goodies. Got my 2nd shoria lithium ion battery a few weeks ago from GsxfJim.

I am guessing that you still disconnect the battery leads when storing.

I don't winterize my bike so during cold spells (for Colorado) the bike may sit for a few weeks. So far the longest this winter was two weeks. How do these batteries handle the cold with a couple weeks of no use and not being disconnected?

[92xjunker]

Lithium iron batteries prefer the cold, they recommend long term storage to be in the refrigerator, 35 deg if the ambient air is 90 deg or higher.