AGM Voltage

[Cruiserstu]

Hi everyone, just a quick question. What voltage should you be able to run a AGM deep cycle battery down to without causing damage and still be able to charge it properly.

Stu

 

[Leprechaun]

I think 40-50% max. Best to do some googling me thinks.

 

[tagMan]

I have AGM's in my camper trailer - lowest i have had a battery was 9.8 volts - recharged ok with a c-tek charger.

Maybe would of gone lower but the 12 volt fridge stopped working on under voltage.
Great batteries - i can run 2 - 12v fridges for 3 days before i need to connect the solar panels.

cheers..

 

[Leprechaun]

My understanding AGM batteries advantage is they can be mounted in any position/ don't vent explosive gasses and they have a long shelf life. I've never read about them being better deep cycle, actually I thought it was the opposite, better crankers?

 

[Old.Tony]

AGM are good duration batteries, but I wouldn't pull cranking-current levels out of them.

ANY lead-acid battery starts to sulphate once it's charge level is below 100%. Until it passes 50%, you won't notice it much and a recharge causes the newly-formed crystals to dissolve again (most of the time). Below 50% and sulphation starts in earnest.

Here's a website with some decent info and a table of charge levels for each battery type. You'll see that 50% charge in an AGM battery is when the unloaded (everything disconnected) voltage is 12.3V.

You'll note that further down that page, they recommend not discharging the battery more than 50% of its full charge, because the battery will last longer.

 

[Leprechaun]

AGM are good duration batteries, but I wouldn't pull cranking-current levels out of them.

AGM's are fitted standard in Jeep diesels. It is one of those yellowtop Optimas.

 

[Old.Tony]

Must be a new type of AGM. They'd be good to put in the vehicle, definitely get some better life out of them - although most reports in here say the standard Navara battery goes for 4-5 years, which is not bad considering they're only supposed to go for 2!

 

[4.8GU]

Gel batteries and AGM's are a slightly different animal. The optima's are a spiral wound gel.
AGMs are not recommended for cranking and don't like heat.
Great for fridges etc though

 

[Leprechaun]

Yellow top are AGM.
AGM Deep Cycle Battery, Batteries - Optima Yellow Top

This is the one we have.
http://www.optimabatteries.com.au/Content/Documents/Group D27F YellowTop.pdf

 

[Cruiserstu]

Thanks for the quick reply's. I got given a 74 a/h AGM from a mate as he wasnt using it so i was testing it running my engel in the shed at home. I got 3 days out of it before it dropped below 12V, so it appears to be allright. Now i just have to fit it into my d22, im thinking at this stage of using the ABR isolator has anyone used one of these before and how did you like them.

stu

 

[ljacko78]

lucky bugger getting a free AGM

My mate ran one of those ABRs. He loved it and had no troubles. Cost heap less than other brands. Ran for a good 5 yrs before he rolled his truck and wrote it off. I personally went for Projecta kit, which I found exceptionally easy to install.

hae fun

 

[Leprechaun]

Thanks for the quick reply's. I got given a 74 a/h AGM from a mate as he wasnt using it so i was testing it running my engel in the shed at home. I got 3 days out of it before it dropped below 12V, so it appears to be allright. Now i just have to fit it into my d22, im thinking at this stage of using the ABR isolator has anyone used one of these before and how did you like them.

stu

I've used the ABR isolater, it worked fine, but they are not fully waterproof and the connections are a bit to small to run a decent sized cable lug. I'd recommend a redarc over the ABR. They have a excellent reputation, and are quite inexpensive. Think I paid $125 off Feebay.

 

[tommy222220_0]

Thanks for the quick reply's. I got given a 74 a/h AGM from a mate as he wasnt using it so i was testing it running my engel in the shed at home. I got 3 days out of it before it dropped below 12V, so it appears to be allright. Now i just have to fit it into my d22, im thinking at this stage of using the ABR isolator has anyone used one of these before and how did you like them.

stu

I run a 100a/h apollo agm in the rear of my ute for the fridge/lights etc. All runs off a redarc isolator. Very happy with the setup. Don't forget to check what wire size you require.

Charges at around 14.4V and lasts around 3 days until it drops to around ~12.1/12.2V (that as low as i let it go)

This site has heaps of good info:
Technical Information

 

[4.8GU]

sorry I made a mistake about the gel side of it but they are definitely different to traditional agm style. Spiral wound
The optimas have much higher cca ratings and lower ah ratings. They apparently take charge quickly though.

Most agm style batteries do not like heat ie engine bays and are absolutely not made for starting or high current discharge like winches etc.