Discussion
clockworks said:
Why would you want to do this, unless the car was originally fitted with an AGM battery? My understanding is that AGM batteries are "better", but only if the car was designed to have one - electronics to closely control charge and discharge rates.
Higher cranking amps mainly. With twin fuel pumps, lumpy cam and supercharger, my Monaro can struggle to start when hot, especially when the fans are going. I could also fit a slightly larger battery but at the moment I'm exploring my options.swisstoni said:
I thought AGM batteries were basically not ‘wet’ but that they could be treated the same as ordinary batteries in terms of their application.
They do contain acid but it's absorbed into glass matting. They are better than normal lead acid batteries are sensitive to overcharging and heat. If you believe the internet though, plenty of people have done it with good results. The popular ‘red top’ batteries are in fact AGM batteries. Certainly on my e65 bmw you have to code the car for wet or agm. AGM’s typically have a lower float charge of about 13.4v whereas wet is about 13.8v
My smart battery charger has a specific setting for AGM - so there is a difference.
Having said all that, I’m running a red top on my dakar (rr classic with a 5.7 small block) using essentially the original alternator and I’ve found the starting speed to be very good even though it’s stood for weeks at a time.
My smart battery charger has a specific setting for AGM - so there is a difference.
Having said all that, I’m running a red top on my dakar (rr classic with a 5.7 small block) using essentially the original alternator and I’ve found the starting speed to be very good even though it’s stood for weeks at a time.
I run one in my RX7 for similar reasons (ported rotaries can be a bit if an arse to get going)
Work fine, but mine's in the boot, not the bay.
However, I've killed 2 by letting them go completely flat. They are really sensitive to this. One full discharge and they really suffer, to the extent I had to scrap one after only using it a couple of times then forgetting to put the car on the battery conditioner
Work fine, but mine's in the boot, not the bay.
However, I've killed 2 by letting them go completely flat. They are really sensitive to this. One full discharge and they really suffer, to the extent I had to scrap one after only using it a couple of times then forgetting to put the car on the battery conditioner
FD3Si said:
I run one in my RX7 for similar reasons (ported rotaries can be a bit if an arse to get going)
Work fine, but mine's in the boot, not the bay.
However, I've killed 2 by letting them go completely flat. They are really sensitive to this. One full discharge and they really suffer, to the extent I had to scrap one after only using it a couple of times then forgetting to put the car on the battery conditioner
Allowing any battery to go flat will kill it. Anything under 10.5v is considered flat. Even 11.5v is only 10% charged.Work fine, but mine's in the boot, not the bay.
However, I've killed 2 by letting them go completely flat. They are really sensitive to this. One full discharge and they really suffer, to the extent I had to scrap one after only using it a couple of times then forgetting to put the car on the battery conditioner
Yes, but conventional lead acid batteries are a lot more tolerant. I've done it multiple times with 'normal' ones and then rescued them either with a jump and good run, or my trusty CTek on it's magic revive mode.
With the three AGM ones I've had experience of, it seems once they're dead, there is no second chance.
With the three AGM ones I've had experience of, it seems once they're dead, there is no second chance.
I’ve had a Bosch AGM battery in my ‘87 911 for 10 years plus, with zero issues.
Yes, they flatten in the same way as lead acid batteries, but having no power in the various places/lockups my car has been located, its taken lot of abuse (several deep discharges to <3v) - they always recover once recharged via a CTek or similar.
I doubt a lead acid would have taken the same abuse.
Yes, they flatten in the same way as lead acid batteries, but having no power in the various places/lockups my car has been located, its taken lot of abuse (several deep discharges to <3v) - they always recover once recharged via a CTek or similar.
I doubt a lead acid would have taken the same abuse.
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