AGM Batteries in older cars
- Thread starter real0803
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See post #14.
I posted a link to another thread here. FBBO member J C C started a thread about one he found for $200. It weighs 6 1/2 lbs instead of 40.
I posted a link to another thread here. FBBO member J C C started a thread about one he found for $200. It weighs 6 1/2 lbs instead of 40.
real0803
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Is it safe to pair up a AGM with a lead acid in parallel as long as the amps are the same ? Is it a good idea to have one in the trunk (in a battery box of course) connected with the main battery and grounded in the trunk ? I also have a battery isolator I can work with .
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Way back when, I was very disappointed if a battery didn’t last about 12 years in a daily driver.
Used to buy Sears batteries.Bought a 1981 Ram 150 in 1983. Battery calved in 1984. Very ticked off. Bought a Sears battery still was in it when we sold it in 1999.
Bought our boat with a 230hp Lazer in 2001 from a cousin. I think 900 cranking amps . It quit in 2021.
The battery in our 2006 4Runner is 5 years old.
Used to buy Sears batteries.Bought a 1981 Ram 150 in 1983. Battery calved in 1984. Very ticked off. Bought a Sears battery still was in it when we sold it in 1999.
Bought our boat with a 230hp Lazer in 2001 from a cousin. I think 900 cranking amps . It quit in 2021.
The battery in our 2006 4Runner is 5 years old.
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The oem agm in my 2012 camaro crapped out in 2022. Good thing it went ten years. Cheapest replacement I could find was nearly $200, and went up from there.
Low original mileage might have had something to do with the battery life. Car averages about 1000mi/yr.
Low original mileage might have had something to do with the battery life. Car averages about 1000mi/yr.
70bigblockdodge
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My wife's AGM in her Jeep GC lasted 11 years. The starter and the fact that it is her car I just replaced it. In hind sight I should have kept it and cored a really dead POS, oh well. I have a AGM in a couple of cars. They actually are a lead acid battery, just the acid is in a (wait for it) Absorbent Glass Mat against the lead plates.
Advantage is they can be inside the car with no acidic gasses expelling from the no vent. The can also be mounted on their side or end, if you need it like that? No box with external vent required for battery in trunk of race car.
Bad is the do not do well with deep cycling because they can't "boil" to desulfate the crap off the plates.
Personal opinion is they don't do well with slow rate of charge, like a maintainer. The vehicles they are normally in have huge alternators, wife's Jeep is 200 amp! Alternator actually has a surge clutch on it to reduce the stress on the belt. So IMO they need charge-discharge, just no deep/dead cycling and no constant 14.1 volt maintainer. Maybe a maintainer on a timer to only charge for a couple hours then off again. I plug in my maintenance charger when I'm in garage in the winter and unplug when not. During car use months I do nothing but drive like a normal car.
Advantage is they can be inside the car with no acidic gasses expelling from the no vent. The can also be mounted on their side or end, if you need it like that? No box with external vent required for battery in trunk of race car.
Bad is the do not do well with deep cycling because they can't "boil" to desulfate the crap off the plates.
Personal opinion is they don't do well with slow rate of charge, like a maintainer. The vehicles they are normally in have huge alternators, wife's Jeep is 200 amp! Alternator actually has a surge clutch on it to reduce the stress on the belt. So IMO they need charge-discharge, just no deep/dead cycling and no constant 14.1 volt maintainer. Maybe a maintainer on a timer to only charge for a couple hours then off again. I plug in my maintenance charger when I'm in garage in the winter and unplug when not. During car use months I do nothing but drive like a normal car.
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ynst
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I've had an AGM battery in one of my Magnums for nearly 12 years now and the car starts right up every morning, even in the winter up in New England.
It has far outlasted ANY of the lead acid batteries in the rest of my fleet. The best ones only last about 72 months before the starter starts groaning in cold weather signalling a trip to the store for a new battery.
The key to AGM battery longevity is to never let it get drawn down or charge it too fast. AGM batteries are NOT well suited for deep cycle operation.
Start the engine then drive the car for a few miles to replenish the voltage drained during the initial start-up. If you only go a few miles to work then shut the engine off, an AGM battery won't last any longer that a lead acid battery.
Another thing you don't want to do with an AGM battery is slam it with the "boost" cycle on a battery charger.
Most EVs have a separate 12 volt battery, usually around 50 amp-hour size to operate the few 12 volt devices in the vehicle and they get charged by the propulsion battery once every 48 hours. The exception to this schedule occurs when the tiny battery goes below 20% capacity and then it gets an emergency boost but ONLY if the RUN button is turned OFF.
If they're charged any more frequently than 48 hours, the lifespan of the AGM battery is reduced drastically. We're seeing that phenomenon with police cars that can only use the 12 volt battery to power the light bar, radio, radar gun, etc and need to get the tiny 12 volt battery recharged every day.
The only time the 12 volt battery can get charged is when the RUN button is switched off. The 12 volt battery cannot be charged with the RUN button turned on. It does NOT get charged by a mechanical charging device, either. It only gets charged by the propulsion battery when the vehicle is out of operation and/or plugged into a charging station with the key/button in the off position.
We're seeing AGM battery life of around 7 months when the 50 amp-hour AM battery is being subjected to frequent overcharging.
In a normal situation, like in a DPW truck, the AGM battery will far outlast a lead acid battery. The engines are always running long enough to replenish the lost voltage right after start-up and the voltage regulator drops the charging current down to an amp or two.
If all you do is drive to cruise nights, buy a lead acid battery every couple of years. If you use the vehicle more often and put a few miles on it VERY time you start it up, the AGM battery is the way to go.
It has far outlasted ANY of the lead acid batteries in the rest of my fleet. The best ones only last about 72 months before the starter starts groaning in cold weather signalling a trip to the store for a new battery.
The key to AGM battery longevity is to never let it get drawn down or charge it too fast. AGM batteries are NOT well suited for deep cycle operation.
Start the engine then drive the car for a few miles to replenish the voltage drained during the initial start-up. If you only go a few miles to work then shut the engine off, an AGM battery won't last any longer that a lead acid battery.
Another thing you don't want to do with an AGM battery is slam it with the "boost" cycle on a battery charger.
Most EVs have a separate 12 volt battery, usually around 50 amp-hour size to operate the few 12 volt devices in the vehicle and they get charged by the propulsion battery once every 48 hours. The exception to this schedule occurs when the tiny battery goes below 20% capacity and then it gets an emergency boost but ONLY if the RUN button is turned OFF.
If they're charged any more frequently than 48 hours, the lifespan of the AGM battery is reduced drastically. We're seeing that phenomenon with police cars that can only use the 12 volt battery to power the light bar, radio, radar gun, etc and need to get the tiny 12 volt battery recharged every day.
The only time the 12 volt battery can get charged is when the RUN button is switched off. The 12 volt battery cannot be charged with the RUN button turned on. It does NOT get charged by a mechanical charging device, either. It only gets charged by the propulsion battery when the vehicle is out of operation and/or plugged into a charging station with the key/button in the off position.
We're seeing AGM battery life of around 7 months when the 50 amp-hour AM battery is being subjected to frequent overcharging.
In a normal situation, like in a DPW truck, the AGM battery will far outlast a lead acid battery. The engines are always running long enough to replenish the lost voltage right after start-up and the voltage regulator drops the charging current down to an amp or two.
If all you do is drive to cruise nights, buy a lead acid battery every couple of years. If you use the vehicle more often and put a few miles on it VERY time you start it up, the AGM battery is the way to go.
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