AGM batteries as regular lead-acid replacement

[CBR.worm]

Is there any advantage for the price? Will a standard flooded cell charging system charge it properly?

My G35 battery is dead again, the OEM battery lasted one year, the replacement (either from Costco or Walmart) about 1.5 years the warranty replacement about 1 year and the current Bosch battery just over 3 years. My usage specifics: The car sits for weeks at a time sometimes - usually at an airport, has a stereo system in it that can pull in excess of 100 amps (I rarely listen to it that loudly, but I have blown the 100 amp inline fuse multiple times over the years), I live in S. Florida, only driving into the snow a few times a year. I average a little over 20K miles a year on this car. A good portion of those miles are on bumpy roads and/or or high G cornering on mountain roads.

I would like to find a longer lived solution although realistically I don't know if I will have this car in 3 more years. It has been very reliable though and if it continues to be, maybe I will. I definitely don't want to get another
What is interesting is that I have not yet had a typical battery failure mode where it gets slow to crank and then one day won't start. In each case it was fine and then one day it is almost dead and won't hold enough charge to crank even after being on an external charger or jumped.

My inclination was to replace with another Bosch battery, as it has held up fairly well, but was curious about the AGM batteries. My wifes car has an AGM battery from the factory (located in the trunk - so no heat) and it lasted 4 years w/ no maintenance req'd. However, BMW had to register the replacement battery so the car would charge it properly (so they say). Luckily the whole process was covered under warranty. Infiniti wouldn't replace my 13 month old battery under warranty (no sour grapes or anything).

My motorcycle has an OEM AGM battery that still works, it is 5 years old - which is a record for me - prior to this bike, my bike batteries always lasted 1 year. Of course this bike doesn't get the track time or the abuse that prior bikes have.

If an AGM battery is likely to have a benefit over a standard battery, and work properly, I don't mind spending extra money to get it - the downtime costs me more than a battery. I don't want to spend extra money on an AGM battery to find out that my car doesn't have the ability to properly charge it and have it last less than a standard battery. Any experienced battery guys have any suggestions? I am sure my charging system is the same as every other 7 years old V6 Nissan car.

 

[JHZR2]

Id want to get to the bottom of why the battery is failing. Self discharge is higher at elevated temperatures, but shouldnt be that bad.

I want to know what your parasitic drain is when the car is sitting. Do you keep a maintenance charger on it? THat would indeed help.

Under most cases, an alternator wont put out much past 14.7V, so I wouldnt be concerned. If it does, it is likely very cold (temperature based voltage reguation) and its again not much of a concern, especially given your location.

With 20k per year, the car should be operating long enough that chaging isnt an issue.

So I come back to parasitic loads that deep discharge the battery and cause issue. We need to know what they are.

I run AGM in two of my cars where flooded were originally implemented. They are both fine and many years old now.

But Id prefer a good flooded one where I can, since you can top up electrolyte - something you cannot do with AGM.

 

[Chris142]

If its sitting weeks at a time at the airport you should remove a battery cable. I'm also thinking that your boom boom radio is pulling more amps than your alternator can put out so your battery never gets fully chaged.

 

[JHZR2]

Originally Posted By: Chris142
If its sitting weeks at a time at the airport you should remove a battery cable. I'm also thinking that your boom boom radio is pulling more amps than your alternator can put out so your battery never gets fully chaged.


Yeah I was going to mention that as well. It is also very possible that the amplifier or some part of the stereo stays on and is killing the battery...

 

[Quest]

My suspicion is that granted that the car is stock (no aftermarket alarms, immobiliser, boombox, whatever, etc.), and given that it's a rather luxury car, with amenities such as heated seat, full-fledged LCD onscreen display, and various creature comforts, etc. The parasitic draw on the battery would be considerably higher than that of a typical "utilitarian" automobile.

For that I would investigate the "parasitic current draw" first to determine how bad it is before proceeding into the next step RE: what type of battery would suit the operating scenario.

Q.

 

[Donald]

I am thinking the battery is never getting fully charged after sitting.

Certainly check the draw when the key is off using an ammeter.

Did you replace the original battery with one that has a lot higher CCA?

Consider playing the music at a normal loudness. Your car, neighbors and battery will thank you.

 

[3311]

I agree with JHRZ2 by first finding out if you any vehicle issues and then secondly going to a flooded battery. AGM batteries do not have the service life that flooded batteries have, especially in a less than ideal location as an engine compartment.

AGM batteries are originally designed and still best used for climate controlled stationary applications in order to reduce labor maintenance costs. Remote applications/areas where regular maintenance is not feasible or where they need to mounted in awkward angled or inaccessible locations, a boat for example. They no have place in a hot engine compartment IMO.

They are only prevalent in the replacement market because they are a very high margin item for the manufacturures in an industry that typically has a profit margin in the mid single digits.

Edit: I just notice your in Florida like me. I would be shocked if the battery is not spent.

 

[tc1446]

Back in the day when I had a plane hangered at a grass strip with no electricity i bought one of the small solar panels from Harbor Freight...about $15-18...wired a plug that went into a "cig lighter outlet" and that kept the battery charged. Obviously, it has to be fully charged for the tiny solor output to work.

Seems that would work at the airport.

 

[bullwinkle]

You'd be amazed at the difference a couple of solar battery chargers, propped up in the sun or stuck to the inside of the windshield, can do to keep a battery from discharging from parasitic loads. I have 2 on the seldom-driven Mercedes, never fails to start (would go dead in 2 weeks without them, eventually the battery fails).

 

[bullwinkle]

Dang-tc1446 can type faster than I can!

 

[CBR.worm]

The solar charger is an interesting idea for when it is at an airport.

I checked the parasitic draw before putting in the last battery - it was surprisingly low. What is interesting to me is that the battery works fine, then one day it is dead and can't hold a charge - even out of the vehicle. I don't know if an internal short is happening, or what. I suspect that physical damage is occuring, but I don't know when or if it is caused by vibration or heat or just short life span. This is not the smoothest riding car and I do drive it like a teenager. I have a voltmeter in my radar detector and it is usually around ~14.x while the engine is running.

As for the stereo, I always keep it low when I am in town or in a neighborhood. I am in my 40's, so I am not interested in attracting a any attention from anyone - quite the opposite. It's usually low anyway - I also have no interest in losing my hearing - but every so often I will overdo it. It's not a bass system so much as a loud SQ system with matching bass, but I have inefficient speakers, seperate amplifiers for each speaker set and my sub is in a sealed enclosure which is less efficient (but sounds better to me). It is all class AB stuff - less efficient than the modern stuff.

The only key piece is that two of the times the battery died, one of the headlight ballasts failed and blew the fuse, first the drivers side, then the passenger side. Ironic since not a single incandescent bulb has burned out in 150K miles, but I have now had to replace both HID ballasts. My only thought with them is that when the vehicle voltage is low, they have to work harder to get the output voltage they need to fire the headlights, and since the car is kept in the garage, as soon as I turn the key on the headlights come on.

I will probably just get another regular battery, it's just inconvenient when I drive somewhere and the battery is dead with no warning and won't take a charge. Luckily it only happens every couple years - I just wish I got the warning that I have gotten with previous vehicles - the couple weeks of slow cranking before complete failure.

The wiring is all as new, no corrosion anywhere, the terminals, etc. The ECU apparently watches voltage drop across the battery ground cable to figure out what the battery charge state is while charging and uses that measurement to control alternator output.

No aftermarket alarms, remote start, etc. It is possible that there is something that occasionally stays on and kills the battery, but it seems like it would recover from this at least a few times during the battery life.

 

[chrome]

Your scenario sounds like sulphation of the battery due to low state of charge over extended periods of time. Apparently the sulphate crystals grow slowly over time, when the battery is at a low state of charge. The battery continues to work, albeit CCA drops... if you are in warm weather, your car continues to start fine.

Once the crystals grow enough, the battery plates start to buckle, and before long an internal short occurs, and you suddenly have a no-start condition.

You need a battery tender, solar or mains. That should help immensely.

 

[asand1]

Dec 19th 2009 installed an AGM Werker 55ah fire panel battery in my 96 Maxima. I have had 0 charging issues, and after replacing the old cable ends I have very high cranking speed in the coldest weather here (39*).

Here was the original cable setup.

Here is the new.

The E52/E53 connectors and negative cable bracket I deleted.

[youtube]FcxtCDvwkSM&feature[/youtube]

 

[asand1]

After thoroughly reading OP, I will say this. You need a higher output alternator for that sound system because you are draining the battery faster than you can charge it. Sitting for weeks at a time also allows the BCM to drain the battery. You are essentially deep cycling a starting battery. An auto-start device to start the car once a day would be cool, probably doesn't exist in an automotive form though.


According to this http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm AGM will cycle deeper and more times than Flooded cell batteries.

 

[OVERKILL]

Originally Posted By: asand1
After thoroughly reading OP, I will say this. You need a higher output alternator for that sound system because you are draining the battery faster than you can charge it. Sitting for weeks at a time also allows the BCM to drain the battery. You are essentially deep cycling a starting battery. An auto-start device to start the car once a day would be cool, probably doesn't exist in an automotive form though.


According to this http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm AGM will cycle deeper and more times than Flooded cell batteries.



The deep cycling would make him a candidate for something like an Optima Yellow though, which is far more tolerant to that kind of use than your typical starting battery.

 

[meep]

AGM does not neccessarily = deep cycle. cycle depth is determined by plate density, qty and thickness. AGM does provide internal bracing however that can make them less prone to damage during deep cycling, such as reducing the likelihood of plate material sluffing off.

The only real drawback I can see to AGMs in this application is that they do not do well if charged at too high a rate. If the battery is at 30% SOC, or 70% discharged after 3 weeks at the airport, it is going to receive huge bulk current for some period of time every time you return from a trip. That will theoretically shorten its life.

OTOH, AGM cells do not self-discharge as badly as flooded cells do. IDK why. I recall reading something like 1/3 the rate, so it could be ideal for you.

You need to shop by the numbers. You want the largest RC (reserve capacity) you can find. You just need the factory-required CCA. Start with the Platinum series Autozone battery. last time I checked, the RC on those is higher. It is AGM, btw.

3 year full replacement on that one, btw. I installed it in my jeep and the engine never spun that quickly when it was brand new.....

good luck

 

[CBR.worm]

Interesting.

 

[asand1]

Originally Posted By: meep
The only real drawback I can see to AGMs in this application is that they do not do well if charged at too high a rate.

Everything Ive seen states that AGM batteries charge 5 times faster than flooded cell batteries, So how is a car designed to charge a flooded cell battery going to charge an AGM "too fast". In three years of running an industrial grade AGM (Not a POS Optima or house brand knock off) Ive not seen a single drawback. In reading industry material regarding AGM batteries, I have not seen any evidence of negative aspects of an AGM battery in an engine compartment. I've only seen speculation and opinons from people who imagine what COULD happen.

 

[meep]

If you check the fine print, all batteries have a recommended charge rate... C20, C5, whatever. AGMs are more specific in this area. In your industrial application I guarantee that it's specified in the data sheets, and probably with different charge float voltages depending on standby or cyclical use.

The last time I looked around, it was harder to find, BUT was still listed on the casings of some of the AGM car batts.

The RISK with overcharging an AGM is... because it's not flooded, if you outgas too much of the electrolyte, like a gel cel, you can leave pockets of gas inside the pores of the plate or even in the matte, resulting in lost surface area. in a flooded cell, the electrolyte will readily rush back and fill the void.

and btw, I *like* agm... it's my preferred. I'm just trying to educate...

what industrial batt did you source? i'm curious as I would love to look at the same...

M

 

[Cardenio327]

If it blew a 100 amp fuse even once, it is a sign of a problem. Every time the fuse blew the voltage had to drop very low to cause it. Low voltage would have caused the HID ballast failures as well. This indicates too small of wiring feeding the amplifier, a threaded connection somewhere that should be soldered, or a loose or corroded connection. It would be a good idea to install a dual battery setup or remove the amplifier. Disabling the automatic headlight system would help, as well as shutting off the stereo & amplifier 10 minutes before shutting off the car, and making sure they are shut off every time before starting the engine.