Battery Replacement-How often & which one?

[Capri to ST]

I'm having a hard time justifying the extra $150+ for an AGM over the $110 Interstate 96R from Costco.

The way I justify it is that an AGM battery can't leak. I've seen a decent number of people on here complaining about their conventional flooded lead acid battery leaking, and the mess it made. The engine compartment in our cars is tight, so there's a lot of important stuff near the battery. I think one of the main engine control computers is right on the side of the battery box if I'm not mistaken, and protecting that alone would justify it to me.
I'm not trying to tell you what to do, just telling you what was important to me in making the decision to pay the extra money for an AGM battery.
A secondary consideration is that I believe they deep cycle better, IE start better after a discharge than a conventional battery.

 

[akiraproject24]

The way I justify it is that an AGM battery can't leak. I've seen a decent number of people on here complaining about their conventional flooded lead acid battery leaking, and the mess it made. The engine compartment in our cars is tight, so there's a lot of important stuff near the battery. I think one of the main engine control computers is right on the side of the battery box if I'm not mistaken, and protecting that alone would justify it to me.
I'm not trying to tell you what to do, just telling you what was important to me in making the decision to pay the extra money for an AGM battery.
A secondary consideration is that I believe they deep cycle better, IE start better after a discharge than a conventional battery.

Check Rock Auto. Look at the batteries listed for the 1.6 Turbo. They have an AGM listed thats not too bad price wise.

 

[Capri to ST]

Check Rock Auto. Look at the batteries listed for the 1.6 Turbo. They have an AGM listed thats not too bad price wise.

Thanks for the heads up. I was getting ready to look up something else on RockAuto so I went ahead and looked at that AGM battery too. I see it listed on there, but it does appear to be a group 47 size. There's a discussion on the previous page of this thread about making some modifications to the battery tray and the hold down bolts to make a group 48 battery fit, but I'm not sure about fitment for a group 47 size.
Is this the battery on RockAuto that you saw?
https://www.rockauto.com/en/catalog...+turbocharged,3345249,electrical,battery,2476

 

[akiraproject24]

Thanks for the heads up. I was getting ready to look up something else on RockAuto so I went ahead and looked at that AGM battery too. I see it listed on there, but it does appear to be a group 47 size. There's a discussion on the previous page of this thread about making some modifications to the battery tray and the hold down bolts to make a group 48 battery fit, but I'm not sure about fitment for a group 47 size.
Is this the battery on RockAuto that you saw?
https://www.rockauto.com/en/catalog...+turbocharged,3345249,electrical,battery,2476

Yes thats the one. I assumed that they had it listed for the FiST it would fit but didnt look into dimensions nor have I tried it myself.

 

[akiraproject24]

Its a shame the Motorcraft AGM in 96R is complete vaporware. While looking for one I found one site that stated it is unavailable due to supply issues.

 

[Intuit]

The way I justify it is that an AGM battery can't leak. I've seen a decent number of people on here complaining about their conventional flooded lead acid battery leaking, and the mess it made. The engine compartment in our cars is tight, so there's a lot of important stuff near the battery. I think one of the main engine control computers is right on the side of the battery box if I'm not mistaken, and protecting that alone would justify it to me.
I'm not trying to tell you what to do, just telling you what was important to me in making the decision to pay the extra money for an AGM battery.
A secondary consideration is that I believe they deep cycle better, IE start better after a discharge than a conventional battery.

There's a ground underneath the battery tray. (Ford pulled that same crap with my previous vehicle. Had to add a whole new ground cable in a different location.)

 

[M-Sport fan]

There's a ground underneath the battery tray. (Ford pulled that same crap with my previous vehicle. Had to add a whole new ground cable in a different location.)

That ground, the metal straps in the tray itself, the co$tly fuse/battery monitor setup on the one cable, and even the engine compartment unibody structure itself are enough justification for the higher cost of the AGMs and their no leaks possible construction.

Even before (and besides) any other advantages they might have over flooded lead acid products.

 

[Capri to ST]

Its a shame the Motorcraft AGM in 96R is complete vaporware. While looking for one I found one site that stated it is unavailable due to supply issues.

I feel the same way. I looked for that battery and it was not available anywhere. Even my local Ford dealer couldn't get it.
It was sort of like Bigfoot, reputed to exist but no one's ever actually seen it.

 

[XanRules]

That ground, the tray itself, the co$tly fuse/battery monitor setup on the one cable, and even the engine compartment unibody structure itself are enough justification for the higher cost of the AGMs and their no leaks possible construction.

Even before (and besides) any other advantages they might have over flooded lead acid products.

This is helpful. I've had batteries leak before, but I've only ever had Subarus in the past, and on the ones I've had the battery trays were specifically designed around that possibility (easily replaceable plastic liner inserted into a reinforced/welded tray with no essential engine, electrical, or sructural components around it). But given this, I will indeed spring for an AGM unless the battery dies before funds allow. Thanks for the perspective.

 

[akiraproject24]

This is helpful. I've had batteries leak before, but I've only ever had Subarus in the past, and on the ones I've had the battery trays were specifically designed around that possibility (easily replaceable plastic liner inserted into a reinforced/welded tray with no essential engine, electrical, or sructural components around it). But given this, I will indeed spring for an AGM unless the battery dies before funds allow. Thanks for the perspective.

The more I look at pricing. I feel like replacing the OEM battery with OEM every 4 or 5 yrs (depending on your environment) good or bad is a good option. Clean/treat your terminals each year.

I went the AGM route on another car. It added weight (not a ton) and the AGM's sometimes require an input voltage higher than the alternators give to reach full state of charge. I havent researched whether or not the Fiesta has this issue. Many have gone the AGM route on here that are smarter than me so my guess is its probably a non issue.

 

[M-Sport fan]

I am not sure if the reported PID for system voltage for our platform is taken from the battery terminal, or the alternator (generator??) output line or not, but, my UltraGauge is always reading between 14.3 volts and 15.1 volts with the engine running, even with many accessories on as well.

That is plenty to keep an AGM battery of our 96R size fully charged.

 

[Intuit]

AGM are actually more sensitive to overcharging versus FLA.

More information...
https://www.fiestastforum.com/threads/agm-battery-concerns.24120/


.

 

[M-Sport fan]

AGM are actually more sensitive to overcharging versus FLA.

More information...
https://www.fiestastforum.com/threads/agm-battery-concerns.24120/


.

True, but they also will slowly discharge over time if the car's generator/alternator output drops below ~13.9 or so volts, consistently.

IF you leave them on a (even 'proper' for AGMs, with supposed auto regulation built-in) charger (NOT a 'maintenance' or trickle charger) for extended periods, the case will swell, and it will burn out the internal grids and circuitry over time.
(Yeah, ask me how I know this. )

 

[rallytaff]

I'm on my 2nd battery in 9+ years. Regular ones and never leaked or let me down. Why pay extra to save a couple of pounds?

 

[Intuit]

From the prior thread...

Re AGM adding weight:
<< ... These batteries pack a lot of power for their size and weight, which allows manufacturers to shave off a few pounds from the vehicle. That’s a big reason why they are being found more and more on late-model vehicles. ... >>
If anyone is worried about weight, simply get a smaller battery and shim it.

The reason you may see lower output in modern vehicles...
<< ... [AGM] batteries like to be charged slow and low due to differences in internal resistance. Many AGM battery chargers have microprocessors that collect information from the battery and adjust the current and voltage accordingly. ........... Newer GM vehicles have a Battery Sensor Module on the negative battery cable. Ford has the Battery Monitoring System (BMS). Other manufacturers have similar systems. These systems require recalibration with a scan tool if the battery is replaced. If the system is not recalibrated, the alternator might overcharge the new battery and cause the battery to fail soon after replacement. Some vehicles can perform a self-learn for the battery by measuring the internal resistance of the battery. But often a scan tool can force the procedure so you know there will be no issues with the battery. >>

The only time I've seen lower output from my full time readout is when I've been consistently driving it for awhile (which is rare); presumably because the BMS has determined that the battery has a full charge.

Also, just added from the Fiesta ST manual...

 

[Intuit]

........... IF you leave them on a (even 'proper' for AGMs, with supposed auto regulation built-in) charger (NOT a 'maintenance' or trickle charger) for extended periods, [damages battery] ............

Similar experience except, I've stopped charging when I noticed that I was hearing a bubbling sound... which didn't take long... and by that time it's already doing damage. The damage was evident when I put it back in and saw standby voltages were lower than prior. Next time you charge, put your ear on it from time-to-time.

Also of note, my full time readout shows me not only cranking voltage, but also voltage immediately following start. For the first several seconds after engine start, the vehicle is running purely off the battery. After that point the voltages begin steadily ramping up.

The prior Ford was way too old to have a BMS, but a weak engine ground (revealed by voltage drop testing) caused the alternator to run at much higher output than was supposed to. That ground BTW was underneath the battery tray. It was rusted out by runoff from the tray.

 

[M-Sport fan]

Similar experience except, I've stopped charging when I noticed that I was hearing a bubbling sound... which didn't take long... and by that time it's already doing damage. The damage was evident when I put it back in and saw standby voltages were lower than prior. Next time you charge, put your ear on it from time-to-time.

Also of note, my full time readout shows me not only cranking voltage, but also voltage immediately following start. For the first several seconds after engine start, the vehicle is running purely off the battery. After that point the voltages begin steadily ramping up.

My first original (one of the first produced in our size) Odyssey 96R-600 did NOT make any sounds at all when charging (even at a high rate!), nor did it get even slightly warm.
It was only when the case started bulging out on the short square sides that I knew anything was wrong, and of course by then it is way too late.

I now just stash the charger, do NOT even do any periodic 'top up charges', and just let the alternator/generator do all of the charging.

Our charging system must be fully programmed to compensate for various loads, since I've noticed that my PID reported voltage does not drop/fluctuate by more than 0.02 or so, regardless of how many (or ALL!) accessories are running at the same time.