Replacing an AGM with a Flooded Lead Acid Battery

[Nick1994]

Last summer my grandma's 14' Grand Caravan had a dead battery so I stopped at Costco and got a new one. Took the old battery later on to the dealer and it turned out it had a few days of warranty left so they swapped it out.

Anyways it's the same size as my 14' Grand Cherokee (Limited 3.6L if it matters) so I decided to replace it as the last battery has been in there for about 4 years, that's getting close to quitting time here in AZ.

But I pulled out an AGM, does it matter that the replacement wasn't AGM?

 

[LvR]

I'd say it's a function of the BMS (battery management system) if fitted or if you have a simple voltage-regulated alternator.

If a simple alternator, then no problem (particularly THAT AGM in the picture where the AGM's chemistry dictates a 14.4V max).

If you have a BMS with coding abilities, I'd say just check on the parameters included there - most modern BMS is battery chemistry, capacity, etc aware and adapts charging strategy accordingly.

 

[RooflessVW]

I would not replace a four year old AGM, especially not with a lead acid battery.

Charge it and have it tested.

 

[sk_pete]

modern cars store energy during braking into agm. voltage can rise up to 15,2v ! (not holding constant 14v as old cars do)
which is deadly for normal battery
put at least efb.

 

[Skippy722]

Assuming the GC has the battery under the passenger seat like the Durango does, I’d be a bit leery about using a flooded battery. God forbid you get into some horrific rollover accident that breaks open the battery (yes absolute worst case and extremely unlikely, but possible). Plus… mopar electronics… 2011-2013 are different from 2014-2015 which are different from 2016+.

 

[Jmlo96]

I’d say that’s a big no. Get an AGM. Those batteries are AGM because they are in the passenger area of the vehicle. AGM is less likely to leak or off gas than a traditional lead acid.

 

[LvR]

modern cars store energy during braking into agm. voltage can rise up to 15,2v ! (not holding constant 14v as old cars do)
which is deadly for normal battery
put at least efb.

You are making a really dangerous generalization re AGM only ................ I can show you Porsche, BMW, VW, MB etc vehicles where the BMS is in control of the charging strategy as a function of the type of battery, capacity, etc as I said already. Those vehicles, without fail, will also do regenerative charging with ANY compatible battery type when the BMS has been told what got fitted.

While I agree with 15.2V (and even higher in certain BMS ) .................... how do you then explain the 14.4V limit sticker on the old AGM battery ?

Just asking - not trying to start a fight.

The fact is if the BMS fitted on the vehicle allows/handles the battery type its safe to use electronically .............................. human nature and fear may dictate a different approach

 

[JHZR2]

Ive run AGM successfully in place of flooded in older cars with dumb alternators. They handled the slight undercharge fine for years.

But I wouldn’t swap the other direction.

It’s curious that the van came with an AGM, but the reasons noted above are sensible.

I’d say that’s a big no. Get an AGM. Those batteries are AGM because they are in the passenger area of the vehicle. AGM is less likely to leak or off gas than a traditional lead acid.

Assuming the GC has the battery under the passenger seat like the Durango does, I’d be a bit leery about using a flooded battery. God forbid you get into some horrific rollover accident that breaks open the battery (yes absolute worst case and extremely unlikely, but possible). Plus… mopar electronics… 2011-2013 are different from 2014-2015 which are different from 2016+.

I think this points to the answer. If in the passenger area, AGM is necessary because they don’t readily vent hydrogen, the valves on an AGM (valve regulated lead acid) allows 99% hydrogen recombination. You don’t want hydrogen buildup…

 

[CarDoc66]

I’m leaning towards the idea that passenger compartment mounted batteries should never be lead/acid type for collision reasons.
That said I never see modern vehicles charging past 14.0 volts anyone. Most AGM equipped vehicles have a sensor on the negative terminal that sends charging information back to the ECU. I assume it’s got to do with AGM since that’s when they started using them.

 

[LvR]

I’m leaning towards the idea that passenger compartment mounted batteries should never be lead/acid type for collision reasons.
That said I never see modern vehicles charging past 14.0 volts anyone. Most AGM equipped vehicles have a sensor on the negative terminal that sends charging information back to the ECU. I assume it’s got to do with AGM since that’s when they started using them.

It's a sensor for the BMS and has absolutely nothing to do with AGM/EFB or whatever - the BMS monitors battery voltage and does coulomb counting (only put back in what got taken out) on modern charging systems - it then tells the alternator via the comms bus (LIN) to regulate to a certain point and to even stop charging altogether.

When you have regenerative charging systems present you do NOT want a fully charged battery in the vehicle - those vehicle BMS's normally only charge to around 80% so that the regenerative energy has a place to go - ie the battery's 20% undercharge

LIN-Controlled Alternator Voltage Regulator

International Rectifier (IR) recently introduced the local interconnect network (LIN)-controlled alternator-regulator for next-generation vehicles. IR’s solution optimizes performance...

www.powerelectronics.com

 

[wpod]

modern cars store energy during braking into agm. voltage can rise up to 15,2v ! (not holding constant 14v as old cars do)
which is deadly for normal battery
put at least efb.

How does that happen?

 

[mightymousetech]

You are making a really dangerous generalization re AGM only ................ I can show you Porsche, BMW, VW, MB etc vehicles where the BMS is in control of the charging strategy as a function of the type of battery, capacity, etc as I said already. Those vehicles, without fail, will also do regenerative charging with ANY compatible battery type when the BMS has been told what got fitted.

While I agree with 15.2V (and even higher in certain BMS ) .................... how do you then explain the 14.4V limit sticker on the old AGM battery ?

Just asking - not trying to start a fight.

The fact is if the BMS fitted on the vehicle allows/handles the battery type its safe to use electronically .............................. human nature and fear may dictate a different approach

Yes, but you have to program a BMW to tell it what type and capacity of battery is installed or it will not charge properly.

 

[LvR]

Yes, but you have to program a BMW to tell it what type and capacity of battery is installed or it will not charge properly.

Isn't that what I have been saying all along?

When you replace the battery, you use your scanner, enter the BMS service mode, tell it all about the battery's properties, save the new settings and you are good to go.

 

[sk_pete]

Assuming the GC has the battery under the passenger seat

in that case, it makes sense

 

[Nick1994]

It’s curious that the van came with an AGM, but the reasons noted above are sensible.

The van just had a regular battery, but when I went to Costco all they had in stock was an AGM.

I've ordered an AGM through O'Reilly, they have a 10% deal right now for October (last day) for ship to home.

I also upgraded to an H8 (same price, $199) as it gives the option, they use those in the diesel Grand Cherokees typically. I ordered the different battery hold down plate as well to accommodate for the bigger battery.

 

[JHZR2]

The van just had a regular battery, but when I went to Costco all they had in stock was an AGM.

I've ordered an AGM through O'Reilly, they have a 10% deal right now for October (last day) for ship to home.

I also upgraded to an H8 (same price, $199) as it gives the option, they use those in the diesel Grand Cherokees typically. I ordered the different battery hold down plate as well to accommodate for the bigger battery.

H8 AGM is a good choice. If the battery controller adjusts charge based upon battery size (my BMW does), you may need to code it.

 

[Peted]

I have the H6 AGM from Costco and so far it's a stout battery. Great warranty too.

 

[Nick1994]

I installed the H8 today, a fair amount bigger. For anyone wanting to upsize the battery the Mopar battery hold down plate on Rock Auto is part# 68039242AA.

Now to figure out to do with the new H7.

 

[meep]

Big fan of the h8 here. P2 volvos hold them, the 18 f150 handles it… solid upgrade.