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Quick dumb question.
My current Duralast battery looks to be dead. I was thinking about returning to an Optima red top. But Optima says they don't have a battery for my truck.
I used one for years. Is it just because the battery is small for my battery tray? Or they just don't deal with checking to see if their battery will work?
There isn't anything special about a battery for our trucks is there?
I just sent an email to Optima to ask the same question.
The Red Top 6V should work just fine. Yes, it is a different form factor - that and the vehicle age is why Optima doesn't have accurate application information.
I'd say Optima doesn't know (and doesn't care to find out) the size of your battery tray or the "headroom" available under your hood. If you've used their 6 volt battery in the past, it should still work for you. Be sure to let us know what Optima says.
53 to 56 trucks have the battery under the passenger side floorboard. So there is no headroom issue under the hood. And because it is out of sight, looks don't make a difference. And because the hold down goes over the top that shouldn't matter .
Dennis, I like that setup. Having a spare handy is good, but not for the price of them nowadays.
My Duralast only had a one year warranty. Dang! I have it on the charger in parallel with my optima that won't hold a charge. We will see if that brings it back to life.
Otherwise I will be getting a new Optima.
Not a great idea to have multiple batteries on a typical charger like you describe, especially different types. They won't charge properly and actually damage them.
Your Optima Battery is a gel cell and it has to have a gel cell charger or you'll ruin the battery.
Optima told me that when I had to warrantee my Optima battery.
I went out and bought a charger that has the gel cell option. Never had a problem with my new Battery charging after that.
Not a great idea to have multiple batteries on a typical charger like you describe, especially different types. They won't charge properly and actually damage them.
Interesting. We will see how they fare. Someone here taught me the parallel battery trick and I used that to bring a dead Optima back to live and used it for a few years. That was done with two Optima's though.
I just did it with the Optima and Duralast, now they are both up to 6.2 volts. I assume the Optima won't hold the charge because it hasn't when I've charged it before by itself. I will watch the Duralast. I have no carb for about a month so I've got time.
For this there was nothing I could harm. The battery would only charge to about 1.2 volts with extended charging. So it was either try this or replace it. Time will tell.
The question I can't answer is whether a charger at an auto parts store would have worked where my basic charger I have at home didn't. I'm sure their charger is much higher quality than mine.
There is a "hack" that a dead unchargeable battery can be revived by charging it in parallel because the other battery fools the charger into seeing a battery. This is a hack, and not something to regularly be done. It poses minimal harm because the dead battery is really already roast anyways and the stand in battery can do this infrequently with indiscernible consequences.
Originally Posted by *two2fords*
Your Optima Battery is a gel cell and it has to have a gel cell charger or you'll ruin the battery.Optima told me that when I had to warrantee my Optima battery.I went out and bought a charger that has the gel cell option. Never had a problem with my new Battery charging after that.
Optima batteries are NOT gel batteries. They are Absorbed Glass Mat batteries (AGM). They do benefit from a charger that has an AGM mode, especially when being brought up from a drained condition, but it is a stretch to say it is an absolute requirement - how often are you really charging it? A trickle charger may be a good investment so that one doesn't have to worry about flat batteries and special chargers and whatnot.
Joe, with your new alternator, a regular old flooded cell battery will last longer compared to when you had your troubled generator system. Do you really need the Optima?
Well since my current battery is back alive, definitely I don't need the Optima. One benefit of the Optima would be 800CCA vs 575CCA. And yes, my new alternator should change the dynamic of my needs.
Note: Sorry for the long post....nerded out a little.
That gets me wondering about AGM, Gel, and Standard. A generator/alternator is the main charging source for our batteries and I assume those don't have special charging features.
So why does a charger need to be special? We it be because a charger is used to bring a battery from lower voltage and the alternator is more intermittent charging?
Here is what the ChatGPT has to say. As a tech person, you always question what ChatGPT returns but it is similar to my google search:
As for Alternator I'm reading that is says they aren't the best for AGM batteries unless they have a lot of newer tech. ChatGPT doesn't seem to understand differences between a generator and an alternator.
Why a special charger is recommended:
🔋 1. Charging Voltage Sensitivity
AGM batteries require tightly controlled charging voltages, typically around 14.4–14.7V for bulk charging and 13.2–13.8V for float charging.
Overcharging (even slightly) can cause gassing, overheating, and reduce battery life.
Undercharging can lead to sulfation, which also shortens battery life.
⚠️ 2. No Gassing Tolerance
Unlike flooded batteries that can vent gases, AGM batteries are sealed.
Overcharging can build up pressure and damage the battery because it can’t safely release gas like a flooded battery.
⚡ 3. Multi-Stage Charging Needed
AGM batteries benefit from smart multi-stage charging:
Bulk: Fast charge until 80% full.
Absorption: Slower charge to 100%.
Float: Maintains full charge without overcharging.
Special chargers recognize and switch between these stages to maximize lifespan.
🔌 4. Temperature Compensation
Some AGM chargers adjust voltage based on ambient temperature, which helps prevent overcharging in warm conditions or undercharging in cold.
✅ Bottom Line
Using a regular charger:
Might overcharge or undercharge the AGM battery.
Could cause permanent damage or reduce capacity.
Will shorten the battery’s lifespan.
A charger labeled “AGM-compatible” or “smart charger” is recommended for safe, efficient, and long-term use of AGM batteries.
Here are notes on an Alternator and an AGM Battery:
When an Alternator Can Charge an AGM Battery Effectively
Voltage output is in the correct range: Most alternators charge at ~13.8–14.4 volts, which is close enough for basic charging.
Short-term or occasional use: If you're just maintaining the charge or driving frequently, the alternator can keep the AGM battery topped up.
Modern vehicles: Some newer vehicles have smart alternators that adjust charging voltage, which can be more AGM-friendly.
⚠️ Limitations of Using an Alternator Alone
Not Ideal for Full Charge:
Alternators typically don’t reach the 14.7V needed for a full AGM charge.
This means the battery might only reach 80–90% charge, leading to gradual capacity loss.
✅ Best Practice
Use the alternator for general use and topping up.
Periodically use a smart AGM charger to:
Fully charge the battery.
Perform proper absorption and float charging.
Maximize AGM life and performance.
No Multi-Stage Charging:
Alternators only do bulk charging, with no absorption or float stages.
This can reduce AGM lifespan over time, especially if deeply discharged.
Heat Sensitivity:
Alternators don’t adjust charge voltage for temperature.
Overcharging risk increases in hot weather, which can damage a sealed AGM battery.
Not Good for Deep Discharge Recovery:
If the AGM battery is deeply discharged (<12V), the alternator may not charge it well—or at all.
A smart AGM-compatible charger is better for recovery.
Newer vehicles, such as my 2018 F-150, actually need the dealer to program the BMS computer with the battery type and size the vehicle has so that the computer can smartly charge it. The battery is not charged directly from the alternator.
