Sears Diehard Platinum 31M issues

[Ducky's Dad]

Optima Yellowtops are my favorite overlanding battery. Thin plates, 99.99% pure lead, low internal resistance, and only about 1/3 of the parts of other batteries in their class (less to vibrate apart).

I have been using Optima Yellows since about 1999. They were very good back then, then hit a rough patch with very spotty quality after they moved production to Mexico, and now they seem to be OK again. For my use, I prefer the Optima Blue Dual Purpose because they have the marine studs that make it easy to wire a fridge, compressor, battery monitor, etc. Electrically, they are the same as the Yellows. The Blue starting batteries are electrically the same as the Reds. The Optimas, size for size, have less capacity than the Odysseys, so there is a tradeoff.

 

[Hilldweller]

I have been using Optima Yellows since about 1999. They were very good back then, then hit a rough patch with very spotty quality after they moved production to Mexico, and now they seem to be OK again. For my use, I prefer the Optima Blue Dual Purpose because they have the marine studs that make it easy to wire a fridge, compressor, battery monitor, etc. Electrically, they are the same as the Yellows. The Blue starting batteries are electrically the same as the Reds. The Optimas, size for size, have less capacity than the Odysseys, so there is a tradeoff.

The Yellowtops and Bluetops are the same except for the posts. The Redtops are just SLI and are different.
The Enerysys products do have more overall amperage in reserve but not more CCAs. Optimas can crank...
Neither of them like to be deeply discharged though. And the Optimas are so much easier to charge off of our alternators.

 

[gravedgr]

I have my big charger in the Jeep, Doug....
Got lots of meters here too. Real meters.

So how do we coordinate a charge & test session?

 

[Ducky's Dad]

The Yellowtops and Bluetops are the same except for the posts.

Optima makes the Blues in both starting and deep cycle versions. The only visible difference, other than the part number, is the shade of gray on the case. Even the Optima dealers are confused about the Blues.

 

[comptiger5000]

I did put a bigass 270 amp alternator (bench tested at 285amp max, producing 116amps at idle in the truck), and it produces plenty of amperage but my Dodge alternator voltage is regulated by the ECU in the low 14s. Dodge service managers have told me that even they cannot reprogram or reflash the ECU to boost the voltage. All sane advice is to not add an external voltage regulator to this truck, hence the use of the Ultimizer.

My Jeep has the same ECU regulated voltage setup, but with a temp sensor under the battery for voltage compensation. I popped a resistor (can't remember for sure, but I think it was 1k ohms) in line with the sensor to trick the ECU into thinking the battery is colder than it really is. That bumped the voltage up by about 0.2 volts at any given temp.

In the heat of the summer, it'll get down to 13.8 or so volts (battery temps over 100* F). In the dead of winter, I've seen it get to around 15.4 volts. Since I added the resistor, the group 34 AGM I've got in there (Duracell branded, made by East Penn) seems to charge back up faster if I've drawn it down a bit.

 

[Ducky's Dad]

Optima Blue Grp 31M Dual Purpose:

Battery Model: D31M
Part Number: 8052-161
Performance Data
Cold Cranking Amps: 900
Cranking Amps: 1125
Open Circuit Voltage (fully charged): 13.1 volts
Internal Resistance (fully charged): 0.0025 ohms
Capacity: 75 Ah (C/20)
Reserve Capacity: BCI: 155 minutes (25 amp discharge, 80°F (26.7°C), to 10.5 volts cut-off)

Odyssey 2150 31M:

PC2150
31M-PC2150
CCA 1150
HCA 1545
MCA 1370
RC 205

At least per published specs, the Odyssey 31M has 1150 CCA vs 900 CCA for the Optima, and 205 mins Reserve Capacity vs 150 mins for the Optima. Even allowing for marketing hype and different measurement conditions, those seem to be pretty big differences. The Northstar 31M claims 1150 CCA and 220 mins RC.

 

[BigSwede]

If you look at an Optima 31 you can see how their spiral cell configuration ends up costing them capacity, the internal volume is quite a bit less.

 

[Ducky's Dad]

My Jeep has the same ECU regulated voltage setup, but with a temp sensor under the battery for voltage compensation. I popped a resistor (can't remember for sure, but I think it was 1k ohms) in line with the sensor to trick the ECU into thinking the battery is colder than it really is. That bumped the voltage up by about 0.2 volts at any given temp.

In the heat of the summer, it'll get down to 13.8 or so volts (battery temps over 100* F). In the dead of winter, I've seen it get to around 15.4 volts. Since I added the resistor, the group 34 AGM I've got in there (Duracell branded, made by East Penn) seems to charge back up faster if I've drawn it down a bit.

That's very interesting. My Dodge has what is probably the same temp sensor, spring-loaded on the bottom of the battery tray. Most of my driving with this truck is in summer temps in the southwest, and even with ambients well above 100F, I'm still seeing system voltage consistently in the 14.2-14.3V range. I'll do a little research on your idea. Thanks.

I'll note here that one trick I often use on Ni-Cad power tool batteries that are getting tired is to chill them in the refrigerator before charging them, so the idea of higher charge voltage in colder temps seems to make sense.

 

[Ducky's Dad]

If you look at an Optima 31 you can see how their spiral cell configuration ends up costing them capacity, the internal volume is quite a bit less.

Yep! And they weigh less than the Odyssey or Northstar, so less lead. But I still bought Optima Blues for my house batteries because they are just so much less trouble.

 

[Hilldweller]

So how do we coordinate a charge & test session?

C'mon over tomorrow morning. Unless you can get here real quick now...

Optima makes the Blues in both starting and deep cycle versions. The only visible difference, other than the part number, is the shade of gray on the case. Even the Optima dealers are confused about the Blues.

The D31M doesn't have a Yellow that matches; I had two of them for house batteries in my trailer. I ran them flat too many times to count but they lasted 3 years.
Their starting Blues are the ones that are the same as the Yellows inside. The Yellows have a better warranty; the Blues have better terminals..
They're not really good house batteries, btw. Or the Enerysys for that matter.
IMHO, the best things about Optimas are their quick charge time, high output for cranking, and resistance to vibration.
I'll give the nod to Enerysys if you have to cycle them more often but I found my DHP very very hard to live with and was glad to be rid of it.
I have two JCI-made Wallyworld boat batteries and they're easy to charge and maintain. 122 ah each and only $86...

When my Wallyworld batteries croak, I'd like to try one of these: http://www.vmaxtanks.com/XTR12-155-12Volts-155AH-Deep-Cycle-XTREME-AGM-Battery_p_154.html

 

[Ducky's Dad]

Their starting Blues are the ones that are the same as the Yellows inside. The Yellows have a better warranty; the Blues have better terminals..

That's not what Optima told me last summer when I was buying batteries. In that case I was buying Grp 34s as my house batteries, and I had already ruled out the Blue Grp 31M as my starting battery. Word from them was that the starting Blues (Grp 34) were internally the same as the Reds, and the dual purpose Blues were internally the same as the Yellow. I'll see if I can find the specs to support that.

Sears also has a longer warranty on their PM1 in the gray auto version vs the blue marine version. Batteries are internally identical except for the extras set of studs on the blue one, but blue gets three years and gray gets four years. Odyssey explained that they do that because they believe the marine batteries get harder use and more frequent deep cycling in trolling operation.

 

[gravedgr]

C'mon over tomorrow morning. Unless you can get here real quick now...

I have calls from 3:30 - 5:30, but I have a couple of hours tomorrow AM after the kids get on the bus. I'm essentially free from 7 am to 9:30 am.

 

[Hilldweller]

I have calls from 3:30 - 5:30, but I have a couple of hours tomorrow AM after the kids get on the bus. I'm essentially free from 7 am to 9:30 am.

I'm here at 0700.
The charger is in my lab at your disposal....

 

[Ducky's Dad]

Found the Optima specs, and the Grp 34 Yellow and Blue (dual purpose) appear to be identical except for terminal configuration.
This is for
D34 Yellow top post
D34/78 Yellow dual terminal (GM side terminals)
D34M Blue dual purpose marine with top posts and marine studs (light gray case)

All specs are listed as:
CCA 750
Capacity 55 Ah
Rsrv Cap 120 mins
OCV @ 100% 13.1V
Internal
Resistance 0.0028 ohms

Those look the same to me.

https://d26maze4pb6to3.cloudfront.net/optimabatteries/4713/4583/5068/YELLOWTOP_Full_Specs_Sheet.pdf
https://www.optimabatteries.com/en-...d34m-bluetop-marine-boat-deep-cycle-starting/

The Blue 34M has the same specs as the Red 34, and those specs differ from the G34 Yellow/Blue dual purpose:
This is for
34 Red top post
34M Blue top post (dark gray case)

CCA 800
Capacity 50 Ah
Rsrv Cap 100 mins
OCV @ 100% 12.8V
Internal
Resistance 0.0030 ohms

So those Reds and Blues appear to be electrically identical, and they differ significantly from the Yellows and the Blue Dual Purpose in the same group size. And some dealers don't know the difference between the Blue 34 with the light gray case vs the dark gray case.

https://d26maze4pb6to3.cloudfront.net/optimabatteries/9513/4583/5023/BLUETOP_Full_Specs_Sheet.pdf
https://d26maze4pb6to3.cloudfront.net/optimabatteries/9613/4583/5078/REDTOP_Full_Specs_Sheet.pdf

Optima's charging specs for the starting vs the deep cycle Grp 34s differ, but for all of the above they clearly state "10 amps maximum," and "All limits must be strictly adhered to." So that seems to rule out use of the 40 and 50 amp Ultimizer on the Optima batteries, and that is consistent with what they told me when I called last summer.

 

[comptiger5000]

Optima's charging specs for the starting vs the deep cycle Grp 34s differ, but for all of the above they clearly state "10 amps maximum," and "All limits must be strictly adhered to." So that seems to rule out use of the 40 and 50 amp Ultimizer on the Optima batteries, and that is consistent with what they told me when I called last summer.

Interesting... By saying 10 amps max, they're basically saying you can't charge them from an alternator (as many could easily push more than 10 amps into a sufficiently discharged battery).