Anybody tried a group 31P battery in place of our group 49? - PeachParts Mercedes-Benz Forum

tjts1 · #1 02-26-2017, 03:26 PM

I was checking out batteries at NAPA the other day and noticed that a "commercial" 31P battery might fit in place of my group 49.

BCI 31P:
1190 CA
950 CCA
Height 9 1/2 in.
Length 13 in.
Width 6 3/4 in.
Battery Weight 56.5 lbs
$87

BCI 49:
1000 CA
825 CCA
Height 7 1/2"
Length 13 15/16"
Battery Weight 43.3 lbs
$157

The only issues I see that its 2" taller and mounting it to the battery tray. The W124 easily fits the extra height and I would have to figure out how to strap it down. A lot of diesel truck people are swapping these batteries since they're cheaper, easily available and out crank anything else that fits. Has anybody else tried one of these in an MB diesel?

SD Blue · #2 02-26-2017, 07:08 PM

I looked at those a while back for my W126 and found out they were too tall. It was just enough to touch the hood when closed.

ROLLGUY · #3 02-26-2017, 08:45 PM

Also, most if not all the battery cables barely fit with the 49. Even if the extra height was not a problem, the cables may have to be lengthened.

sloride · #4 02-26-2017, 10:58 PM

Thanks for that info @ $87.00 thats whats going in my camper when my six year old Interstate bruised and reduced shows signs of failure. Plenty of extra length on the cables so no problem and the hold down is just some all thread and nuts.

gatorblue92 · #5 02-27-2017, 06:40 AM

Those might fit in a W124 but there is no way you could fit one of those in a W123. Way too tall.

BillGrissom · #6 02-27-2017, 04:19 PM

A bit different, but I'll add that in my two W123's, I use an H8, instead of the factory Frame 47(?). Cheaper, 10 lb lighter, and about the same CCA, as I recall. My son recently replaced the Frame 47 in the 1984 and Autozone showed the H8 listed as a choice, even though they carry the 47. BTW, I always buy Autozone's Gold brand (longer warranty). In one car, I have replaced the battery twice, both free. Perhaps not the best quality, but the warranty works.

tjts1 · #7 02-27-2017, 05:26 PM

Quote:

Originally Posted by BillGrissom

A bit different, but I'll add that in my two W123's, I use an H8, instead of the factory Frame 47(?). Cheaper, 10 lb lighter, and about the same CCA, as I recall. My son recently replaced the Frame 47 in the 1984 and Autozone showed the H8 listed as a choice, even though they carry the 47. BTW, I always buy Autozone's Gold brand (longer warranty). In one car, I have replaced the battery twice, both free. Perhaps not the best quality, but the warranty works.

One thing I learned after speaking with a fleet manager is he picks the batteries based on weight, the heavier the better. Basically the manufacturer can save money by using fewer of small lead plates in the same case. My old Napa branded group 49 weighted 43lbs. A new Duracell is 57lbs. He has each battery weighed before he has it installed. Anything under the specified weight is returned.

Still debating whether to go for a 49 or 31p. The group 49 selection at NAPA is lackluster, checking out batteries plus in a couple of days.

Amazon had the solar ba5 battery tester under $40 so I picked up one of those. Any new battery I buy will get tested first. The old Napa battery still starts the car but does t glow nearly as well as I'd like. Basically the car starts a lot more smoothly. If I put it on the float charger over night. I checked and there's no drain.

Maxbumpo · #8 03-01-2017, 09:32 AM

Let us know what you find out, I'll be shopping for a new battery soon for my 124 wagon, I'd love to save $40 vs. a group 49 for $122 at Wal-Mart, while getting a bigger battery.

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