Left car parked at a hotel a week at Christmas. When arriving back to hotel on Christmas night, the battery was dead. Waited a couple hours for repairman to come and start car. (Never will be without jumper cables again) Finally got car started to discover we must have bumped side door light, as it came on after jumped. Figure this was our fault, as it was there for a week. A few weeks later we drove to FL and spent the night in another hotel. Coming out in the morning, the car barely started. I checked to make sure I had not left anything on. Nothing was on. Car is normally parked in garage and didn't have any more problems. A month later, I was searching for papers in the glove box around 6 in the evening. Forgot to close lid. Next morning around 7:30, I ran out to leave, and the battery was dead. Just doesn't seem right that the battery should be dead from a light in the glove box being on for 13 1/2 hours. Thoughts?
Battery issues
Rail1
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I guess I'm the lucky one. I've left the car parked at our second home unused for more than a month, some sub-zero nights, 12" of snow on the car when we were next up there, and it started fine.
A group 27 battery will have the terminals reversed. Group 27F has the correct terminal locations. Would be nice if it still fits with the extra 3" length. Group 24F is another alternative that may fit better. Either one will be a nice boost in CCA/reserve capacity compared to the OEM though.
Thanks, I checked the cables it doesn’t look like there is much slack. A plastic mount/wire guide attaches to the tie down post too. We also lose the insulation of battery jacket. I’ll compare the size in person, if I can go larger I definitely will.
I did a 5 mile drive after being parked for 2 days and saw it at 11.9 after a few hours.
I’ll check again this weekend after a 500 mile trip
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Since the parasitic drain is not a problem the OEM battery will work fine unless it is previously run down by other loads when the engine is not running. The OEM battery does not appear to have adequate reserve capacity which is the real issue here.
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Battery Replacements
Here is some info on possible battery replacements.
The first place to check for a better battery was CR's Car Battery Ratings. CR does expert and exhaustive tests on automotive batteries, far more than any other source. For Group 35 batteries which is the proper size for the Ascent, the EverStart MAXX-35N (North) came out on top with excellent scores for:
Life
Life test measures how a battery endures repeated charge-and-discharge cycles at hot-climate engine-compartment temperatures. The more cycles endured while maintaining a higher voltage, the higher the score.
Reserve capacity
Reserve capacity estimates how long batteries can run a car if the charging system fails. It also estimates how long the battery will last using lights and accessories with the engine off. This is where the OEM Ascent battery appears especially weak so pay special attention to this rating.
CCA
CCA performance reflects voltage at a load of half the average claimed CCA for each group size after cranking for 15 seconds at 0º F.
![Image]()
The EverStart battery is sold exclusively at Walmart which makes purchasing it convenient for almost everyone. Walmart may sell a lot of lower priced items, but their auto department is actually quite good. The Sears DieHardGold 50835 (North) battery also did well. The EverStart or the Die Hard may work appreciably better than the OEM battery. Both of these batteries are reasonably priced.
Specs for the EverStart MAXX-35N (North):
Model: MAXX-35N
C20 Capacity: 42 Ah
CCA: 640 Amps
Width: 6.90 in
Length: 9.10 in
Height: 8.90 in
Warranty: 36 months
Specs for the Sears DieHardGold 50835 (North)
Model: 50835
Weight: 33.5 lb
C20 Capacity: 37.5 Ah
CCA: 625 Amps
Width: 6.90 in
Length: 9.80 in
Height: 8.90 in
Warranty: 36 months
Here are some other batteries which I trust but were not tested by CR:
NAPA Legend Premium
Model: BAT 8435
Weight: 35.0 lb
C20 Capacity: 39.6 Ah
CCA: 640 Amps
Width: 6.90 in
Length: 9.75 in
Height: 8.88 in
Warranty: 84 months
Bosch High Performance AGM™ Battery
Model: S6
Weight: na
C20 Capacity: 50 Ah
CCA: 680 Amps
Width: na
Length: na
Height: na
Warranty: 48 months
Next, are the super premium batteries. These are considerably more expensive but have excellent specs and purported high performance.
Optima YELLOWTOP® D35
The Optima Yellow Top Absorbent Glass Mat (AGM) batteries are designed to provide excellent starting (CCA) and deep cycling capability (AH reserve capacity). They are expensive at around $255. Optima does not list a battery for the Ascent but they do sell a Group 35 battery which should fit. If you're interested in this battery then try to find a local Optima dealer to ensure the fit in the Ascent. You can order one online, but if it didn't fit it would be expensive to return.
Model: D35
Weight: 36.4 lb
C20 Capacity: 48 Ah
Post Type: SAE Post
CCA: 620 Amps
Width: 6.75 in
Length: 9.38 in
Height: 7.69 in
Warranty: 12 months
Odyssey 35-PC1400T
If you thought the Optima was expensive the Odyssey tops it at around $305, but it has one of the best overall specs I've yet seen for a Group 35 battery. If money is no object then this is one of the best Group 35 batteries you can buy.
Model: 35-PC1400T
Weight: 50 lb
C20 Capacity: 65 Ah
Post Type: SAE Post
CCA: 620 Amps
Width: 6.84 in
Length: 9.46 in
Height: 8.69 in
Warranty: 48 months
Again be careful about the fitment. It's very close to the size of the OEM battery but not exact.
Are the super premium batteries worth 2-3 times the cost of a standard battery? Hard to say, some people swear by them others swear at them. I personally wouldn't spring for one unless I had a very critical use.
So these batteries are some examples of replacements for the OEM battery. I think I'll give the EverStart a shot. I've used EverStarts before and I've generally had good luck with them. When I didn't, Walmart gave me no problem returning them for a full replacement within the warranty period, so be sure to save your receipt. Sears is on the way out so I wouldn't recommend the Die Hard battery, but you may be able to find them on closeout at Sears stores which are closing.
All of these batteries will probably be a superior replacement to the OEM Ascent battery. But before you buy a replacement also consider a Battery Jump Starter. If your OEM battery ever is too weak to start the car, one of these will get you going again. I just picked up a Duracell Powerpack Pro 1100 from Costco for only $89. Not only is it a battery jump starter, but it also has dual 120VAC outlets, dual USB outlets, an air compressor, and an LED light.
Here is some info on possible battery replacements.
The first place to check for a better battery was CR's Car Battery Ratings. CR does expert and exhaustive tests on automotive batteries, far more than any other source. For Group 35 batteries which is the proper size for the Ascent, the EverStart MAXX-35N (North) came out on top with excellent scores for:
Life
Life test measures how a battery endures repeated charge-and-discharge cycles at hot-climate engine-compartment temperatures. The more cycles endured while maintaining a higher voltage, the higher the score.
Reserve capacity
Reserve capacity estimates how long batteries can run a car if the charging system fails. It also estimates how long the battery will last using lights and accessories with the engine off. This is where the OEM Ascent battery appears especially weak so pay special attention to this rating.
CCA
CCA performance reflects voltage at a load of half the average claimed CCA for each group size after cranking for 15 seconds at 0º F.
The EverStart battery is sold exclusively at Walmart which makes purchasing it convenient for almost everyone. Walmart may sell a lot of lower priced items, but their auto department is actually quite good. The Sears DieHardGold 50835 (North) battery also did well. The EverStart or the Die Hard may work appreciably better than the OEM battery. Both of these batteries are reasonably priced.
Specs for the EverStart MAXX-35N (North):
Model: MAXX-35N
C20 Capacity: 42 Ah
CCA: 640 Amps
Width: 6.90 in
Length: 9.10 in
Height: 8.90 in
Warranty: 36 months
Specs for the Sears DieHardGold 50835 (North)
Model: 50835
Weight: 33.5 lb
C20 Capacity: 37.5 Ah
CCA: 625 Amps
Width: 6.90 in
Length: 9.80 in
Height: 8.90 in
Warranty: 36 months
Here are some other batteries which I trust but were not tested by CR:
NAPA Legend Premium
Model: BAT 8435
Weight: 35.0 lb
C20 Capacity: 39.6 Ah
CCA: 640 Amps
Width: 6.90 in
Length: 9.75 in
Height: 8.88 in
Warranty: 84 months
Bosch High Performance AGM™ Battery
Model: S6
Weight: na
C20 Capacity: 50 Ah
CCA: 680 Amps
Width: na
Length: na
Height: na
Warranty: 48 months
Next, are the super premium batteries. These are considerably more expensive but have excellent specs and purported high performance.
Optima YELLOWTOP® D35
The Optima Yellow Top Absorbent Glass Mat (AGM) batteries are designed to provide excellent starting (CCA) and deep cycling capability (AH reserve capacity). They are expensive at around $255. Optima does not list a battery for the Ascent but they do sell a Group 35 battery which should fit. If you're interested in this battery then try to find a local Optima dealer to ensure the fit in the Ascent. You can order one online, but if it didn't fit it would be expensive to return.
Model: D35
Weight: 36.4 lb
C20 Capacity: 48 Ah
Post Type: SAE Post
CCA: 620 Amps
Width: 6.75 in
Length: 9.38 in
Height: 7.69 in
Warranty: 12 months
Odyssey 35-PC1400T
If you thought the Optima was expensive the Odyssey tops it at around $305, but it has one of the best overall specs I've yet seen for a Group 35 battery. If money is no object then this is one of the best Group 35 batteries you can buy.
Model: 35-PC1400T
Weight: 50 lb
C20 Capacity: 65 Ah
Post Type: SAE Post
CCA: 620 Amps
Width: 6.84 in
Length: 9.46 in
Height: 8.69 in
Warranty: 48 months
Again be careful about the fitment. It's very close to the size of the OEM battery but not exact.
Are the super premium batteries worth 2-3 times the cost of a standard battery? Hard to say, some people swear by them others swear at them. I personally wouldn't spring for one unless I had a very critical use.
So these batteries are some examples of replacements for the OEM battery. I think I'll give the EverStart a shot. I've used EverStarts before and I've generally had good luck with them. When I didn't, Walmart gave me no problem returning them for a full replacement within the warranty period, so be sure to save your receipt. Sears is on the way out so I wouldn't recommend the Die Hard battery, but you may be able to find them on closeout at Sears stores which are closing.
All of these batteries will probably be a superior replacement to the OEM Ascent battery. But before you buy a replacement also consider a Battery Jump Starter. If your OEM battery ever is too weak to start the car, one of these will get you going again. I just picked up a Duracell Powerpack Pro 1100 from Costco for only $89. Not only is it a battery jump starter, but it also has dual 120VAC outlets, dual USB outlets, an air compressor, and an LED light.
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757 Posts
Thanks for doing the research. I can personally vouch for the Walmart battery. When my Porsche battery died the dealer wanted near $400 for a replacement. I followed the recommendations of the folks over on Rennlist and installed the Ever-Start Maxx. I’ve had no issues with it since and the price was excellent.
walmart shows this doesn’t fit the ascent, but I assume their “database” isnt accurate. Autozone also doesnt show any batteries fitting the ascent. How long does it take for these retailers to have accurate info? The Ascent had been out for almost a year...
Not lucky - just expected/normal.
There are a few legitimate battery concerns, and probably even fewer actual failures. I have a "concern" from a one-time weak start. My car has started just fine every time since, whether the battery was at 12.6, 12.4, 12.2, or 12.0V (I've measured all of those values recently). If I ignore the concern, I wouldn't be surprised if my batterty lasts another 3 years.
But this is a car forum. Sometimes we're just looking for something to do/modify/change. I probably don't need a new battery (I should have it properly tested), but I just found myself looking at pro10is's list and shopping for batteries! :dunno:
Last night I came out to the garage to measure the space around the battery and it doesn't look like a 27F will fit at all. On the left of the battery (looking from the front), that post is stopping the battery from moving any further left. And being 12.5" long, the 27F will hit the headlight assembly on the right. So 24F is the only other alternative without lots of modifications because it's only 10.75" long. However, my OEM battery is still doing well due to me always keeping all my cars charged up so I won't be trying a different battery/battery size any time soon. But as soon as it dies I will replace it with something bigger for sure, probably AGM too. That's what I have done to my Acura RSX and 1.7EL (same as Civic) with the tiny 51 or 51R batteries. Upgraded them to the huge (to them) 34 or 34R and no more dead car in -30 C or below.
It looks like the Ascent is one of those vehicles with larger parasitic draw even when off similar to my '02 GMC Envoy which I still haven't figured out where the source of the draw is even after owning it for 9 years. Even changing out the alternator made no difference (bad diodes in alternator can drain battery fast). In the mean time, using a good quality AGM battery + topping off the charge every few weeks with a smart charger is my workaround.
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1,439 Posts
No, the Ascent has a very modest parasitic drain of only 15-25ma, well below the 50ma acceptable limit. I very carefully measured it with a professional Fluke multimeter. This is not the problem.
The problem is that the OEM battery has a poor reserve capacity and cannot tolerate any moderate load for long with the engine off.
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1,439 Posts
I came across this too, no one seems to have the Ascent in their database yet. No issue though, any Group 35 battery should fit.
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This is excellent research, if someone could find a larger battery that would fit, it could certainly help. I've tried this before on other cars, it's difficult to pull off successfully.
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1,439 Posts
To test it, try leaving the interior lights on for a while or other loads when the engine is off. This is what drains the OEM battery fast. I think the Odyssey will do much better.
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102 Posts
I beat those batteries to death fishing grass mats all week long using the trolling motor without recharging. They are great indeed.
Since my Ascent is my travel baseball rig, I planned to do exactly what you requested. Battery is suppose to be here Tuesday (day I also have 6k service scheduled). I will install it when I get back from the apt and report back after some use and testing.
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119 Posts
Interesting, installing camera that work in parking mode. Was already considering a better battery and this looks really nice... and expensive :smile:
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102 Posts
The Odyssey 35-PC1400T arrived about a half hour ago and I’m already done installing. Easy breezy using the VSTM OBD II Vehicle ECU Emergency Power Supply Cable Memory Saver that I connected to my boat battery parked next to the Ascent. It’s a Group 35 size so it fit perfectly with zero mods.
Again, my past experiences with Odyssey batteries have been wonderful. I would rather do it right the first time. If Subaru replaced the battery it would have been with the same problematic one. It’s better to spend a few bucks.
Have a great day everyone.
Again, my past experiences with Odyssey batteries have been wonderful. I would rather do it right the first time. If Subaru replaced the battery it would have been with the same problematic one. It’s better to spend a few bucks.
Have a great day everyone.
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Awesome! Please let us know how it performs compared to the OEM battery.
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