Purchasing a 12V battery? Advice...

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gncndad

Well-known member
Joined
Feb 22, 2016
Messages
299
Location
Ft. Worth, TX
Purchasing a 12V battery? Make sure you check the production date. My local PepBoys tried to sell me a battery that was manufactured 22 months ago.

Also, I strongly recommend you have the shop fully charge the battery prior to the sale. The 2nd battery they showed me was only 40% charged, when they hooked it up to charge.

Hope this helps!
 
With an ICE vehicle the car's alternator will usually charge a new battery right up. In the case of a Leaf - and especially an older Leaf - this may not happen. So yes, always have them fully charge a new battery before installing it. The correct "group" (size) is 51R and for older Leafs it may be wise to get an AGM battery which can better tolerate the charging patterns of the older cars, especially if you have had repeated problems with dead batteries.
 
PepBoys had 51R listed, in stock, then brought out a 51, which has the reversed terminals. They show the 51R, but don't seem to have one in the DFW area.
 
Here's some more info: I decided to replace the Champion with the correct Bosch (51R) AGM battery. (Four year free replacement) It was manufactured in Oct, 2018, instead of Feb, 2018.

I asked 2 different battery shops about charging characteristics of traditional vs. AGM batteries, because I was concerned how long the AGM took (Battery Tender Plus, 1.25amp) to come to full charge. I was advised that, because of the density of the glass mat material, the AGM batteries take longer to charge than a traditional battery.

I hope this info is useful.
 
Yes, an AGM is slow to charge, but can be discharged much lower than a starting battery without significant damage, if recharged again soon thereafter. They were originally developed for use in fighter planes, IIRC.
 
AGM batteries have lower internal resistance than flooded cell batteries so they will accept charge faster from a high current charger like the DC-DC converter in the LEAF. Since they generally have more ampere-hour capacity than the same size flooded cell, they do take longer to charge with a trickle charger. AGM batteries are available with internal characteristics optimized for starting or for deep cycle use, but even starting type AGM batteries can tolerate deep discharges better than flooded cell batteries.
 
GerryAZ: Thanks for the further clarification.
The Pep Boys shop that sold me the Bosch put it on a very old (amp gauge completely unreadable) charger, as their "state-of-the-art" charger only worked in diagnostic mode. I was concerned about the charging amperage, but they assured me the older machine would work w/o damaging the AGM battery.

The "diagnostic" printout, after the charging, showed 100% SOC, 12.9v, rated 440CCA, measured 480CCA.

I installed the battery, hooked it up to my BatteryTenderPlus 1.25a charger, and it immediately started charging, only getting to 80% overnight. I've driven the car for 50-60 miles with no apparent issues.

I hooked up the BatteryTender again last evening, and now, after 12 hours on the charger, it's still showing only 80% charged.

Does this sound normal? The BatteryTender is 5+ years old. Is it possible it isn't reading accurately?

FYI, all of this is at 35-50f ambient...
 
Others will disagree with me, but the charging algorithms of the DC-DC converters in the LEAF (2011 was OK; 2015 algorithm is better) are ideal for the characteristics of AGM batteries. I have never connected an external charger to the 12V battery in either LEAF. I had to jump start the 2011 after forgetting to remove the Bluetooth adapter from the OBDII port when I parked it at the office for a few days. The OEM battery was at least 60% charged after driving 26 miles home and fully charged after charging the car overnight. I had to jump start the 2015 after it was parked in the driveway during a weekend motorcycle trip. The upgraded telematics unit locked up and stayed active so it drained the OEM battery. I started the car with a booster battery and left it in READY mode for a few minutes in the driveway to see if the battery would take a charge. It took enough charge to reliably start the car so I drove around to run errands. Again, the OEM 12V battery was fully charged after charging the car overnight. In both cases, the deep discharges damaged the 2+ year old OEM batteries and they failed about a month later. In both cases, I put the new AGM deep cycle batteries in and left it to the DC-DC converters to fully charge them during driving and charging overnight.

AGM batteries will absorb charging current until they get to a slightly higher voltage than flooded cell batteries so your battery tender may not be able to reach the level needed for it to show full (especially with residual load from LEAF systems. If you have LEAF Spy, look at the 12V battery voltage and current after driving for a few minutes. If it shows normal float voltage (around 13 volts, depending upon temperature) and less than 0.5 amperes, your new battery is fully charged. The DC-DC converter will put out over 14 volts to charge the battery until the absorption current drops; it then switches to float mode at about 13 vo!ts to avoid overcharging. This is good for AGM batteries because overcharging shortens their life.

How long did Pep Boys charge the battery before performing the diagnostic test?
 
"How long did Pep Boys charge the battery before performing the diagnostic test?"

That's what concerned me. It went from about 50% to 100% in less than 30 minutes.

My car is Leaf S, No nav, no telematics. All very simple.
 
gncndad said:
The Pep Boys shop that sold me the Bosch...
A friend who borrowed one of my vehicles purchased a Bosch battery from PepBoys to replace the one in the vehicle (which wasn't bad: it was the alternator). It's probably the worst 12V battery I have ever had. One cell would not hold a charge. So I had them replace it. The replacement had the same problem.

I will never purchase a Bosch battery.
 
RegGuheert said:
gncndad said:
The Pep Boys shop that sold me the Bosch...
A friend who borrowed one of my vehicles purchased a Bosch battery from PepBoys to replace the one in the vehicle (which wasn't bad: it was the alternator). It's probably the worst 12V battery I have ever had. One cell would not hold a charge. So I had them replace it. The replacement had the same problem.

I will never purchase a Bosch battery.

Sheesh...NOW you tell me!! :D

Was it an AGM? Clearly not in an EV, as you say your alternator was bad.

PS: After 12+ hours of 1.25a charging, BatteryTender shows it is fully charged! :D So far, so good...
 
gncndad said:
Sheesh...NOW you tell me!! :D

Was it an AGM? Clearly not in an EV, as you say your alternator was bad.
Good point. It was NOT an AGM battery. It was a "Bosch Premium Power". Since AGMs have a lower self-discharge rate that SLIs (IIRC), I doubt you will have the same problem I have had.
 
Bosch are made by Exide:

“ALPHARETTA, Ga., May 20, 2008 (PRIME NEWSWIRE) -- In conjunction with its new agreement with Robert Bosch Corporation, Exide Technologies (Nasdaq:XIDE) (www.exide.com), a global leader in stored electrical-energy solutions, announces a new supply agreement with Pep Boys. Starting this month, Exide will begin shipments of Bosch branded automotive starting batteries to all Pep Boys stores across the United States and in Puerto Rico.”
 
gncndad said:
"How long did Pep Boys charge the battery before performing the diagnostic test?"

That's what concerned me. It went from about 50% to 100% in less than 30 minutes.

That is reasonable if the charger was capable of high output current. AGM batteries have low internal resistance so they can charge quickly if the charger has high capacity (like the DC-DC converter in the LEAF). Others on this forum have reported good results with the Bosch Platinum AGM and you have a 4-year warranty so don't worry about it too much.
 
LeftieBiker said:
Yuck. Rebranded Crap.

12V auto batteries are like tires. There's really only a few companies that make them. Rebranding is pretty much a given.

That being said, the (so-called) Bosch Platinum-Plus AGM 51R has worked well for me and the warranty is exceptional. I'm fairly certain you can get the same exact battery under the "Rural King" brand for somewhat less money, but shorter warranty.

If you want a battery made in the USA, I think Odyssey still does. Or their parent company, that is :)
 
joeriv said:
Bosch are made by Exide:

“ALPHARETTA, Ga., May 20, 2008 (PRIME NEWSWIRE) -- In conjunction with its new agreement with Robert Bosch Corporation, Exide Technologies (Nasdaq:XIDE) (http://www.exide.com), a global leader in stored electrical-energy solutions, announces a new supply agreement with Pep Boys. Starting this month, Exide will begin shipments of Bosch branded automotive starting batteries to all Pep Boys stores across the United States and in Puerto Rico.”

Hmm...I'm wondering if this article from 2008 has any current validity? All marketing is clouded by smoke-and-mirrors... ;)
 
Final...OCD...post...HAHA!

Finally got the BatteryTenderPlus to fully charge the Bosch AGM 51R battery. Drove the car for 75 miles, put it on the charger again, and within 2 hours, was fully charged again.

Done. I will now return to my regularly scheduled programming...

TYPO: AGM 51R
 
40-day update: Plugged the Battery Tender into the new Bosch AGM battery, ambient 35f. Went to a full charge within 30 minutes.
I consider my 12V battery issues to be resolved.
FYI: daily driver, rarely over 45-50 miles, always charged fully overnight. Main battery now at 11 bars (29.5k miles)
 
LeftieBiker said:
gncndad said:
40-day update: Plugged the Battery Tender into the new Bosch AGM battery, ambient 35f. Went to a full charge within 30 minutes.
I consider my 12V battery issues to be resolved.
FYI: daily driver, rarely over 45-50 miles, always charged fully overnight. Main battery now at 11 bars (29.5k miles)


Great news. Did you have to modify the battery or cables to install the 61R? I'd like to start recommending that as an option, but want to know more. Forgive me if you already wrote about that.

No modification of any kind. So far, so good!
 
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