Lesson learned: bring a voltage tester to the store
- Thread starter DemoFly
- Start date
On my flooded cell 3 3/4 yr old 585cca battery, I charged on a BatteryMinder 2012 and made a 16 and 24 hr in car measurement.
16hr
24hr
It is an estimate of life remaining. Theoretically it should last almost twice as long as it has so far. Personally I pay attention to the percentage that the CA or CCA is of what it was originally. At 75%, I replace.
In round numbers if a 1000 CCA battery tests at 750, it is likely to fail in the next few months.
I wouldn't put much, if any, faith in the health figures those types of testers return.
Their methodology is to test voltage and internal resistance, and then conjure up an estimated figure based on the input parameters and some assumptions.
Those two measures are probably reasonably accurate, but the other results can be flat out wrong.
I fail to see the use-case for AGM's for passenger vehicles. They have lower energy density than flooded conventional batteries, are way more sensitive to over charging, they do lose capacity over time and are significantly more expensive. The original factory batteries in my new Chrysler vehicles (new circa 2000 - 2004) lasted 10 and 12 years.
When they first came out, they were billed as being more for off-road / atv use because they withstand vibration and shock better, and that's probably true, but that advantage is lost on a conventional on-road passenger vehicle.
Electrochemistry is the same, a fully-charged "resting" no-load battery should give you 12.8 volts. 12.2 volts corresponds to about 65% charge level.
A car not specifically designed for an AGM might not have a properly-tuned charging system for an AGM and hence you can expect over-charge damage to happen over time, with corresponding loss in capacity.
When they first came out, they were billed as being more for off-road / atv use because they withstand vibration and shock better, and that's probably true, but that advantage is lost on a conventional on-road passenger vehicle.
Electrochemistry is the same, a fully-charged "resting" no-load battery should give you 12.8 volts. 12.2 volts corresponds to about 65% charge level.
A car not specifically designed for an AGM might not have a properly-tuned charging system for an AGM and hence you can expect over-charge damage to happen over time, with corresponding loss in capacity.
f355spider
$50 Site Donor 2025
I run AGMs in several cars that never came with them...never had a problem and typically gotten more years than I did with flooded. 1978 Ferrari 308 GTS, 1997 Ferrari 355 spider, my current 2001 BMW 540 has a 6 year old AGM doing just fine.
My newer cars all came with AGM.
I think the issue of "properly tuned" charging system is over played. My 2009 Ferrari 430 Scuderia came with an AGM battery...yet all previous years had flooded. There was no change to the charging system, all years have the same alternator part number. I have seen other car manufacturers do the same thing.
To each their own, but I prefer AGM. No checking electrolyte is nice too...especially with the locations some car manufacturers put batteries these days.
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Yes it is correct.
My sister and her husband have one of the biggest and best jump packs and I remind her to top off the charge of it every few months. She had checked it and it still showed full charge, and a few weeks later December 3 The 5 yo ( it was exactly 60 months old ) 51R Honda dealer battery in her CRV failed as a dead short. Her husband tried to use the jump pack without success. It showed a significant reduction in remaining charge each time he tried it, and it was given to them new a year ago at Christmas.
So, even the best jump packs can't start a vehicle if the battery fails as a complete short.
She called me, I picked up a new 12/24 date coded 51R Walmart MAXX and cleaned the terminals of vehicle and battery with some red scotchbright ( I have the metal battery post and terminal cleaning tool, but it's too agressive and removes too much material, red scotchbright ( plastic steelwool works better and does not remove too much )), put Corrosion X aviation spray on the terminals and copper of the cables, put new felt battery pads on, and installed it.
So, carrying a charged top end jump pack is not a guaranteed gonna get it to start. If it fails dead short, no jump pack can get it to start.
Bottom line, if you want to not get stranded, replace the battery when it has aged out, before it fails.
So, even the best jump packs can't start a vehicle if the battery fails as a complete short.
She called me, I picked up a new 12/24 date coded 51R Walmart MAXX and cleaned the terminals of vehicle and battery with some red scotchbright ( I have the metal battery post and terminal cleaning tool, but it's too agressive and removes too much material, red scotchbright ( plastic steelwool works better and does not remove too much )), put Corrosion X aviation spray on the terminals and copper of the cables, put new felt battery pads on, and installed it.
So, carrying a charged top end jump pack is not a guaranteed gonna get it to start. If it fails dead short, no jump pack can get it to start.
Bottom line, if you want to not get stranded, replace the battery when it has aged out, before it fails.
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Really, really lucky the shorted battery didn’t blow up when trying to jump it. I’ve seen it happen, acid literally everywhere, even seen it hit the ceiling!
I saw one blow once also. I was watching someone across the street while I was on my living room couch. Looked like a gallon of water exploding upward everywhere. The guy ran into his house and into a shower. I talked to him the next day, and he said that he had the polarity correct.
Not necessarily true. I just had to buy a Group 35 for my kid’s car. The 520CCA FLA was $199.99 with a 2 year warranty. The 660CCA AGM (with a 12/24 sticker as well) with a 3 year warranty was $244.99. I snagged a great 20% off coupon and managed to talk them into honoring the military discount on top of it, so essentially the AGM (for me) was actually cheaper than the lowest-end FLA if my son had bought his own.
While that deal was pleasing, NOTHING prepared me for the deal I got on his alternator the next day! Advance Auto in town is closing. But they had the cheapest price on remans, a CarQuest Reman with lifetime warranty was like $202 here, and anywhere from $250-420 at other locations, manufacturer, and new or reman. I ordered online. I get to the store and tell the manager I have online pickup. He says “they took our store off that since we’re closing”…. I had gotten a confirmation! So I open my email, find the confirmation, and right above it, 17 minutes newer, was the cancellation. Darn! So I asked if he had the alternator. I wasn’t going to waste a trip. He goes back, grabs the alternator and as he’s scanning the tag he says “With the $44 core charge, your total comes to…. $66.17.”
HOLD THE PHONE… wut?!? I said “WITH the core charge?” “Yep. With 95% off, the alternator is $18.00 even.”
Me: “Do you have any more of this part number on the shelf??”
I would email East Penn your battery questions. They will respond promptly and have been helpful with the answers to my battery questions.
I was in a similar situation once.
While working in the garage, an older/elderly couple, temporary/renters, across the street was trying to jump a dead battery. I could hear the arcing and popping from whatever they were doing while trying to figure out it.
I came out to see what they were doing and offer some guidance, but was summarily brushed off.
Nothing did blow, but my conscience would have been clear if it had.
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