Voltage and AMPS
 

So I have a few cars on battery tenders. Now that winter is over I have checked the voltage. The batteries show 12.6 to 12.8 Volts. I just bought a battery tester. It too shows good voltage, but the CCA are in the 200 range and not 500. So it comes up with the message: REPLACE BATTERY. What do you think? I really don't want to waste my money on new batteries but I also don't want to be stuck at the side of the road. I only drive these cars above 40 degrees so CCA was of little concern, but should I be concerned? Thanks.

Are they lead acid batts? Make sure they aren't low on fluid.

What kind of tenders? The newer 'smart' tenders are the way to go, like the Noco ones. They also do cycled tending.

What kind of battery tester? Not all actually work right.

Batteries are usually only good for 3-5 years, depending on the type. AGM batts can last up to 7-8 years. Good ones. Marine AGM batteries also go 7-8 years, some even to 10 years.

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Answers to questions:
Mix of both lead acid and AGM
Tenders are smart tenders from Griots Garage
Battery tester is typical Chinese made for NAPA
One lead acid battery is 2 years old, one AGM is one year old. Both tested as Replace Battery because of low AMPS, not low voltage, so are they both important or one more than the other.

You can have 12-13 volts and still have a bad battery. Load (Amp) test is the only way to tell

Makes me wonder if it's the tenders. Batteries should go bad in 1-2 years.

Those Griots Garage chargers say they are for lead-acid batteries, no mention of AGM by the way. And t can surge to 20a, never heard of a 'tender' that does that. Most are 2a-5a range.
This is the only one I use on my cars:

https://no.co/genius5

I have yet to find a better, and they can charge/recover batteries that are fully discharged, a rare feature. They also make single units that can manage up to 2 or 4 batteries at the same time.

https://no.co/genius

Anyway, on the lead acid ones, make sure you have enough acid in them. The AGM ones, once there is a dead short, even momentarily, it will cook one or more cells. No recovering those.


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They also make a full line of accessories, extension cords, different size eyelets, etc.

https://no.co/collection/accessories/genius-accessories

They come with a wall mount, the unit can be easily removed from the mount if need be.

They are only 4.25" long, easy to pack and take with you on trips.

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Thanks for the info. I bought a new battery amp tester. Only the older AGMs need replacement.

My blue top is almost 6 years old, my yellow top is more than 8 years old, both still working well.

The OE Delco AGM in my 2018 truck I just replaced before the winter. It would have probably been fine, but noticed the ALT was cycling the charge more often and didn't trust it to make it thru the winter.

Something is amiss, you should look hard at your setup.


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Research proper charging for AGM batteries, It is different than lead acid charging

Yes, I have a Griot's charger/tender/maintainer that does 6v, 12v, flooded, spiral, AGM at 2 amps, 10 amps or 20 amps

No real pattern here. I have one AGM still good from 2012, lead acid from 2017 still good, yet newer others are bad.

Swap a good one from one of the other cars into one of the ones that have a bad and see if it goes bad.

I guess it could just be bad batteries, but that seems way too soon for them to go bad. Like I said, I would be looking hard at the systems on the cars that went bad.


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Battery swap
 

That's a good idea on the swap. Thanks

I have a newer B&D charger that has a battery recondition function that has saved me a couple batteries that had gone completely flat or wouldn't carry a load. I can't explain the science behind how it works but, it works.

https://www.amazon.com/BLACK-DECKER-...RU8-&hvexpln=0

I haven't found those new-fangled battery load testers to be as accurate as the old school carbon pile testers for lead acid batteries.

Yes, the NOCO ones I had mentioned do the same:

"The GENIUS5 automatically detects sulfation/acid stratification. If any is found, the GENIUS5 will automatically repair and reverse the damage done to the battery, extending the usable life and increasing the performance."

It also has thermal charge compensation:

"The new integrated thermal sensor automatically monitors and adjusts the charging cycle based on fluctuations of ambient temperature, limiting the chance of under-charging or over-charging, providing a more accurate and fully charged battery. Avoids under-charging in cold weather down to -4 F and avoids over-charging in hot weather up to 104 F."



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I’m late to this but I’m totally on the same page. So many battery “tenders” practically do more harm than good. I will only use the NOCO or CTEK chargers. The CTEK is often relabeled/rebranded for certain manufacturers/models (like for Subaru, and is also shipped as the OEM charger for the C7/8 Corvettes). I have more if the CTEK (MUS 5.0) versions now since the price is back under $100.

You can also run your charger(s) through digital repeat cycle timers like the ones offered by BN-Link (under $20) so they only come on every few hours at a time or once every day for an hour or so if you want. These are outdoor rated and capable of 15A unlike those old school ones you used to use indoors for Christmas lights.

Yes, NOCO and CTEK are the way to go. I know the NOCO actually does go thru certain cycles, on, off, trickle, etc. There are other good ones out there now, but NOCO is working for me, so no need to break the habit.

An interesting note. I bought a new KTM EXC-F 500 in spring of 2022, and used a NOCO for it. By fall, I was having an issue with gas in the oil, and took the bike in for a warranty service. Service department knew exactly what was going on, and told me it was the NOCO smart charger. Those cycles would impact the ECU programming, which also had a type of 'smart' capabilities, specifically to cycle the fuel pump for startups (efi). I switched to a Battery Tender and all is fine. The factory even issued a reprogramming TSB, they applied it on the following service interval, but I had already switched anyway. The service notice had a list of chargers that were known to cause the issue, and a list of suggested ones to use, Battery Tender being one of them.

I can't even count how many battery chargers I've owned over the years, 99% of them were junk, and not inexpensive ones either. I had some issues with some early AMG batteries and learned from those experiences. That's what eventually led me to NOCO.


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Ok, being curious and not knowing ay differences, I went to the Interstate website to see what is different about charging an AGM battery. A car does not know what kind of battery is under the hood and yet AGMs are used in cars........So the website says "to charge an AGM battery connect a AGM rated charger........... Ok, going further, it says AGMs do not like higher voltages like some chargers use, it says. There is a pressure relief valve there and Interstate also says "That one-way valve is supposed to relieve excess pressure from the harmless gases that come when a battery’s charging"

Excuse me, harmless gases like HYDROGEN, which, when mixed with oxygen and a spark, can explode?

I think they should rewrite that section. In any case, so if you use a constant voltage charger you should be good to go. Your car charging system is a constant voltage source.

George