Agm Battery / Charger Questions

[outback97]

Hey guys, I have some AGM charger questions. We have two Xterras with AGM batteries. One is a 24F from Exide and the other a 34R from Odyssey. They've been great but they're getting older, and unfortunately we haven't been driving as much lately, so I'm thinking that I should get a charger to top them up.

I have an older 6V / 12V charger that works well for traditional car batteries, but it doesn't have an AGM mode.

Woot (through Amazon) has a Noco 3500 on sale today for $35:
https://tools.woot.com/offers/noco-genius-g3500-charger-maintainer

Any electrical gurus on here that can comment on this option? Anything better at a reasonable price?

 

[BillySpivitz]

For the Odyssey, they have an approved list of chargers that they recommend for their batteries - I don't think the NOCO's are listed. Here's the list: https://www.odysseybattery.com/documents/ODYSSEY_approved_12V_chargers.pdf

I remember when I was researching this, I came across a post on some forum from someone who had reached out to Odyssey specifically asking why the NOCO's weren't approved - here is the reply they got:

Thank you for contacting EnerSys/ODYSSEY. While most of us enjoyed our holidays here at EnerSys please forgive us as we are now trying to catch up with our emails and phone messages. I apologize for the delayed response.

Unfortunately, research about the charging algorithm for the Genius chargers shows that it is not acceptable for the ODYSSEY battery and therefore they are not listed as an ODYSSEY program approved charger or brand. Even though the ODYSSEY battery is an AGM battery not all chargers with an AGM setting are acceptable for charging or maintaining an AGM TPPL Technology ODYSSEY battery.

Charge maintenance is critical to maximizing the life and performance of any battery including the ODYSSEY battery. Here is a little ODYSSEY Battery 101…

The usable energy of the ODYSSEY battery is from 11.2V (0% state of charge) OCV to 12.84V OCV (Open Circuit Voltage should be checked after a minimum of 6-8 hours rest period with no loads) or higher. When the battery goes below 10.0V OCV, you are getting into the chemical part of the battery and can cause permanent damage. At less than 8.0V the ODYSSEY limited warranty deems the battery over-discharged due to abuse or neglect, usually unintentional. At less than 6.0V the battery can develop reversed cells and once reversed, the cells cannot be reversed back. If the battery becomes over-discharged (below 11.0V OCV), then the sooner the battery can be fully charged properly, the better. If the battery remains connected to the application during storage for extended periods of non-use, an approved 12V maintainer can be used to prevent over-discharge and maintain the battery at a full state of charge and counteract the parasitic loads of the application. There is a link to a list of ODYSSEY program approved 12V chargers (and maintainers) linked on the ODYSSEY website Product Support page for your reference.

The list of approved 12V chargers is provided due to the many chargers that are programmed for the vast majority of batteries on the market that prefer low amp charging and lower float voltages that do not fully charge or maintain the ODYSSEY battery properly. The recommended charging current for an ODYSSEY battery is 40% of the 10 hour amp hour rating of the battery for cyclic or deep discharge applications (about 10A for a single 27Ah PC925), a constant float voltage of 13.5-13.8V and no constant voltages exceeding 15.0V in any kind of de-sulfation/reconditioning/equalize mode. At greater than 15.0V the battery can overcharge, overheat, and/or go into thermal runaway. Maintaining a fully charged battery at less than 13.5V will bring the battery down and maintain it in an undercharged condition causing premature sulfation and premature failure.

For seasonal applications (non-daily use applications that set for more than 3 days in a row frequently) regular use of an approved maintainer that meets the charge voltage requirements noted in the previous paragraph is highly recommended during the season. The preferred storage method is to fully charge the battery before storing and disconnect the battery from the application (shelf storage mode). Stored in or out of the application fully charged, with no loads, the battery would not require charging for up to 2 years at 77°F or until it reaches 12.0V, whichever comes first. The self discharge rate increases significantly for temperatures above 25°C (77°F) and for every 10°C (18°F) temperature increase the storage time to recharge is decreased by half. Charge maintenance is critical to maximizing the life and performance of the battery. Freezing will not harm the battery and self discharge rates reduce significantly at colder temperatures.

It is recommended that the ODYSSEY battery be charged if it is less than 12.65V when put into use per the ODYSSEY Owner’s Manual (link provided on website Literature page for your reference). Most standard alternators/stators are not meant to be deep discharge recovery chargers and can damage the alternator/stator as well as not fully charging the battery with limited use. The Cyclic Charge Voltage range printed on the top label of the battery is the recommended voltage at the battery from the applications charging system (alternator or stator). At less than 14.1V the battery may not be getting fully charged for infrequently used applications. You can verify the battery voltage by checking the voltage at the battery at least 8 hours after application use (or off charge) and if the battery voltage is not at least 12.84V then the battery is not considered fully charged. Voltage readings taken right off charge or after use (alternator/stator charging) will be inflated and inaccurate so for a true OCV reading, you should wait at least 8 hours before checking the voltage (OCV) with 24 hour rest period being preferred.

I hope this information gives you an understanding of the product. We want you to have great success with your product as well. Please contact EnerSys/ODYSSEY if you have any questions, concerns or need further assistance.

Sincerely,


Kathy Mitchell
ODYSSEY Sales/Support Representative
Phone: 660-429-7551
Toll Free: 888-422-0317
Fax: 660-429-1758
Email: kathy.mitchell@enersys.com
Web site: ODYSSEY Batteries - Official Manufacturer's Site
Corp site: EnerSys Home
​

I ended up going with the CTEK Multi US 7002 - a few other Xterra Odyssey owners recommended it:

https://www.amazon.com/gp/product/B000FRLO9Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

May be a bit more $$ than what you were looking for, but it works great and I have piece of mind that I'm not damaging the battery and shortening its life.

​

 

[IM1RU]

Odyssey Charger FTW!

I have one if you need to borrow it.

 

[kryter]

TP108MB amazon

 

[westslope]

Would not any trickle charger that manages 2 volts be adequate for an AGM battery?

 

[outback97]

For the Odyssey, they have an approved list of chargers that they recommend for their batteries - I don't think the NOCO's are listed. Here's the list: https://www.odysseybattery.com/documents/ODYSSEY_approved_12V_chargers.pdf
...
I ended up going with the CTEK Multi US 7002 - a few other Xterra Odyssey owners recommended it:

https://www.amazon.com/gp/product/B000FRLO9Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

May be a bit more $$ than what you were looking for, but it works great and I have piece of mind that I'm not damaging the battery and shortening its life.

​

That's a lot of good info, thank you.

TP108MB amazon

Thanks for the recommendation.

Odyssey Charger FTW!

I have one if you need to borrow it.

Thank you Rob, that's generous of you!


Sorry, I have been neglecting following up on this thread I started. This was a one day sale that could sell out at any time. I had waited until later that day before BillySpivitz posted, and I went ahead and bought the Noco G3500 charger, not seeing anything suggesting otherwise in my small amount of research. Oh well.

It sounds like it might not be the best option, but it was too hard for me to pass up the $35 price. Plus, if you poke around the internet enough you can find information that directly contradicts other information... apparently Odyssey used to be OK with recommending the Noco for their batteries:
http://www.vansairforce.com/community/showthread.php?t=125488

And some other positive feedback here:
https://www.ferrarichat.com/forum/threads/battery-maintainer-for-odyssey-battery.436200/

But more recent posts (including here) are saying the Noco is not great for the Odyssey. So for now it's still in the box unopened.

Here's my follow up question: For someone with just one battery, what is the actual real world benefit of having your AGM battery fully charged?

As I understand it, our alternator / charging system can't do it alone... it will only bring it to a certain state of charge, because the voltage it's putting out is not high enough. This is why you need the special approved list fancy charger, right?

Imagine this hypothetical situation. You're going out for a day trip (or overnight, or weekend) of wheeling and exploring in the desert or the mountains. You drive an hour or two to get there, using your headlights, stereo and HVAC. You air down your tires, then spend hours driving around having a great time, still using electrical accessories, maybe even your winch. When you're done and it's time to go home, you air back up (using your electrical compressor) and drive an hour or two back home.

Wouldn't your battery now (or even during this trip) be back to where it was had you not used the charger at all... at the state of charge you'd get from your vehicle charging system alone? Or does it somehow hold on to the higher state of charge through all that electrical draw?