yeah, when I know car is not likely to be driven for a week, I plug in and leave it. It stops charging when fully charged and goes to maintenance mode.
not a bad item to have even after covid is over.

 

cables with my battery tender are long enough to go to the locations you show. They recommend not to attach to battery directly both ends.

 

Just curious if you noticed stop/start function working sooner after the charger is used?

 

will check it out, I have a habit if always disabling it. I hope it breaks and never works!😆

 

Yeah, I was deciding between Deltran battery tender 4amp (the one russiaDude is using) VS noco genius 2 (2 amp version that you recommend). I think I read some reviews saying the genius 2 won't charge more than 40 ampHour batteries. The RDX has 70AH.

I do like the extra display ( 25% increment) and extra modes that Noco provides. However, the genius line seem to be a relatively new series (half a year?). Not as much reviews on Amazon.

 

The Battery Tender brand has been around a long time and no doubt is safe. The Genius line was just one example of a brand with a dedicated AGM mode.

These batteries are becoming commonplace and manufacturers surely build their chargers with AGM requirements in the design spec. I just tend to look for ideal solutions from options available. Good luck.

 

Some data points:. I drove about 45 min (approx 25 -30 miles) mostly high way / suburban. The auto start stop kicked today around mid drive. I measured voltage after the drive, it was 11.98v. i thought it's supposed to be 12.6v for a fully charged battery. Maybe some electronic in the car pulling down the voltage? (Ie. That animation that shows on dash everytime I open/close the driver door.)

 

Mine says its compatible with AGM batteries. Most
of the new ones can be used with AGM. They
put micro controllers in them that have a lot of safety checks

 

It would be interesting to know what the current draw is when the car is off. It's still listening for the key fob continuously, periodically activating LTE checking for updates and listening for AcuraLink requests, various self-tests, and probably other things I can't imagine.

One of the benefits of AGM batteries is a lower self-discharge rate, but tech-laden cars counter that by never being truly off.

 

We have two cars, a Fit for "local" drives and our RDX which is more for trips or for me if the wife has the Fit out. (Fit gets 35 MPG city and nearly 44 on the highway). The Fit is like driving a little sports car, the RDX is a nice ride for a highway trip. Anyway, the RDX, especially with the current lock down, often sits idle in the garage for weeks at a time. Never, ever has the battery gone down. I have never considered putting my Battery Tender (special one made for the AGM batteries, BTW) on the RDX as I have never had cause to do so. I have checked the battery in the RDX with my tester (electronic one that does all the internal tests on the plates and such) and the battery always tests fine.

Even with computers in cars the draw from the battery is no so much as you might think. The computers go into a sleep mode and after some time a "deep sleep" mode where they only power up very briefly from time to time and even that power up only brings them into a low power mode for micro seconds. You can do a simple test to see this happen if you have a good meter and can understand the process to do it.. I use to do it in class when I had the dealership techs in to demonstrate what was normal and what was not and how to get the vehicle to go to sleep. In addition, the battery in the RDX is a monster compared to its Honda CR-V cousin.

As a side note: Even our Fit doesn't get driven every day. ours is five years old this month and last week I ran a test set on the battery. (Original OEM Honda that came with the car). Five years old and still tests at 95+% of its rated capacity and has perfect internal resistance. The original battery in our previous Fit, a 2007 was still going strong at seven years of age when I broke down and replaced it as a precautionary measure as we we expecting a harsh Winter. My sister's Honda did the same, they finally had to replace their original battery in their Fit at seven years of age. On the other hand my brother's CR-V had a battery fail at only three and a half years. He doesn't drive the vehicle every day and when he does drive it its trips of like three miles at a time. Its rare for him to travel more than a few miles as he lives in a very small town and rarely travels. My CR-V batteries generally lasted five or six years. Our Accord did at least as well as that.

 

I drove about 1 1/2 hours yesterday for an errand. The idle-stop began working again about half way.

A lot of cars on the road.

 

What is the downside of using a battery charger when car is sitting in the garage fo weeks? The goal is not to be able to simply "start" the car. I am trying to keep battery fully charged at all times to prevent from premature failure. The life of batteries is shortened when they are kept under charged, which will still start your car.. It takes 30 seconds to plug in battery tender. I will let you know if it restores AIS function.
Even when COVID is over, I sometimes go on vacation for 3-4 weeks, with RDX being in the garage, this is perfect.

 

I don't know of any downside to keeping an unused battery on a proper charger for weeks, or even months. You are correct that a charged battery is a healthy battery and allowing extended and/or deep low voltage conditions shorten battery life through sulfation.

I have another car that I only drive in warm weather, so that typically sits on a maintainer from Oct-March. The OEM battery in that car was still in use after 10 years. I finally changed it out only because I knew it was beyond the safety margin.

Smarter people may have concerns I do not.

 

No downside that I know of. When we leave town for a couple of months, one of the cars goes on the Deltran. I have not had any battery issues since using it.

 

Hey everyone... I read through the posts in this thread and didn’t find this information, so I’ll ask ... Regarding the connection of the battery tender itself or any of you using the smart battery charger with the cigarette lighter connection? Or are you all using clamps connecting to the posts under the hood? I have a smart tender I have for my Porsche - it is a CTEK with AGM mode. It connects via the cigarette lighter socket - can this be used with RDX?

 

Connect like in this picture. This is also what owner manual states when you get a jump start.

 

Following the manual recommendation is the best answer.

I use a maintainer regularly for another car and used to use the alligator clips. I'd make the battery connections first and then power on, to avoid any sparking. I later added permanent leads to the battery (similar to picture below) and now just plug in when needed. I was able to find a hidden spot inside the grille on that car and I can connect without opening the hood. I don't think the RDX has a similar hidey-hole that would permit this remote connection, but it's still possible inside the engine compartment. You'd have to be comfortable with working on battery connections, however. This is NOT a carefree procedure if you don't understand what's involved. This is just an option if you are technically savvy.

As for the cigarette lighter connection... I can't give a good reason, but I've never been comfortable with that charging method. It's commonly done, but I just don't like sending current from a third party device through the internal network. YMMV.

 

did you connect both of them to battery terminals, or only red one to battery and black one to the body of the car?

 

<disclaimer> I'm not an expert, but I did a lot of reading on the web about this recently. </disclaimer>

Like many have stated, car batteries (lead acid) like to be fully charged. When the battery is not fully charged, the material inside the battery degrades. Hence, we need battery tender technologies. However, there is *potentially* a downside to this. While batteries like to be fully charged, it doesn't like to be OVER charged. AGM / sealed batteries are more sensitive to this. If the battery tender is not functioning properly and not switch to "float" voltage when the battery is fully charged, it could damage the battery.

https://batteryuniversity.com/learn/...d_acid_battery -- "Setting the voltage threshold is a compromise and battery experts refer to this as “dancing on the head of a pin.” On one hand, the battery wants to be fully charged to get maximum capacity and avoid sulfation on the negative plate; on the other hand, over-saturation by not switching to float charge causes grid corrosion on the positive plate. This also leads to gassing and water-loss."

https://batteryuniversity.com/learn/..._glass_mat_agmAdvantages

Spill-proof through acid encapsulation in matting technology

High specific power, low internal resistance, responsive to load

Up to 5 times faster charge than with flooded technology

Better cycle life than with flooded systems

Water retention (oxygen and hydrogen combine to produce water)

Vibration resistance due to sandwich construction

Stands up well to cold temperature

Less prone to sulfation if not regularly topping charged

Has less electrolyte and lead than the flooded version

Limitations

Higher manufacturing cost than flooded

Sensitive to overcharging (AGM has tighter tolerances than gel)

Capacity has gradual decline (gel has a performance dome)

Low specific energy

Must be stored in charged condition (less critical than flooded)

Table 1: Advantages and limitations of AGM.

 

<disclaimer> Not an expert, but did a lot of reading recently <disclaimer>

For the battery tender scenario, it doesn't matter. The reason why the manual recommend connecting the 4th connection (ie. negative lead to the ground/chassis) is to reduce the chance of the spark igniting the hydrogen gas from the battery causing an explosion. Apparently, car battery can emit hydrogen gas. Since the 4th connection (when you complete the circuit between the two battery) usually generate a spark, so it is recommended that you make the 4th connection to the chassis and far away from the battery terminal, so even if the battery does emit hydrogen gas, it would ignite the gas.

However, for the battery tender scenario, the final connection should be made at the SAE connector (the black plug at the other end of the red/black leads). The SAE connector shouldn't cause any spark due to the spark free technology that all battery tender features. Even if it does spark, it should be far away from the terminals, that it wouldn't ignite the gas.

Reference:
https://www.motorists.org/blog/safel...-dead-battery/

"Finally, connect the remaining black/negative jumper cable clamp to a “ground” on the car to be jump-started. A “ground” is a metallic/unpainted part of the engine or frame/chassis. An accessory bracket or large bolt usually works well. The reason for connecting the negative cable to ground rather than to the negative terminal of the dead battery is to minimize the chances of a spark near the battery, where there may be potentially explosive gasses. "

 

Another negative AGM characteristic is lower tolerance to heat. This is one of the reasons the battery is in a fan-cooled enclosure.

 

Maybe. But it's potentially being asked to do a ludicrous number of repetitive engine restarts and rapid charging cycles, each of which generates lots of heat. I think that's the main reason for the actively vented enclosure.

As for making the final electrical connection away from the battery ( @pcmcia ), it's almost never a problem except when it turns out to be a really big problem. Getting blasted in the face with shrapnel of plastic and lead mixed with sulfuric acid doesn't sound like something I want to do on my vacation. It happens. Why mess around?

 

"Maybe" works since we can't really know for sure. Stop/Start cycling is certainly a high demand requirement for a battery. So even though their lower internal resistance and higher charge efficiency result in significantly lower heat generation by AGM batteries -- another of their many inherent benefits -- stop/start could be a bigger factor. But there are likely various factors that caused engineers to actively mitigate heat.

I have to say that after looking more closely at this technology, it's fully clear that AGM is a superior way to make a battery. The benefits significantly outweigh the limitations -- certainly as compared to flooded cells. Look for AGM to become the new lead-acid normal. Until something better yet comes along.

 

These Schumacher SP1297 clamp clips wire are not lengthy enough for the suggested negative ground point. I removed the plastic engine cover and found a bolt that looked to be connected to the engine mount and used that for the negative connection.

Wanted to see what everyone was doing with their vehicle maintenance with the stay-at-home orders. This is how I worked around the short clamp clips length. The SP1297 doesn't have a dedicated AGM mode, so I just selected the standard mode (options are standard or Lithium ion, but no AGM option) since AGM is still a lead acid battery. It detected the battery, analyzed it and charged it. The battery started off at 70%, which the multimeter showed somewhere around 12.3 or 12.6 (I can't remember exactly) initially. When the charger was charging, the voltage displayed no more than 14.4v, which I believe that's what Schumacher Q&A indicated it would top out at.

From my experience 3 AMP / 4 AMP chargers are SLOW and could take HOURS (many many hours) to charge a battery (depending on how depleted it is and the health of the battery). But seems like the microprocessors in new chargers are very good (that's if your charging unit isn't a defect, etc). Mine took maybe total 6 hours, maybe more... I monitored it for an hour or two and then just left it to go do other things, but it wasn't switching over to maintain by the time I needed to sleep so I disconnected it as I didn't trust leaving it running overnight.

The next day, I reconnected it and allowed it to continue charging, this time I returned to see the "FULLY CHARGED AUTO MAINTAINING" message. Plus, the green LED light switched from solid to a slow pulsating green. I checked the voltage and it was back down to 12.4 or 12.6 (during charge it was 14.4).



Recently, I decided I wanted to find a charger that had an option for selecting AGM mode. I went to Harbor Freight and found this 4 AMP Viking charger. Looks VERY similar to the Schumacher SP1297 (and many other brands). However, the Viking 4 AMP clamp clip wires are much longer than the Schumacher 3 AMP. It is able to stretch out from the positive battery terminal to the Acura owner manuals suggested jumpstart contact point. I allowed it to analyze/recondition and charge the battery overnight this time and the next morning the Viking 4 AMP was in maintain mode. The only problem I seem to see with the Viking 4 AMP is that the clamps clips are SMALL. It doesn't really fit over the battery terminals used on the battery. I had to clamp the clips to the narrow point of the terminal, so I am not sure if that reduces the contact point or not. In any case, the charger still completed the charge and switched over to maintain mode just fine.

I'm also no expert with battery chargers, so I can't say for certain which is good or bad. However, I don't necessarily think you have to spend $100+ for a battery charger to keep a battery maintained. Maybe you would do better with an expensive battery charger if you needed to quick charge or jump start a car. The less expensive chargers seems to lack a feature or two that other less expensive chargers would have, vice versa. For example, Schumacher SP1297 does not offer AGM mode so yo have to just use Standard mode for your AGM battery. It also does not have the option to display the charge voltage level during charging. The Viking 4 AMP charger does not have the option to show the percentage of charge that the battery is at during charge. It just fluctuates the voltage level up and down in red display and finally switches over to a steady voltage number and green display when it is in maintain mode.

In summary, I think a 3 AMP or 4 AMP charger will take a long time to charge this AGM battery. I would recommend monitoring the initial hour or two hours when you first charge the battery and if all feels and looks well then allow it to complete for the long haul... depending how badly your battery needs to be refreshed. Since I bought the vehicle last May I put almost 2000 miles on it, so I don't drive it very often.

 

I don't think I would leave a budget charger hooked up in "maintain" mode. The risks could include damaging the battery by overcharging, or potentially even causing a car fire which could spread to an attached home. For that matter, I wouldn't use any charger in "maintain" mode, for the same reasons.

They may be fine for an occasional "top-off", but I would disconnect it between uses.

YMMV

 

I think you are over-analyzing, just charge the damn battery with a charger that is compatible with AGM batteries. The battery is $200, I am not going to obsess with getting top of the line charger.

 

I'll take that a step further... I don't have a charger and I don't intend to get one. I've been driving cars a long time. Have I ever gone to start the car and found a dead battery? Of course. Yes, the new cars have more drain, and the RDX has a "new fangled" battery (I can say that now that I am over 65!) I have road side assistance X2, and another car if I need it. I don't want to be constantly dealing with a charger and opening/closing the hood, plugging/unplugging, connecting/unconnecting all the time. I get in the car and drive. Like you said, "I'm not going to to obsess" over it.

For those who feel this is necessary, go for it. No worries.

 

Maybe when you’re over 65 you don’t need to worry about getting somewhere exactly on time....

 

Point taken, but uhm...I care for my 88 year old mom, who lives alone. When she calls, I go.

 

the only time I would consider plug in is when I know car will not be driven for 1 week or more. The choice is yours,

 

Let's agree that, as always, people are free to make whichever choice fits their personal needs and concerns. There's no right answer here.

 

I was just aiming for a joke. Clearly I missed. No offense meant.

 

None taken, it's all good!

 

TL;DR - Should battery make bubble sounds when being charged? I measured the voltage while being charged. It was 14.4 volt (absorption phase). I don't think bubbling is a good sign, so I disconnected the battery tender. And the battery was reading 12.78 volt. A full battery should be 12.6 v. Does that mean it's overcharged?

Long version:
My battery tender arrived from amazon. I got the Deltran Battery Tender 4amp ( ). I was testing it on my other vehicle (lexus IS250), which didn't start last week and required a jump start. It is a group size 24 battery. According to internet, it should be an 70-80 ampHour battery. Initially, it was reading 11.98 volt. I connected the battery tender and monitored it every hour or so.

Time Charging Voltage
0 hour 12.3 volt
1 hour 12.6 volt
2 hour 12.9 volt
3 hour 13.2 volt
4 hour 13.8 volt
5 hour 14.4 volt <--- The tender now say it is 80% charged. It should be in the absorption phase.

At 5th hour, the battery started to make bubbling sound. So I disconnected it. I measure across the battery terminal, it's at 12.78 volt and re-measured 15 min later, it's at 12.68 volt. Is this normal?

 

To be clear, this was a conventional flooded battery, not AGM? If so, I don't think that's unusual voltage. But like many of us here, I'm enrolled in Google Click University for my battery education. Not sure about the bubble sound, but did see this: (fwiw)

"It’s normal for lead-acid batteries to gently bubble in charging ranges (14-15.5 volts). Add distilled water to flooded batteries to replace the water lost."

If you look, you'll see LOTS of people ask this question...

 

Yes, this is a flooded battery. I saw a lot of people asking the same question, but it didn't give a consistent answer. Hence, asking the experts here.

 

Yeah, that's the biggest problem with Google Click University, the instructors can be inconsistent. But, the pattern of answers seem to concentrate on this being common, but also disconcerting. Make sure to avoid sparks, especially around a percolating battery being charged.

 

I have same exact charger, never heard any sounds, but did not listen closely

 

Have you used it on a conventional battery or just the RDX AGM?

 

Used on my wifes battery that is flooded, it was dead, so ended up replacing it. Then used it to charge new battery, which was full in 30min.
mostly using on rdx.