AGM Battery maintenance/charging for dummies?

[dwh]

Ok, I understand that w/wet cell batteries voltage readings on case are common requiring a cleanup. I have a 100 lb 134 AH AGM battery that I'm getting voltage readings (7.0 volts max) on its case I'm guessing it vented gas while charging anyway I've never had to clean an AGM battery case is it even recommended, or?

Wait, what? Voltage readings on the CASE? You mean, the plastic outer shell of the battery?

Well...yea I guess it could have some stuff on the outside that is carrying current. It must, since the plastic doesn't carry current.

If that came from your sealed battery venting, then that might be from holding that battery at 14.4v for a long time.

Sealed batteries aren't supposed to vent at all under normal conditions. Once they do, they are screwed, because there's no way to replace the lost water. It's all downhill once that happens.

As for cleaning it - it's a plastic brick. As long as the lead terminals aren't corroded, and the pop-off valve isn't plugged (and there's no current carrying goo bridging the terminals), dirt doesn't matter. Clean it or not, your choice.


EDIT: Or maybe, you're getting a voltage reading due to a hairline crack. AGMs supposedly don't leak when they crack (I've never seen a cracked one myself), so um...could be.

 

[dwh]

NoCo just caused my BS detector to start twitching.


I went to their site to look more at the de-sulfation, and the link for "Learn More" takes me to a (stupid worthless posing hipster) video which doesn't give jack for information other than, "the 16v and 32v boost modes melt down the lead-sulfate and turn it back into active material again".

Well...um...sounds a bit like BS to me.

The reason why, is that what he described, is what happens in a normal battery under normal use. A bit of lead sulfate forms when the battery is discharged, and dissolves when the battery is recharged.


From what I understand, the problem is that eventually, it hardens into crystals and then it doesn't dissolve when the battery is recharged. "De-sulfators" are supposed to work by *breaking up* the crystals (have to break them, since they don't melt). They do that by *vibrating* the lead plates with an electrical pulse of a certain frequency.

Some, use a low freq (bass) pulse and some use a high freq (treble). I think Battery MINDer says they use a "patented full-sweep" - which I suppose means from low freq to high freq and back again. Sort of like grabbing the "tone" control on your radio and turning it back and forth.

If the crystals don't dissolve, then when you break them up, they fall to the bottom of the battery and just lay there. Or, with an AGM or GEL I guess they just sort of hang there, stuck in the material between the plates.

When you break the crystals off the lead plates, you regain some lost capacity, because now, more of the lead is exposed to the electrolyte instead of being coated in a layer of crystals. But I don't think you ever regain 100% because some of the sulfur has been turned into crystals and doesn't melt back into acid again.



Now, when you take the battery up to 16.5v as the NoCo says it does with its "Boost Mode" - that isn't the same as vibrating the plates to break up crystals.

I can see that it might cause some of the lead sulfate *which hasn't hardened into crystals yet* to dissolve...just as it does under normal charging.
16.5v probably does dissolve a bit more of that than 14.4v does.


Taking the battery up to 16.5v is more like what is called, "equalizing" than it is like what is called, "de-sulfation".

And equalizing, is something which almost all battery manufacturers recommend that you DO NOT DO to their sealed batteries. It can cause them to vent, and you don't want a sealed battery to vent. Ever.


I got a feeling that taking most sealed batteries up to 16.5v is (if they know you did it), going to void the warranty.

 

[Xterabl]

Thank you for your insights. I probably jumped the gun with this charger...but now I'm more or less all in.
Seems kind of silly. It's microprocessor-controlled so I would think the pulse desulfation would be a no brainer...so long as they took the time to learn that it is the proper way to do it.
Perhaps, they decided to "keep it simple" in those videos and it really is pulsing and they didn't want to confuse the common folk with such engineering minutiae. Pffft, I don't know. But I'm gonna try calling them to find out what the skinny is.

So, the latest on my experience with the Noco Genius is that, after the 3rd round of desulfation (each "round" is 2x iterations of the approximately 4-hour desulfation routine), the battery measured 12.6 V after ~16 hours removed from the charger. This compares to: 11V after 9 hours for the 1st round of desulfation; and 12V after 9 hours after the 2nd round of desulfation. So, in this basic no-load test, there appears to be incremental improvement. But for all I know the battery might be more or less ruined by now.
I am doing one more round and that will be it. Probably Wednesday, the 2nd stage of the test begins...actually driving the damn rig and seeing if the battery functions with anything close to normality.

 

[dwh]

I don't think it's a bad charger at all. Actually looks pretty decent to me. I don't think overcharging to 16.5v is actually de-sulfating so much as it is equalizing, and I'd probably avoid using that feature except on a flooded battery with caps so I could replace the lost water.

But other than that, I would bet it does a pretty good job of charging.

 

[FellowTraveler]

Wait, what? Voltage readings on the CASE? You mean, the plastic outer shell of the battery?

Well...yea I guess it could have some stuff on the outside that is carrying current. It must, since the plastic doesn't carry current.

If that came from your sealed battery venting, then that might be from holding that battery at 14.4v for a long time.

Sealed batteries aren't supposed to vent at all under normal conditions. Once they do, they are screwed, because there's no way to replace the lost water. It's all downhill once that happens.

As for cleaning it - it's a plastic brick. As long as the lead terminals aren't corroded, and the pop-off valve isn't plugged (and there's no current carrying goo bridging the terminals), dirt doesn't matter. Clean it or not, your choice.


EDIT: Or maybe, you're getting a voltage reading due to a hairline crack. AGMs supposedly don't leak when they crack (I've never seen a cracked one myself), so um...could be.

DWH, I cleaned the case a few times I now suspect a crack it looks more like a small scratch and that's where I'm getting highest reading meter connected to neg then move pos probe over case and when I get to the scratch voltage jumps. I'll post image later.

 

[Xterabl]

Well, I did call the technical support to inquire about how the 16.5V "boost" desulfation actually worked. The person definitely knew more about battery tech then the dude(s) in all the videos. I, on the other hand, could obviously not keep up with him. When I tried to parrot then line about pulsing for desulfation, he got slightly defensive and claimed that rapid pulsing isn't the only way to desulfate, but that very low current at higher voltage also works. He also claimed that the charger was outputting variable voltages during the desulfation process based on sensing, algorithms, etc.
At the end of it all, we basically concluded / agreed that I recovered some capacity but probably not a lot; and a test with heavy loading would be required in order to know the state of the battery with any reasonable amount of confidence.
Anyways, if someone more knowledgeable than me (ahem dwh) wants to have a chat, their open until 5PM east coast time and the number is 1-800-456-6626. I think you press 3 for tech support.

EDIT to add: Drove the rig to work & back; parked, and a few hours later measured the voltage and got 11.5V. Ugh. Disconnected battery negative from ground post and observed sparks between the two. And the ground post showed +11.5V relative to my battery negative...and electrical continuity between ground post/engine block and the battery positive...******??? This persisted for a minute or two, then it stopped. Seems like some shorting. Sheesh...forget the charger/desulfation stuff...seems I got some real work to do.

 

[dwh]

<Don Johnson Sonny Crockett voice>
Not me, bubba.
</end DJ SC v>

I think Martyn at Adventure Trailers said they are using the Genius chargers now...he knows about batteries and is...I guess...a dealer. Let him do it.

 

[Pathfinder]

I have had dozens of chargers over the years, and still use Battery Tenders for my motorcycles, but for Optima and gel cell batteries I use a CTEK-7002. It works better than any charger I have previously used, and brought back to life Optimas that I thought were gone for good!

http://smartercharger.com

 

[teotwaki]

I have had dozens of chargers over the years, and still use Battery Tenders for my motorcycles, but for Optima and gel cell batteries I use a CTEK-7002. It works better than any charger I have previously used, and brought back to life Optimas that I thought were gone for good!

http://smartercharger.com

I am lusting for a CTEK 250S dual to install in the truck and take care of my second deep cycle battery. If I can beat this eBay price I may go for it.

http://www.ebay.com/itm/CTEK-D250S-...Parts_Accessories&hash=item5d340255c1&vxp=mtr

 

[Xterabl]

Huh, comparing CTEK with Noco genius, Noco seems to win. For similar price point (actually Noco 10-15% cheaper), both offer similar features: microprocessor controlled, regular vs. cold/AGM charge modes, 13.6 supply modes...and actually, Noco has a higher voltage recovery mode (Noco "boost" mode is 16-16.5 V vs. CTEK 15.7V).
Noco seems to win, especially considering their 7.2A model is the same price (actually $6 cheaper) than CTEK's 7.0A model.

But, now that I look more closely, CTEK calls their cold/AGM charge mode "snowflake"...obviously this is a reason to choose them over the Noco's...LOL.

Also, teotwaki, at a glance,seems you could save some $$$ by going with Noco's GEN2 onboard charger:
http://www.amazon.com/NOCO-GEN2-On-Board-Battery-Charger/dp/B003JSJS5I

 

[teotwaki]

Also, teotwaki, at a glance,seems you could save some $$$ by going with Noco's GEN2 onboard charger:
http://www.amazon.com/NOCO-GEN2-On-Board-Battery-Charger/dp/B003JSJS5I

Ummm, that NOCO has an AC plug on it. How'z that gonna' work while I'm driving? :sombrero:

 

[Xterabl]

What, no inverter??? :smilies27
Yeah, sorry, I totally missed that "detail".
So this actually "goes between" the alternator and battery(ies) and properly adjusts charging? Yeah, OK, sound like a definite battery life extender.

 

[teotwaki]

What, no inverter??? :smilies27
Yeah, sorry, I totally missed that "detail".
So this actually "goes between" the alternator and battery(ies) and properly adjusts charging? Yeah, OK, sound like a definite battery life extender.

LOL! They are actually a full service charger and use a DC-DC converter to provide what is needed regardless of the alternator's output voltage. being a gadget geek makes them even more attractive but it is a shame to have to add a $200 gadget to keep a $200 AGM battery alive. :sombrero:

 

[dwh]

and actually, Noco has a higher voltage recovery mode (Noco "boost" mode is 16-16.5 V vs. CTEK 15.7V).

I'm not sure that's really a good selling point, considering that either 15.7v or 16.5v would exceed most manufacturer's specs for just about any VRLA battery.

Optima is one of the few who state that you can take their battery that high under certain circumstances:

"Rapid Recharge:
Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below 1 amp."

http://www.optimabatteries.com/product_support/charging.php

 

[Xterabl]

Interesting. Their "Genius" line still seems to be same price.

By the way, I just read more about the CTEK D250S mentioned in previous posts and learned it has auxiliary charging input i.e. from solar, and there is built in MPPT capability for that.
So, seems like a really nice feature set for just over $200, if you're currently looking to install 2nd battery + solar. Max input voltage is 22V, I'm not sure how that compares with most dedicated MPPTs.