Battery / Solar Question

[dwh]

The Odyssey procedure is dated March 2016. The Technical manual I have from them is dated September 2016. For completeness, also attached the procedure to recover a deeply discharged battery they emailed me along with the conditioning one.

The reason for getting the documents is one of my PC1400 is apparently weaker than the other (resting voltage 12.65 V vs. 12.8 V), so this is what they thought would help.

Okay, so the 2016 tech manual also doesn't mention that procedure. The "procedure to recover" is the same trick that Optima recommends for fooling a smart charger into firing up by jumping in a second battery with a higher voltage.

But finally, in the battery reconditioning doc, I see an answer as to why the deep discharge and heavy recharge procedure - desulphation.

So instead of doing an EQ, they set a do not exceed voltage of 15v and instead do this deep discharge and recharge with high amperage...hoping that will be enough to blow the sulphation off the plates.

I have seen some reports that it worked for some people, not so well for others.

Did it work on your low battery?

 

[dwh]

Each manufactuer lists the charging parameters.

If the life of the battery is important don't take specs from one type/brand and use the specs. on another.

Yea...not really. Lead-acid batteries are chemistry experiments in a plastic box - not precise electronic components. Pretty much what works on one will work on another.

There are a few outliers, such as the Odyssey TPPL Starved Electrolyte design. Since I happen to have the Odyssey Tech Manual open at the moment, let's see what it says...

"The message to be taken from this graph is clear – in deep cycling applications it is important to have the charge voltage set at 14.4 – 15.0V. A nominal setting of 14.7V is a good choice, as shown by the test results."

Which is pretty much the same for any "12v nominal" lead-acid battery. Except gelled electrolyte - higher voltages tend to break down the gelling agent.



The manual also says...



"CHARGING ODYSSEY® BATTERIES

Charging is a key factor in the proper use of a rechargeable battery. Inadequate or improper charging is a common cause of premature failure of rechargeable lead acid batteries. To properly charge your premium ODYSSEY® battery, EnerSys® has developed a special charge algorithm. It is designed to rapidly and safely charge these batteries.

Called the IUU profile (a constant current mode followed by two stages of constant voltage charge), Figure 6 shows it in a graphical format. No manual intervention is necessary with chargers having this profile.

Figure 6: Recommended three-step charge profile

If the charger has a timer, then it can switch from absorption mode to float mode when the current drops to 0.001C10 amps. If the current fails to drop to 0.001C10 amps, then the timer will force the transition to a float charge after no more than 8 hours. As an example, for a PC1200 battery, the threshold current should be 4mA. Another option is to let the battery stay in the absorption phase (14.7V or 2.45 VPC) for a fixed time, such as six to eight hours, then switch to the continuous float charge." (my bold)


So even the Odyssey "special charge profile" is actually an approximation. The only thing special about the Odyssey charge profile is it prefers (but does not require) 14.7v bulk and absorb. Which also happens to be exactly the same as what the Chinese AGMs in my camper van want...

 

[john61ct]

Of course we can do whatever we like with our banks once we own them.

Proper care in the first place is much better than **any** procedure or gadget claiming to "recover" or "recondition" them.

It is good advice to obtain and follow the mfg specs for that care.

Equalization is best seen as a regular maintenance routine, preventing damage not repairing it "after the horse got out"

And of course buying from known-good vendors who make their tech details and quality tech support readily available.

 

[DaveInDenver]

But finally, in the battery reconditioning doc, I see an answer as to why the deep discharge and heavy recharge procedure - desulphation.

So instead of doing an EQ, they set a do not exceed voltage of 15v and instead do this deep discharge and recharge with high amperage...hoping that will be enough to blow the sulphation off the plates.

Yeah, it's no big secret on why and how.

I have seen some reports that it worked for some people, not so well for others.

Did it work on your low battery?

As you'd expect, it didn't miraculously recover to >12.8 V but it hasn't gotten any worse in about 18 months either (they're about 5 years old). So not really a success but also may have stabilized it. But I haven't changed that I use the same DLS-45/IQ4 periodically to top them, so it's also possible it had already found it's plateau and the conditioning didn't do anything.

The two are sitting physically next to each other paralleled with a ML-ACR, so they are getting treated alike. It's the one on the left that settles lower. It's the starter/winch battery, the right one feeds the panel with the fridge and radios.

 

[burleyman]

Anecdotal only. No graphs, charts, internet links, or large, impressive-sounding engineeringeze. No proof, only conjecture and personal experience with some flooded batteries.

My solar power camping experience began only three years ago. Before investing in new, latest and greatest, I purchased two used 6v golf cart batteries from a supplier I've known for years. Best matched pair from a golf cart set, bought for core charge. No dead cells or exposed plates, matched lower voltages and lowered specific gravity. Main load a 12v compressor fridge.

My smart charger and a 15v dumb charger could not raise the specific gravity, even after long periods of charging.

Then I found a used Renogy 100 watt suitcase solar panel with a Renogy Viewstar PWM controller. Six days of sunlight raised the specific gravity to normal. At first I thought just more charging time.

One day, I noticed electrical noise in the audio of my dash cam. It was from the PWM solar controller. Rather high frequency pulses. I drug out the ancient oscilloscope, and it appears that when the controller connects to the battery, the battery sees solar panel voltage during that pulse. Since solar voltage rises as battery voltage increases during charging, the battery SEEMS to receive higher voltage pulses that a simple battery charger cannot produce. In my case, nearly 20vdc.

Maybe, possibly, perhaps, those pulses help clean plates?

Since then, with an extra 100 watt solar panel and a Chinese PWM controller with no timed equalization, but a manually set 15v charge limit, four other batteries' specific gravity levels improved versus a standard charger.

 

[john61ct]

The two are sitting physically next to each other paralleled with a ML-ACR, so they are getting treated alike. It's the one on the left that settles lower. It's the starter/winch battery, the right one feeds the panel with the fridge and radios

Well two batts only combined for charging and with different usage patterns will always age unevenly, nothing necessarily "wrong" there.

Just as an idea FFR, I'd combine both into a single bank for normal use in the higher SoC ranges, but

put an adjustable LVD in between to keep one as Reserve for cranking purposes.

Starter and winch can be on the same Load circuit behind a robust 1/2/B switch, so once SoC drops and the pair of batts are isolated from each other, you can choose how to feed those big loads.

Once voltage rises again, the automatically get joined. Basically the same function as the ML-ACR, but with lower (user selected) combine / isolate setpoints.

This gives greater capacity overall via Peukert, less voltage drop under load, more even and shallower discharging so more even lifetime and greater overall longevity.

 

[DaveInDenver]

Well two batts only combined for charging and with different usage patterns will always age unevenly, nothing necessarily "wrong" there.

That's the way I approached it. It wasn't a warranty question as such, since it's not really "failed". So the word is "curious" because both began life as expected but one seems to be aged faster and it's not the one I would have expected.

Just as an idea FFR, I'd combine both into a single bank for normal use in the higher SoC ranges, but

put an adjustable LVD in between to keep one as Reserve for cranking purposes.

Starter and winch can be on the same Load circuit behind a robust 1/2/B switch, so once SoC drops and the pair of batts are isolated from each other, you can choose how to feed those big loads.

Once voltage rises again, the automatically get joined. Basically the same function as the ML-ACR, but with lower (user selected) combine / isolate setpoints.

This gives greater capacity overall via Peukert, less voltage drop under load, more even and shallower discharging so more even lifetime and greater overall longevity.

I've considered re-arranging into a true primary/backup configuration, my electrical system is a mess of hastily done adds and last minute changes anyway.

There's enough unknowns not to draw any real conclusion. Same in-service age and types (PC1400) but not the same group (25 vs mirrored terminal 35) so probably not the same batch of materials or manufactured date. It's possible if the two batteries were reversed things would be different.

Perhaps the periodic deeper discharge is actually what Odysseys want and being constantly held near top wears them faster. Use as a fridge/radio battery is actually not all that different than that conditioning procedure. I don't take it fully to 10.0 V but it's been drawn down to the low to mid-11s a few times. I have a 130 amp alternator so when the aux battery gets latched in it'll easily get 0.4 * C10 (they are 65 A-hr), so it does mimic the conditioning steps now that I think about it.

 

[ITTOG]

Okay, so the 2016 tech manual also doesn't mention that procedure. The "procedure to recover" is the same trick that Optima recommends for fooling a smart charger into firing up by jumping in a second battery with a higher voltage.

But finally, in the battery reconditioning doc, I see an answer as to why the deep discharge and heavy recharge procedure - desulphation.

So instead of doing an EQ, they set a do not exceed voltage of 15v and instead do this deep discharge and recharge with high amperage...hoping that will be enough to blow the sulphation off the plates.

I have seen some reports that it worked for some people, not so well for others.

Did it work on your low battery?

You obviously have a lot of battery knowledge. What battery do you use for your solar system? What are the top three batteries you know of for this use case?

 

[dwh]

You obviously have a lot of battery knowledge. What battery do you use for your solar system? What are the top three batteries you know of for this use case?

A documentary filmmaker here on ExPo built a campervan to use for a year in the desert. After the project was done, he stripped out the van and put the stuff up for sale here on ExPo. The solar was a 300w Astroenergy PV module (36 Vmp), a Midnite Solar Kid charge controller and a pair of Chinese 4D size 200ah 12v AGM batteries.

The Kid sold fast, but months later he still had the PV and the batteries. My nephew was looking to build a backup for his computer network at home and was talking solar. I hooked him up with the guy from ExPo, who was local. He ended up buying the PV and the batteries.

He never ended up using the stuff and it sat around in his garage for 6 months. Then he took a job out of state and moved. He tried to give me the PV and batteries, but I wouldn't have it. Instead I paid him what he paid for the stuff.

Since the 40 y.o. ammonia fridge in my campervan was acting up, I went ahead and ordered a Victron charge controller, put that and the PV and batteries in the camper and got a 12v fridge.

Otherwise I still wouldn't have solar because I usually throw a parachute over the whole truck to make a giant awning, which would cover the solar.

Before all that, my method was buy cheap deep cycle batteries, drain way past 50%, recharge with a generator and replace the batteries every two years.

I view lead-acid batteries as disposable commodity items.

Sure you can buy expensive batteries, but then you have to baby them and worry about it...

But I don't.


What I have now is way overkill, but it was cheap so ******. After about a year the batteries are still in float by noon and rest at 12.9v. I rarely even have to think about it.

These guys around here like to recommend the 6v deep cycle golf cart traction batteries from Sam's Club. Fine with me. I don't see any reason to disagree with that - other than Walmart being a corrupt scumbag corp. that I don't ever buy from - but that's got nothing to do with the batteries being good enough to do the job.

 

[dwh]

The case in favor of abusing cheap batteries instead of babying good batteries goes like this...

You can buy 2 100ah batteries, drain no more than 50% and replace - on average for full-time use (retired, not weekender) - every four years.

Or you can buy one 100ah battery, drain 100% and replace - on average for full-timing - every two years.

Either way costs the same. Either way gets you a 100ah energy budget.

But the cheap method is half the weight.

 

[dwh]

Anecdotal only. No graphs, charts, internet links, or large, impressive-sounding engineeringeze. No proof, only conjecture and personal experience with some flooded batteries.

My solar power camping experience began only three years ago. Before investing in new, latest and greatest, I purchased two used 6v golf cart batteries from a supplier I've known for years. Best matched pair from a golf cart set, bought for core charge. No dead cells or exposed plates, matched lower voltages and lowered specific gravity. Main load a 12v compressor fridge.

My smart charger and a 15v dumb charger could not raise the specific gravity, even after long periods of charging.

Then I found a used Renogy 100 watt suitcase solar panel with a Renogy Viewstar PWM controller. Six days of sunlight raised the specific gravity to normal. At first I thought just more charging time.

One day, I noticed electrical noise in the audio of my dash cam. It was from the PWM solar controller. Rather high frequency pulses. I drug out the ancient oscilloscope, and it appears that when the controller connects to the battery, the battery sees solar panel voltage during that pulse. Since solar voltage rises as battery voltage increases during charging, the battery SEEMS to receive higher voltage pulses that a simple battery charger cannot produce. In my case, nearly 20vdc.

Yup. That's exactly right, and is one of the reasons why MPPT is not always superior to PWM.

Over on the NAWS forum (the oldest Internet solar forum), a decade ago the engineers there hashed out the MPPT vs. PWM question down to the hundredth of a decimal point and the eventual concensus was that for "12v nominal" PV of less than 200w, MPPT wasn't worth bothering with.

Maybe, possibly, perhaps, those pulses help clean plates?

It's been pretty widely accepted for many years that they do.

 

[luthj]

I was doing some reading on desulfating. To do it in a reasonable time frame (days instead of months) you need current pulses over 2C. These pulses can be really short, but the high current is much more effective than thousands of small low current pulses. This obviously can't be done with any equipment hooked up, as the voltage spikes would nuke sensitive electronics. Some guys over on hackaday designed a unit which can do this, the specs and diagrams were interesting.

https://hackaday.io/project/25741/instructions

The reason you can't just desulfate in an couple hours is that this type of charge current would cause rapid gassing, heating, and battery explosions if not pulsed.

Contrary to much published data, this paper found that for deeply cycled batteries (such as EV applications) high charge rates, pulsed charging, and high voltages were critical to long life. In addition they found that "dry out" of AGM type batteries is not a common failure issue? To prevent sulfation, they applied a measured overcharge on every cycle. A weekly equalize type charge may be called for in many applications. It needs to be carefully controlled in sealed batteries.

https://cdn.hackaday.io/files/257411101302944/Pulsechg & overcharge- good data.pdf

 

[luthj]

The problem with AC (charge then discharge). Is that you may end up just shuttling lead from one plate to the other. Will the improve crystal breakdown? I doubt it. There is some evidence that several deep charged followed by very high current recharges may help break up sulfate layers? Not enough data to know really.

 

[dwh]

Dry out was not a failure mode using their current interrupt (CI) finishing method. Trying to achieve the same thing with either constant current or constant voltage likely would pop the blowoff valve.

 

[dwh]

Also note that in the big battery pack they had a 50% battery failure rate.