Understanding Lead-Acid Battery Life

[john61ct]

There are "semiflex" panels designed with non-slip to be walked on.

Quality ones are 10x more expensive than mass market.

And I don't recommend them anyway, rigid framed last much longer.

[john61ct]

Originally Posted by sailcrazy

Please ID what negative reports and documents you are referring to regarding the PulseTech unit

Many reports by long term respected members like Maine Sail, here and other forums.

https://goo.gl/UAM6FU

No one says they do harm, but none of the hundreds of such products have been shown to deliver on their claims.

So by default snake oil, unless credibly proven otherwise.

Proper care and regular equalizing as per mfg specs would make them redundant even if they did work.

[sailcrazy]

john61ct...Thanks for the "link". But, as I wrote, please ID these negative reports-specifically, so they can be looked up and read. The generalized inuendos are everywhere.....I'm looking for SPECIFIC reports that can be pulled up. And since 2 contributors talked to them, I merely asked for the specifics!

[john61ct]

I'm looking for specific reports verifying their extraordinary claims.

Or those of any of the others, each has different output patterns, yet they all claim amazing results.

By default should be treated with skepticism.

Let me know if you find credible evidence.

As I said, they seem to at least do no harm.

[GrowleyMonster]

While AC is available from shore power or generator, one of the best things you can do to extend FLA battery lifespan is to equalize once in a while. SOME few "smart" chargers can do this but honestly I haven't seen one that does a good job yet. To do it right, battery temp must be monitored and both voltage and duration need to be adjustable. I prefer a fully manual method, using a large Variac to reduce AC voltage/current and a rectifier from an old arc welding machine mounted on a large heat sink to convert the AC to a ripply but still acceptable DC for the batteries. Proper metering is important, and careful monitoring is needed to avoid damaging the batteries or worse. Careful wiring practices, too. But you have total flexibility. My 48v bank I can equalize as a unit, with a 62VDC charge. Or I can do single 6V batteries one at a time. Whatever. Or help a neighbor with his 12V battery. Equalizing and agitating a "dead" battery can often bring it back to usefulness for another year. Agitation works great when poor maintenance has allowed electrolyte levels to get too low. Fill until the plates are JUST covered, apply a normal bulk charging current, put on your goggles and face shield and PVC gear, put the cell caps back on and rock it back and forth for a few minutes over a stick of wood. You would think that this would never be necessary in a boat, but a lot of dock queens don't see much rocking and rolling. Equalizing is something that well maintained batteries ought to get twice a year, and frequent PSOC victims should get monthly or bimonthly. Excessive equalizing can actually reduce the life of a battery due to plate material loss. Once you have significantly raised the temp of the case and observed vigorous gassing for a half hour you can let them rest for 24hrs and do your SG and voltage checks. Well equalized batteries will as the term suggests have cell voltages and SG very close to one another. Yes, you can check voltage of individual cells in a multicell battery. Just dip the probe right into the electrolyte briefly, just long enough for a reading, wipe it off and done. I prefer gold plated test leads, out of probably an overabundance of caution regarding electrolyte contamination from metals dissolved by the acid.


If you have a bank of several monoblock batteries, you should shift them or rotate them around at the same time you equalize. The different length of the electrical charge/discharge path can have one battery working harder than another. Intelligent layout of battery cables can minimize this but I still like to rotate, whether the multi bank is parallel, series, or series/parallel. On that subtopic I will state that while I will not participate in an argument about it, I personally do prefer not to wire batteries in parallel unless absolutely necessary. I would rather have batteries big enough to do the job, for the amp hours. I am of course not picky about connecting in series if the connections are good and the cables are low loss. But frequently rotating the batteries around will help mitigate the disadvantages posed by parallel wiring.


I am often disappointed when I am asked to check out someone's batteries and find that the electrolyte levels are low, the battery tops are filthy, connections are loose and corroded, and a totally unsuitable charger is used for a bank, and the owner can't understand why his 10 month old bank is underperforming. And I am not even a professional service tech, just a helpful neighbor that word of mouth says knows a bit about batteries for having an electric boat. My batteries are over four years old, and just about the cheapest deep cycle batteries you can buy, but still doing their job. Proper monitoring and maintenance are everything. Poor charging practices while cruising or anchored can shorten battery life but good maintenance and at least occasional full charges, multi day float charges, and scheduled equalization can help a lot. Even with the cheapest type of deep cycle battery, the humble GC2 golf cart battery. "Nice" batteries probably even more so.


I would love to have a boat big enough to carry a couple dozen big single cell telephone exchange batteries for a 48v bank. Actually, we are looking at a 44' Bruce Roberts with a nearly bare interior right now, just waiting for us to customize, and that might be my opportunity. But I digress. The higher the construction quality and higher electrolyte/plate mass density and thicker the plates, the more you can help the batteries live longer through good maintenance practices. More room under and between the plates means that more material can be sloughed off the plates before you get irreversibly shorted cells.


Keep in mind that FLA batteries properly used are extremely unlikely to reach out and bite you without you making some mistake. However, if you are careless there are a lot of ways a big FLA can injure you. If your batteries do not have trustworthy handles, get or make some. Golf cart style batteries often do not have handles but you can get very good rubber strap handles with hooks that connect to lugs on top of the case. In the case of 8D or L16 or other large heavy batteries, check the handles carefully and watch that you don't pinch or crush a finger or toe. Goggles are great. So is a full face shield. Both at the same time, even better. A tiny splash of electrolyte in the eye, and you could lose or seriously impair vision in that eye. At best, it burns like the fires of hell concentrated into a pinpoint of chemical fury. Don't ask me how I know. I used to be stupider than I am now. A splash of acid on your skin won't immediately melt you like the witch in Wizard of Oz. You have a couple seconds to get it rinsed off. But that's all you got, so you better have a charged garden hose at the ready whenever you mess with batteries. A gallon jug of water and baking soda solution is nice, too, in addition to the hose. PVC slickers make pretty good protective clothing. Offgassing of hydrogen and oxygen is a very real hazard, and smoking or other open flames or lights or electrical sparks can ignite and explode stuff, if gasses are allowed to accumulate. Remember that hydrogen is significantly lighter than air, and will happily float free and self dilute if allowed to do so. Forced ventilation is needed if your batteries are serviced in an enclosed space though. Even in the open, if they are bubbling you better not be smoking when you peer into the cells. Electrical shock and burns can suck, too. Take off that metal watchband. Be careful with metal tools. Don't be a conductor... only be touching one terminal and remember that in most DC systems, any grounded object is a negative terminal so watch what you lean against. Charging systems, especially homebrew manual systems like the Variac/Rectifier setup I mentioned earlier, are potential killers if you are careless or if you don't wire and insulate and/or enclose connections properly. If you aren't sure, don't do it.

[David B]

Originally Posted by Dockhead

We recently discussed the failure modes of lead-acid batteries in a tremendously popular, but unfortunately acrimonious thread. Despite the minority of participants who disrupted the tone of the thread, however, I think many of us learned a lot from discussing how sulphation works and how lead-acid batteries die.


I continue reading and thinking about these issues, and recently learned that there is an actual test regime which seems to be quite representative of how some of us use our batteries -- IEC 61427 -- which contains a great deal of PSOC cycling, just like what we do.


This makes really interesting reading: https://www.trojanbattery.com/pdf/RE...7_Standard.pdf


and from this:


https://www.trojanbattery.com/pdf/RE...27_Premium.pdf


I find it quite believable that these heavy duty L16 batteries will really last more than 1000 cycles in realistic off-grid cruising.



It's the first time I've seen a cycle life rating which I thought could be applied to what we do. I know that my own Trojan batteries (27TMX) are rated for 600 cycles @ 50% DOD, but in my usage, which includes PSOC cycling, they don't give even half of that.

Thanks for posting. I will read through when I get a chance.

For what it is worth, our bow thruster batteries are over 7 years old now and still good. The service and engine start batts were killed due to a wiring issue so are only a couple of years old.

Also, just replaced the battery in our MB Vito van - original battery so 11 years old. Varta brand, and going by that life, replaced with another Varta !

FLA batteries can last a long time if looked after, and still seem best value for money if you have the space and weight capacity.

[Dockhead]

Originally Posted by David B

Thanks for posting. I will read through when I get a chance.

For what it is worth, our bow thruster batteries are over 7 years old now and still good. The service and engine start batts were killed due to a wiring issue so are only a couple of years old.

Also, just replaced the battery in our MB Vito van - original battery so 11 years old. Varta brand, and going by that life, replaced with another Varta !

FLA batteries can last a long time if looked after, and still seem best value for money if you have the space and weight capacity.

FLA batteries are cheap, they work, and there is a whole infrastructure of equipment and knowledge to make them work. There's a lot to be said for them. I'm still using them myself.


But engine start and bow thruster batts are not deep cycled -- so no challenge for lead acid batteries. Cheap is good there.


As to whether FLA batteries are "best value for money" or not -- that really depends on a lot of things. If you don't cycle your batteries much, then that's definitely true. But if you are off grid for extended periods of time, cycling the batteries on a daily basis much of the year, the economics might be very different.



If you are not including the cost of conversion into the calculation, it looks to me like LiFePo4 (real ones, bare cells with external BMS, not pre-packaged ones made to fit where lead acids used to be) starts to pay for itself quite quickly. The cells themselves, where I am, are only about double the cost of even medium quality lead batteries, per unit of real capacity, so vastly cheaper per cycle than lead. Relatively few people can actually use that cycle life, so that's not for everyone.


When you factor conversion cost back into, that can change the picture. However: (1) the conversion is forever; you don't buy it again everytime you buy batteries; (2) if you're building a new boat or fundamentally rewiring an old one, it might not matter.

[john61ct]

Originally Posted by rgleason

If these batteries are left in place over winter where it can get down to -10F + wind chill, what can be done if no shore power lines are allowed to the boats by the yard?

I suppose they are left at 50% SoC and then they have to be checked every week (not possible)

Saw you bring this up in the LTO thread.

Look at the low temp specs for your cells, one is for use discharging, another much higher is for charging, a third the lowest is for storage isolated.

No need to pull them off the boat, if the ambient won't reach the storage spec temp, just keep them on board isolated. No need to inspect.

This issue is not worth experimenting with a completely different lithium chemistry.

[sailinglegend]

Originally Posted by sailcrazy

StuM and kmacdonald.....Please ID what negative reports and documents you are referring to regarding the PulseTech unit. .....,. And while I can't point to specific proof that the PulseTech units have extended our battery bank life, they certainly have not hurt it either......

I would forget the negative reports but look for the positive reports.

As far as I know there have been no recommendations by any reputable battery manufacturer that you should use any of these kind of units to extend your battery life. If you follow their standard charging recommendations - and information from these forums - then your batteries will last longer.

If there was a magic cure from a magic device to extend battery life then everyone would be recommending them - and a lot of well known manufacturers would be making them or distributing them.