Duracell 8Ds, Sams Club, $199

[GrowleyMonster]

The sorta good news is after four semismart charge cycles at 20a to 14.7v with a neat little Stanley 6v-48v portable charger that I am starting to kinda like, one of the old 8Ds seems to be getting its second wind. I think I will go get the variac and rectifier setup from the old boat and give that battery a good hard equalizing. Maybe I can get another year or two of srrvice from it.The other old one shows no signs of life whatsoever so it is a core return. And another 8D to be moved. Urg.

I wish people would equalize their batteries. Owning a FLA deep cycle or multipurpose battery and never actually equalizing it is like owning a dog and never feeding it. Or owning a knife and never sharpening it. And then I get stuck with it.

I might add here that if a 12v FLA charger never goes up to 15.5v, it is NOT NOT NOT NOT equalizing. If the battery case never gets warm and you never hear electrolyte bubbling, it isn't getting equalized. I have only seen ONE so called smart charger that did a true equalizing charge, a cheap Chinese 48v unit I bought as a backup for the electric boat. Wanna know what I think? If it is safe to walk away and leave it unmonitored while equalizing, it isn't equalizing. Equalizing is supposed to get that electrolyte perking like a coffee pot and put all those sulfate deposits back into solution. It is not a gentle process. It is kind of a scary one. So don't believe the brochure until you see with your own eyes the voltage go to at least 2.55v per cell and hold there long enough to gas vigorously for a half hour. Now really, in our litigious corporate world how many charger manufacturers will sell you a charger that actually does this? Okay that's my rant for the day. I feel better now.

[john61ct]

Originally Posted by GrowleyMonster

Stanley 6v-48v portable charger

That being the GBCPRO?

Is that 2A rating only at 48V, so 6V gets up to 16A?

> And then I get stuck with it.
Why / how do you end up with them?

> If it is safe to walk away and leave it unmonitored while equalizing, it isn't equalizing.

Well so many different chemistries nowadays, plain FLA designed for deep cycling getting rarer in many markets outside NA, each maker publishes their own protocol for maintenance routines.

For AGM other than Lifeline, I had very aggressive know-it-alls pushing the line hard that the vendors still recommended "equalizing".

Turned out once we retrieved the detailed specs for these "recovery" et al procedures, none involved extended pushing of high voltages.

I pointed out then therefore by definition, these weren't instructions for Equalizing, and they reacted like I was being nit-picky 8-)

Anyway, my point is, to own the right gear to do proper equalizing while keeping the bank on the boat, is actually a pretty big ask, and some cruisers don't even have regular access to shore power.

And many (most?) just don't care about longevity that much, if they need to replace the bank every few years, so be it. . .

> the variac and rectifier setup

I'd really love to see a detailed Instructables-style howto on building one of those one day, written for complete noobs to component-level electronics and using easily sourced parts.

Lab-quality PSUs with variable voltage at high currents are very expensive and not compact nor salty-weather-resistant enough IMO to keep on a fulltime cruiser?

[GrowleyMonster]

Originally Posted by john61ct

That being the GBCPRO?

Is that 2A rating only at 48V, so 6V gets up to 16A?

> And then I get stuck with it.
Why / how do you end up with them?

> If it is safe to walk away and leave it unmonitored while equalizing, it isn't equalizing.

Well so many different chemistries nowadays, plain FLA designed for deep cycling getting rarer in many markets outside NA, each maker publishes their own protocol for maintenance routines.

For AGM other than Lifeline, I had very aggressive know-it-alls pushing the line hard that the vendors still recommended "equalizing".

Turned out once we retrieved the detailed specs for these "recovery" et al procedures, none involved extended pushing of high voltages.

I pointed out then therefore by definition, these weren't instructions for Equalizing, and they reacted like I was being nit-picky 8-)

Anyway, my point is, to own the right gear to do proper equalizing while keeping the bank on the boat, is actually a pretty big ask, and some cruisers don't even have regular access to shore power.

And many (most?) just don't care about longevity that much, if they need to replace the bank every few years, so be it. . .

> the variac and rectifier setup

I'd really love to see a detailed Instructables-style howto on building one of those one day, written for complete noobs to component-level electronics and using easily sourced parts.

Lab-quality PSUs with variable voltage at high currents are very expensive and not compact nor salty-weather-resistant enough IMO to keep on a fulltime cruiser?

Dont know charger model off the top of my head. I am at GF's house. Not living aboard currently. I dont remember what current at 48v charge TBH but 12v bulk charging current is 20a. until it gets to 14.6 or 14.7v and switches to constant voltage, falling current. At 3.8a, switches to float. Can't remember charging just a single 6v with that charger, specifically, but 20a for charging a 12v, for sure.







Well, the old 8Ds were in the boat when I bought it last year. The entire boat had been sorely neglected for quite a long time. One battery was completely unresponsive from the first time I looked at the boat. I have bought other boats with unmaintained batteries, including a pair of T105s that were less than two years old, already gone metric. Nobody even thinks about batteries. Nobody bothers to learn about them. And it's not rocket science.






Yes I agree there are a lot of different types but I was specifically referring to FLA. Never once mentioned gel, LiIon, LiFeP04, AGM, or any others. Hope nobody got the impression that you should equalize other sorts of batteries without mfgr recomendation. Your know it alls advising you on your AGMs apparently do not know what equalizing is, Probably mislead by fancy charger sales brochures using sloppy terminology. I hate to think what you would do to an AGM with a half hour or an hour at 15.5v. And I honestly don't know cause I have never owned AGMs.






I might have pics on my website of the variac and rectifier. It is just a full wave bridge rectifier module from an old stick welding machine. Nothing fancy. You can buy a new one for probably $30 with a suitable rating. Essentially all a full wave bridge rectifier is, is four diodes. Two series pairs of diodes. The cathode of both series pairs connects to the negative DC output. The anodes to the positive DC output. One AC leg goes to the junction between the diodes in one pair. The other leg, to the other pair. So, looking at one leg, the positive half of the cycle sends juice to a junction and since it is positive, it can only flow through one diode, to the positive DC output. The other leg, vice versa. On the other half of the cycle, same thing but the first leg is negative and current can only flow into the negative DC output. Opposite for the other AC leg. Most units that you buy will not be made up of four discrete diodes. It will be one monoblock unit with four terminals. Two will be AC input. Polarity doesn't matter. The other two will be + and - DC output. So what it is doing, is turning AC into somewhat ripply DC, for charging batteries or whatever.


The Variac is simply a variable tapped autotransformer. No electronics. An autotransformer is just a transformer with one set of windings. Assuming step-down, the primary is the full lentgh of the coil. The secondary is some percentage of the coil. There is no isolation. With a Variac, the tap for the secondary is adjustable by usually a large knob on top. Typically there will be an output voltmeter and sometimes an ammeter. They can be rated for as little as 250w, or as high as 5kw. "Variac" is actually a brand name. Like Kleenex or Frigidaire or Crescent Wrench. But everybody says "Variac".



So how it works is AC is input to the Variac. Output is user adjustable variable voltage AC to the rectifier. Rectifier turns it into DC. Wa Lah. User adjustable DC.



In use, you start out with the knob on zero. Monitor current and voltage as you adjust the Variac setting. For manual charging of FLA, pick an arbitrary bulk current. I try to use about C/10. Voltage will rise as battery charges. You will have to constantly check and adjust output to keep current constant. At the recommended absorption stage voltage, begin adjusting downward so that voltage stays constant. Check mfgr specs but around 14.4 to 14.7 seems to work pretty good. When current has fallen to about C\70 or so, the battery is about 98% or 99% charged. You can now float charge with voltage fixed to 13.6v to 13.8v using a smart charger or "battery maintainer" float charger. Or you can go ahead and equalize. To equalize, simply bring the charge voltage up to 62v or so for a 48v bank, 15.5v for a 12v battery. Hold the equalizing voltage long enough to perk those batteries for at least a half hour. Watch the battery temp. A warm case is okay. Very warm is still okay. HOT is not okay. Should be able to hear them bubbling. If they are spewing and barfing acid all over the place you got carried away LOL. If you don't hear bloop bloop sounds, you are not accomplishing anything.


Note that there is no isolation whatsoever. So there should be no connection to vessel's ground. Stray currents can induce paralysis in divers, causing them to drown. Not to mention it causes severe and rapid electrolysis. Batteries should be completely disconnected, actually, so you don't fry your electronics with the overvoltage. Hatches should be open. Hydrogen is lighter than air and will float away if you let it, but it doesn't hurt to have some mechanical ventilation as well. Doing this out in the cockpit or on the dock is even better. Take all normal and all paranoid precautions regarding electricity. If you have an isolation transformer you can use, that's a good thing, yeah. Consulting a friendly electrician is lets just say a very good idea if you are not absolutely sure of how everything goes together. Maybe I will do a youtube one of these days.



An electronic adjustable regulated power supply capable of sufficient current would indeed be kind of expensive, yeah. A Variac is a lot cheaper. Divide battery capacity at the 20 hour discharge rate by 10. Multiply that by equalization voltage. That is the maxwattage going into the batteries. Call it 380w for a single 8D. Give it some fudge factor. Over rated electrics last longer. So between 500w and a 1kw rated Variac for an 8D or smaller. I would lean toward the 1kw size, actually, due to losses. Price 1kw Variacs on fleabay or amazon and you will see that the cost is not prohibitive.



I actually used my Ryobi portable generator and the Variac as a range extender on my 48v electric boat. All manual, so I had to watch it closely, but I just wanted to prove the concept. My smart charger went schizo on me and wouldn't work off the generator with the propulsion motor operating. Variac didn't care. Variac just worked.