I found this and thought it's a good write up and should be read by all. Sorry don't remember where I found this so if its yours.. Thank You!
""" This was written by John Harries of Morgan's Cloud. Thanks a good write-up
Commonly Known Stuff
The first three rules are known by most live-aboard voyagers. But if they are-all you do, as most did prior to this project
, you will actually go through a lot of batteries, just like some did. Still, they bear repeating:
1. Don’t regularly discharge your batteries
over 50% of rated capacity.
Breaking this rule
occasionally is no big deal, but if you break it regularly be prepared to replace your batteries often… really often.
2. Charge your batteries back to at least 80%+
of capacity after every discharge cycle.
It’s also important that you do this sooner rather than later. On no account should batteries sit for more than a day or so in a “deeply discharged state”. Your typical AGM battery
banks will be close to this 80% status when the charge current
(amperage) starts to drop below the maximum that a well regulated alternator
or AC charger
can supply at the proper acceptance voltage (typically about 14.4 volts).
3. Charge your batteries to “100%” as often as you can.
Now we are getting to the hard stuff. Note: Many battery
manufacturers really want you to charge your batteries to 100% after every discharge. But that is simply not practical for the live-aboard voyagers because, although you can honor Rule
#2 in an hour or so with good charging equipment
, getting it to 100% typically takes another five to eight hours! Still, do it as often as you can—read on for how.
The New Stuff That is Saving Our Batteries
4. Make sure you have access to shore power for at least a week
after installing new batteries.
The reason here is, that batteries when shipped from the factory are not “fully finished” and it takes several discharges, followed by charges all the way to 100% even to bring them up to 100% capacity.
By the way, you do not need to “form” new batteries by fully discharging them and then recharging them as some “pundits” will tell you.
5. Don’t leave a shore power charger on for long periods.
There are some AC chargers that are smart enough not to damage your batteries by being left on for long periods, but very few. And that indictment includes most of those that claim to be three stage, all singing, all dancing, etc.
*More on how to tell how smart your charger really is, or more likely, is not.
6. Only buy batteries that can be equalized.
Remember rule #3 that none of us live-aboards can really follow? Regular equalization
is the next best thing.
7. Equalize your batteries once a month
or so. Like clockwork.
Make yourself a document chart in your maintenance
book, to record
all your events
so you have a good record
of what, when and where.
8. Install a “user-programmable alternator voltage regulator”
and reprogram it to actually fully charge your batteries.
For most of the live-aboard voyagers, or at least those like us who are way to0 cheap
to spend a lot of time in marinas
, the one and only time we will get to fully charge our batteries will be when doing a longer passage
under power. The bad news is that most alternator voltage regulators and yes even the expensive three stage ones, won’t do the job unless it’s reprogrammed.
9. Install a smart measurement system and use it.
Contrary to what many manufacturers will tell you, this stuff is generally anything but “fully automatic”. You need to skipper
your charging system, just like you skipper
your boat, and to do that you need to know what’s going on.
Minimum acceptable measurement capabilities:
A. Volts at the battery (requires a wire going to the battery positive post).
B. Amps going into the battery (requires a shunt).
C. Amp hours going in and out of the battery (requires a shunt).
10. Install an alternator regulator and AC charger(s) that have temperature measurement probes on the batteries.
The reason is that the proper voltage to charge and equalize batteries varies with temperature. This feature is particularly important for sealed batteries like wet, gell’s and AGMs.
11. Know how your batteries should be charged and how to tell they are full.
There is more inaccurate information about this out there than just about any area of cruising knowledge. And yes, to really understand the real facts, you’re going to need to read all that mind numbing detail that’s mentioned—sorry. But here is the short version:
1. Batteries like to be charged hard until they are fully charged.
2. Batteries are fully charged when the current (amps) they are accepting at their specified acceptance voltage—typically about 14.4 volts at 70f or (20c), but check with the manufacturer—has dropped to 1-2% of their total capacity measured in amp-hours. This is the only practical way to know that they are 100% charged.
3. At that point, and at that point only, the charge voltage should be dropped to the float level, typically about 13.4 volts.
Sure, there are a lot more things you can do to improve battery life: wind and solar power (if used correctly), and complex and expensive fully automated systems, to name just two.
But these eleven steps are all you really need to do to get a dramatically improved battery performance that we would all desire…
- With the previous two sets of house batteries that failed prematurely, we had done all the usual things that conventional wisdom dictates, including installing a three stage alternator regulator
and battery charger, and never discharging below 50%.
- This time we took a much more active approach including reprogramming our alternator regulator from the factory defaults, equalizing our batteries once a month where possible, and manually managing our shore-power and alternator charging.
This has been an interesting and rewarding process that we have drawn the following conclusions from:
** The standard wisdom about battery care is flawed and, on a sailboat that spends most of her time far from shore power, will result in premature failure.
** Most charging equipment
, including the fancy three-stage stuff, that claims to automatically take care of your batteries, won’t.
** There is a huge amount of absolute rubbish published and rumored about battery care, and the so called “professionals” are often the worst offenders in this regard.
** Most staff in boat yards are almost totally ignorant about proper battery care, but that does not stop them having opinions. However, there are shining exceptions to the last two points, but distressingly few.
** You don’t need a lot of highly expensive or complex gear
to take care of your batteries properly.
** If you follow the relatively simple “Eleven Steps to Better Battery Life” you will do fine.
** The single
most important of the eleven steps is monthly equalization
** Batteries that can’t be equalized have no place on a cruising sailboat far from shore-power.
** The testing seems to indicate that good AGM batteries that can be equalized can last just as long as liquid-filled, although the latter can probably take more abuse since fluid that has been lost
can be replaced.
Safe Winds.. Linda