Batteries, batteries everywhere.

[Levitation]

This is a cross post of some of my babblings on another forum.

Became involved with batteries at a professional level when I was 19. Now these were fleets of 4000 pound monsters, but they were still just batteries.
So, I have opinions - hoo boy, do I.
My comments here are aimed at the typical pleasure boat battery banks consisting of a few 6 volt or 12 volt batteries.
Large battery banks as found in commercial vessels are a different critter - but not by much.
Anyway, here I am speaking to golf cart batteries or the typical Group 21 through 31 that we see in our vessels.

Lost in the fumes from the bubbling batteries is the fact that the float voltage is too high - way too high.
At 13.2 to 13.6 volts the cells are still bubbling. Leave the battery on float long enough and it will run out of water.
The float voltage should not be higher than 12.75-12.80 volts.(This is called a battery maintainer)
Your method of cycling the charger once a week is a vast improvement over leaving them at float voltage 24/7.

But (there is always a but) with these 3 stage marine chargers intermittent charge cycling causes the evil equalizing charge to raise its head.
Every time the marine chargers I have used go into a charge cycle, they finish it off with an equalizing charge - 1 to 4 hours of too much voltage into a fully charged battery causing it to bubble like cheap champagne. So, if you do something to pull the battery down in the morning and cycle the charger on, the charger will recharge and then go through 4 hours of bubbling. If you do something in the afternoon to again pull the battery down enough to trip the charger on, guess what? Another additional 4 hours of bubbling.

And there goes your water.

Now, there is a need for an equalizing charge, perhaps once every 25 to 50 charging cycles - or twice a year on lightly used batteries. Not every time.
I have had this discussion with three well known manufacturers of marine chargers and I might as well have talked to the wall. The equalizing charge is a religion for them.

So, what's a fella to do?
Well, for batteries left on float in the off season, using a timer to turn the charger on once a week is excellent.
Even better is to limit the time the charger is on so that it is not going through a 4 hour equalizing charge every time it cycles and bubbling the batteries.
An hour of charge would be more than enough since idle batteries do not drop appreciably and will recharge within minutes. Consider the remainder of that hour to be your equalizing charge.
Another method would be to clip a battery maintainer across the main terminals and leave it on - do not bother with turning on the charger if you do this.

Desulphators I do not have an opinion on. I have actually built a couple of them and fooled around with trying to recover weak batteries. I do not use them any more. My suspicion is that a stored battery on a battery maintainer has more than enough electrons jiggling back and forth on the surface of the plates to discourage growth of sulphate crystals. The desulphators probably do no harm. ymmv, sar, bni


denny / k8do

 

[trailertrawlerkismet]

Thanks Denny for your thoughts and suggestions, but you've made me think of a question you may know the answer to. What are your thoughts on disabling ones boat batteries completely during winter storage therefore having no charge available to them for 6 months? And does the answer make a difference if the batteries are gel type or not? Just curious if this is a viable option rather then worrying about overcharging the batteries and cooking them.

Jim

 

[knotflying]

Jim,
I usually take my batteries out of the boat during a winter layover. This gives me the time to clean all terminals and check the water levels and top off if necessary. I join all the batteries together in parallel and then check the voltage every couple of weeks. I will then throw a trickle charge on to top them off. So far, so good.
Now stop reading tugnuts and get back to your kitchen renovation!

Mike

 

[walldog]

Thanks Denny for your thoughts and suggestions, but you've made me think of a question you may know the answer to. What are your thoughts on disabling ones boat batteries completely during winter storage therefore having no charge available to them for 6 months? And does the answer make a difference if the batteries are gel type or not? Just curious if this is a viable option rather then worrying about overcharging the batteries and cooking them.

Jim

I look for Denny's answer to your question. Last summer we turned everything off in the motorhome while we were in the Northwest. I turned all the battery disconnects off and unplugged everything. It was a disaster. I am just now getting everything back operational. I still will need to replace the 8 six volt golf cart house batteries. I was trying to keep them from running dry while I was not here to tend them. We will do something different this year. In the boat I have been religious about not letting the battery voltage drop below 60% charge or so. I have a chart that I will be taping to the wall by the solar meter control.

 

[rt11002003]

Great comments! 😀 I've learned a lot of what Denny said from experience with motorcycle and boat batteries. I didn't know about the four hour equalizing cycle. 😱 Tried to figure out what was causing excessive water loss in my RF-246. Finally shut off the expensive, complex, high technology charger and ran it every couple of weeks. But, I've probably let it run too long. Next time, I'll use the one hour rule.

With motorcycle batteries, both gel and wet cell, I've always used battery maintainers. Never kept them hooked up all the time, just hooked up the changers enough to keep the voltage up.

One other thought; I've always fully charged all my batteries before installing and using them, including automobile batteries. Can't remember why.

Thanks!

gene

 

[Levitation]

OK, you guys stole my thunder - good analysis - and I'll just slide over here into the shadows and be quiet now - Bartender I'll have another, a double, and keep em coming. They don't need me anymore (sob) :mrgreen:

On the motor home disaster I suspect that turning off the breakers left other things still energized.
For example, on the R25 the bilge pumps are still hot with the switches off as is the CO detector. Both pull resting currents of less than a milliamp each. So in your motor home the only sure way is to take the negative battery clamps off of the battery posts so that the batteries are open circuited.
The brake sensor on my boat trailer pulls down the battery for the electric winch - wench - whatever - so I have to keep it on a maintainer. Learned that the hard way, and one $80 battery later I am waay smarter than I was.

Batteries in good condition will sit open circuit for 6 months with no problem (there will be minor sulphating from being idle)
An older battery that has grown some sulphate crystals may self discharge slowly due to a high resistance internal short.
I bought a combine that had set on the dealers back lot for 2 years with no attention to the batteries, and it cranked over and started. The salesman admitted they had installed new batteries to start it and bring it to the dealership after the farmer traded it for a newer machine, then forgot to remove the new batteries - which they normally do.
Even though the batteries seemed OK after that abuse they failed the following year - right during harvest, of course..

Always do a charge on a new battery before turning the key for the first time. Yes, there is energy in the plates from the wham-bam-thank-you-ma'am activating process at the factory (there is more to it than pouring acid on top of some lead) but the plates still need a nice gentle charge before being asked to slam out 800 amperes on that first start or be asked to discharge below 12 volts for the first time.
Do a google on manufacturing batteries - fascinating dance between high technology and brute force.

The main difference between gel and flooded batteries is that gel cannot keep up with recombining the hydrogen and oxygen that gets split during the charging process (bubbling) if they are charged at flooded battery voltages and will pressurize and blow out the vent seal (leak).
Flooded will tolerate higher currents than a gel at the cost of lost water. Gel's real claim to fame is not leaking. I don't use gels.

AGM also need a bit lower charge rate and the charge voltage is about 0.3 volts lower than a flooded and the float is about 0.2 volts lower than a flooded (still too high)

Here is a rough guide:
Flooded charge 14.7v float 13.5v
AGM charge 14.4v float 13.3v
Gel charge 14.1v float 13.8v (yes, gels are a different critter)

Notice that by setting your charger to AGM with your flooded batteries you get a slightly longer charging time (good for the battery unless you are in a hurry) and a lower float voltage (all good) hint hint

OK I have babbled enough on this.

 

[Todd]

If you have batteries connected together it is a good idea to separate them during storage. Charge them and then disconnect the wires. This will allow you to identify a single bad battery. Check the voltage after about a month, if one is significantly lower you may consider replacing that battery before the boating season starts. If left connected together the bad cell will discharge all the others connected to it over time.

 

[NewMoon]

FWIW, my over-winter battery charging is with a Heart Freedom 10 inverter/charger and a Link 2000 inverter control, charging regulator, and battery monitor. Batteries are all AGM, 2 Deka g31's for the house bank, and 2 g34's for the big diesel's starter bank. My last set of house batts lasted 11 summers - must have been at least 600-700 discharge cycles. I replaced them with another pair of the same last spring.

I don't turn off or disconnect the batts over the winter, but rather leave the boat plugged into 110V power with charging on. The Link 2000 has an multi-stage intelligent charging program, settable to various battery types. It does not seem to do any equalizing, at least for my AGM's. It does run a float charge from time to time, when it sees the need, and keeps them in fine shape. Since they are AGM and do not self-discharge as rapidly as flooded batts, I could just leave them turned off and they'd be fine 6 months later.

We anchor about 2/3 of the time all summer in SE AK. We have no generator, and only sometimes plug into shore power. Charging underway is done by a Balmar 75A alternator and Balmar MaxCharge regulator, also set for AGM's.

The g34 AGM starters in our Cummins diesel truck sit all summer while I'm out cruising, and turn over that big diesel easily after 3 months or so. Optimas in the truck lasted 10 years. Deka g34 AGM's now.

 

[commander bill]

I agree completely with New Moon. My OEM batterys died after 2 years due to overcharging by the OEM "Smart Charger". I had originally left the charger "ON" 24/7. Batteries needed water about every 3 months or more often in hot weather. I replaced all 4 batteries and now run charger only about 36 hours out of every 2 weeks. Boat stays in covered slip so very little water to pump out of bilge. I suspect most voltage losses are due to solid state bilge level sensors & various memory circuits which are mostly on the on house batteries.

After 3 years since battery replacement & using above charging method the house batteries will still be above 75% and engine/thruster batteries near 100% capacity prior to each 2 week charging period. Also I need only add water about once/year. One of the things I notted about the OEM Proline charger is that it is supposed to be a "Smart Charger" but it only has monitoring ckt for 1 of 3 battery systems which means it makes it decisions based on that single battery voltage and the other 2 battery systems just get whatever output charger decides to send.

 

[LADYBUG TOO]

Denny,

A heart felt thanks for your post. I have observed the impacts of leaving the charger on too long. I just left the shore power connected and the ProMariner that came with my R-29 on. I damn near ruined the batteries by getting the electrolyte levels too low. I supervise my charge cycles now and I don't let the float level stay on. I was guessing but your post will help me improve my battery maintenance plan. I have to do my own maintenance or I would never be able to keep Ladybug, Too. I just could not justify the cost.

Pat and Carolyn, Ladybug, Too

 

[knotflying]

Looking for a clarification here. I read several times in this thread about not leaving the charger on, but are we talking about when the boat is unoccupied or even when you are using it at a slip. My experience has been that after over night on the hook my house batteries go down to about 70% (12.32 V) since i am using the refrigerator as well as a c-pap. I would think that by not leaving the charger on even when occupied at the slip and having a continual discharge and then charge would be worse for the batteries. Any comments?

 

[HRowland]

The concern is chargers that have a too high float voltage and constantly boil the batteries. The ProMariner ProNauticP 1220 charger that Ranger installed in my R27 has the following feature:

FLOAT MODE OPERATION - When charger is in Float Mode for more then 72 hours and providing less then 5 amps output the unit will go into standby (lowering the float voltage). If amperage is increased above 6 amps for more then 2 minutes charger will come out of standby. When charger is in Float Mode or Standby Mode for 21 days, charger will initiate battery Health Mode and fully recharge batteries ensuring they are ready to go.

It has 12 charge profiles including a custom profile. In the custom profile you can configure the charge and float voltages. I cannot comment on electrolyte loss, the batteries Ranger installed are maintenance free (flooded, not AGM) so I cannot check the level. They are still working well after two years. I leave the charger powered constantly while docked, which is most of the time from early April through late October.

Howard