Winter Battery Storage

[BunnyPlanet169]

In the interests of battery life, I've taken the 3 group 24 wet cells out of Bunny Planet and put them in my garage. I intend to trickle charge them over the winter. It's the first year I've done this - the batteries don't get strenuous use, and they're about 5 years old. I haven't killed them yet - more luck than good sense. I would top them off once and a while doing work on-board during the winter.

I only really did this because I suggested to my GF that we take the batteries out of her boat and charge them over the winter. You know, 'best practice' and all.... She takes good care of her boat.

So actually I have 5 batteries to deal with.

I have a 10A/2A Sears dumb charger. I have a single bank ProMariner smart charger (I don't know how smart). Not in the mood for more expense.

I could just put them all in parallel and trickle. I could charge individually with ProMariner, and then put them into a parallel trickle. Parallel trickle every week for a day. I don't want to switch cables every week, but I could... Probably don't want a live chemistry experiment on my bench all winter.

What are your thoughts?

[hanleyclifford]

I leave mine in the boat, charger on which holds them at 13.6 volts. This is the best charger I have ever owned. http://www.iotaengineering.com/dls30.htm

[Hymodyne]

reasonably mild Maryland winters and a small solar panel at the stern have kept the batteries charged.

James

[roadnsky]

...This is the best charger I have ever owned. http://www.iotaengineering.com/dls30.htm

I have that charger and don't use it anymore.
I used it for 3 years to keep my AGM healthy.
I found a Pro Mariner on eBay that does both of my AGM's now so I don't use the IOTA IQ4.

If someone wants it, PM me and let's talk...

[romantic comedy]

I would leave the batteries in the boat on a trickle charger.

I keep my batteries in the boat all summer long, when I dont sail in florida. I h ave a stat power 20 amp smart charger.

[Al Schober]

I've been charging my batteries fully in the late fall, then leaving them on the boat over the winter. So far so good. Used to bring them home but the darn things get heavier and heavier..
If you're going to leave them on a trickle charger, I'd want to monitor the voltage periodically to make sure it's reasonable. I'd expect something in the 13-13.5 range. I'd be worried about a 'wild charger' cooking things. I've also learned to turn off my fume sniffer when charging - I've had a couple of instances of the alarm going off while charging (followed by frantic phone calls).

[sastanley]

Bunny Planet, I bring my house batteries (2 GR29s) home and store them in the garage. Sometimes I think about charging them..the garage is 42°F in the winter. Last winter I didn't touch them and they were still 12.6v in March.

I keep the starting battery on board with a 3.2w solar panel that only gets direct sunlight about 4 hours/day in the winter, and that battery has been on the boat when I got it in 2008. That way I have at least one battery on board in the event I am there in the dark and need a light, or the bilge pump float switch trips, etc.

So far so good. Like Al, I stick my meter on it when I visit in the winter and she is always up above 12.6v.

I would not leave unattended batteries in freezing conditions, but if they have even a solar trickle on them, I think they are A-OK, & mine have survived.

[Administrator]

I leave mine in the boat, charger on which holds them at 13.6 volts. This is the best charger I have ever owned. http://www.iotaengineering.com/dls30.htm

+1

Bill

[TomG]

I think if I were going to try this, I would:

1. Fully charge each battery

2. Assuming similar battery chemistry (wet, gel, AGM), battery age, and similar SOC, I would parallel those two batteries and attach a charger to the ends of the circuit and do the same with the other two like this:



Since I use AGMs, I just leave mine on the boat over the winter. (I also have an ACR setup, but don't tell anyone! AGMs and ACRs! Oh the horror!)

[BunnyPlanet169]

All:

Thanks - If you have room in your barn, Hanley, I'll tuck BP in with you....

Tom - that about what I was thinking also. I'll charge each individually to nominal full SOC, and then string them together for trickling...

I would normally keep them in the boat, but I'm going to move some electrical things this winter while the engine is out.

AND, I don't want to leave a long extension cord in the driveway. I snow blow with a tractor, and that's about the last thing I want to wrap up in the auger.

[Sea Haven]

Personally, as a belt and suspenders guy, I've always removed my battery's during winter and used an automatic charger rotating once a week. Not fun removing them on the hard, but worth it for peace of mind.

3 years ago a sign went up in my Boat Yard

ABSOLUTELY NO UNATTENDED ELECTRICAL CORDS SHALL REMAIN PLUGGED IN FOR BATTERY CHARGING OR OTHER PURPOSES.

What can I say? "LIABILITY"

This is Don Casey's recommendation.....
Protect batteries
If wet-cell batteries are allowed to discharge the electrolyte becomes pure water, which will freeze and ruin the battery. On small boats, bring batteries to a fully charged condition, then remove them from the boat and store in a dry, cool (not frigid) location. Wash and thoroughly dry the tops of stored batteries to reduce the potential for self-discharge. Do not leave stored batteries connected to a portable charger. Unless the charger turns off completely--few do--the batteries will suffer damage. However, stored batteries should be brought to full charge once a month, so post yourself a reminder.
If the batteries will be stored aboard because they are too heavy for convenient removal, they must be maintained in a full charge condition all winter. This requires a charger with a "float" stage and power connection. In lieu of an unattended power connection, a solar panel might be employed to counter self discharge.

Finally, from BoatUS and Seaworthy:Tip # 7: Battery Chargers in Winter


I guess I have two points here....
1-It's a free country...until you're sued.
2-"Murphy's law" is a clear and present danger in my life.

"Sub" Ed
SY Sea Haven
'78 Pearson 323

[gregsails]

I remove mine and bring them home and put them in the basement.Put the trickel charge on them around Feb.and they are good to go. I ll top up the day before launch.They have never failed me.In fact, I'm going to replace 1 this year because it is 8 years old, but still holds 13.4 volts

[sastanley]

TomG, how does that work? I have my house bank wired in parallel like your diagram, but I have my solar charger on the (+) & (-) post of the same battery.

I am wondering if the diagram you show confuses the charger about 12v, seeing twelve 2.1v cells, or am I confused..

Please enlighten me.

[edwardc]

The purpose of cross-connecting a charging source to two different poles on different batteries in a paralleled bank is to even out the (tiny) voltage drops across the interconnecting wires.

If both leads of the charger are connected to one battery, and the second battery is connected to the first with a set of wires, the second battery sees a slightly lower charging voltage than the first, due to the voltage drop across the interconnecting wires. Although this differance is small, it can be significant, especially at high charging currents. The two batteries will charge slightly unevenly.

If, on the other hand, the + from the charger is connected to the + on one of the paralleled batteries, and the - is connected to the - terminal on the other paralleled battery, each battery will see a charging voltage that is diminished by the drop across only one of the interconnect wires. If the two interconnecting wires are of equal gauge and length, these two drops should be equal, and the two batteries will see equal charging voltage and charge evenly.

A friend of mine actually did experiments on this, and recorded that, in the first case (non-cross connected charger), the farthest battery always got slightly overcharged, as evidenced by the fact that it lost fluid level a little more quickly than the other due to more boil-off. When he restrapped it cross-connected, the two batteries maintained equal fluid levels.

[sastanley]

Ok...well that explains that. Thanks, Ed.

For the record, My batteries are 6" apart and have a roughly 10" long 4# cable between them, wiring them in parallel.

The farther battery will get slightly less charge makes sense given the scenario you presented, but it still does not compute to me how you can wire a charger to (+) on battery #1 and to (-) on battery #2 wired in parallel..but I trust you guys here.

I'd still like to understand it.