How long can I safely trickle charge?

Grant Brown

Grant Brown

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Mar 13, 2004
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390
1989 Merc 70hp on 16ft Glastron.
I have some sort of slow drain on my battery that I wasn't able to get time to fix last season. If I leave the boat wi the battery hooked up for a week or so the battery goes flat and won't start the boat. If I'm using it daily it stays charges and no problem.
If I'm concerned about the charge on the battery and plan to use the boat the next day, I'd like to ensure the battery has a full charge - just in case the motor is hard starting for some reason.
Could I safely trickle charge the battery at 2 amps overnight with no worry? What is the maximum time? My charger is not automatic shut off and I'd hate to cook a good battery.

Grant
 
Boatist

Boatist

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Apr 22, 2002
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4,552
Re: How long can I safely trickle charge?

I can not answer your question. Really depends on a lot of things, how much drain you have, how big the battery is, how good the battery is.

Put a volt meter on it and when the battery starts to climb above 13.8 volts turn it off.

A good smart charger will save you a lot of money over it life. I would get at least 10 amps if you do not have a trolling motor battery. 15 amps if you do.

Normaly the drain on a battery with the key off is going to be something installed after the boat left the dealer. Automatic bildge pump with something stuck under the float switch, A new stereo or some other electronics.
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

Yes it probably will be safe to leave a 2 amp trickle charge on your battery overnight without hurting the battery. RV's stay plugged in for months with a 1 1/2 amp trickle charge running. I am assuming the battery has water in it. However this is what you need to do first.

First - Determine how old the battery is. If it's over three years old. It's probably the battery.
Walmarts or Auto Zone will check the battery free with a load test. But if you choose.
Disconnect the positive battery cable and fully charge the battery. Leave the cable off until the next morning or even a full day would be better.

Second - Then hook up the battery cable. If the battery will not start the motor. Go buy a new battery. If the battery will start the motor the next morning or after sitting all night even a day or two. Then you have to find out what is drawing the juice out of the battery.

Third- If the Battery is good then Start by disconnecting your latest add on's until you find the culprit drawing the power. You then can toggle it to cut the power to whatever is drawing the current assuming the battery is good.

You never said what kind of boat, engine or how old the battery is but I would guess you have a battery with a weak cell. Check Fluid level first unless it's a closed cell before charging.
 
Gary H NC

Gary H NC

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Re: How long can I safely trickle charge?

2 amps overnight will not hurt anything but will not fully charge a low battery. Agree the battery needs a load test.
Do you have a stereo with a memory or built in clock? These will put a slow drain on the battery but would not kill it overnight.Usually takes days..
 
bruceb58

bruceb58

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Re: How long can I safely trickle charge?

cbavier@charter.net said:
RV's stay plugged in for months with a 1 1/2 amp trickle charge running.
Click to expand...

If you leave a battery with a trickle charge on it for months, you will boil out your battery.

A float charger, on the other hand, will not.
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

With the Clocks, Carbon Monoxide Tester and Gas Leak Detecter there must be enough draw to prevent any battery damage on an RV plus they do step down or shut off before overcharging. Suppose to anyway. I plug it in a couple weeks in the winter and then unplug it when i think about it. Then when I'm out and think about it I plug it back in. Batteries were still strong enough this Spring to put both slideouts out when I De-Winterized the Fifth Wheel so apparently everything is working Ok.

Leaving a 2 amp charger on a battery overnight is NOT GOING TO BOIL IT DRY! I doubt if even over a 24 hour period it would boil it dry or cause the plates to come in contact with each other. of course I'm not a battery expert. I jusst have 40 + yeras worth of boat and RV experience. I'm sure somebody out there is an expert in Battery Technology.
 
bruceb58

bruceb58

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Re: How long can I safely trickle charge?

I agree, leaving it on over night will not boil the battery. Leaving it on for months like you said before will however. If it is a "trickle charger", those chargers never turn off.

Best thing to do is to purchase a smart charger that will give your battery a bulk charge, get the battery to its full charge quickly, and then let the float keep it there. Keeps the battery from sulfating and allows it to last as long as possible.

I am not a battery expert...just 25 years experience as an electrical engineer with part of that time at Delco electronics.
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

Do they make a smart charger that is solar powered?
 
bruceb58

bruceb58

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Re: How long can I safely trickle charge?

You can buy solar controllers that will be ok. The smaller 10W panels that you often see are not regulated so, in theory, they could overcharge but not that much risk.
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

Thanks Bruce
Our Boat sets in the Lake three weeks at a time with no shore power so a solar smart charger would keep the battery charged. I only have one battery and yes I have, thought of adding another one, but that's down the road a ways.
I only have the manual Bilge pump now and with a second battery, I could add a second Bilge pump, an Automatic and then I wouldn't have to be concerned about battery drain especially if we were gone a day or two. Now I have to have someone, if it rains in the night or so go down and turn on the Bilge Pump on to pump any rainwater out. If we are gone away. Yes I do have Bow and Cockpit covers Sumbrella, but water still seems to find a way to get in if it rains very hard or very much. Probably through the vents or edges.

If I were to addd a second Battery I would use an Isolator like Our Motorhomes had.

Chuck
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

Tashasdaddy
Is this solar powered?
 
S

sc_shane

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Mar 1, 2007
Messages
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Re: How long can I safely trickle charge?

If you feel confident something in the boat is drawing the power, just pull one of the leads on the battery when you're done for the day. Of course, a switch could do the same thing, but pulling the positive or negative leads to the battery does just as good for free. I've got a switch on mine, and turn it off after I'm done for the day. Just a thought!
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

Does anybody know is an " AUTOMATIC BATTERY FLOAT CHARGER "
solar powered? Well that's out of the question for him. I just checked prices. A toggle switch to cut the power from the battery is only a couple bucks. It's a cheap solution to a potential problem.
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

All he needs is a simple Toggle switch from Radio Shack to cut the power from the battery to everything else $2.49 Even walmarts sells them. Nothing fancy just on and off. Auto Zone the same thing!
 
S

sc_shane

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Re: How long can I safely trickle charge?

Youre exactly right cbavier. But sometimes it's nice to have a little BLING on your boat! Honestly though, this switch has been on my boat for around 6 years now and is still like new. Just wanted to recommend a nice product.
 
cbavier

cbavier

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Re: How long can I safely trickle charge?

Originally Posted by tashasdaddy
i keep one of these on each my batteries, when not in use 24/7 365. the battery is ready when you are. great for winter storage.

http://www.harborfreight.com/cpi/cta...emnumber=42292

I just ordered two!





Nobody has answered the question. Do these have to be plugged into 110
volts? Or are they Solar Powered?
 
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