battery drained is it dangerous to boost with another Battery in the Boat

[discover]

I have drained my battery try to start the engine, the battery is Brand New...Is it dangerous to boost with another Battery in the boat incase of a spark? Can I use one as a spare in case I need a boost.Will the battery recharge while I am cruising or do I have to take it back to the store to get it recharged!<br /><br />Thanks

 

[Solittle]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Best bet is to get your own charger. Pull the battery out and charge it on the low setting for a couple of days. The alternator on most motors does not put out enough juice normally to do much to a drained battery.<br /><br />You can use a second battery to give you a boost to get started but you don not want to leave the two connected for any period of time. The good battery will drain into the discharged one leaving you with two low batteries.<br /><br />Now - The next thing is to do "whatever" to get your motor to start quickly - - That may not be much more than having a fully charged battery to start with.

 

[ZmOz]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Come on now...the battery will charge just fine while cruising. (Unless you've got an older outboard with a ~9 amp alernator) Jump starting a boat is the same as a car, jump it and leave it running a while to charge. How many people take the battery out of their car and charge it when it dies? Yes, it would be better for the battery to charge it on a low setting with a charger, but using the engine won't be bad. Buying one of those portable jump start batteries would be a really good investment, I allways have one in my boat and it works GREAT to start it. They're often on sale for around $25.

 

[rickdb1boat]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Agree with both posts. Jump starting will not hurt anything, as it's done all the time on the water when you are left with a dead battery and you're on your way. But as was said, do not leave it connected for a long period of time. I would just carry a spare battery for safety sake, (and I do) and would just hook it up in place of the old one if I had problems with the original. Why jump it, just replace it on the water and off you go. A fully charged spare will get you along way, even if you charging system is not working...

 

[ED21]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Get a good automatic charger & keep the batteries topped off. Especially when you've drained one.<br />Your batteries will thank you & will last longer & maybe have a little more power when you need it one day.

 

[discover]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Thanks for the good advise!<br /><br />This weekend some guy's boat caught fire because he did not beleave in using the blower for 5 min. before starting the engine. Never can tell if there is fumes and batteries can give off a spark!<br /><br />Still trying to figure out how to re-start engine easier.<br /><br />Discover..trade in the batteries for trolling motor...so you can get back to the dock !

 

[quantumleap]

Re: battery drained is it dangerous to boost with another Battery in the Boat

It would take quite awhile to charge enough with the motors' alternator just for the battery to hold a charge, and even if you ran it all day and the tested the battery, you would find it was not completely recharged. Continuing to use it in this partially discharged state will reduce it's effective lifespan. Even a high output auto alternator cannot fully recharge a discharged battery.<br /> <br />To answer the second part of your question, the battery that has just been cranked is the one that has excess gas built up. The other onboard battery is not much of a danger. Take off the caps of the depleted battery to vent any built up gases, then loosely attach them and charge with an appropriate charger.

 

[BF]

Re: battery drained is it dangerous to boost with another Battery in the Boat

It would take quite awhile to charge enough with the motors' alternator just for the battery to hold a charge, and even if you ran it all day and the tested the battery, you would find it was not completely recharged. Continuing to use it in this partially discharged state will reduce it's effective lifespan. Even a high output auto alternator cannot fully recharge a discharged battery.

I gotta question this... Years back I put an ammeter in my old truck... I can watch the charging current immediately after startup, it can peak at 30+ Amps for a short period, then quickly steadies at some single digit current while running. The state of the battery dictates how much current flows. If you boost a car having a dead but otherwise good battery and a good alternator, it is surprising how soon you can turn it off and have charged the battery enough to be able to restart it (a minute or two). Of course a full charge will take longer. My external charger (a small one) has a 6 amp "fast" charge and a 2 amp "trickle charge" mode. I'd bet a dollar that my truck alternator would charge a fully discharged battery faster than my charger will! Charger on 6 A takes a few hours.<br /><br />Living in the frigid north, we get a lot of first hand experience with this type of thing! Also, this is my experience with automotive alternators, charging circuits on OB's are a different kettle of fish (very low output in many cases I think). The current draw from the starter can equal quite a long time running to re-charge. On my 150 Merc the charging system can just keep up. I usually top it up with the charger once in while.<br /><br />anyhow, that's my $.02<br /><br />Brent

 

[quantumleap]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Yes, it will charge faster, but not be able to fully charge it, That's why the alternator or a quick "jump" type charger is not the type used to restore a full charge to a battery. Call your local Interstate battery guy or any other battery dealer and ask him if you don't believe me.

 

[ZmOz]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Yes, an alternator will FULLY charge a battery, and do it quite well. Like I said above...how many people remove the battery from their car and recharge it every time it goes dead? Not very many. Those people aren't driving around with a half charged battery. Most cars have around 100 amp alternator...that will fully charge a battery in an hour at highway speeds. Boats usually have smaller alternators; however, the battery doesn't need to be FULLY charged to start the engine. Even if you have a 9 amp alternator, which is the lowest I've ever heard of in any outboard, it would only take around 10 hours of "cruising" to charge the battery. (and that's if your battery is COMPLETELY dead, which it probably isn't) That's only about 2 days worth for alot of people. After only a few hours the battery will most likely be able to start the engine.

 

[discover]

Re: battery drained is it dangerous to boost with another Battery in the Boat

The battery in the boat is Brand New (1 week old) but I drained it ...trying to start a cold engine.. gave a boost with another battery and ran the engine for over two hours at high speed the battery did not charge up. gave another boost ran again for a few hours ect.. and all day ... she did not gain enough juice not even for one start. the charging system on the boat sucks..I took it back to the store and got another one ..now I have two brand new ones just in case! I am also going to buy a charger!<br />Good input from you sportsmen

 

[Solittle]

Re: battery drained is it dangerous to boost with another Battery in the Boat

You guys can qoute all you want about what car or truck alternators will do. As for me I want my batteries fuly charged before I go to the ramp. I have seen too many boats at the dock with mom, dad & the kids hot & disapointed cause the boat won't start. Even worse think about bein 10 miles off shore and you turn the key to start up - - hear the solinoid klick - - then nothing. I bet more trips are ruined due to low batteries than any other reason.<br /><br />One of the above wrote "After only a few hours the battery will most likely be able to start the engine. " Not sure I would be comfortable with the "most likely" part.

 

[ZmOz]

Re: battery drained is it dangerous to boost with another Battery in the Boat

Originally posted by SoLittle:<br /> One of the above wrote "After only a few hours the battery will most likely be able to start the engine. " Not sure I would be comfortable with the "most likely" part.

And did you notice the part where I said you should buy a portable jump starter to keep in the boat? Not to mention, many outboards can be pull started if need be...

 

[JasonJ]

Re: battery drained is it dangerous to boost with another Battery in the Boat

When it is cold out, I don't even bother trying to start my motor on one battery. I hook jumpers from my trolling battery to my starting battery, and it fires right up. Optimally, having a 2 battery switch is the way to go, so you can place it on BOTH to start, then you can place it on 1 or 2 to charge (you don't want to try to charge both at the same time). One of these days I'll install one of these switches, but for now the jumpers are great (when it is 30 degrees, obviously don't need them when warm). You also really should find out why you had to crank that motor so much to drain the battery in the first place.

 

[quantumleap]

Re: battery drained is it dangerous to boost with another Battery in the Boat

I was a little misleading on my statement that the altenator can't fully charge a battery. It can, but is very hard on the alternator to do so. Check here for more info: http://www.carcarecouncil.org/Electrical/alternator.shtml

 

[BF]

Re: battery drained is it dangerous to boost with another Battery in the Boat

solittle, good that you point out that making sure your battery is fully charged before going out is a good practice. I wasn't intending to condone doing otherwise. As I said, I use an external charger to periodically top up the charge on my boat (OB) battery to avoid problems on the water.<br /><br />What prompted my post was the statement that an auto alternator cannot fully charge a battery. An ammeter is the only real way of seeing what's happening, so that's why I mentioned it. It would probably be a handy guage to have in the cluster, but I don't think I've ever seen one in a boat. (and they're not very common in cars either)<br /><br />happy chargin'!<br /><br />Brent

 

[discover]

Re: battery drained is it dangerous to boost with another Battery in the Boat

The battery shop said they could fully charge the battery in 15 minutes is that truly possible

 

[quantumleap]

Re: battery drained is it dangerous to boost with another Battery in the Boat

It's always been my undwerstanding that a slower charge is better for the battery than a quick charge. The faster you charge, the more gases build up which is hard on the case and causes build-up on the plates.