# Unregulated small outboards and deep cycle battery charging



## FuzzyGrub (Jun 20, 2011)

On my latest project, I am considering using only one battery, vs a seperate starting and deep cycle, to save on weight. The 25hp merc has both elec and manual start, and starts easily from manual. I could easily not need the elec start. I am concerned if I did go to one seperate DC battery, about battery longevity giving the numerous light charging cycles from the unregulated source. I seem to go through more starting batteries than DC on my current outboards, but there have been other possible contributing factors. 

I'd like to hear from people that have run with one DC battery connected to their small outboards, and have a couple of years of running that way. Has the DC held up well? 

Note: I will have an onboard charger and battery will be charged after every trip.

The DC will power a 45lb trolling motor, nav and anchor lights, FF's, bilge pump, aux outlet, and some led lights. I'd probably go with a Wally world group 29, that I have been having good luck with.


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## moloch16 (Jun 20, 2011)

Interesting question. I'm putting the finishing touches on my new Jon and am quite happy to have a single battery running the entire show. I have electric start, spot lights, nav lights, bilge, fish finder, and trolling motor all hooked up to one battery. I look forward to hearing answers, to me it doesn't seem much of a problem as long as you put it on a charger when you get home to top it off.


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## FuzzyGrub (Jun 20, 2011)

One concern is over voltage / over charging. On my starting batteries (which are topped off at the bigging of a trip) on long runs the voltages goes over 14V and will continue to slowly climb. The FF and LED lights can not put enough load on it it to keep it in check. 

I think I will put a disconnect switch to the motor positive lead. Once I've used the tolling motor some, that should keep it in check. The disconnect will provide option/choices.


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## TNtroller (Jun 20, 2011)

the reason you run thru so many cranking batts is because you are using a cranking batt on the TM, which draws a steady amp on a battery that is not designed for a long steady pull of power. Cranking batts are designed to give/provide high levels of power for short periods (getting the motor started) and then recharged. TM or deep cycle batts are designed to handle the long steady amp draw from the TM and other electronics on the boat BUT not designed to start an outboard. You can swap their intended use when needed, but not on an ongoing basis.

if you want to save weight, then get a deep cycle/TM batt for all the electronics, and use the manual start function on your OB motor. jmo.


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## FuzzyGrub (Jun 20, 2011)

TNtroller said:


> the reason you run thru so many cranking batts is because you are using a cranking batt on the TM, which draws a steady amp on a battery that is not designed for a long steady pull of power. Cranking batts are designed to give/provide high levels of power for short periods (getting the motor started) and then recharged. TM or deep cycle batts are designed to handle the long steady amp draw from the TM and other electronics on the boat BUT not designed to start an outboard. You can swap their intended use when needed, but not on an ongoing basis.
> 
> if you want to save weight, then get a deep cycle/TM batt for all the electronics, and use the manual start function on your OB motor. jmo.




On my current fishing boat, I do have a marine cranking battery for starting the engine, and a seperate DC for the troller. My plan for the latest project is to go to a single DC for both. I'm looking for people that have run that way with an unregulated charger and what the battery life they experienced.


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## po1 (Jun 20, 2011)

For me I keep it simple with one deep cycle marine battery(it's a dual purpose deep cell battery good for cranking to). I've got my Nissan 18hp electric start, trolling battery, and both fish finders hooked to the one battery. This allows me to keep the battery topped off when running the motor for extended weekends at the lake. My navigation lights and bilge pump, I hooked up to small Cabela's 8amp 12 volt battery. I've had this set up for the last 3+ years with the same battery and this setup hasn't failed me yet and in the worst case if it did fail me, I could pull start the engine or use the 8amp battery.


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## flatboat (Jun 20, 2011)

oddesy batteries like a lot of power goin' in em , you can charge em on a battery charger with start mode real fast . i've put 50 amps in for about 20 minutes and they are ready to go. so i would think the unregulated input from a motor would be fine . they are a dual battery , mount in any position , upsidedown if you want . kinda expensive . you don't need a very big battery i have 2 1200's 24 volt . i can fish 2 days on a charge with a 82 lb motor, for a 37 lb battery thats ausome. they say they deliver 60 percent more power than convential batteries . sometimes they really take a beatin ,being up front but never had an issue with acid spilled like regular batteries. and i dont have to change them every 18 months .just my 2 cents


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## FuzzyGrub (Jun 20, 2011)

po1 said:


> For me I keep it simple with one deep cycle marine battery(it's a dual purpose deep cell battery good for cranking to). I've got my Nissan 18hp electric start, trolling battery, and both fish finders hooked to the one battery. This allows me to keep the battery topped off when running the motor for extended weekends at the lake. My navigation lights and bilge pump, I hooked up to small Cabela's 8amp 12 volt battery. I've had this set up for the last 3+ years with the same battery and this setup hasn't failed me yet and in the worst case if it did fail me, I could pull start the engine or use the 8amp battery.




Thanks po1. That is the kind of input I'm looking for. Do any of your FF have a voltage monitor? If so, have you watched it on your 1st runs down the lake? 

PS: Curious on why the bilge pump on the 8amp hour battery? When you need it, its generally to pump out a large wave or heavy rain.


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## po1 (Jun 20, 2011)

> PS: Curious on why the bilge pump on the 8amp hour battery? When you need it, its generally to pump out a large wave or heavy rain.



I set up the 8amp battery so I could move the bilge pump from my 16' jon boat to when I borrow my brothers smaller 12' jon. I've yet to have the 8amp battery give out on me on weekend trips. And on longer trips I keep a extra 8amp at the campsite if needed. I have a portable Toho-Rig Livewell and with my bilge pump being portable it comes in handy for filling and empting the livewell.


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## shawnfish (Jun 21, 2011)

FuzzyGrub said:


> One concern is over voltage / over charging. On my starting batteries (which are topped off at the bigging of a trip) on long runs the voltages goes over 14V and will continue to slowly climb. The FF and LED lights can not put enough load on it it to keep it in check.
> 
> I think I will put a disconnect switch to the motor positive lead. Once I've used the tolling motor some, that should keep it in check. The disconnect will provide option/choices.




are you talking about your motors alternator overcharging your battery? whats the most volts a 12v should have before its not good? what is FF? also i always thought if your alternator keeps your battery around 12v you should not have to put on a trickle charger over night after going out, is this not true? sorry about hijacking the thread....


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## FuzzyGrub (Jun 21, 2011)

shawnfish said:


> are you talking about your motors alternator overcharging your battery? whats the most volts a 12v should have before its not good? what is FF? also i always thought if your alternator keeps your battery around 12v you should not have to put on a trickle charger over night after going out, is this not true? sorry about hijacking the thread....



Most/many small outboards do not have an alternator. None of mine do, including the 40hp nissan that I had the experience with. Altenator has a regulator that will keep voltage to 14V or less. Small outboards have a magneto that feeds a rectifier for a very choppy and unregulated output. Output is low at 10-15amps. 

FF = Fish Finder (sorry for my shorthand)

I have onboard chargers, so when you plug it in, both the starting and DC get charged. Typically, the starting battery indicator will go green within the 1st hour, but that really dpends on what loads you have on it. 

I am not a fan of trickle chargers or even leaving smart chargers on for extended times. Too many issues can occur from brown outs or lightning or other voltage spikes. Most marine electronics don't have protection circuitry that some home electronics do.

PS: I take no offense on side track conversations in threads I start. Threads are like conversation, if you knew where it was always going to go, what fun would that be? Now, moderators tend to have a different view on that on some boards.


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## shawnfish (Jun 21, 2011)

FuzzyGrub said:


> shawnfish said:
> 
> 
> > are you talking about your motors alternator overcharging your battery? whats the most volts a 12v should have before its not good? what is FF? also i always thought if your alternator keeps your battery around 12v you should not have to put on a trickle charger over night after going out, is this not true? sorry about hijacking the thread....



Most/many small outboards do not have an alternator. None of mine do, including the 40hp nissan that I had the experience with. Altenator has a regulator that will keep voltage to 14V or less. Small outboards have a magneto that feeds a rectifier for a very choppy and unregulated output. Output is low at 10-15amps. 

FF = Fish Finder (sorry for my shorthand)

I have onboard chargers, so when you plug it in, both the starting and DC get charged. Typically, the starting battery indicator will go green within the 1st hour, but that really dpends on what loads you have on it. 

I am not a fan of trickle chargers or even leaving smart chargers on for extended times. Too many issues can occur from brown outs or lightning or other voltage spikes. Most marine electronics don't have protection circuitry that some home electronics do.

PS: I take no offense on side track conversations in threads I start. Threads are like conversation, if you knew where it was always going to go, what fun would that be? Now, moderators tend to have a different view on that on some boards.[/quo

glad you are not upset, my motor does have the magneto/rectifier. let me rephrase my question, even with my magneto/rectifier keeping juice in my battery while fishing should i be charging it at night too? also how could a smart/trickle charger hurt your marine electrictronics? when i have used one i always remove the battery from the boat and charge it... thanks.


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## FuzzyGrub (Jun 21, 2011)

shawnfish said:


> glad you are not upset, my motor does have the magneto/rectifier. let me rephrase my question, even with my magneto/rectifier keeping juice in my battery while fishing should i be charging it at night too? also how could a smart/trickle charger hurt your marine electrictronics? when i have used one i always remove the battery from the boat and charge it... thanks.



I would charge it at night, just to be sure. There are times when I don't use the gas motor for anything outside of low/idle rpms. To get any meaniful charge from it, you have to be at mid-throttle or so. So on a long fishing day, running color FF, airator, bilge pump, lights, etc, the magneto/rec charger can't keep up. If you are having motor problems (lots of cranking), that will eat it up, as well.

It can't hurt the electronics if you are removing the battery from the boat. I only do that for the winter season. If you have an onboard charger then all electronics could be exposed to a lightning spike. 

Even with the battery out of the boat, I don't leave it on a charger. I charge it for 24 hours and it should be good (10amp charger). If not, there is some issue with the battery. For winter, I fully charge at the start, twice during the winter, and again at spring commisioning. If your battery is loosing significant charge at sitting, there is another problem.


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