Marine Battery Charging Question

[J.D.]

I keep 2 batteries on my 17 footer. One is the starting battery, the second is isolated as a backup and drives the bow mount electric.

 

Question: If i connect both batteries together with jumper cables, positive to positive, negative to nevative, and connect a 2W trickle charger to one of the batteries, can I safely assume both batteries will accept a charge and come to full charge?

 

I had an on board charger malfunction last fall, both batteries gassed out, leaked acid and destroyed some wiring. Planning on using an external charger and topping the new batteries off the night before a trip, hoping to charge both safely at once.

 

Thanks for the help.

 

Jim S.

[Sk8man]

I'm assuming that the second battery is DEEP CYCLE but regardless If it were me I'd do them SEPARATELY. They will be drawing current differently. Usually there is a different setting on the conventional charger for each type battery as well that you select before charging.

[Don Supon]

I'd invest in another trickle charger for the other battery. Best option is to consider an onboard charger for the boat to recharge all batteries and just plug it in when you get back from fishing.

[kchamp]

this is what i use and love it. 1.5 Amp Three Stage Onboard Battery Charger/Maintainer

http://www.harborfreight.com/catalog/product/view/id/4231/category/428/

Edited March 24, 2013 by kchamp

[DoubleG]

Kchamp will that charge a starting battery or just deep cycle? How does it hold up on your boat?

GG

[jimski2]

Trickle chargers are known to boil out the water in a battery if you leave them on too long. Deep cycle and starting batterys have different charging voltages so make sure your charger is set for the right type. The three stage charger I use is left on my battery all year long and I have never had a battery problem [kiss of death] over three winters. It can charge two batterys at once.

[Kuba]

Look into battery tender or Goco- wicked smart chargers, both of these are an excellent choice in battery chargers, maintainers.

[kchamp]

Kchamp will that charge a starting battery or just deep cycle? How does it hold up on your boat?

GG

it works fine on both battery's, I have one for main motor and one for down rigger and other equipment, I also use it on my wheeler battery too. I plug them in the night before I go fishing so its good to go in the morning, my main motor charger is broke so these work fine for me

[Knotlost]

The short answer is yes your idea will work, but the battery on the down line side will be much slower in charging once it the don-er battery reaches 80%. Nothing more than that, and if a meteor hits your boat it will probably damage the battery..... Yes there are always, no matter what you do, ways for things to go wrong. There are no perfect answers, but some are better.

 

I invested in some good quality chargers (there are big leaps in components that go into a high end charger)  that will charge in stepped manner, and they work OK. But just because you had one failure with one system doesn't mean that is a bad way of doing it. In every way there is to charge a battery there have been failures, they are not fool proof (the chargers), but there are some better than others out there.  Harbor freight is bottom rung stuff, it works but don't trust it to far..

 

All batteries will charge at a slow rate, there are a lot of people that do not understand batteries giving advice. The changes occur when trying to fast charge and or maintain and or desufite the battery's, but all 12v will trickle charge don't listen to anyone telling you otherwise.

 

A 2 amp trickle will not hurt any good batteries over night doing what you prescribe, anyone who believes so dose not understand whats going on.

[jimski2]

 Over a month or winter charging periods are where trickle chargers can do damage. Overnight or two they are fine but long term charging will cook the water out of a battery with a trickle charger. The modern chargers give a small pulse every few seconds to top off a charge on your battery after it is fully charged.

[J.D.]

Thanks for all the imput. Again, I'm talking about charging with a 2 amp trickle charger for a few hours overnight before a morning trip just to top them off. I have no intention of leaving the new batteries on the charger all the time like I did with the old onboard charger.

[A*M]

JD

 

Go to batterytender.com, click on the link for technical info, it shows how to do this ( attach positve to one battery and negative to other ) Advance auto sells the jumpers made up to fit the top of a deep cycle. I use wing nuts.  The amp hours actually need to be close not exact. 

 

I'd look into getting another battery at some point, you don't want to use up more than 60% especially on the trolling battery.  It will take longer and longer to recharge.

 

FYI, Johnson Control sells and let's companies put there own brand name on batteries to companies like Advance Auto, Auto Zone, Interstate, Walmart and many more.  So watch, the same group size might have different CCA, amp hours, and rc. The highest amp hrs ,or rc are the best.  Some sites also give you the weight.  More weight means thicker lead plates that would also correspond to rc.  In other words you can buy a good battery at Walmart for much less than say an Interstate would be , but they are actually the same battery.

[jimski2]

Batterystuff.com has a tutorial on batterys and charging that might answer your worries.

[Frisco]

Isolate the batteries & use 2 trickle chargers, I have a perko switch between mine and keep it in the open position isolating the 2 batteries, If one fails I can close the perko it to use it as a jumper.

[jimski2]

If you have the bucks, a Dual Circuit plus switch will allow you to start your engines with both batterys. Make sure you have an alternator disconnect circuit with it to protect the diodes in your alternator when your helper shuts the switch off with the engine running. Some older and cheaper switches do not have this feature.

 

Another deal is an Automatic Charging Relay which will charge both batterys from a single engine installation.

 

I noticed my three amp battery tender has an automatic shut off when the battery is fully charged.