Charging deep cycle and starting battery together??

[blindb9]

Hey guys, just wondering if it would damage the batteries if i were to charge my trolling motor and starter batteries together? I use a smart charger from canadian tire to charge, and usually charge on the lowest setting which is 4amp but the charger will drop to lower amps as it sees fit. I guess thats why its called a smart charger...
I would like to just hook up the charger to one battery and run a set of heavy booster cables to the other one and let them both charge at the same time? I have an older boat with a early 70's evinrude 25hp that does not charge the main battery so both batteries need to be charged each time i take the boat out.
Any tips or advice would be great!
Thanks

 

[UncleWillie]

Re: Charging deep cycle and starting battery together??

It is Doable.
Charging two unequal batteries in parallel is what ACR systems do every day.

Attach the charger to the Deep Cycle Trolling Battery first.
Do not attach the starting battery to the charger until the Trolling Battery reaches at least 12.7 volts or the Nearly full starting battery will discharge itself into the nearly Empty trolling battery.

The Jumper cables do not need to be Heavy Duty as the current is very low (<4amps);
But, if you have them, use them.
The risk is if the cables come loose and short out when you are not watching and a fire ensues.

Installing an ACR would be the best solution if it is in the budget.
It doesn't care if the charge comes from an alternator or a smart charger.

 

[calvinator]

Re: Charging deep cycle and starting battery together??

That approach will equalize/combine the batteries and dumbs down the smart charger :blue:
The charger doesn't see the batteries individually so it can't smartly charge the batteries.
It will work, how well and how long will the batts last ?

Get a 2-bank battery charger. Wireset #1 goes to batt#1, wireset #2 goes to batt#2. Or buy an additional charger in addition to the one you have.

 

[DLaMar]

Re: Charging deep cycle and starting battery together??

The ARC will work but will be slow. 4 AMPs into a deeply discharged deep cycle battery for the trolling motor could take some time.

For about the same $s a 2nd smart charger, a separate charger for each battery, will get both batteries back to full charge quicker and without additional wiring.

 

[Silvertip]

Re: Charging deep cycle and starting battery together??

Agreed. By paralleling the batteries you essentially reduce the 4 amp charger to almost a maintainer level so getting the troller battery topped off is now going to take much longer. My suggestion would be to leave the current 4 amp charger dedicated to the troller battery. Your 25 HP engine can be started half the summer without recharging a battery provided it is tuned up, there is no operator error and the battery is in reasonable condition. Therefore, buy another 4 amp charger or even a 1.5 amp maintainer for the starting battery. That battery will rarely get deeply discharged so it will be kept topped off.

 

[UncleWillie]

Re: Charging deep cycle and starting battery together??

I use a smart charger ... and usually charge on the lowest setting which is 4amps ...

Better yet, don't use the charger at its Lowest setting. Crank it up to 10 or 15 amps!

 

[glenn property of pam]

Re: Charging deep cycle and starting battery together??

be lazy and install a 2 bank charger. When you get home just run a extension cord out to the boat plug in and go have a beer and forget about it. A 2 bank charger is not all that expensive and unless you fish every day 4 to 5 amps per bank will be fine (cheap end of the scale for 2 bank chargers compared to the 10 amps per bank type). My 3 bank was the best investment ever as it stays plugged in year round and charges when it needs to so even if I get busy for a few months I don't have to worry about the batteries.

 

[blindb9]

Re: Charging deep cycle and starting battery together??

Thanks guys, I think I'll just get another charger and be done with it. Thanks for the tips.