I have my starting battery and my deep cycle battery

[Tiger J]

connected in parallel. Is this a bad thing? I always read to only connect “like” batteries.

 

[Hector]

Do you have a battery selector switch?
Two batteries without a means of isolating one from the other defeats the purpose.
If you are isolating them not good to have dislike batteries in parallel specially if your not isolating them at shore charging.

 

[Tiger J]

Do you have a battery selector switch?
Two batteries without a means of isolating one from the other defeats the purpose.
If you are isolating them not good to have dislike batteries in parallel specially if your not isolating them at shore charging.

I haven’t been isolating them when charging. I know people say not to do this, but no one can tell me what actually happens.

I originally only had the one starter battery and it was powering everything.
I wanted to add the deep cycle for more amp hours for music/leds so I connected them in parallel.

Ps. Everything has been running and charging fine so far.

 

[Mainah]

Different types of batteries store and give up electrons using different chemistry at different peak voltages and different rates. One battery will draw the electrons from the other weaking both through charge cycles. Even given two batteries of the same health the same will occur if in different states of health. Each battery only has so many charge cycles.

 

[Hector]

Different types of batteries store and give up electrons using different chemistry at different peak voltages and different rates. One battery will draw the electrons from the other weaking both through charge cycles. Even given two batteries of the same health the same will occur if in different states of health. Each battery only has so many charge cycles.

What he said ^^^^^^

In all seriousness get a 2 bank charger and minimum a perko battery switch and keep on rocking..

 

[Betik]

What he said ^^^^^^

In all seriousness get a 2 bank charger and minimum a perko battery switch and keep on rocking..

2 bank chargernia fine but what happens when you are runing the engine ....!?

 

[Tiger J]

Thanks Hector. Thats what I will do.

I just never knew if anyone else had any success breaking the "Like" battery rule.

 

[Sbrown]

What will actually happen is your deep cycle battery will last forever and you will shorten the life of the starting battery exponentially. By this I mean you may only get two years out of the starting battery instead of five years. The two batteries are constructed a little differently and also discharge and recharge at different rates. Nothing is going to explode or spontaneously combust, however it is best practice to isolate them.

 

[Hector]

2 bank chargernia fine but what happens when you are runing the engine ....!?

Engines will send a charge to both batteries which will be isolated by the switch.

 

[Marvin willis]

Oops. Never knew that. Thanks

 

[Beachbummer]

While the deep cycle battery is not ideal for starting, I use it often for that purpose with no identified ill effects.

Run on one, switch as I arrive, return on both. Never use the onboard charger unless I make a mistake and leave something on discharging the system. Try to start opposite battery on each outing. So far has not failed me yet.

 

[Marvin willis]

I have a starting battery I bought last year and my deep cycle battery is 7 years old.

 

[Sbrown]

While the deep cycle battery is not ideal for starting, I use it often for that purpose with no identified ill effects.

Honestly, I'd rather use a deep cycle as a starting battery than use a starting battery as a house battery.

 

[Sbrown]

2 bank chargernia fine but what happens when you are runing the engine ....!?

The engine will only charge the battery that the switch is set to. If you want to charge both batteries you have to set the switch to "both", but then you're back to your initial problem of having the batteries not isolated.

 

[Jgorm]

I drive and charge with the switch on both, then switch to aux if i want to play the stereo with the engine off.

 

[Beachbummer]

I drive and charge with the switch on both, then switch to aux if i want to play the stereo with the engine off.

My fear is that if something inadvertently drains the battery, the switch was in both, so you have neither. That's why I'm always on one or the other unless I need both, or in on my way back to charge them both.

It seems there are many strategies, and all have some extra switch operations, risks and rewards.

Pick the one you like the most and can remember to apply

 

[Jgorm]

My fear is that if something inadvertently drains the battery, the switch was in both, so you have neither. That's why I'm always on one or the other unless I need both, or in on my way back to charge them both.

It seems there are many strategies, and all have some extra switch operations, risks and rewards.

Pick the one you like the most and can remember to apply

You need to add an isolator or solenoid so both batteries charge if you want to just leave it on one. I use a solenoid on my rv.

 

[Beachbummer]

But won't that drop the voltage ?

 

[Jgorm]

No. trigger the solenoid to connect the aux battery with key on.

 

[Beachbummer]

Ah, that is a very good idea.