battery question?

[albright4]

Can you use two differant batteries such as a 75 amp hour and a 100 amp hour? I need 24 volts and already have a 75 amp hour battery but want more amps for trolling.

 

[Dunaruna]

Re: battery question?

[colour=blue]It will work but you will considerably shorten the life of both.

 

[raylab]

Re: battery question?

I don't agree that you will shorten the life of both. Used in series as he plans will simply sum up the capacities of both batteries. When either one drains down, his effective voltage will drop off to something less than the required 24 volts.

This setup will work, but I'd strongly reccomend a gauge to allow you to see the 'status' of the voltage supply.

I don't have marine experience but been working in electronics for lots of years.

Just my 2c.

Ray L.

 

[Major Woods]

Re: battery question?

[colour=blue]It will work but you will considerably shorten the life of both.

He's got it right on the money.
I was a QC Supervisor in a battery manufacturing plant for 8 years.

 

[raylab]

Re: battery question?

Not being argumentative here, but can you explain why? I always understood it to NOT be detrimental and would like to understand better.

Ray L.

 

[jtexas]

Re: battery question?

...Used in series as he plans will simply sum up the capacities of both batteries...

I believe that in series you sum the voltage of both batteries, and get the capacity of the lesser...to sum the capacity they would need to be parallel (of course then only 12 volts).

 

[Dunaruna]

Re: battery question?

[colour=blue]Eggzachary what jt said.

Also, the 75amp batt is (presumably) not new, the 100 amp will be new. Not withstanding the reserve difference, they will deplete at different rates. More than likely, the 75amp batt will go below 50% well before the 100amp batt - but you won't know because your motor will still be buzzing away happily. When charge time arrives, the 75 amp batt will not accept a full charge - this scenario will perpetuate with every charge/discharge cycle. The 100amp batt will also be dragged down below 50% because it is 'carrying' the other one.

It will work but you will considerably shorten the life of both.