1 big - or several small? Battery choices?

[jamesurq]

So in setting up a more powerful battery supply, what's the expert's thoughts surrounding smaller 'motorcycle' or 'golf cart' batteries versus larger traditional RV/Boat/Car batteries?

I noticed that smaller batteries are quite cheap - and having say, 10 smaller batteries for the same price as a single traditional deep cycle, would that have any advantage? Assuming the disadvantage of additional space isn't that much of a concern.

For instance: $10 each:

Amazon.com: Securitron 24V 4.5Ah 12V 4.5Ah Alarm Battery - This is an AJC Brand® Replacement: Electronics

Or 8 for $100:

Amazon.com: (8 Pack) ExpertPower EXP1245 12V 4.5 Amp Rechargeable Battery for Security Systems: Automotive

As info, assume I'll be running a fridge and a medium sized inverter on it.

 

[george_tlc]

So, you spend $100 and get 4.5AH x 8 or x 10, so 45AH for $100. That's cheap?

Now you have 8 or 10 batteries to charge and maintain and then when one goes south (you will have them all in parallel)... you will disconnect everything and then try to figure out which battery is bad? You have to come up with a box and all the wiring to make a single 'battery'...

All this for 45AH and $100 + the hassles. Ummm... doesn't seem a good idea to me.

Plenty of large batteries that aren't stupid priced, just search some more.

Quick google, here's interstate $110 and 96AH -> Interstate SRM-27 Deep Cycle Marine & RV Battery 600 CCA from Battery Town

cheers,
george.

 

[jamesurq]

Thanks!

What about leaking or gas concerns with the battery in the passenger compartment?

Sorry my questions are probably in a FAQ somewhere

 

[george_tlc]

No sure why you would mount a battery in the cabin. The vehicles in your sig have room for a battery in the engine compartment.

If you really must have the battery in the cabin (now you need to run charging cables in and presumably you aren't planning on jump starting yourself unless you have BIG gauge wiring running all the way back to the main battery) then of course you want a sealed AGM etc - now you are going to spend more $$. A decent capacity agm (like an odyssey etc) will run you closer to $200 for that 70/80 AH.

cheers,
george.

 

[Cruiserdrew]

@george_tlc for the sanity check! Practically and normal lead acid battery is going to be better, and a better deal than what you are thinking.

Decent deal at Lowes:

Shop Deka 12-Volt 810-Amp Marine Battery at Lowes.com

 

[jamesurq]

No room under the hood to mount a battery unfortunately. Now the many small batteries make more sense when you're shopping them against big AGM batteries. Cost wise

And yes the plan was to run zero gauge to the battery pack in back.

 

[george_tlc]

Small batteries - consider their maximum charge current. Your vehicle alternator (and main charged battery) can provide a heck of a lot more current than the small batteries can handle... (overcharge current could be catastrophic...)

Get a properly sized agm if you are installing in cab. You should get at least 4 yrs life out of it, so even a $200 AGM over 4 yrs is $50/year, or $4.50 per month. I bet you spend more that $4.50 per month on starbucks/petes or pizza or ....

Which vehicle are you installing in and why isn't there room under the hood?

cheers,
george.

 

[jamesurq]

The 80.
Turbo setup takes up a lot of room.

 

[Jakes40]

I have 2 extra 65Ahr SLA batteries in my tow rig for my fridge. The Alternator charging circuit does not charge the batteries correctly and has shortened there life span. They do not last as long as they did when new.

 

[jamesurq]

Not sure I understand why the stock charging circuit would have a problem?

Again if I'm asking basic stuff here please feel free to point me to a FAQ

 

[Bogo]

Who knows? it could be many things. We don't know enough about the electrical setup and battery types. Mixing lead-acid battery chemistries can even do it. Even different plate styles can change charging voltages.

If the wires are big enough, the connections are good, and there is a good ground circuit, it could be the battery separator unit. Diode based ones are notorious for not 100% charging the house batteries due to the diode voltage drop. Many modern alternators have smart battery charging circuits in them. When the main battery gets to full charge it slowly drops it back to a float voltage for the battery to keep it from overcharging. The diode voltage drop in the battery separator then doesn't allow the house battery to charge fully.