Confirm my ‘basic’ understanding of single-dual batt set up comparison

[Photobug]

yeah not really, in that case you make both big batteries a house bank and toss in a little deka AGM racing/cycle/mower battery for starting.

My truck is a Dodge with a Cummins. It has two huge batteries it needs to start. I just recently replaced them both. The auto parts store guy thought they were original batteries, they were certainly OEM batteries but after 14 years I doubt they were original. When they started acting up I upgraded my jump start to one that would start the truck if it came to a no start situation again but doubt a single small AGM could do the job itself.

 

[dreadlocks]

So a jump start thats smaller than your 2 big house batteries can start it but if you took the battery out of the jump start and wired it up it wont? yeah thats not how this works.. This lil bad boy will often output 2x its rated CCA, which is probably as much as one of your batteries now: https://www.amazon.com/Deka-ETX30L-Sports-Power-ETX-30L/dp/B004XQME74 and if its really cold you can always toss your house bank into the mix for a boost.

Its not the size of the battery that determines how many amps it can put out, its the chemistry and how the battery is designed.. if you put in a house bank with all loads on it and starter is only ever used for starting now, it can be downsized in capacity while retaining high amp output.. especially with AGM and LFP chemistries, thats what powers most Jump packs.

 

[john61ct]

Having a smaller number of bigger batteries gives higher total capacity and less voltage sag, for loads pulling high C-rates

than a collection of more smaller units.

Look up "Peukert Effect".

But the chemistry makes a bigger difference, advantage AGM

Odyssey line has the PC-2150 highly reco for "dual use" like that, also true deep cycling performance

Forget about CCA, that's usually only used for Starter types, many quality makers leave that rating out for deep cycling to avoid confusion.

Ah capacity at the 20-hour rate is standard for apples to apples.