Aux battery

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Kenny

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What is best auxillary battery to use in cold weather region and with a redarc BCDC1225D charger/isolator? Want a 100AH battery that will fit on auxillary battery tray in SUV (tray size 11"x10" ) Thx.
 

rtexpeditions

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You are best to go with an Aggregated Glass Mat (AGM) battery. They are designed to work in the heat of an engine bay and can cope with cold without having heating elements (as required for lithium batteries).
AGM batteries cannot be fully discharged without shortening their lifespan so if you can fit a battery with a higher AH rating into the space you are best to do that.
 

Guest_e9be97

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Typical 100ah battery won’t fit. I presently have the optima yellow top 55ah. Just looking for something larger but, yes, worried about cold weather charging with a lithium. Thx.
 

K1mj

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Here is a chart to common car battery sizes. As you can see 24, 34, 35 should fit and there are AGMs within those sizes.


But like others mentioned AGM will never give you the full rated capacity. You should try to keep it 70% charged. Discharging below 50% will rapidly reduce battery life.
 

KS_Explorer

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Typical 100ah battery won’t fit. I presently have the optima yellow top 55ah. Just looking for something larger but, yes, worried about cold weather charging with a lithium. Thx.
How cold are you talking? There are LiFePo4 batteries that will charge down to -4F now. LiTime comes to mind. They also have self-heating options. I would think your RedArc would keep you from changing a cold battery. Also, if you need to charge it on a really cold day/night, since it will be in the engine compartment you will be able to heat it up by running the engine.