Auxiliary Battery #2

[organize4u]

Wow, I just discovered (after 2 years of ownership) that my 2008 RT 190 Popular has a second battery behind the passenger side rear wheel.

So, here's a dumb question. Why do I need two batteries? What is the function of battery #2? When I check the panel for battery health which battery is it monitoring?

I have attached a picture of the discovered battery. It's one that you have to add water to. I replaced battery #1 with one that does not have that requirement. Besides, you almost have to disconnect and remove battery #2 to even get to the cells!

Thanks,
Marie

[booster]

Originally Posted by organize4u

Wow, I just discovered (after 2 years of ownership) that my 2008 RT 190 Popular has a second battery behind the passenger side rear wheel.

So, here's a dumb question. Why do I need two batteries? What is the function of battery #2? When I check the panel for battery health which battery is it monitoring?

I have attached a picture of the discovered battery. It's one that you have to add water to. I replaced battery #1 with one that does not have that requirement. Besides, you almost have to disconnect and remove battery #2 to even get to the cells!

Thanks,
Marie

The battery behind the wheel well is the standard battery for single battery systems. The one in front of the wheel well is the optional second battery. They are wired in parallel so work together and charge together all the time. If you replaced the front one, you should replace the rear one with an identical battery as soon as you can so they match and work well together. The monitor is checking both of them at the same time so one good one can look like two good when may not be very good.


Two batteries give you twice as much time when you can be without shore power or the engine running. For instance if you stay in a campground or Walmart that doesn't have plug ins for RVs. If you always have plug ins having two is less important but most of us are often or at least sometimes on batteries for days at a time without driving. You would be surprised how quick non LED lights, charging phones and computers, watching TV and such can drain a single battery.

[organize4u]

Thank you so much for the explanation. I will be replacing the battery, hopefully, this coming week.
Marie

[engnrsrule]

Booster nailed it (as usual) but I thought I'd add the numbers for you.

When the batteries are in parallel, they provide the same output voltage, but the Ampere-Hour ratings get added together. Example, two12v batteries with a 90 aH rating give you 12v at 180 aH. That goes to how long they will last.

Conversely, in my rig I have two 6v 235 aH (golf cart) batteries in series, which makes the voltages add together (for 12v total) at the same 235 aH.

Golf cart batteries make good house batteries because they generally have higher aH and are designed for deep cycle operation. Typical car batteries are designed to manage peak outputs, represented by their Cold Cranking Amps (CCA) rating.

Booster did I say it right?