Second Starting Battery

[aa9zz]

I have a 2010 unit and my starting battery is under the floorboard. Is there a bracket or holder to hold a second under the hood?

[wayneskid]

Depending on the MY of your Sprinter (vs the Airstream MY), there may have been an option for a second starting battery that gets mounted under the hood above the main computer module. Just out of curiosity, why do you want a second starting battery?

[Protagonist]

I looked into getting one retrofit on my Interstate. Way too complicated, and way too expensive for what it's worth, based on information I got from my Spritner dealer. I would have to get the bracket, the battery (which has to match the chassis battery you already have), the relay, several feet of 10-gauge wire, a larger alternator, AND get the sliding step, awning, and alarm system wiring transferred from the original battery to the auxiliary battery. Those three systems are the only ones that I could power from the auxiliary battery.

The second battery under the hood is meant to run auxiliary systems. It's not a second starting battery. The relay doesn't even allow that battery to be connected to the main battery until after the engine is running, so that it can recharge.

The auxiliary battery under the hood is primarily used for ambulances, news vans, and other commercial applications where they've got equipment that has to be kept running even after the engine shuts off. In other words, it's their "house" system.

[gmillerok1]

I wonder if you could just use the bracket to mount another AGM and hook it up to the house batteries? It would be nice to add another one to simply increase the amp hours since there sure isn't room in my standard lounge (without the basement) to put one. I can't figure out how the bracket is mounted.

Gerald

Originally Posted by Protagonist

I looked into getting one retrofit on my Interstate. Way too complicated, and way too expensive for what it's worth, based on information I got from my Spritner dealer. I would have to get the bracket, the battery (which has to match the chassis battery you already have), the relay, several feet of 10-gauge wire, a larger alternator, AND get the sliding step, awning, and alarm system wiring transferred from the original battery to the auxiliary battery. Those three systems are the only ones that I could power from the auxiliary battery.

The second battery under the hood is meant to run auxiliary systems. It's not a second starting battery. The relay doesn't even allow that battery to be connected to the main battery until after the engine is running, so that it can recharge.

The auxiliary battery under the hood is primarily used for ambulances, news vans, and other commercial applications where they've got equipment that has to be kept running even after the engine shuts off. In other words, it's their "house" system.

[David M]

Originally Posted by gmillerok1

I wonder if you could just use the bracket to mount another AGM and hook it up to the house batteries? It would be nice to add another one to simply increase the amp hours since there sure isn't room in my standard lounge (without the basement) to put one. I can't figure out how the bracket is mounted.

Gerald

Yeah, I was thinking the same thing because having the "basement" for hoses and tools instead of for batteries is very handy.
David

[73shark]

Originally Posted by David M

Yeah, I was thinking the same thing because having the "basement" for hoses and tools instead of for batteries is very handy.
David

If the house batteries use a common chassis ground then you would only need to run 1 heavy cable to the rear of the RV. Not sure if they do however.

[lewster]

It's not a good idea to add a battery to an existing battery bank, as the charge profiles will be different. Plus, I would not rely on the chassis ground as multiple batteries should be connected with parallel positive AND negative cables to the appropriate terminals.

[aa9zz]

My original intent was not to use it as a second starting battery but to have an accessory battery under the hood. It looks like it is more complicated than I thought it might be. My expertise is in marketing and advertising. I rely on you guys to set me straight on things Airstream. You all did a very good job here again.

Originally Posted by wayneskid

Depending on the MY of your Sprinter (vs the Airstream MY), there may have been an option for a second starting battery that gets mounted under the hood above the main computer module. Just out of curiosity, why do you want a second starting battery?

[David M]

Originally Posted by lewster

It's not a good idea to add a battery to an existing battery bank, as the charge profiles will be different. Plus, I would not rely on the chassis ground as multiple batteries should be connected with parallel positive AND negative cables to the appropriate terminals.

Thanks Lew,
Good info to have before spending money down that path
David

[Boxster1971]

If you would like to know what is involved in the Sprinter Aux battery installation see the attached pdf file from Sprinter Engineering & Compliance. It even says: "For cost and practical reasons we recommned to order this option directly from the plant."

[Protagonist]

Originally Posted by Boxster1971

If you would like to know what is involved in the Sprinter Aux battery installation see the attached pdf file from Sprinter Engineering & Compliance. It even says: "For cost and practical reasons we recommned to order this option directly from the plant."

I confirmed with my Sprinter dealer that the instructions and parts list are much the same regardless of the model year. And, it's impossible to buy the whole thing as a kit; you have to order each of the parts a la carte.