Extra Sprinter chassis battery under hood.

[curmugeon]

I just took delivery of a 2015 Interstate Grand Tour. The chassis has a battery under the driver's seat and another battery under the hood. I am told the battery under the hood serves no useful purpose but is charged by the engine alternator. Has anyone figured out some cool things to do with this battery?

[drboyd]

An extra battery costs the factory money. I promise you it's not there for decoration. I know Ram Diesels (and probably most others) have two engine batteries for starting.

[73shark]

Originally Posted by curmugeon

I just took delivery of a 2015 Interstate Grand Tour. The chassis has a battery under the driver's seat and another battery under the hood. I am told the battery under the hood serves no useful purpose but is charged by the engine alternator. Has anyone figured out some cool things to do with this battery?

Welcome to the Airforums.

A previous poster indicated in another thread that it wasn't connected to anything significant, if anything at all.

[oldiesel]

The one under the hood is the "house"battery it supplies the 12volts for lights ect when the engine is off and you are not plugged into shore power. They are setup so you cannot run down the engine starting battery with lights ect

[Protagonist]

Originally Posted by oldiesel

The one under the hood is the "house"battery it supplies the 12volts for lights ect when the engine is off and you are not plugged into shore power.

Actually it's not. There are two Group 24 house batteries in the rear for that.

Most— but not all— Sprinters purchased by authorized upfitters come with dual batteries, because most upfitters, such as the folks who turn Sprinters into ambulances or news vans, use the auxiliary battery under the hood as a house battery. Airstream and most other RV upfitters install their own house batteries so the one under the hood goes to waste.

[cjrdad]

Originally Posted by curmugeon

I just took delivery of a 2015 Interstate Grand Tour. The chassis has a battery under the driver's seat and another battery under the hood. I am told the battery under the hood serves no useful purpose but is charged by the engine alternator. Has anyone figured out some cool things to do with this battery?

This is not anything cool, but I was thinking of somehow connecting the ceiling exhaust fan with a A-B switch to this aux battery. So when you turn off the house batteries, you can switch to aux battery to use the exhaust fan and not drain the main house batteries. Any thoughts?

[73shark]

That should work but you would want to have an isolator between the two chassis batteries so your fan didn't run down your starting battery. Maybe there is already an isolator in place.

[Protagonist]

Originally Posted by 73shark

That should work but you would want to have an isolator between the two chassis batteries so your fan didn't run down your starting battery. Maybe there is already an isolator in place.

There is.

[lewster]

My 2011 Sprinter 2500 service van came with the additional battery and 220 amp alternator package. I also have a 200 amp/hour lithium 'house' battery system powered exclusively by a 500 watt solar array.

I use the aux. battery under the hood for powering additional automotive devices like front driving lights and cell booster. They have performed well using this battery, but there is a caution: since the engine area gets pretty hot during driving, the heat negatively effects this battery.

I had to replace the aux. battery in April, as it would no longer retain charge. The same size/type battery for engine starting is under your feet in a much cooler location, and I still have the original, which is working well.

Moral or the story...........use it if you have it!

[gecko]

We have a custom fitted Sprinter that we use as a day vehicle for windsurfing and a TV for our 28' 2009 Ocean Breeze. The second battery under the hood is the auxiliary battery, and in our case it has been hooked up to run a cell phone booster, internal food cooler, a fantastic vent that we added, and has 5 other outlets for items such as iPhones. We set it up with two control on/off switches located to the left of the steering wheel (for easy access standing outside the vehicle)--one labeled "cooler" for the removable cooler located inside our custom console, and the other labeled "console".

Since the cooler alone draws 4.5 amps/hr, we have learned to be very careful with this battery when the engine is off and we're not being charged by the alternator--it does not have a large capacity, and if you don't drive for a significant distance (or idle the engine, which we don't do) it will quickly run down if you're running even that one appliance over several days since the battery won't get a full recharge with short runs. We have a small solar charger that we use during the winter to give the starter battery (under the driver seat) a trickle charge which works great, but typically when windsurfing, we try to park in the shade, plus we'd have to attach the solar trickle charger with provide clamp clips under the hood, so we have found that to be not practical. We also have a small 110 AC powered charger, and last season we found we had to use that a couple of times to recharge the aux battery when back at our full hookup campsite. This season, we've used the cooler less and also put the fantastic vent on manual, but leaving it open so the fan does not come on and it has no amp draw by itself (it still auto closes in the event of rain, though.) So far, in 7 weeks we haven't had to recharge yet.

But the main take away with you folks with Interstates is that this battery, while definitely separate from the starter battery and your house batteries, does not have a lot of storage. So if you're going to assign it to other appliances, be careful not to use them for very long unless you're driving a distance at least every other day.