Viair compressor using Sprinter jump start connectors

Elkman · 11-20-2020, 03:49 PM

There are two places inside the engine compartment to use when jump starting the engine with a failed crank battery. I need to run a 12VDC air compressor and normally I would attach the leads to the vehicle's battery terminals.

Is there any reason why I cannot use the two connection points inside the engine compartment?

Morich · 11-20-2020, 05:21 PM

Yes, that would actually be the best place if I understand what you describe. If there is a solid path from a remote point to the positive side and you can connect to it and then the other to some part of the ground like the frame of the car, doing the connections away from the battery is safer as it moves any sparks further away from any potential of gas fumes exploding. Most likely that is part of the reason for the design?

Wyatt · 11-20-2020, 08:43 PM

Quote:

Originally Posted by Morich

Yes, that would actually be the best place if I understand what you describe. If there is a solid path from a remote point to the positive side and you can connect to it and then the other to some part of the ground like the frame of the car, doing the connections away from the battery is safer as it moves any sparks further away from any potential of gas fumes exploding. Most likely that is part of the reason for the design?

All true, if you’re running a normal flooded cell battery, as Morich cautioned you, best to not cause a spark anywhere near them. If you use an AGM battery in your starter, as we do, (mostly because it’s really hard to get in there and check the fluid level), then you’re ok connecting to them as they are sealed.

Alternatively, one could also connect to their coach batteries—whichever is closest to your tires and easily accessible—where the cord will reach, with the same admonishment of caution...

Morich · 11-21-2020, 08:18 AM

Quote:

Originally Posted by Wyatt

All true, if you’re running a normal flooded cell battery, as Morich cautioned you, best to not cause a spark anywhere near them. If you use an AGM battery in your starter, as we do, (mostly because it’s really hard to get in there and check the fluid level), then you’re ok connecting to them as they are sealed.

Alternatively, one could also connect to their coach batteries—whichever is closest to your tires and easily accessible—where the cord will reach, with the same admonishment of caution...

Yes, it is true that different RV will have several different places to get a bit of 12VDC power, if we think about it. There are times when we want to power some small item like a small compressor or maybe a pump to pump some waste out of the holding tanks and it can be along way from the front or start battery location. That is a good time to think about where other parts of the RV might be handy.
One is the generator! We sometimes think of the generator as putting out 110 AC and that's not what we want but forget that it also uses 12VDC to to start and that means there is a great big old 12VDC battery cable somewhere on the genset! On mine, the battery cable is just inside the access door under a little plastic cover, so all I have to do is flip that cover, clip the positive lead for my pump on that point and the negative lead to some part of the metal frame and I'm ready to go!
If this is a new idea and seems radical these are the big points to consider.
1. Make sure the point where you connect is fused high enough to support the item you want to power---or you will blow a fuse or breaker! But you can always know that the generator or any starter takes a very large amount of power and they will be fused for at least 40 amp, so if your item is handheld, you most likely can use that point.
2. You do not need to connect the negative feed of your item to a specific negative battery point as the negative side is just ground and most of us have the metal frame of the RV as ground. That means most any metal point that is clean enough can be used for that lead.
3. Don't expect to use a power point like a cigarette lighter to be fused to run very many amps to power things like pumps, etc. as they are meant for far less power.

DesertRatt · 11-21-2020, 11:23 AM

Viair Problem

On the road the other day, I needed to air up my street side tires. The Viair would not reach those rear tires when connected to house battery or car battery. So, I added a pair of battery jumper cables and connected the Viair to them............NO JOY! The Viair simply would not operate when connected to the jumpers! The jumpers were only weeks old, and in perfect cond. Odd?

I am going to try to contact Viair.

daSpud · 11-22-2020, 01:55 PM

I cannot think of any reason how the Viair would know you were not connected to the battery unless you really were not. If you have a volt meter (a good thing to have) you could check to see if you really have 12v at the end of the jumper cables. Also be very careful that the far ends where you were going to attach the Viair do not touch! That is a dead short and sparks will fly.

On the subject of using the MB jumper points remember they are for putting juice INTO the battery. It is possible they have diodes in the circuit which will prevent current from coming OUT that path. I do not know if hey do, just saying that is possible.

Elkman · 11-22-2020, 01:58 PM

I have several Viair compressors and the 300P works the best to provide 80 PSI for tires without blowing a fuse. I found that the connection points under the Springer hood are what Mercedes recommends for jump-starting the vehicle and for charging the chassis batteries.

There is a 30' coiled extension hose for the Viair 300P that sells for $35 and attaches between the compressor and the standard hose with the filler chuck and pressure gauge. The two hoses easily reached the 25 feet to the rear tires. I did have to also buy for $10 a pair of rubber valve stem extenders so I could reach the valve stems for the inner tires. I only plan to attach the flexible extensions when using the Viair compressor.

Better to have the compressor as close to the battery as possible and then run a long enough section of air hose to reach the tires. I do that with my SUV and sedan as well but with one of the smaller Viair compressors and 3 of the Viair 6 foot extensions screwed together. Big fan of the Viair products.

daSpud · 11-22-2020, 02:29 PM

Yes, air extends easier than electricity. Don't have voltmeter with me (note to self get that toolkit in the new camper ASAP) so can't check if 12v available at the charging points. I would not put it past them to make sure it was really safe and only for charging hence no 12v out.

mdstrum · 11-25-2020, 04:37 PM

Yes, we have done that...no issue but something to think about is that the Sprinter battery is an AGM is not very big reserve...if you bring down below 50% AGM are not happy, we did this and had to replace that chassis and house banks recently. We have Era 70A 4X4 and putting an ARB onboard compressor in that same general area that you plan to connect to the battery terminals, to have a built in system so we do not have store and connect and we can run it with the engine running more safely to air up the tires or water toys etc
https://agileoffroad.com/product/agi...sprinter-2019/

Accipiter · 11-25-2020, 04:38 PM

MB Sprinter has a separate ground is you ever jump start or need to charge the battery, that is what I would use to run the compressor. Nothing wrong using the battery ground but there maybe a reason MB added a detected ground post in the engine compartment.

sajohnson · 11-25-2020, 05:56 PM

The "jump starting connection point" under the hood can be used -- just as if it were the pos(+) battery terminal. It is connected directly to the starting/chassis battery under the floor.

There is a bare metal post for the ground/neg(-) connection inside the fender.

The red plastic cover over the jump starting connection point is spring loaded, to ensure that when not being used the pos(+) connection point is not exposed. It's been a while since I connected my Viair compressor to it, but I seem to recall having to use a clip or something to hold the red plastic cover back. Otherwise it would spring forward and push the Viair clip off.

What I find easier is to just connect the Viair to the coach batteries. The more central location allows the air hose to reach all 4 'corners' of the rig.

There was a comment about using jumper cables. There is absolutely no reason that shouldn't work. One thought -- most (all?) jumper cables only have one half of each clamp connected to the cable. When connecting a device to the clamp, the user should confirm that they are connecting to the clamp that has the cable connected to it.

Hope that makes sense.

Sailorman76 · 11-25-2020, 07:58 PM

Question: Why is there not a 12 VDC power port on the inverter? On my View, that would permit me to easily reach all wheels with a 12 volt air compressor.

sajohnson · 11-25-2020, 09:40 PM

Quote:

Originally Posted by Sailorman76

Question: Why is there not a 12 VDC power port on the inverter? On my View, that would permit me to easily reach all wheels with a 12 volt air compressor.

We have an older View, a 2009 VJ, so I'm not familiar with the stock inverter or it's location. I assume it's someplace handy.

What you might consider is using the coach batteries. It means removing the step, but that's not difficult. You could connect a 12V power port to the batteries using ring terminals, or you could us alligator clamps. Ring terminals would be the best electrically, less potential for voltage drop.

If you are more ambitious you might find someplace to install a 12V power port inside the coach door.

Elkman · 12-02-2020, 12:00 PM

I run the engine when using any of the Viair compressors to inflate the tires. No worries about the voltage level feed to the compressor motor and no loss of charge with the crank batteries.

If my tires are at 80 PSI there is negligible loss of pressure over a period of months so I do not carry the Viair in the coach but leave it at the house.