Jumping Sprinter from isolated battery bank

We've managed to leave the headlights on a couple of times because we exited the slider door and forget they're on - dead battery :(. My "house" system is not connected to the vehicles electrical system, I believe in theory I should be able to jump from it. But I'd appreciate comments from this experienced group.

Van - 2015 170 Ext

House system:
400W solar panels feeding Victron MPPT 100/50 Controller
4 12V 100 AH AGM Deep Cycle batteries in parallel
Victron MultiPlus 12/3000 Inverter charger
Victron BMV712 Battery Monitor

Steps/questions
1. Turn off switch between Charge controller and 1st positive. As a precaution, but is it necessary?
2. Turn off switch between 1st positive and inverter/charge. Again, as a precaution, but is it necessary?
3. Connect jumper cables (25 ft 1 AWG, 800A) to 1st positive and last (4th) negative. Is that the correct placement of the cables to spread the draw?
4. Let vehicle battery charge for a few minutes, then turn ignition while still connected to the house system.

Alternative
Leave the solar charger on and let the van battery charge from the house system for a while (?? not sure how long - BMV should be showing output...)
Disconnect jumper cables and see if enough charge has reached the van battery to start...

I hope to never/rarely need to do this, but is there risk to use the deep cycle batteries in this manner? Other thoughts?
 

tinman

Active member
Can't speak to the necessity of disconnecting the charge controller and the inverter, but it seems like a good idea. Since your house bank is paralleled, connecting your jumpers to any of the positive and negative terminals will be fine. They (assuming roughly equivalent state of charge), will function as a unit. On the other end, make your last jumper connection to a good ground on the chassis or engine rather than on the battery itself. This is important, as there could be hydrogen gas buildup in and around the chassis battery, especially if there have been recent failed start attempts. The spark generated by the final connection can set off a heck of a battery explosion. Dangerous and messy, sulphuric acid all over. (Ask me how I know!) This is, or should be, S.O.P. any time jumper cables are used. If the chassis battery is completely flat, it would be a good idea to leave the setup to charge for a while before attempting a start. I would leave the house batteries connected for the start. The better choice if it's an option is to charge the chassis battery properly before use. These Sprinters can incur strange and potentially expensive damage from bad battery practices.
 

borabora

Active member
Either of these two procedures should do the trick.
If you want to try a more leisurely and maybe somewhat safer way then just buy a 12V battery charger suitable for the AGM starter battery. Plug it into your inverter AC outlet, connect to charger and verify that it is charging, take a walk for 1/2-1 hour and then start your engine. That would be the same charger you'd use to completely recharge your starter battery once you are back in an AC available location.
 

Mr. Bills

2016 170 HR 4x4 Class B Conversion
Jumping the starting battery with the house batteries can certainly be accomplished in an emergency, but a lithium jump pack is much more practical.

Jump packs are quick, convenient and considerably more compact than a set of 25' jumper cables that would have to be carted around and stored in the Sprinter at all times.

I carry a Noco Boost Plus GB40 1000 amp jump pack in my jeep and a Noco Boost XL GB50 1500 amp jump pack in the Sprinter.

https://www.amazon.com/gp/product/B07MVY7K43/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
 

sparkplug

Active member
Mr. Bills beat me to it.

I haven't chosen my jump pack yet as I'm still doing my research on them.

It takes a slightly bigger pack to jump start a big diesel lump!

I do currently keep jump leads in the passenger side lower door compartment but would be reliant on a kind passer by to help me.

A jumper pack would be more versatile and would allow me to be that kind passer by for other people too without having to manoeuvre a big van close enough to their vehicle to jump start them, or push their vehicle so that mine can reach it... Been there, done that (many times!)

@Mr. Bills - have you had a need to use the Noco on the Sprinter yet? I'd be curious how you got on and what made you choose that over the others?
 

Mr. Bills

2016 170 HR 4x4 Class B Conversion
I have not had the opportunity to use the Noco GB50 yet, but I have used the smaller Noco GB40 that I keep it the jeep which I have owned for several years.

My impression is that the GB40 would have no trouble jump starting the MB 3.0 diesel, but I purchased the higher output GB50 for the Sprinter out of an abundance of caution.

The Noco units have been around for quite a while. The vast majority of reviews are positive although there are some "mine didn't work for me" complaints as there are with all products with a substantial number of units in use.
 

tinman

Active member
Going from memory here, and mine's a T1N, but I believe there's a placard warning against using a jumper pack.
 

Mr. Bills

2016 170 HR 4x4 Class B Conversion
No warning placard on my NCV3 relating to jump packs nor is there any such cautionary language in my owner's manual.
 
On the other end, make your last jumper connection to a good ground on the chassis or engine rather than on the battery itself. This is important, as there could be hydrogen gas buildup in and around the chassis battery, especially if there have been recent failed start attempts. The spark generated by the final connection can set off a heck of a battery explosion. Dangerous and messy, sulphuric acid all over. (Ask me how I know!) This is, or should be, S.O.P. any time jumper cables are used. If the chassis battery is completely flat, it would be a good idea to leave the setup to charge for a while before attempting a start. I would leave the house batteries connected for the start. The better choice if it's an option is to charge the chassis battery properly before use. These Sprinters can incur strange and potentially expensive damage from bad battery practices.
Thanks for the warnings. The chassis battery connections won't be to the battery itself. Battery is external, under the driver seat and under the hood are chassis ground and + pegs to clip onto.
 

mikecol

Active member
I've let my van sit too long several times and got tired of jumping/charging while the house bank sat with lots of charge. I added a Xantrex Echo Charger and it keeps the van starting battery topped off without trouble.

My Echo Charger is connected across my Sterling Battery-to-Battery charger, but in reverse (i.e. House charging van). It is one of the best gadgets I've added. When on shore power: the inverter/charger keeps the house bank up, and the Echo charger keeps the van battery up.
 

marklg

Well-known member
I've let my van sit too long several times and got tired of jumping/charging while the house bank sat with lots of charge. I added a Xantrex Echo Charger and it keeps the van starting battery topped off without trouble.

My Echo Charger is connected across my Sterling Battery-to-Battery charger, but in reverse (i.e. House charging van). It is one of the best gadgets I've added. When on shore power: the inverter/charger keeps the house bank up, and the Echo charger keeps the van battery up.
How can you make sure the Echo Charger is not on when the Sterling is on? If both are on, i think you will have a current loop with 15A of the Sterling output current going back to the starter battery, so you really only get about 32 A net charging current. In my setup, the Sterling output is for a LiFePO4 bank that is often at a higher voltage than the alternator output, so the Echo Charger would be running.

I have a switchable direct connection from the house batteries to the starter battery to boost it up. I just don't have the switch on when the engine is running so current won't go back from the Sterling output. The switch is the big red guarded one on the left, so not likely to make a mistake.

Big_Red.jpg

Regards,

Mark
 

mikecol

Active member
How can you make sure the Echo Charger is not on when the Sterling is on? If both are on, i think you will have a current loop with 15A of the Sterling output current going back to the starter battery, so you really only get about 32 A net charging current. In my setup, the Sterling output is for a LiFePO4 bank that is often at a higher voltage than the alternator output, so the Echo Charger would be running.
Hey Mark,
On my 2019 Cargo the alternator is usually 14V or more running. My Sterling is usually putting out less than 14V (until last minutes). I do have the Sterling enabled only when van running and also a manual switch for control.

Not sure I would notice the 32A net charging from the Sterling, since it goes in and out of temp limiting anyway....not a good thermal design for sure.

When running usually run both 2nd Alternator and Sterling (also Echo Charger left on) and get about 2.5KW at idle and 3KW charging driving. Have Balmar set real low on Field Voltage limit and also temp limit so 2nd alternator runs real smooth. 14KW lifepo4 bank still takes a while to charge.
 

marklg

Well-known member
Hey Mark,
On my 2019 Cargo the alternator is usually 14V or more running. My Sterling is usually putting out less than 14V (until last minutes). I do have the Sterling enabled only when van running and also a manual switch for control.

Not sure I would notice the 32A net charging from the Sterling, since it goes in and out of temp limiting anyway....not a good thermal design for sure.

When running usually run both 2nd Alternator and Sterling (also Echo Charger left on) and get about 2.5KW at idle and 3KW charging driving. Have Balmar set real low on Field Voltage limit and also temp limit so 2nd alternator runs real smooth. 14KW lifepo4 bank still takes a while to charge.
For the Sterling, I added a Bilge Blower and a 3D printed adapter to improve the cooling, a necessity here in AZ when it is really hot.

Sterling_Cooling.jpg

The plastic tote covering the junctions has since been replaced by a 3D printed enclosure. With the added cooling, I get full output most of the time. Before, it would hit the temperature limit in about a minute.

Regards,

Mark
 

Kevin.Hutch

2011 Mercedes 313 906
I have a Lithium house and AGM start so I chose to add a changeover switch to transfer the solar charge to the start when stored for any length of time with no house load. I occasionally check the lithium charge state as it has a permanent BMP power monitor. I figure this would get me out of trouble if I ever get the start battery down.
 

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