Charging House Batteries

[mattdanger]

Hey Guys!

Recently picked up 2012 Sprinter that the PO converted for camping.

First on the list of mods is to get the power system dialed in:

The "house" batteries and loads (lights, water pump, etc.) are currently completely isolated from the "starting" batteries and vehicle electrical system.

This is super annoying because the only way to charge the house batteries is by plugging the van into shore power.

Specs:

Magnum MS2000 Inverter/Charger
ME-BMK Battery Monitor Kit
ME-RC Remote Control
Battery Bank: Qty (2) LifeLine GPL-4CT 6 Volt AGM Deep-Cycle batteries wired in series


Currently, we use our MS2000 to keep the bank charged when we are at home, and if we happen to be at a camp site where there is electricity.

We would like to modify the system to be able to charge the batteries using the output from the engine alternator, so that they can charge up while we are traveling between destinations.

My main concern is damaging the batteries by over charging them if i just connect the battery bank direct to the main vehicle charging system.

It seems like we need some kind of standalone 12v-to-12v 3 stage smart charging charging system that

Thanks for your help!

 

[Joe917]

The Magnum is an excellent charger. LifeLine is a great choice for deep cycle batteries.
You need to add 3 additions to the system: solar. solar and SOLAR.
You can connect the charging system to the house batteries to charge, Blue sea or Sterling would be the way to go.
SOLAR might also be worth looking at. (Morningstar)

 

[ajmaudio]

The Magnum is an excellent charger. LifeLine is a great choice for deep cycle batteries.
You need to add 3 additions to the system: solar. solar and SOLAR.
You can connect the charging system to the house batteries to charge, Blue sea or Sterling would be the way to go.
SOLAR might also be worth looking at. (Morningstar)

this

 

[luthj]

If you just need some extra charging the alternator does a great job. It won't get the batteries to 100% on its own, so a full three stage charger will be needed for regular top ups. Your magnum charger will do a great job if its setup correctly.

The simplest and cheapest way is to add an isolation relay such as a cole herse unit or a Blue Sea ACR. There are some guides on the sprinter-source.com forums for installing a charging relay on the NCV3 sprinter models.

As the others suggested, a correctly sized solar array can supply enough power to charge the batteries and handle regular loads. Obviously your location and usage will influence the necessary size of solar setup. For many users a reasonable solar system is the answer. For those in poor sun areas, or for those with large power usage solar may not be enough on its own.

I know of several installs that use alternator for bulk charging, and a shore power charger for complete 100% charging every 3-7 days. This can work well as long as the batteries are not abused by regular discharges below 40% SOC. With deep discharges like this, the batteries will need to be returned to 100% on a daily basis ideally. The alternator is not high enough voltage to bring the batteries to 100% without VERY long drive times. This is why a true three stage charger is needed.

Now, regarding overcharging. This is not a concern with the ~14v alternator output. Note that the rate at which you charge from the alternator will be dependent on battery bank size and the wiring gauge between the chassis system and the AUX battery bank. Use as large of cable as practical, the shorter the better.

If you can provide some details on your usage we can provide more detailed recommendations. Off the top of my head a Blue sea 120A ACR and 200W solar array would be good for many. If you have a dc fridge more solar may be needed.

http://amzn.to/2dHqIsL

Edit: I see you have lifeline batteries. These batteries have lower charging voltage requirements, and will bulk charge well from the alternator. Just make sure your charging path is low resistance.

 

[Bbasso]

Blueseas ACR 7622 with solar power input and you won't have to be worried about power anymore.

 

[blackwood]

The Ctek D250S does battery isolation (alternator charging) and has a solar charger (MPPT) all in one. This is the one I use on my Tundra.

-Fully automatic 5 step charger adjusts the charging voltage and current according to the state of charge and temperature of battery.
-Great for "off the grid" applications with its multi-step charging from alternators and solar panels.

 

[brianjwilson]

Blueseas ACR 7622 with solar power input and you won't have to be worried about power anymore.

This is how I powered my tacoma and four wheel camper. Blue sea 7622, 300 watts on solar through an mppt controller. The only time I ever got to 50% charge was after being completely shaded for several days, no driving, running fridge and fan all day in hot weather and furnace at night to keep the baby warm. Otherwise the batteries were maintained amazingly well.

The Ctek D250S does battery isolation (alternator charging) and has a solar charger (MPPT) all in one. This is the one I use on my Tundra.

-Fully automatic 5 step charger adjusts the charging voltage and current according to the state of charge and temperature of battery.
-Great for "off the grid" applications with its multi-step charging from alternators and solar panels.

This is likely the direction I'll go with my van, just to have everything combined and have a multi stage charge from the alternator rather than just a bulk charge. Ideally a larger alternator, ctek d250s and smart pass, with 200-300 watts of solar.

 

[_hein_]

+1 on utilizing the alternator and solar panels as additional charge sources.
Ctek D250S + SmartPass can allow for up to 80A from the alternator and will
also accept input from a parallel solar array. We plan on using their system
in our Transit.

We can help you with a nice roof rail mounted solar array for your Sprinter.
PM me.

400watts

300watts

 

[Bikersmurf]

1) If your Sprinter is under warranty be sure you don't void it by the alterations... They have some rules up here at least.

2) Blue Seas ARC is likely the best option... I'll be replacing my diode isolator with one some day.

3) X10 on solar... especially for camping where there isn't a plug. Who wants to run a generator for hours or the truck for that matter.

 

[mattdanger]

Thanks for all the replies guys!

I really, really like the idea of solar, but i am a little worried about cleaning/maintaining/protecting the cells on the roof because the roof is so high.

Would it be weird to just run a large, high quality inverter from the Sprinter charging system and hardwire the output to the Magnum input?

That way I would still be using the Magnum charge controller that is custom tuned to my battery bank to do the actual charging.

Pic of the new rig from our first trip:

 

[dwh]

Would it be weird to just run a large, high quality inverter from the Sprinter charging system and hardwire the output to the Magnum input?

That way I would still be using the Magnum charge controller that is custom tuned to my battery bank to do the actual charging.

That's an old trick and works fine if you do it right.

 

[Bikersmurf]

I contemplated just the same thing when I was looking at AGM batteries. Highly inefficient to go 12->120->12.

 

[DiploStrat]

...

My main concern is damaging the batteries by over charging them if i just connect the battery bank direct to the main vehicle charging system.

It seems like we need some kind of standalone 12v-to-12v 3 stage smart charging charging system that

Thanks for your help!

You won't, for any number of reasons ranging from the way batteries work, to the way your vehicle's charging system works, to the fact that you probably couldn't drive that long.

That said, with a Sprinter (and some Toyotas) the question is the "magic" number - 14.4v @ 20c/70F. What is the charging voltage of your vehicle's electrical system? If it is above 14v, then a relay system, with properly sized wires, will work perfectly to charge your camper batteries. I have 600Ah of Lifeline batteries in my truck and have been doing it for years. (Why would you want to convert 12v to 110v and then convert it back to 12v when you are already getting that 12v from a regulated battery charger?)

If, as I suspect, your Sprinter tops out at about 13.9v, then you need to raise the voltage of the vehicle or consider some form of separate system (CTEK/Sterling/Redarc, etc.) to charge the camper batteries to assure that they receive a full, temperature compensated 14.4v. I am partial to the CTEK D250S/SmartPass system as it combines an intelligent relay, a battery to battery charger (voltage boost) and includes a small solar controller. I don't know of a plug and play device to raise the charging voltage on a Sprinter.

Incidentally, the difference between charging at 13.9v and 14.4v is not trivial; it is about 400%. Well worth the difference

You may find this useful reading: https://cookfb.files.wordpress.com/2016/09/dual-battery-slides-2016.pdf (There are several more related documents on the same page.)

And, as noted, you need solar. Period.

Best wishes.

 

[luthj]

The inverter to inverter system works, but you will loose some efficiency, and it can cost more than a simple charging relay/isolator.

I also have lifeline batteries. They will happily bulk charge from ~14V with a decent sized cable. My 510AH bank will charge at over 50A until about 85% SOC from my sprinters alternator. I have a long charging path which consists of 8ft of 4/0 wire and 7ft of 2/0 wire (my batteries are near the rear door). Lifeline batteries do not require the higher absorb voltages that other brands do (they have very low internal resistance). So they will charge fairly rapidly in the 14-14.4V range. You will still need another charger (With temperature compensation!) to apply 14.4V for a few hours to get them to 100% SOC. Other battery makers have higher internal resistance, so they will charge slowly at voltages below 14.2V.

As far as maintaining solar panels goes, you really don't need to do much to them. Just clean them off every few weeks or so. The frequency of cleaning will vary with rainfall and local dust conditions. I have found the best way to clean my panels is a 6-8ft ladder and a long handled squeegee. I wet the panels with a hose and squeegee the water off. This usually removes 90% of the dust/dirt without the need for scrubbing.

Anyways, my recommendation is a small solar array, and an isolation relay or ACR. The CTEK products look intriguing. I have read about a few instances where the smartpass? does not have integral current limiting, so with a deeply discharged battery bank it will overheat, and turn itself off. So there is obviously some research you would need to do before implementing that product.

 

[dwh]

I contemplated just the same thing when I was looking at AGM batteries. Highly inefficient to go 12->120->12.

The inefficiency doesn't much matter. Getting a properly dialed in muti-stage charge would make up for it.

Inefficiency matters with some things, like solar, in other situations...bleh, who cares?

Though using a big inverter to feed a big battery charger is also highly inefficient in financial terms.

Best would be ACR + solar. But inverter to charger works too.