MultiPlus and LifePo4 Upgrade...What Additional Accessories Are Needed???

[Vibe101]

Greetings,

First Post Here so Hello Ya'all!!!

In addition to the "Victron MultiPlus Inverter/Charger 12V 3000w 120a 120v BNIB" what other components/ accessories will I need?

I have a 2021 Forest River Vibe and it is considered to be a "30 Amp 12 VDC" travel trailer and I am installing a new LifePo4 battery system in it "from scratch" and I wanted to get advice from the Borg Collective in the Cyber RV Campground.

I say "from scratch" because the existing converter/ battery charger has been removed from the WFCO 8955 panel and the previous lead acid battery and associated wiring has been discarded so the only electrical components remaining in the trailer are the following:

-OEM WFCO 8955 panel (minus the converter)
-Battery disconnect switch
-Microwave
-Dual source fridge
-13000 BTU air-conditioned (single unit)
-DC energized/ propane fueled furnace
-40 inch LCD AC powered television
-Furrion 12 VDC radio
-Single brand new LifePo4 200 AH battery
-Of course the usual AC wiring and outlets and DC powered LED interior lighting
-There is currently no solar panels however that might be an option in the future.

The goal is to boondock almost exclusively with very minimal use of AC powered components (microwave popcorn and occasional use of a power pack for a notebook computer or (not at the same time) watch a movie on the 40 inch AC powered television. We will have a small generator available for the rare times that we will use the single air-conditioner system.

So if I buy the "Victron MultiPlus Inverter/Charger 12V 3000w 120a 120v BNIB" what other accessory will I need?

THANKS All and I am grateful for any help/ advice/ well wishes/ moments of silence/ shoulda-Woulda-Couldas you can provide!!!

 

[Vibe101]

Another question is what about charging from the truck alternator?

The previous system had the "Pin 4" of the GM 7 pin connector wired directly to the battery + terminal.

With the Victron MultiPlus, how is the truck battery connected to the system and what would happen with the LifePo4 battery during a long drive?

 

[Rob&Deryl]

The truck alternator is fine for minimal charging while driving between sites but i don’t think it can be a significant source of power.

 

[chovy]

I boondock on private land fulltime. I have 500ah lithium batteries and 600 watts of solar. Ok cloudy days I do run the generator maybe once a week.

 

[Vibe101]

I know everyone was impatiently waiting for me to announce my decision on my LiPo upgrade to my travel trailer.....drumroll...

I decided on the following:

Items mounted right next to each other in the front pass through:
-Single LifePo4 200 AH battery
-Victron MultiPlus Inverter/Charger 12v/3000w/120a-50a transfer 120 volt
-Victron VE Bus Smart Bluetooth Dongle

Items mounted inside the trailer behind the rear wheel:
-WFCO 8955 power panel with converter/ charger removed

I hope that the above system will be sinple enough to where I do not need a shunt based system monitor?!?!?


Of course I now have more questions...can someone PLEASE give some advice on these components:

-Type and gauge of AC cables 28 Lineal Feet from shore power receptacle mounted behind the rear wheels forward to the multiplus installed in the front pass through compartment

-Type and gauge of AC cables 28 Lineal Feet from multiplus back to WFCO power box AC source mounted inside the trailer behind the rear wheels

-Type and gauge of DC positive cable 4 Lineal Feet from battery + terminal to multiplus (I presume it should have an inline 60 AMP fuse)

-Type and gauge of DC negative cable 4 Lineal Feet from battery - terminal to multiplus (presume that since no shunt that it just goes from battery to multiplus connector and does it need a second cable from the battery negative to the chassis like in a car application)

-Type and gauge of DC ground cable 4 Lineal Feet from multiplus to chassis ground as called for in the instructions

-Type and gauge of DC positive cable 28 Lineal Feet from multiplus to WFCO power box DC source

-Dongle (it gets taped to the battery) the questions is should the dongle + cable get connected to a dedicated fuse on the fuse block installed next to the multiplus or is it best if it gets connected directly to the battery poles...then how can the dongle WIFI get turned off)

Anyway I am getting close so THANKS for the help!!!

 

[jackiemac]

Welcome to the forum. Those questions could be in Klingon and I still couldn't help. Hopefully one of someone can help you out though.

Live long and prosper!

 

[Vibe101]

Sorry I have already been assimilated

Thanks for the welcome.

 

[zulu]

The Victron MultiPlus II is a 50A inverter that can be wired right to the incoming AC power like the diagram below.

For your 30A setup use a 30A inverter. See my post #14 in Solar Charging Systems > Inverter Wiring.

 

[niget2002]

I have 0 practical knowledge of any of this, only theoretical from what I've been reading on my own so far.

My understanding is that a DC/DC converter is recommended between the tow vehicle and the battery for charging while travelling down the road.

I'm looking at using one of these:

https://www.amazon.com/dp/B0851TPKV7/?coliid=I1FUPQHB5HRLLA&colid=2K8024IK5XSM5&psc=1&ref_=lv_ov_lig_dp_it

My understanding is also that the Multiplus II can be setup to limit input current to run as a 30A unit. I don't know if that's appropriate usage for this device or not. I'm not sure if I'm going to with this part of my setup. I'm still figuring this out myself.

 

[DonTom]

Another question is what about charging from the truck alternator?

If you want the lith battery to charge to full as you drive, buy one of these thingies. I just installed one in my Y2K RV and I am in the process of installing one in my new RV for my added lith battery.

-Don- Reno, NV

 

[UTTransplant]

Adding a 30 amp DC to DC charger between the alternator and battery system is needed if your alternator isn’t beefy or if you let your Li batteries get particularly low. Our alternator is beefy (diesel Class A), but Kevin loves gadgets so he put one in anyway. Makes for one less thing to worry about. The one he put in is the Orion Smart Shunt from Victron, but I can’t remember the specific model. We can monitor it via Bluetooth, but we haven’t needed to after we saw it working well.

 

[DonTom]

Adding a 30 amp DC to DC charger between the alternator and battery system is needed if your alternator isn’t beefy or if you let your Li batteries get particularly low.

Or if you want the lith batteries to charge to full 100% SOC as you drive, or do diesel alternators have a higher voltage output than a gas rig? I wouldn't think so.

-Don- Reno, NV

 

[UTTransplant]

My alternator puts out 160 amps, but many smaller rigs put out 75-100 amps. If the SOC is low, there will be a heavy pull from the alternator that can burn the alternator up. Alternators aren’t designed to have large continuous pulls. We never worry about charging from the alternator because we run a bunch of solar. We can get up to 130 amps dumping into the batteries with 100 from the solar and 30 from the alternator. Like I said, we don’t really need the limit on the alternator, but Kevin likes electrical gadgets (old electrical engineer), and if the alternator gets weak in the future, we have nothing to worry about. Bored at home due to COVID plus opportunity to modify electrical components means Kevin installs “stuff.”

 

[DonTom]

If the SOC is low, there will be a heavy pull from the alternator that can burn the alternator up.

To be safer, I always have my lith battery fully charged before a trip in my Y2k RV. But I recently installed a DC2DCC in it.

My added lith battery in my new RV doesn't charge while driving, but I will soon be changing that with the same type of DC2DCC as I added in my Y2k RV. I am not sure why I am even doing this, because it has worked out perfectly as it is during my 3 month trip.

Now I have a DC2DCC installed in my old RV, but I cannot claim that I understand how the thing works. How can it reduce the load to my alternator?

Since it is raising the voltage, the current draw on its input should even be higher with the DC2DCC installed than not having it. There is no possible way to get more wattage than I started with. So what does this thing do to save my alternator, if anything? I know the DC2DCC will charge my lith battery to full, but I wondered what happens then the lith battery SOC is low and askes for a ton of current.

Anybody here know how the thing works?

-Don- Reno, NV

 

[Lou Schneider]

Since it is raising the voltage, the current draw on its input should even be higher with the DC2DCC installed than not having it. There is no possible way to get more wattage than I started with. So what does this thing do to save my alternator, if anything? I know the DC2DCC will charge my lith battery to full, but I wondered what happens then the lith battery SOC is low and askes for a ton of current.

Anybody here know how the thing works?

-Don- Reno, NV

It's basically acting like a two stage battery charger, similar to a constant voltage regulated AC converter. If the 30 amp current limit is reached, the output voltage sags to the point where the current doesn't exceed 30 amps. Just like a converter/charger in Bulk mode.

Once the current demand decreases (i.e the battery is charged), the voltage rises to the 15 volt regulated setpoint, where it stays unless the current draw again exceeds 30 amps.

The reduced stress on the alternator comes from the load not exceeding 450 watts (15v x 30a), less if the output voltage is reduced due to reaching the current limit.

 

[DonTom]

The reduced stress on the alternator comes from the load not exceeding 450 watts (15v x 30a), less if the output voltage is reduced due to reaching the current limit.

I was hoping you would reply to that!

But . . .

How can it NOT exceed 450 watts if the DC2DCC is drawing 450 watts alone, when the alternator is running much more than the DC2DCC? It's also charging the engine battery and running other stuff in the vehicle.

What is in the DC2DCC to tell the alternator to not exceed its 450 watt capacity?

-Don- Reno, NV

 

[DonTom]

@Lou Schneider

I see most alternators are usually rated well above 30 amps, so my question really should be how can we be sure we are not overloading things by adding that 30 amp additional draw?

-Don- Reno, NV

 

[Mark_K5LXP]

What is in the DC2DCC to tell the alternator to not exceed its 450 watt capacity? how can we be sure we are not overloading things by adding that 30 amp additional draw?

I can't speak to this converter specifically, but Lou described it correctly. It's going to be a form of current limit, the supply senses the current through it and will reduce the output voltage to not exceed that setpoint. In a past life I worked a lot with Vicor converters and they will hold whatever current setpoint you program, even into a direct short. To your second point, there is nothing to stop you from overloading the alternator. It has a finite generation capacity, determined by the windings, regulation and rotational input. When it runs out, it basically will fall out of regulation and you get what you get for current and voltage. I wouldn't assume that any alternator is rated for 100% continuous output, they will typically have peak and continuous ratings. This is where the DC to DC comes into play for lithium. It's not a stretch to think that a dead lithium can soak up enough amps, in addition to operating the vehicle loads, that will exceed the continuous limit and burn it up. The DC to DC doesn't prevent this depending on the other loads, but it does at least reduce the demand from the battery.

Mark B.
Albuquerque, NM

 

[DonTom]

To your second point, there is nothing to stop you from overloading the alternator.

So what it is really doing is limiting the increase of load to 30 amps more than I now have in my new RV (my added lith now does not charge at all while I drive, until I install the DC2DCC).

IOW, If the 30 amp increase will overload the alternator, it overloads even with the DC2DCC.

The way it is advertised makes it seem like it was somehow doing the impossible, and that is what I wanted to be clear on.

IOW, I need to be concerned if an extra 30 amps will overheat my alternator.

-Don- Reno, NV

 

[niget2002]

Remember, anything I write is still theory. I haven't ordered anything yet

My plan is to get either the 15A or 20A DC2DC when I set mine up. The idea being that 'most' of the time the lith will be charged before we leave the house. At that point, the DC2DC is mostly just keeping the battery charged while it runs the 12V refrigerator keeping the cold snacks cool.

This should help to keep the wattage consumed by the DC2DC well within the capabilities of most alternators.

Also remember that the battery on your TV should act as a buffer for the alternator. If the DC2DC has a short high-amp power draw, it can pull some from the TV battery if it spikes above what the alternator can provide. Once DC2DC draw is back down, the alternator will top the TV battery back up.