DC to DC charger question - Montana Owners Club

The McCoys · 08-07-2021, 08:14 AM

Hello all, I have two questions that I can’t seem to get definitive answers for to save my life. I should have posted here sooner. Here’s the equipment I’m using;

2017 Chevy 2500HD with Duramax Diesel.

Factory GM (Denso) 150 amp Alternator

My 5th wheel is a 2019 High Country 330RL

I have replaced the original 60 amp converter with a Progressive Dynamics PD9160ALV, which has lithium battery charging capability.

I’m replacing my single lead acid battery with (3) Battleborn Lithium Iron Phosphate batteries and relocating them aft to the heated area behind the storage compartment.

I’m installing a Victron BMV-712 Smart battery manager today. My questions are these;

1) Am I okay to install my new lithium batteries and converter, using the the 6 gauge wire used by the manufacturer to connect the original converter and battery?

2) Do I need a DC to DC charger, or will my alternator do the job by itself?

Thanks much, David McCoy

Ahdmeyer · 08-07-2021, 10:32 AM

just a question doesn't your fifth wheel have a charger converter in it ?

like this
https://www.amazon.com/gp/product/B0...KIKX0DER&psc=1

rames14 · 08-07-2021, 10:35 AM

Question 2 first. If you run wire direct from the battery to battery, you will burn out your alternator. There are two ways that I am aware of, a BIM or a Renogy type unit. I went with the Smart BIM, charges 20 minutes, off for 40.

As for the wires, mine are much heavier, but I might not be understanding which wires you are describing.

RipNC · 08-07-2021, 10:57 AM

David,

The PD in the lithium profile mode charges at 75 amps, make sure your coach 12v service wire is 4 gauge (our 2021 is) and replace the typical 50 amp auto-reset breaker with a 75 or 80 amp breaker (I prefer manual reset). If you don't change that breaker it will "break" whenever shorepower is on and you'll still have 12v in the coach from the converter but converter won't be charging the batteries.

The McCoys · 08-07-2021, 11:40 AM

The charger charges at 75 amps? But, it’s a 60 amp charger. It’s a PD9160ALV. I didn’t think it was supposed to be able to do that.

RipNC · 08-07-2021, 11:45 AM

Sorry! You're correct (thinking of my PD4575). You still should have 4 gauge but only need 60 amp breaker, the 50 amp will trip.

The McCoys · 08-07-2021, 11:54 AM

Quote:

Originally Posted by RipNC

Sorry! You're correct (thinking of my PD4575). You still should have 4 gauge but only need 60 amp breaker, the 50 amp will trip.

No worries, I appreciate the help. I’ve got 3 fuses mounted to the wall near the battery. I’ll have to find out which one of them is the one I need to change

RipNC · 08-07-2021, 01:09 PM

Top photo is what mine looked like before my changes, mine had the 80A manual reset breaker for hydraulics installed by factory. The red auto-reset in the center is the 50A I replaced (with 80 for mine - 60 for yours). In my case you can see the large #4 wire coming in from battery and a short #4 jumper to the manual reset breaker (hydraulics). Yours may be similar. The smaller wires on the left side auto-reset are loads that don't disconnect with the battery switch in the convenience center.

Bottom photo shows new configuration. The top breaker feeds the coach 12v (converter charge comes back on this wire). Same jumper to OEM 80A for the hydraulics (assuming you have hydraulics you may want to replace OEM 50A auto-reset with an 80A as many have done).

I realize yours won't match what was in mine but hopefully this helps.

Daryles · 08-07-2021, 04:04 PM

1) For your batteries, look at the specifications for max discharge rate. I have 552Ah lithium. I tried 4 gauge cables. When I ran the 1000W microwave from the 2000W inverter, the cables between the batteries and inverter reached 138⁰F in 5 minutes. I upgraded the wiring to 0 gauge welders cable. Repeated the test. They barely get warm now. I had my cables made at my local auto parts store.

2) I installed a Renogy DC-DC charger. Here's my install and test results.

https://www.montanaowners.com/forums...hlight=charger

hemiallen · 08-07-2021, 04:09 PM

Slight diversion from OP's question.

(I don't get internet / phone signal in my steel storage building, very frustrating situation, lol)

I just took a picture of what you posted above Rip and my 3120rl came with a black plastic cover hiding the breakers in your image with the #4 red hot from the battery. I am tempted to remove the cover mainly to see what size breaker came on mine. We did get the 80A hydraulic slide system upgraded from the factory.

I just finished installing my 300Ah Battleborns and have both the PD4575A charging them up, and a smart shunt to verify - monitor the batteries.

Surprisingly the PD ran them up to 14.4V ( 14.7 initially) and kept them at 14.4 overnight, and verified by the in command and inverter's readouts. I just turned off the main battery switch in the convenience center and after an hour they bottomed out at 13.3v, and the system has a I believe 0.5 Mah draw ( hate that the smart shunt doesn't allow me to read data stored when I am away from the rig ( won't connect). I turned the switch back on to charge them and the PD ramped back up to 14.4.

I am surprised the PD doesn't seem to be going into "float stage" like I thought it would do once the batteries get to 14.4, I thought it would back off and keep them at 13.6v.

Allen

RipNC · 08-07-2021, 04:18 PM

Daryl,

My discussion referencing 4 gauge above is regarding the 12v supply to the coach which is also the path for the converter to charge the batteries when on shorepower. Not sure what the OEM gauge is on the feed to the Magnum inverter (good size but unmarked or hard to see) but I will upgrade mine to either 2/0 or 4/0 when I install my Victron inverter.

RipNC · 08-07-2021, 04:46 PM

Allen,

When I initially installed mine, I had not yet installed my shunt and Balmar SG200 monitor. BTW I should have gone Victron like I'd done on my boats (for less money too!) but I wanted to see how the new Balmar worked (jury still out but 1st impression not good). Anyway... are you sure about what you're seeing on the batteries? Mine would read 14.4 on the Magnum display but wasn't actually charging the batteries because they'd suck down 75 amps and trip the auto-reset which would not reset unless I switched off shorepower (or threw the breaker to the converter). My house feed auto-reset was only 50 amps, perhaps they beefed yours up?

I don't believe the PD profile does drop into float when on lithium, but lithium doesn't need float per se, the current will just drop off to nothing. Battleborn even mentions this in a blog somewhere (though I use SOK batteries). I believe the Victron inverter/charger I'm waiting on will drop to float and/or I could change to a customized profile.

Photo shows mine (just taken) at 14.6 also using the PD4575 (sorry about photo - had to shoot portrait mode to read the Balmar in the photo).

hemiallen · 08-07-2021, 09:35 PM

Thanks
Yes, the batteries are also at 14.6 state just now, so the PD isn't dropping. I misread the draw, it is 0.5A with the main battery switch on, and the inverter reads 14.4, probably not as accurate as the shunt's readout.

I need to disconnect from shore power and run the tv, radio, etc to see the batteries actually drop some.

Allen

RipNC · 08-08-2021, 06:44 AM

Allen,

I'm curious, did you look to see what size the breaker is on that 4 gauge wire?

hemiallen · 08-08-2021, 04:37 PM

Ok Rip
I removed the cover and it looks similar to yours. Mine they eliminated the soft red covers and opted for a form-molded shield screwed cover. On mine the row of grey automotive breakers are very close, the left side one is a 30A unit, so I assume all of them are the same.

I disconnected from shore power and ran the batteries down to 95%, and need to go back out and run them down farther so I can run the generator/ pd4575 and see how fast the converter recharges them.

Allen

The McCoys · 08-11-2021, 07:03 AM

Thanks for all the input guys, it is certainly appreciated. It looks like I’ll have to replace the 6 gauge, with 4 gauge wire. There’s one thing I’m not clear on. That’s whether, or not I should put in a dc to dc charger. Is it common for the batteries to charge directly from the vehicle’s alternator, or does the alternator go through the converter first?

RipNC · 08-11-2021, 07:56 AM

Converter uses 120 volt AC which it converts to 12 volt (nominal) current to power coach and charge patteries when on shorepower ot generator. A DC to DC charger setup is great for charging batteries while moving. Setting up a DC to DC charger requires some careful planning. The charging wire in your 7 pin connector IS NOT what you use to supply the DC to DC charger.

My truck charging circuit isn't done but my shopping list for it is:

1 gauge cable (overkill)
175A Anderson connector
MRBF fuse holder and fuse (at truck battery)
Heavy duty 12v relay
60 DC/dc charger

Power will come into relay from MRBF (fused) and relay will be operated by an upfitter switch that only has power when the truck is running. Anderson connector at rear of truck will connect to pigtail to dc-dc charger. Charger connects to + and - busbars that connect to batteries.

My truck has 397 amp alternator and 2 batteries.

rames14 · 08-11-2021, 08:18 AM

Rip, they used 2/0 on our BIM install. Either way, wire is one of the big costs in a DC-DC project. Nice getting in with 100% battery. We also on hot days run both AC’s a while before arriving.

RipNC · 08-11-2021, 08:54 AM

Ron,

Mine calculated to 1 gauge using ABYC standards which are usually overkill. If I go up to single ought I might need to get some help to get that wire run. Doing a neat, protected jon of running the wire is my biggest concern on the project (so waiting for some cooler days here in NE AL).

A couple questions:

Were they able to run 2/0 thru the same path the truck harness uses or did they strap and protect it? Did you run negative back to the battery or to the frame?
Did you use welding wire or tinned copper?

PS - now I stop an hour out and fire the generator for AC, looking forward to doing my Victron inverter/charger so I can run a unit for that hour off batteries w/o the generator.

Thanks!

rames14 · 08-11-2021, 09:51 AM

They ran it at Future Sales. They ran it all the way back and protected it to the Anderson Connector, which is next to my 7 pin plug. With the BIM, I have an 80 amp manual breaker near the battery and also near the Super Solar box. The BIM is in the top of my front basement. They used welding wire. We were already in Goshen for a trip to MorRyde, so it was a dual trip. We are having our Jaboni 30 amp charge controllers upgraded to Victron 50 amp controllers in September. So, we’ll have BIM, 1200 watts of solar and our two Honda’s to keep our batteries charged. Our longest boondocking trip with the new camper is next week. Looking forward to it.

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