Question for DC-to-DC charger users

[user 423]

Where have you located the unit?

 

[PlethoraOfGuns]

Depends on the unit I guess. But they can really be placed anywhere.

I placed my Victron unit inside, under kitchen seat, which is next to where I have my green batteries stored. My thinking was that I'd have it safe and dry. Also, I now have wiring straight from the starter battery to the rear electrical cabinet for any future reason. Not sure what, but the option is there.

 

[user 423]

^
So you have a short wiring run to the batteries and a long one to the charger input? How long is that run? Also, which model Victron?

BTW: if this is covered in your build thread,sorry.

 

[PeterPiper]

Depends on the unit I guess. But they can really be placed anywhere.

I placed my Victron unit inside, under kitchen seat, which is next to where I have my green batteries stored. My thinking was that I'd have it safe and dry. Also, I now have wiring straight from the starter battery to the rear electrical cabinet for any future reason. Not sure what, but the option is there.

Wanted to take a look at the P30 build.
Link seems broken for me?

 

[PlethoraOfGuns]

^
So you have a short wiring run to the batteries and a long one to the charger input? How long is that run? Also, which model Victron?

BTW: if this is covered in your build thread,sorry.

The positive wire from starter battery to charger is about 18'. The positive wire from the charger to the house battery is about 5'. I went with the Victron Orion TR Smart Non-isolated 30amp charger. Love it, works great with the flick of a switch. I do wish I had a slightly larger unit. But the 30amp is ok enough, and my stock alternator isn't upset about it. What dc-dc charger did you go with?

Wanted to take a look at the P30 build.
Link seems broken for me?

Hmmm, it appears the link was the for the old CRVL site. Good call, I guess we all need to update these things with the new forum. I updated the hyperlink so it should work now, thanks!

 

[user 423]

The positive wire from starter battery to charger is about 18'. The positive wire from the charger to the house battery is about 5'. I went with the Victron Orion TR Smart Non-isolated 30amp charger. Love it, works great with the flick of a switch. I do wish I had a slightly larger unit. But the 30amp is ok enough, and my stock alternator isn't upset about it. What dc-dc charger did you go with?

Haven't bought one yet but have been looking at the Renogy 40A. I have a van and may put the chgr under the PS seat. Might be a little dusty there over time but well ventilated.

Would be about 7' to house battery and 8' to starter battery so I can get by with 6awg which I already have. Did you run separate wires for ground or use chassis ground?

Can the Victron be wired so it's energized whenever the ignition is on? Or is there a reason to put it on a manual switch? Non-isolation?

 

[PlethoraOfGuns]

Everything gets dusty, don't worry about it. Just make sure the ventilation is good because these things put off heat and need to breathe. Be wary about wire sizing. When you calculate for voltage drop and wire size remember to calculate in ground distance as well. So if your wires run the same way from battery to battery, 13' of positive wire and 13' of negative wire means a distance of 26' to account for. I think 6awg is a bit small for 40amp. My whole van in aluminum so it was easy to just chassis ground all my negative wiring.

When talking about chargers and isolation basically they are talking about the ground between the batteries/alternators. Isolated chargers will have a terminal for starter battery negative and another terminal for house battery negative. Non-isolated chargers have one negative terminal if the batteries will share the same grounding.

The Victron units are completely programable. Everyone wants you to install their units into the vehicle ignition so they only turn on when engine is running. I wanted more control so I just wired it into a switch. In case I forget to turn off the switch, I have the unit programed to shut down if it senses too low of a voltage, as if the alternator wasn't putting out power. Wire it any way you choose, but just make sure to have proper fuse protection at each battery terminal.

 

[GoingMobile]

Under bed behind drivers seat. Underneath solar controller. On the Ford Transit there is a negative grounding point between the 2 front seats and a positive terminal on the side of the driver's seat. The starter battery is housed under the driver's seat. 6' and 8' wire lengths from terminals.

 

[PlethoraOfGuns]

Nice neat install!

 

[frater secessus]

I have a van and may put the chgr under the PS seat. Might be a little dusty there over time but well ventilated

I was unable to find a pic of the 20-40-60A DC-DC chargers to see if they have ribbed cooling fins on the back. If not, then orientation shouldn't matter. I bring this up because the 30-50A DC-DC + MPPT combo versions are aggressively ribbed and would prefer to be mounted upright for convective airflow.

Can the Victron be wired so it's energized whenever the ignition is on?

By default the Orion uses voltage detection to know when the engine is running. (source) Similar operation in that aspect to voltage-sensing relays.

Providing power to the remote ON/OFF circuit (and activating the feature) overrides voltage-sensing turns the charging on when demanded. (page 10 of the manual)

Or is there a reason to put it on a manual switch? Non-isolation?

Mine is a Voltage Sensnig Relay not a DC-DC, but here is my reasoning. I added a toggle switch because I prefer gentler charging under normal circumstances. The solar side usually charges at 20-25A (no problem) and the alternator charges at 20-30A (no problem), but 40-55A of the two combined is more than I want to feed the 100Ah LFP. <-- my preference, not telling others how to charge theirs

This particular VSR (Battery Doctor) has Alternator+ and Housebank+ lugs for power transfer and a thin ground wire for the unit's internal electronics. Chassis is the power negative return. I put the switch inline with the thin ground wire.

 

[user 423]

Be wary about wire sizing. When you calculate for voltage drop and wire size remember to calculate in ground distance as well. So if your wires run the same way from battery to battery, 13' of positive wire and 13' of negative wire means a distance of 26' to account for. I think 6awg is a bit small for 40amp. My whole van in aluminum so it was easy to just chassis ground all my negative wiring.

The Victron units are completely programable. Everyone wants you to install their units into the vehicle ignition so they only turn on when engine is running. I wanted more control so I just wired it into a switch. In case I forget to turn off the switch, I have the unit programed to shut down if it senses too low of a voltage, as if the alternator wasn't putting out power.

The Renogy manual specifies 6g for the input and 8g for the output as long as the run is under 10' (each way). But yeah, going bigger would be better. Maybe I'll use the 6g for output only. Since I have just one 100ah AGM battery I'm seeing now that I probably only need the 20A model. I do plan to use two batteries sometime in the future so not sure if that would be adequate for 200ah.

I've been looking at the Victron models and trying to figure which one I need. The BT would be good and I'm surprised Renogy doesn't offer that.

 

[user 423]

Under bed behind drivers seat. Underneath solar controller. On the Ford Transit there is a negative grounding point between the 2 front seats and a positive terminal on the side of the driver's seat. The starter battery is housed under the driver's seat. 6' and 8' wire lengths from terminals.

Very nice! Thanks for the inspiration.

Starter batt under the seat? Unusual but handy.

 

[user 423]

I was unable to find a pic of the 20-40-60A DC-DC chargers to see if they have ribbed cooling fins on the back. If not, then orientation shouldn't matter. I bring this up because the 30-50A DC-DC + MPPT combo versions are aggressively ribbed and would prefer to be mounted upright for convective airflow.



By default the Orion uses voltage detection to know when the engine is running. (source) Similar operation in that aspect to voltage-sensing relays.

Providing power to the remote ON/OFF circuit (and activating the feature) overrides voltage-sensing turns the charging on when demanded. (page 10 of the manual)



Mine is a Voltage Sensnig Relay not a DC-DC, but here is my reasoning. I added a toggle switch because I prefer gentler charging under normal circumstances. The solar side usually charges at 20-25A (no problem) and the alternator charges at 20-30A (no problem), but 40-55A of the two combined is more than I want to feed the 100Ah LFP. <-- my preference, not telling others how to charge theirs

This particular VSR (Battery Doctor) has Alternator+ and Housebank+ lugs for power transfer and a thin ground wire for the unit's internal electronics. Chassis is the power negative return. I put the switch inline with the thin ground wire.

Thanks. I've got some more research to do to try and figure how I'll go with this. Hadn't thought about charge rate so much.

 

[Calaverasgrande]

The manual for my Renogy DC5050S MPPT charger says orientation is not important. It does have big fins on the back and would probably cool more efficiently with fins facing up for convective flow though.
I mounted it sideways because it fit better for cable routing.
Had no problems yet, but it's only been through fall and winter like this.

As far as starter sensing. Most of the Renogy MPPT and other similar products from other brands will have an input for IGN wire which connects to a terminal on your 'Smart Alternator' or on a specific terminal on the fuse block.
I went down the rabbit hole on this.
Turns out my van (2017 Transit 150 cargo) is just shy of having the smart alternator.
If I had the dual battery option, or the XLT package. Or pretty much any other set of options on this van it would have the smart alternator. But I don't.
Except, I've left my DC charger on all freaking day by accident. It is smart enough to know not to pull current from the starter battery when the engine isn't turning over. Once the voltage drops below a spec level. Or perhaps it uses an internal shunt to do current sensing? Either way I look in the app and it shows either "-amps" or "0amps". Meaning it's seeing current go out for the DC fridge and lights. Or nothing is on.
So I don't think it is a huge problem if you don't have a smart alternator or relay.

 

[AmargosaWayne]

Because of space limitations I had to mount a 40A Rich Solar with vertical fins horizontally. No issues in the summertime with it, with high temps up to 100F.
It's not in an enclosed space, though, there is natural airflow in my setup, with a rooftop fridge vent and a lower side fridge door vent, it's also open to the interior of the RV. Reused a RV dual refrigerator's space for a chest type 12VDC compressor fridge and the solar support setup.