Dual Battery - Where to connect load(s)? (1 Viewer)

[ekolpack]

I'm plotting a dual battery setup with a Victron Orion XS 50A DCDC charger (see wiring diagrams here). 200 series Cruiser with Group 27 starting battery and probably an AGM/deep cycle second battery. I'll also be running a pretty beefy stereo system, 2000W inverter, portable fridge, misc stuff to the back). My question, how/where should I connect these loads? I planned to do pos lead of the AGM/deep cycle running to gear, then directly into solid ground on vehicle (everything fused of course).

My concern is that let's say I'm on a road trip bumping some Petty (as one tends to do), got the fridge going, and maybe some misc stuff happening in back, if I'm pulling more than 50A (only 600W @ 12v) then the second battery will slowly discharge by whatever amount I'm exceeding the 50A recharge capacity, correct? My sub amp alone is about 600W. So should I hook my stereo up to the starter battery so it can be recharged by the alternator, and everything else up to the AGM? Thanks fellas!

Also, I notice in this diagram on the Victron site

....battery grounds are tied together, then receive chassis/vehicle ground through the Orion itself. This suggests I'm supposed to disconnect the vehicle ground from the both batteries??? This doesn't seem right. In doing so, the ENTIRE starting current would have to travel through this little Orion unit, as well as any load on the AGM battery....that can't be right? Seems like a good recipe for a fire, or at least a fried DCDC.

Redarc BCDC1250 shows all grounds going directly to ground/chassis (batteries, BCDC itself, etc.)....which makes WAY more sense to me.

I'd call Victron directly but I've heard their support is lacking. Thanks fellas!

 

[ekolpack]

I like this option much better, even though current for the second battery is now passing through a smart shunt....not sure why that needs to happen. Something about isolated vs non-isolated chargers? Either way, this looks like the way to go, I don't trust that other diagram.

 

[cruiserpilot]

Don’t ground batteries together. Scared me there with that first pic.

 

[ekolpack]

Don’t ground batteries together. Scared me there with that first pic.

Well, assuming dual batteries are hooked to car chassis ground, they will be grounded together with a very low resistance path via the chassis, but everything else is grounded there too (alternator, starter, accessories, etc.) so current can flow from pos lead on whatever battery, through fuse(s), through load(s) and back via chassis ground. But if the only path for those batteries to chassis ground is THROUGH THE DC/DC, then all current for EVERYTHING will be forced to travel through the DC/DC. That seems insane. Did Victron just forget to include chassis ground symbols in this diagram? Or are they assuming both batteries will be grounded?

I'm going to contact Victron, unless I'm missing something here (maybe there's a super high current shunt or wire connection inside the DCDC??) this seems like a huge liability.

 

[elemenohpee]

I'm by no means an electrical expert, but I'm planning a similar install with an Orion XS and have been doing a ton of research. Take this with a huge a grain of salt...

My question, how/where should I connect these loads?

You could connect a bus bar between the DCDC and aux battery pos wire. In my case I plan to use a Blue Sea SafetyHub 150 to simplify where everything connects.

if I'm pulling more than 50A (only 600W @ 12v) then the second battery will slowly discharge by whatever amount I'm exceeding the 50A recharge capacity, correct? My sub amp alone is about 600W. So should I hook my stereo up to the starter battery so it can be recharged by the alternator, and everything else up to the AGM?

I'm guessing your amp probably draws significantly lower amps on average. I don't really see a reason to run your sub amp off your aux battery though unless you plan to use it with car off. Even so, you'd still want the rest of the stereo running off the aux battery in that case.

....battery grounds are tied together, then receive chassis/vehicle ground through the Orion itself. This suggests I'm supposed to disconnect the vehicle ground from the both batteries???

No idea why they chose to draw it this way, but I definitely don't think that's what they're suggesting. I think it's just to show that they all need a common ground. Keep all the existing grounds in place on your starter battery for sure. Ground the DCDC and the aux battery to the chassis and you should be good.

The second diagram shows the same ground path, they just added a smart shunt to monitor the battery.