20 replies to this topic

[Jack]

Camelracer, the 30A doesn't have load outputs - only the 15A and 20A. Sure wish it did - the Victron bluetooth is wonderful. I have the remote battery temperature/voltage sensor as well and that too has bluetooth. Just for curiosity, we have queried it from the cab to get an estimate of the temperature in the camper.

[rando]

I am not sure what the purpose is of the relay you are adding?   Why not just connect the iota to the input to the DC-DC directly?  The only possible 'issue' (I would call it an advantage) is that the iota would also charge your starting battery when you have shore power. 

 

Also 10AWG wire is fine with a  DC-DC converter, one of the big reasons to install a DC-DC is so you don't have to rewire the camper connection. 

[Jack]

Interesting. Had not thought to connect the Iota and alternator together. In cold weather, I sometimes start the truck to warm it up while I pack up the camper and disconnect shore power. Not sure how the truck ECU would feel about an outside source, but it should be ok. It would be the same as having a 120V battery charger connected.

[rando]

I don't see any issue with connecting the iota to the starting battery (electrically the same as the alternator, but easier to wire to).   My starting battery is getting charged by the camper solar (bi-directional ACR) which is functionally the same thing, and it has caused no issues.  

 

One other thing to be aware of - if you plumb the iota into the input of the DC-DC converter, it will draw a continuous 30A + from the iota.   You may want to be careful that the iota can handle that, I think my iota is only rated for 30A.   Normally the voltage could sag to reduce the current at high loads, but that won't work with the DC-DC converter.  If the iota voltage decreases, the current will actually increase, which could overload the iota.   It may be safer to limit the Orion to 20 or 25A charge current. 

[veryactivelife]

veryactivelife, if your Iota has the lithium IQ4, no need to run it through the DC-DC. Or if you have the external IQ4 AGM, you can swap it for the lithium IQ4. I also read that if the IQ4 is external, you can remove it and adjust a pot to set the Iota for a constant 13.8V

I have the built in IQ4 AGM. The Iota outputs a float voltage 13.6V The lithium wants 13.8V for float The Iota with IQ4 AGM will still charge the lithium battery, but not fully and not optimally. Since the relay sets me back all of $15 it was an easy and cheap way to "convert" the Iota to a lithium charge profile.

ckent323, I'd have to look at my 30A MPPT - it's behind the front panel (with bluetooth, I don't need to see it). I recall it was easy to wire it, so it probably will at least accept 8 gauge. The DC-DC looks like it will accept 6 gauge.

FWC runs 10 gauge from the solar panel connection on the roof and this will easily handle as much panel as you can get on the roof. (At higher wattages, connect two panels in series and run 24V to the charge controller). The maximum power point for panels is around 17V. That's a maximum 20A at 340W of 12V panels. The round trip run from the panels to the charge controller is about 30', resulting in a voltage drop of .67V or a loss of about 12W. If you go to 7 gauge wire (half the resistance of 10 gauge), your loss only drops to 6W. The cost of 12W more of solar panel is much cheaper than the cost of 8 gauge wire. I don't even want to think about what it would take to rewire the camper.

Jack, I have the Iota with onboard IQ4 same as yours. As you say it will work for lithium, just not as efficiently and will not get the battery up to 100%. I’ll be interested to hear how your switch idea works out.

ckent323 and Jack, the 30A MPPT and the DC-DC will accept 6 gauge wire. The smaller units only 10 gauge.

Dean

[veryactivelife]

I am not sure what the purpose is of the relay you are adding?   Why not just connect the iota to the input to the DC-DC directly?  The only possible 'issue' (I would call it an advantage) is that the iota would also charge your starting battery when you have shore power. 

 

Also 10AWG wire is fine with a  DC-DC converter, one of the big reasons to install a DC-DC is so you don't have to rewire the camper connection. 

rando, I don’t know about other DC-DC chargers but Victron specs either 6 or 4AWG depending on length of run. 

[rando]

rando, I don’t know about other DC-DC chargers but Victron specs either 6 or 4AWG depending on length of run. 

 

While Victron doesn't make this clear - that spec would only apply to the output of the DC-DC converter.   The concept behind the DC-DC charger is that it will convert whatever voltage it gets on the input (between 8 - 17V) to the correct voltage for charging your battery.  Because of this, voltage drop on the input wires doesn't matter as long as the wire is rated to carry the current and the input voltage doesn't go below 8V.   For a 30A charger, standard 10 AWG wire is more than sufficient with a conservative current rating of 51A.   

 

Now on the output side, voltage drop matters, so using heavy gauge wire between the charger and battery is a good idea, as is putting the charger as close to the house battery as possible.

[Jack]

I've pulled the front panel off the kitchen - and lo and behold, there's enough room for both the DC-DC and the MPPT. I'm building an aluminum frame screwed to the top and bottom of the area under the counter to hold both units. I've got some 6 gauge so I'll run that to the battery.

 

I put 2 calls into FWC to get info on wiring the DC-DC but no reply yet.

 

There are two wires connected to the Aux battery post on the battery separator. One wire I'm pretty sure goes back to the battery but with the positive from the Iota tied into it and a wire to the master switch as well - somewhere in that dark cavern behind the circuit breaker and fuse panels. I think if I just disconnect the line from the truck to the battery separator and connect it to the DC-DC and then run the DC-DC directly to the battery (and leave the two Aux post wires tied together), I should be good on charging from the alternator. I can get to the positive wire from the Iota, and if I cut that and run it to the DC-DC, that should take care of the Iota. I'll leave the original wire from the battery separator to the battery connected, since this should be the wire to the master switch.

Edited by Jack, 04 June 2020 - 08:14 AM.

[Jack]

Looking into the warren of wires at the bottom of the cabinet, there are at least two ground buss bars. No way to find a single ground wire for the load for a shunt to measure camper accessory current.

 

When I wired the Iota to the DC-DC Charger, thought I was down to one positive wire from the battery to the fuse panel so I inserted a Hall effect DC doughnut but it does not look like that is the case, but instead, there is another positive path from the fuse panel. I'll troubleshoot that next - I just finished the DC-DC Charger install: https://www.wanderth...-2015-fleet-fd/

 

[Vic Harder]

Looking into the warren of wires at the bottom of the cabinet, there are at least two ground buss bars. No way to find a single ground wire for the load for a shunt to measure camper accessory current.

 

?  Mine is installed in the battery box, a few inches from the batteries.  No need to hunt for a bus bar.  In some cases, people have velcro'd the shunt to their batteries.