New solar user and questions

[Joint Venture]

I recently had 1200 watts (6 200watt panels) of solar installed on roof, a Victron Smartsolar 150/100 charge controller installed, a Victron multiplus 2 3000watt inverter installed, a Victron smart shunt and misc wiring/components installed. So far it appears to be working well. I'm now considering having installed a DC to DC 30A charger for the two 270AH lithium 8D batteries. Good idea?

[Mark B]

I installed the dc to dc charger to limit the current draw of my lithium batteries. It will protect your alternator. You can use other options but Victron only has the 30 amp version. You can use two.

[timaz996]

In answer to your question, Bill, yes, it’s a good idea to add a DC to DC charger and make sure your installation does not charge your lithium house batteries like the factory installation did. I would hope your installers knew that and disconnected that feature from the alternator or your wiring set up. I use a 40 amp DC to DC Renogy charger on my set up.

Edited September 19, 2023 by timaz996

[CAT Stephen]

1 hour ago, Joint Venture said:

I recently had 1200 watts (6 200watt panels) of solar installed on roof, a Victron Smartsolar 150/100 charge controller installed, a Victron multiplus 2 3000watt inverter installed, a Victron smart shunt and misc wiring/components installed. So far it appears to be working well. I'm now considering having installed a DC to DC 30A charger for the two 270AH lithium 8D batteries. Good idea?

Since you are using shunts it is absolutely critical that you utilize ISOLATED DC to DC chargers so that your shunt readings will be accurate.  Renogy does not make isolated DC to DC chargers, but Victron Energy makes a mix of isolated and non-isolated DC to DC chargers.  

In your shunt use case, you should only consider purchasing Victron Energy ISOLATED DC to DC Chargers.

[timaz996]

An isolated DC to DC charger or not isolated DC to DC charger will make no difference if your shunt is wired correctly. The shunt will still measure everything going in the batteries and coming out. I went with the Renogy model because it was 40 A and a very easy wiring job because it just pulls current from the chassis battery while your alternator is charging it and only when the alternator is charging it.

[TomV48]

Well my travel partners have 1000 amps of LiFePo and 800 watts solar.    They still use the factory charging cross over, four years now,  with no problems YET.

I installed a 40 amp DC to DC Renogy and sometimes wish I had done 60 Amp but otherwise seems to keep me topped off every where we go  OH along with the 600 watts of solar on our roof .  With your investment in Victron might as well go with their DC to DC.  In for a dime in for a dollar or what ever.

[Joint Venture]

6 minutes ago, TomV48 said:

Well my travel partners have 1000 amps of LiFePo and 800 watts solar.    They still use the factory charging cross over, four years now,  with no problems YET.

I installed a 40 amp DC to DC Renogy and sometimes wish I had done 60 Amp but otherwise seems to keep me topped off every where we go  OH along with the 600 watts of solar on our roof .  With your investment in Victron might as well go with their DC to DC.  In for a dime in for a dollar or what ever.

Appreciate the response, I'm still wired alternator wise the way OEM wired it and no problems yet also. Just would feel better having it set up correctly with a DC to DC Victron Isolated 30A charger. We bought this coach May 5th and still ironing out details for boondocking which is about 90% of our camping. 

[TomV48]

1 hour ago, Joint Venture said:

Appreciate the response, I'm still wired alternator wise the way OEM wired it and no problems yet also. Just would feel better having it set up correctly with a DC to DC Victron Isolated 30A charger. We bought this coach May 5th and still ironing out details for boondocking which is about 90% of our camping. 

Then go bigger than 30 amp.   In case you need to pump up the coach batteries with the engine, rather than the genset and inverter/charger, faster is better.   Although,that said my inverter will charge at 100 amp and have it throttled back to 80 amps.   So, that charges pretty handily but when I'm on the road from point A to point B if it's a short trip 30 amp is not going to top off the batteries where a 60 amp, might have a better chance

[TomV48]

2 hours ago, CAT Stephen said:

Since you are using shunts it is absolutely critical that you utilize ISOLATED DC to DC chargers so that your shunt readings will be accurate.  Renogy does not make isolated DC to DC chargers, but Victron Energy makes a mix of isolated and non-isolated DC to DC chargers.  

In your shunt use case, you should only consider purchasing Victron Energy ISOLATED DC to DC Chargers.

 

Well it should be simple.   Shunt is the only thing hooked to the Negative terminal of the battery and all negatives or grounds hook to the other side of the hunt.  A simple buss bar can be added to give plenty of hook up points for Negatives.