Using one solar charger and the ACRelays to charge all batts

[serpa4]

So, my 2018 came with the AGM/140watt solar system. The charge controller is 2 channel with 10% to start battery and 90% to house battery and nothing for the thruster/generator battery.
On a perfect mathematical day, it might see theoretically 9.3 amps x 13.5 volts to the house and 1 amp to the engine battery.

The C30 has 2 ACR (automatic charge relays) between the house and starter and between starter and thruster battery.
The ACR specs say: connect the house to engine battery when voltage exceeds 13.6 volts for 30 seconds or voltage exceeds 13.0 volts for 2 minutes. And if the engine battery sees 13.6 volts then the 2nd ACR connects the engine battery to the thruster battery.

So, looking at the wiring diagram I see the following:
House battery positive to to input/hot side of house battery cutoff switch. Hot side of house cutoff switch connects to the cold side of the parallel switch and the cold side of the parallel switch goes to the charge relay for the engine. Then the engine charge relay connects to the thruster battery.
So, if the solar is providing charging (up to 9 amps) to the house battery, the ACR should see the increased voltage on the house battery and close the ACR relay and allow those amps go from house to the engine battery. The thruster ACR should see the charge from the engine battery and thus close and send some engine charging to the thruster battery. I.e. a waterfall effect.
1) so why do we have a 2 channel solar charger for house and engine? If solar charges house, house then closes ACR and charges engine. Then engine charges thruster.
A single solar charge controller should charge all batteries through the two ACR relays.

I'm guessing that the single 140 watt panel will not sufficiently charge the house battery enough to make the ACR to the engine close and start charging the engine battery and thus not enough charge passing through another ACT to connect the engine to thruster battery. Then again, the ACR works on voltage and not amps. So, they should connect when solar sends 13.6 or whatever voltage to the house battery.

I'm installing a lot more solar for time on anchor without running the generator. I'll have a single large solar charge controller and let the waterfall effect charge all batteries.

 

[knotflying]

The acr's should open and close accordingly so the connection to the engine is a bit redundant. I still keep it at 90% house 10% engine. An MPPT controller will deliver more power to the batteries so that may be an item you may want to consider changing first. Interestingly the controller will most likely have only one connection for the battery and there is another one for direct connection to a 12v circuit. Someone like curt can chime in if I am incorrect.

 

[Red Raven]

Knotflying is correct that the ACR’s make the dual capability of the solar controller (and the triple capability of the shore charger) mostly redundant. The only case where I see an advantage of the dual capability of the solar charger would be at low sun levels that to not produce sufficient voltage to close the ACR’s. You are not going to get much charge at those low light levels anyway.

As far as I know there are no MPPT controllers with dual charging capability but I agree dual is likely not needed because the ACR’s will do the job in most conditions and the engine battery is not likely to discharge much at anchor. When on a trailer in storage over the winter with only solar to keep the batteries topped off is the only situation where the dual feature might still be needed. Very low light in winter may not result in the ACR closing but a small amount of charge would still be getting to the engine battery from the dual solar controller feature.

Curt

 

[serpa4]

Thanks all. That's what I hoped to hear.
I have two 435watt panels (not installed) and a 150/70 victron smartsolar charger (partially installed). Plus installed a victron BMV 712 to keep tabs on battery.

 

[Cutwater28GG]

same setup as me
http://www.tugnuts.com/viewtopic.php?f=5&t=16203&p=109584#p109584

ACR's close and charge goes to all batteries.

i didnt install the BMV but use a bluetooth battery sense module to tell the victron the temp and volts at the battery. does the BMV do this? its a cheap part and will make your charging more effective if it doesnt.

you create a network of the two devices in the victron software

 

[Cutwater28GG]

i have some other questions...
I suspect If you have AGM batteries your issue is likely to be battery capacity and not solar panel capacity. i find my 340W panel easily charges my batteries (c28) during the day. do you really need 870W of solar? The charge rates of AGM's are not that high compared with Lithium.

 

[serpa4]

i have some other questions...
I suspect If you have AGM batteries your issue is likely to be battery capacity and not solar panel capacity. i find my 340W panel easily charges my batteries (c28) during the day. do you really need 870W of solar? The charge rates of AGM's are not that high compared with Lithium.

No lithium....yet. one step at a time.

 

[serpa4]

same setup as me
http://www.tugnuts.com/viewtopic.php?f=5&t=16203&p=109584#p109584

ACR's close and charge goes to all batteries.

i didnt install the BMV but use a bluetooth battery sense module to tell the victron the temp and volts at the battery. does the BMV do this? its a cheap part and will make your charging more effective if it doesnt.

you create a network of the two devices in the victron software

Yes the bmv shares its temp and volts to the solar controller by BT. They are on the network. Sounds like we'll have similar setups in the future. AGM should take .2 x 100ahr x 4batt so up to 80 amps which i cannot get from 870 solar. But we have draw for micro, lights, pumps, etc throughout the day.