diy solar

diy solar

System has some issues

My batteries are at 11.8v according to dmm. I'm trying to see if my solar panels will charge the batteries since it's a really sunny day today. I checked the voltage coming in from my solar panels and it's 18v from the solar cable into the charge controller. Is that normal? There are 3 100 watt 12v panels. They are connected in parallel, all 3 positives into one branch connector and same with negatives.
18V is just about Vmp for a 12V panel, suggesting they are delivering Imp.
You can disconnect a panel and measure its Voc. Nicest to shut off whatever is drawing current before unplugging ("cold" not "hot" unmating of connector)
Check voltage of battery before shutting off, again after unplugging all panels. Out of interest, to see if there was a voltage rise due to current in.

If nothing else, you can wire a PV panel directly to the battery and monitor voltage. You are the PWM controller - 100% on during bulk charging, 100% off before voltage exceeds maximum target.
 
18V is just about Vmp for a 12V panel, suggesting they are delivering Imp.
You can disconnect a panel and measure its Voc. Nicest to shut off whatever is drawing current before unplugging ("cold" not "hot" unmating of connector)
Check voltage of battery before shutting off, again after unplugging all panels. Out of interest, to see if there was a voltage rise due to current in.

If nothing else, you can wire a PV panel directly to the battery and monitor voltage. You are the PWM controller - 100% on during bulk charging, 100% off before voltage exceeds maximum target.
I didn't understand any of that
 
I didn't understand any of that

If you have a "12V" panel, label probably says "21Voc" meaning 21 volts open circuit, no load. Probably says 17.5Vmp, meaning 17.5 volts is loaded with current to the point where it delivers maximum power. If a 100V panel, that will be about 6A in full sun shown as Imp . Label might say 7A Isc, meaning short circuit.

Because you measured 18V on the panel, I think it is probably delivering 6 amps or so to some load.
If you unplug the panel and get a higher voltage like 21V, then you know it had been delivering current when connected but now is not.

It is best not to plug or unplug with current flowing, because that burns surface of contact. If possible, shut off whatever charger or inverter might be drawing current.

If you don't have any other charger, you can connect a PV panel directly to a battery. Measure the battery voltage and panel voltage first (panel voltage needs to be higher than battery voltage.) Then connect panel to battery and measure voltage. If battery was 11.8V unconnected, might now read 11.9V at first. Over time, it will rise. Disconnect before voltage exceeds maximum allowed for the battery. The limit could be 13.5V, 14V, something like that. Check the manual, or look up on line.
 
The charge controller doesn't have an off. I'd just have to disconnect all of the connections.
 
Bribenn, I'm having the same issue, but only when my house battery is identified as being fully charged by the charger, indicated by the green light next to the battery image on the charger. When there is solar input and the the charger is in "trickle" charge mode for the the starter battery, indicated by flashing red light next to the picture of an alternator, the dcc50s is drawing from the house battery to support loads on the starter battery. Only in this scenario does the charger behave this way. Once the vehicle starts, the loads are taken over by the alternator and the charger begins charging the house battery. It seems that the charger trickle charges the starter battery at a fixed wattage from solar and any additional loads that aren't covered by solar a drawn from the house battery. Is this similar to what you're experiencing? I'm also using a victron BMV712 which is how I observed all of this. If I end up swapping out the charger, I'll let you know if it fixed it.
 
There are known problems with the Renogy DC to DC charger back feeding the starter battery from the house battery.

The BMV monitor needs careful setting up to ensure its capacity readings are correct. For the moment just refer to the volts and amps to fault find the system. Once you are happy the batteries are being charged correctly, then configure the BMV for your system . The problem with the BMV is that with the default settings and low current solar charging, it will synchronize to 100 charge way before the actual charge is 100%.
I think the basis of your problems in the Renogy unit. Separate solar chargers and dc to dc converters are always superior to combined units in performance, and give more flexibility and redundancy in the system.

The video testing of the Renogy unit did not show real life performance in a vehicle.

Mike
 
Bribenn, I'm having the same issue, but only when my house battery is identified as being fully charged by the charger, indicated by the green light next to the battery image on the charger. When there is solar input and the the charger is in "trickle" charge mode for the the starter battery, indicated by flashing red light next to the picture of an alternator, the dcc50s is drawing from the house battery to support loads on the starter battery. Only in this scenario does the charger behave this way. Once the vehicle starts, the loads are taken over by the alternator and the charger begins charging the house battery. It seems that the charger trickle charges the starter battery at a fixed wattage from solar and any additional loads that aren't covered by solar a drawn from the house battery. Is this similar to what you're experiencing? I'm also using a victron BMV712 which is how I observed all of this. If I end up swapping out the charger, I'll let you know if it fixed it.
Mike got the problem correct. My BMV was saying my batteries were 100% when in reality they were far below that. I did a slow charge with an actual battery charger until it was full and now the voltage is reasonable.

I can't speak to the rest of your issues because honestly, I don't know. My house battery charges well with the dc-dc charger as I drive and the solar charges as well, albeit not as much now that it's full winter in Michigan. I don't know if my alternator is taking power from my house batteries, but one strange thing is that when my car is running and I check my bmv, it says volts is really high, like 17.
 
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