RV with solar and DC-DC charger

[Swamplizard]

Hello again Folks.

RV/VAN has 2S2P 100watt flexible solar panels feeding into a LV2424. Power goes from LV2424 (MPPT) to a positive and negative bus and into my BMS (neg).

I also have an Orion Smart DC to DC 10AMP 12v to 24v connected to the two busses (Neg and Positive).

When sun shines the solar is charging the battery. When the Van is running at night or solar is disconnected, it charges the battery. IF it is sunny and the van is running only the solar seems to be charging. Is this normal? I had hoped to get the benefits of both while driving but I dont see it.

Config issue on Orion perhaps?

Thanks

Swampy

 

[sunshine_eggo]

The chargers need to be configured identically, and there needs to be negligible losses in the connections/wiring.

I suspect that the MPPT may have a better connection to the battery (since they're also the inverter cable), so there is less wiring loss between MPPT and battery. Due to wiring losses, the DC-DC "sees" a higher voltage, and it charges at much lower current than you would expect.

Double check that all crimps are of high quality and all connections are solid and torqued properly. Confirm the wire gauge you have used is suitable for the voltage and current.

 

[MisterSandals]

IF it is sunny and the van is running only the solar seems to be charging.

Why do you suspect only the solar is charging? What does the Orion show in the app? Can you post a screen shot along with what your LV2424 is showing?

In general, chargers charge when they need to. So if your solar is applying a 28V charge voltage, your Orion might see this voltage (and it will be a combination of battery voltage and charge voltage) and determine, based on its settings, that the battery does not need to be charged.

So as sunshine_eggo alluded, they need to be configured identically if you want them both to charge at the same time. Your system sounds like it is setup to charge with solar as a priority (lower charge start voltage than the Orion).

 

[Swamplizard]

Thank you Folks - good answers. I will check the configs on both and make them match. At night one would think that I would see the entire 10 amps out of the Orion or about 240 watts pumping through the smart BMS (assuming battery is low) and I am not. I will check crimps etc.

 

[sunshine_eggo]

At night one would think that I would see the entire 10 amps out of the Orion or about 240 watts pumping through the smart BMS (assuming battery is low) and I am not. I will check crimps etc.

Causes:

1. Battery state of charge (in absorption and won't take more than 10A
2. Too much voltage drop between Orion and battery due to cable size/length.
3. Voltage drop due to bad components (fuses breakers) or poor connections (bad crimps or untorqued bolts)

#1 can be eliminated by imposing a large load on the system that is greater than the charging current of the Orion.

#2 and #3 can be confirmed as contributory by looking at the reported voltage in the VC app and then comparing to a quality calibrated voltmeter measuring voltage at the battery terminals. The difference between the two is the voltage drop resulting from #2 and/or #3.

 

[Swamplizard]

Orion to battery is 24 inches and there is a 50 amp resettable breaker before the positive bus connection. All seems to check out.

I will try load test this weekend.

I have both the lv2424 and orion set to max volts set to 28.2 with float at 27.2 could that be issue?

 

[sunshine_eggo]

Orion to battery is 24 inches and there is a 50 amp resettable breaker before the positive bus connection. All seems to check out.

If it's a cheap Amazon breaker, they've been known to have excessive voltage drop and come nowhere near rated. It's also critical that the connections be secure - good crimps and torqued fasteners.

I will try load test this weekend.

I have both the lv2424 and orion set to max volts set to 28.2 with float at 27.2 could that be issue?

No. You want them the same if you want them to charge the battery. Please read this post in its entirety:

Charging from multiple sources

One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank. Examples (some or all at once, even multiples of a single type, different brands, etc.): Solar PV via MPPT Solar PV via PWM AC-DC...

diysolarforum.com

Especially the "Note:" part.

 

[DJSmiley]

Double check the settings on the DC-DC charger with the app.

a 50 amp resettable breaker before the positive bus connection.

A proper one like BlueSea or a crap red/black chinese/amazon one?

The last ones are known to have massive voltage drop and suck. Replace with a proper fuse.

 

[Swamplizard]

Amazon one….oops

 

[dirt diggler]

Amazon one….oops

I've just replaced 2 of these rad/black amazon crap breakers, took a whole 4 months to crapout, 1 (from battery to fuse box) wont reset (no pwer at all let through) and the other (solar pan to MPPT) wont trip (on all the time) pressing the button does nothing and the trip lever snapped off when i tried to help it move with my finger nail
replaced both with bussman units (blueSea)

 

[Swamplizard]

To be honest it is passing 28v and isnt popping but …. Will replace

 

[sunshine_eggo]

To be honest it is passing 28v and isnt popping but …. Will replace

Breakers pop based on current.

 

[Swamplizard]

I understand that but it hasnt popped or anything.

 

[Swamplizard]

So I removed the ebay breaker to test...no change
Made sure the 280AH battery was at 50%
Then I unplugged solar from LV2424 completely and with van running and Orion saying it was sending 28.4 I saw no activity on the BMS interface.
I then changed Orion settings to 28.2/27 Float and did the same on the LV2424 and still no change....no activity from Alternator charge showing up on smart BMS.

Bit stumped. Maybe I will relocate my shunt to see what it sees coming out of the Orion.

 

[sunshine_eggo]

Show us a picture of the (-) wire from the Orion to where it attaches.

 

[MisterSandals]

no activity from Alternator charge showing up on smart BMS.

Can you post a screenshot of this? And any others with settings?

 

[Swamplizard]

BOOMSHAGALAGAH it was a bad connector on the positive cable to the fuse block. Thanks Folks for the assist!
Swampy