Renogy DC DC Charger w/ MPPT

[chevymike]

Chevymike, that would be awesome. I'm a novice. How would you wire up the relay?

Here is a quick diagram of how you would do it. Make sure you have a relay rated for at least 20% more than your max amps. Common "Bocsh" relays are typically 40 amps but have seen some that were 30. Make sure the Ignition switch + is only on when the key is in the Run position, not also in the accessory position.

 

[8milimeter]

Just got my Van system going using the DCC30. I wanted full control of when the alternator was charging so I installed a Solenoid. Set ups works flawlessly and I am getting 32 amps into the batteries.

 

[UncleTodo]

Here is a quick diagram of how you would do it. Make sure you have a relay rated for at least 20% more than your max amps. Common "Bocsh" relays are typically 40 amps but have seen some that were 30. Make sure the Ignition switch + is only on when the key is in the Run position, not also in the accessory position.

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Could you add a second relay so that when the key is off, it disconnects the starter battery?

 

[chevymike]

Could you add a second relay so that when the key is off, it disconnects the starter battery?

You could. Make sure you have a relay rated correctly for your charge loads. Using the diagram I posted, use the Normally Open (N.O.) connection instead, so this way when you turn off the vehicle, the relay will NOT be drawing any current. It would only connect when the ignition is on and in theory, you would have the engine running.

 

[UncleTodo]

You could. Make sure you have a relay rated correctly for your charge loads. Using the diagram I posted, use the Normally Open (N.O.) connection instead, so this way when you turn off the vehicle, the relay will NOT be drawing any current. It would only connect when the ignition is on and in theory, you would have the engine running.

Okay, great. So let me ask this and veer off topic a little. Instead of the DCC50S, could I just use a regular DC-DC charger and relays to select + input from solar or alternator pending the state of the ignition switch?

 

[chevymike]

Okay, great. So let me ask this and veer off topic a little. Instead of the DCC50S, could I just use a regular DC-DC charger and relays to select + input from solar or alternator pending the state of the ignition switch?

No. You must have a solar controller to regulate the solar power. 12v panels can output at max around 28v. Solar output is not like a standard vehicle alternator that has a very limited output range.

 

[UncleTodo]

No. You must have a solar controller to regulate the solar power. 12v panels can output at max around 28v. Solar output is not like a standard vehicle alternator that has a very limited output range.

Thanks!

So something I'm confused about on this unit, in Will's video he shows several times 25+ amps going into the house battery.
Before I found his video, I'd seen another video pointing out a spec on Renogy's site:
"Maximum Charging Current : 50A (25A Alternator / 25A PV)"
And due to this it got a thumbs down being the charge rating is shared between the two inputs but Will seems to debunk this.
So what's the real deal? (Sorry, newb here, forgiveness please if this has been address in the thread)

 

[dvspl]

Thanks!

So something I'm confused about on this unit, in Will's video he shows several times 25+ amps going into the house battery.
Before I found his video, I'd seen another video pointing out a spec on Renogy's site:
"Maximum Charging Current : 50A (25A Alternator / 25A PV)"
And due to this it got a thumbs down being the charge rating is shared between the two inputs but Will seems to debunk this.
So what's the real deal? (Sorry, newb here, forgiveness please if this has been address in the thread)

There is a lot of confusion on this topic. I have the Renogy DCDC50 installed in my motorhome. I do not have any solar connected (yet) and can get up to 50A from the alternator. The max alternator charge can be configured so I currently have it configured to a max of 30A but have tested it up to 50A. Here's what the manual says:
"Alternator charging The maximum alternator charging for...the DCDC50 is 50A.
Solar Panel input The maximum solar charging for...the DCDC50 is 50A.
Dual input (Alternator/Solar) The DCDC will always take as much power from the solar panel as it can before
supplementing that power from alternator input, up to the rated charging current.
If the MPPT charging current from solar input is not able to keep the service battery at
constant voltage charge stage, alternator will cut in to charge the service battery. In
this case, the maximum dual input charging will be limited to 50% from each source.
DCDC50: 25A from alternator, up to 25A from solar for a total of up to 50A."

 

[Ranchero7]

I have the DCDC50 and can confirm that during the daytime if there is any solar input at all, it limits the charge from the alternator to 25 amps. At night time with no solar I've seen it hit 48amps read off the BMS. I don't have enough solar to see if it will go over 25 amps daytime with no alternator input.

 

[pominoz]

I ordered one of these to go in a Toyota Coaster bus I'm going to be converting.

After ordering it occurred to me the bus is probably wired as a 24v system (unconfirmed at this point)

I emailed Renogy and asked if I could use a 24v to 12v transformer between the 24v starter batteries / alternator and the unit so the alternator power is within the limits of the Renogy spec.

They said "Yes the 24v to 12v transformer can be connected between the starter battery and this charger, please make sure the wiring is correct, thank you!"

Can anyone advise what kind of 24v to 12v transformer would be suitable here? I thought something like this: https://www.ebay.com.au/itm/NEW-DAY...P-DOWN-DC-DC-CONVERTER-INVERTER-/174203892335

But I'm a bit confused, surely this wouldn't trickle charge the starter batteries because the 24v to 12v process is only one way?

COMPLETELY new to all of this, so excuse the really dumb questions

 

[Hedges]

But I'm a bit confused, surely this wouldn't trickle charge the starter batteries because the 24v to 12v process is only one way?

COMPLETELY new to all of this, so excuse the really dumb questions

Seem pretty obvious it can't backfeed the 24V/12V DC-DC converter, so that at least isn't a dumb question!

You would need PV --> charge controller --> 24V battery to trickle charge it.
Maybe you could get away with paralleling a second MPPT charge controller on the PV inputs to the Renogy.
Otherwise dedicate a small one to the starter battery. Probably PWM would do for that charge controller.

 

[Reed Cole]

I ordered one of these to go in a Toyota Coaster bus I'm going to be converting.

After ordering it occurred to me the bus is probably wired as a 24v system (unconfirmed at this point)

I emailed Renogy and asked if I could use a 24v to 12v transformer between the 24v starter batteries / alternator and the unit so the alternator power is within the limits of the Renogy spec.

They said "Yes the 24v to 12v transformer can be connected between the starter battery and this charger, please make sure the wiring is correct, thank you!"

Can anyone advise what kind of 24v to 12v transformer would be suitable here? I thought something like this: https://www.ebay.com.au/itm/NEW-DAY...P-DOWN-DC-DC-CONVERTER-INVERTER-/174203892335

But I'm a bit confused, surely this wouldn't trickle charge the starter batteries because the 24v to 12v process is only one way?

COMPLETELY new to all of this, so excuse the really dumb questions

If your bus is indeed 24v then maybe consider ditching the renogy and getting a 24v to 12v battery to battery charger and a separate solar charge controller.

 

[pominoz]

Thanks both!

I think I'll keep the unit as I need 'something' pretty quick to put in place and if I can at least utilise the alternator > house batteries charging alongside solar this should do,

I'll figure out solar panels and might add a smaller panel to charge just the crank batteries or just install an isolator for when we're parked up - don't intend on stopping places for weeks and weeks on end so that should be OK

 

[pominoz]

Is the step down transformer I linked suitable?

Guessing I shouldn't go lower than 50A as that's what the Renogy unit is rated at?

 

[NelsonB]

So, never got an answer to my question on 11/20 regarding ideas installing a remote switch (up near the driver) to shut down the alternator charging to the LiFePO4 400Ah batteries - to effective "give it a break to cool off". I saw where Tito (RV with Tito) installed one with the 20A unit, but he didn't say how he did it. I was wondering if there was anyway to do it using the alt sensing wire. For the time being (and maybe permanently if I can't configure a remote switch), I've installed a battery cut-off switch inline from the wire going from the starter battery to the house batteries (I can call it remote if I ask my wife to reach back and cut it off for me )

A second question is a result of me being new and totally confused about the Renogy DCC50S and the current it's allowing from the solar panels. In Will's review, he states he's disappointed that the DCC50S limits the solar input to 25A. Then I read (and someone cited the manual to confirm) that the unit will allow up to 50A from the solar array if the alt. is inactive or inputting 0. In my case, if I've cut out the alt charging (using some sort of switch), can I use a solar array (I have yet to purchase) that can output a max of 50A? I'd like to know this before purchasing the panels.

Any help would be GREATLY appreciated!

 

[chevymike]

The DCC50S as I understand it is, if it ONLY sees solar input activity, it will charge up to 50amp (if your panels can output that). If it ONLY see alternator power activity, it will charge up to 50amp (assuming your alt can output that). If the controller see ANY solar input AND alternator input, it will use solar first, up to 25amps max and then add in alternator power up to 25amps max, equaling a total of 50amps. This is assuming your solar CAN actually supply the full 25amps.

Here is where Will did not like how the DCC50S works. If the unit sees any solar input and alternator input, it limits each source to a max of 25amps, regardless of if either can supply that amount. The example is, lets say your solar can only deliver 15amps, it will only allow the alternator input of a max of 25amps, so your total charging amount is 15+25=40amps. This is Will's gripe. If one OR the other input, you can get the full 50amps BUT if you have BOTH inputs running, it limits each to 25amps max instead of allowing the alternator to make up any difference the solar cannot provide. Example Will would have liked to seen was, solar supplied 15amps, so the alternator "should" supply 35amps, to allow the full 50amp charge profile. It does not do this and is the downside of this system.

Hope that makes sense.

 

[Reed Cole]

So, never got an answer to my question on 11/20 regarding ideas installing a remote switch (up near the driver) to shut down the alternator charging to the LiFePO4 400Ah batteries - to effective "give it a break to cool off". I saw where Tito (RV with Tito) installed one with the 20A unit, but he didn't say how he did it. I was wondering if there was anyway to do it using the alt sensing wire. For the time being (and maybe permanently if I can't configure a remote switch), I've installed a battery cut-off switch inline from the wire going from the starter battery to the house batteries (I can call it remote if I ask my wife to reach back and cut it off for me )

A second question is a result of me being new and totally confused about the Renogy DCC50S and the current it's allowing from the solar panels. In Will's review, he states he's disappointed that the DCC50S limits the solar input to 25A. Then I read (and someone cited the manual to confirm) that the unit will allow up to 50A from the solar array if the alt. is inactive or inputting 0. In my case, if I've cut out the alt charging (using some sort of switch), can I use a solar array (I have yet to purchase) that can output a max of 50A? I'd like to know this before purchasing the panels.

Any help would be GREATLY appreciated!

A relay on the voltage sensor wire for the starter battery should work. It would be easy enough to test just by disconnecting the sensor wire.

If that doesn't work then a heavy duty switch on the positive cable from starter battery to the charger definitely.

 

[samhandwich]

I've been trying to get a definitive answer regarding whether or not the DCC50s has a low-temperature cutoff when used with LifePO4 batteries. The "key features" cited by Will in his original post say that the charger does have temperature protection, but I can't find that on the Renogy website or in the manual. Responses to both an email and call to Renogy are that the unit does not cutoff at low temps, because they expect every LifePO4 BMS to have that functionality (which, I believe, is not the case). That said, I didn't get a great feeling of competence from the people I spoke to at Renogy.

Does anyone have an answer? I would try testing it myself, but it's not quite cold enough here yet.

 

[Reed Cole]

The DCC50S as I understand it is, if it ONLY sees solar input activity, it will charge up to 50amp (if your panels can output that). If it ONLY see alternator power activity, it will charge up to 50amp (assuming your alt can output that). If the controller see ANY solar input AND alternator input, it will use solar first, up to 25amps max and then add in alternator power up to 25amps max, equaling a total of 50amps. This is assuming your solar CAN actually supply the full 25amps.

Here is where Will did not like how the DCC50S works. If the unit sees any solar input and alternator input, it limits each source to a max of 25amps, regardless of if either can supply that amount. The example is, lets say your solar can only deliver 15amps, it will only allow the alternator input of a max of 25amps, so your total charging amount is 15+25=40amps. This is Will's gripe. If one OR the other input, you can get the full 50amps BUT if you have BOTH inputs running, it limits each to 25amps max instead of allowing the alternator to make up any difference the solar cannot provide. Example Will would have liked to seen was, solar supplied 15amps, so the alternator "should" supply 35amps, to allow the full 50amp charge profile. It does not do this and is the downside of this system.

Hope that makes sense.

I wish Will

I've been trying to get a definitive answer regarding whether or not the DCC50s has a low-temperature cutoff when used with LifePO4 batteries. The "key features" cited by Will in his original post say that the charger does have temperature protection, but I can't find that on the Renogy website or in the manual. Responses to both an email and call to Renogy are that the unit does not cutoff at low temps, because they expect every LifePO4 BMS to have that functionality (which, I believe, is not the case). That said, I didn't get a great feeling of competence from the people I spoke to at Renogy.

Does anyone have an answer? I would try testing it myself, but it's not quite cold enough here yet.

If it has a temperature sensor you can put the sensor in something cold like salt water that's been in the freezer to test.

 

[pominoz]

A second question is a result of me being new and totally confused about the Renogy DCC50S and the current it's allowing from the solar panels. In Will's review, he states he's disappointed that the DCC50S limits the solar input to 25A. Then I read (and someone cited the manual to confirm) that the unit will allow up to 50A from the solar array if the alt. is inactive or inputting 0. In my case, if I've cut out the alt charging (using some sort of switch), can I use a solar array (I have yet to purchase) that can output a max of 50A? I'd like to know this before purchasing the panels.

In Wills YouTube video where he tests this I'm sure it does pull more than 25A from solar alone if there's no alternator charging occurring (I might be wrong, the video is here.. Easy Solar Power for #vanlife and Off-grid RV Dwellers: Renogy DC to DC Charger w/ MPPT )