Renogy DC DC Charger w/ MPPT

[John Frum]

What is the "load side" of a breaker? A breaker is simply a switch with a monitor for too much current. There is no active or one-way circuitry in it.

Some breakers have polarity.
Sometimes the terminals are labeled "aux" and "bat".
Others may be labeled "line" and "load".
Polarized breakers may not effectively quench an arc if the current flow is opposite polarity.

 

[LSP]

The breakers have "load" printed by one of the lugs and "line" on the other. if you look closely at this image below, you can read the "oad" of the load.

 

[Hedges]

Ordinarily, orientation of polarized breaker could matter, because in case of fault current from battery flowing through it (backwards direction from when charging panel with PV), that is the critical case where you need it to work. So they are wired "backwards."

But in the case of the model shown it may not matter!!

Resettable Circuit Breaker - Voltage Drop

Hi all Thought I would just share this in case it helps save a little time for anyone else! I have had problems recently with my Victron Multiplus 24/3000 repeatedly going into low voltage shutdown when driven fairly hard - circa 80 Amps for 2-3 minutes while the washing machine heater is...

diysolarforum.com

Resettable Circuit Breaker - Voltage Drop

Hi all Thought I would just share this in case it helps save a little time for anyone else! I have had problems recently with my Victron Multiplus 24/3000 repeatedly going into low voltage shutdown when driven fairly hard - circa 80 Amps for 2-3 minutes while the washing machine heater is...

diysolarforum.com

Will says they're OK? Others think not?
"Blue Sea" or "Bussman", we would trust. But consider ratings, including voltage and AIC, vs. your battery bank and the short-circuit current it can supply.

You can select more expensive name-brand hardware, possibly a different form-factor, which would be better to bet your life, vehicle, or house on.

 

[Hedges]

Great, Thank-you. have another question: On the diagram, (again, see below), should the 70 A breaker be flipped over? It looks to me like the load is coming from the charger and going to the battery through the wire from the 70A breaker to the 250A breaker. So should the wire from the charger be attached to the load side of the 70A breaker and then the line side attached to the 250? My apologies for the dumb question, but I am brand new to this.

Wires routed to a higher AIC rated better quality 250A breaker may help. But my concern would be a fault not large enough to trip 250A breaker but sufficient to burn a less capable 70A one. These flat toggle breakers seem to have minimal capability.

Interrupt capacity is relatively low, especially at higher voltages. Good enough for an automotive starting battery only up to 24V.
Larger AGM bank or any size lithium would exceed it.

https://www.bluesea.com/products/7041/187-Series_Circuit_Breaker_-_Panel_Mount_70A

 

[berndpfrommer]

For the life of it I cannot get my Renogy DCC50S to go to "float" mode. It will stay in "boost" mode indefinitely (I waited for >2h). I'm charging from the alternator. I am using the BT-2 to set the float voltage to 13.8V, the boost voltage to 14.3V, using a "user" defined battery. The house battery charges successfully, the battery status light goes green, and no more charge flows into the battery. However, the DC app shows the charger never leaving "Boost" mode, and it holds the battery at 14.3V.

Has anybody observed the DCC50S transition from "boost" to "float" successfully? I would like to get this working because staying on 14.3V reduces the lifetime of the LiFePO4 batteries.

Thanks!

 

[Sgt Raven]

For the life of it I cannot get my Renogy DCC50S to go to "float" mode. It will stay in "boost" mode indefinitely (I waited for >2h). I'm charging from the alternator. I am using the BT-2 to set the float voltage to 13.8V, the boost voltage to 14.3V, using a "user" defined battery. The house battery charges successfully, the battery status light goes green, and no more charge flows into the battery. However, the DC app shows the charger never leaving "Boost" mode, and it holds the battery at 14.3V.

Has anybody observed the DCC50S transition from "boost" to "float" successfully? I would like to get this working because staying on 14.3V reduces the lifetime of the LiFePO4 batteries.

Thanks!

Can you set the "Boost" to 13.9-14.0V. Under your conditions, that might be better.

 

[berndpfrommer]

Can you set the "Boost" to 13.9-14.0V. Under your conditions, that might be better.

Yes, that's something I'll try next. Before I go down that route though I wanted to clarify explicitly that the "float" feature of the Renogy charger does not work (neither in "User" nor in "Lithium" mode). I have seen several posts on this forum saying something like "you need the BT-2 to set the float voltage" but none so far that says that after you set it, it doesn't work.

 

[John Frum]

Yes, that's something I'll try next. Before I go down that route though I wanted to clarify explicitly that the "float" feature of the Renogy charger does not work (neither in "User" nor in "Lithium" mode). I have seen several posts on this forum saying something like "you need the BT-2 to set the float voltage" but none so far that says that after you set it, it doesn't work.

For a test make a charge profile without float.
See if the charge will terminate.
The idea is to see if it is a charge termination problem or a float problem.

 

[berndpfrommer]

For a test make a charge profile without float.
See if the charge will terminate.
The idea is to see if it is a charge termination problem or a float problem.

The Lithium profile does not have a "float" entry, and the charger keeps the voltage up at "boost" voltage, even after no more charges flow into the battery, and the Renogy's battery status light is green (indicates charged battery).

 

[John Frum]

The Lithium profile does not have a "float" entry, and the charger keeps the voltage up at "boost" voltage, even after no more charges flow into the battery, and the Renogy's battery status light is green (indicates charged battery).

Ok, seems to be a charge termination problem.
Have you tried Renogy support.
My personal experience and reports from others indicate that it is terrible.

 

[RandyP]

For the life of it I cannot get my Renogy DCC50S to go to "float" mode. It will stay in "boost" mode indefinitely (I waited for >2h). I'm charging from the alternator. I am using the BT-2 to set the float voltage to 13.8V, the boost voltage to 14.3V, using a "user" defined battery. The house battery charges successfully, the battery status light goes green, and no more charge flows into the battery. However, the DC app shows the charger never leaving "Boost" mode, and it holds the battery at 14.3V.

Has anybody observed the DCC50S transition from "boost" to "float" successfully? I would like to get this working because staying on 14.3V reduces the lifetime of the LiFePO4 batteries.

Thanks!

The boost duration is 2 hours by default. You may have to wait longer for the device to go into float, unless you have successfully used the BT-2 to limit the boost duration to lesss than 2 hours.



And from a previous commen in this post (Select the link to see the comment I am refering to):

Renogy DC DC Charger w/ MPPT

The circuit breaker on the Rover looks like one that was posted a few months back that melted. It does not look like a high quality breaker. It looks like it is for an audio system, not a PV system. Its just sad. PSA: Please don't use knock off or "audio style" breakers!

diysolarforum.com

 

[berndpfrommer]

The boost duration is 2 hours by default. You may have to wait longer for the device to go into float, unless you have successfully used the BT-2 to limit the boost duration to lesss than 2 hours.

View attachment 67492

And from a previous commen in this post (Select the link to see the comment I am refering to):

Renogy DC DC Charger w/ MPPT

The circuit breaker on the Rover looks like one that was posted a few months back that melted. It does not look like a high quality breaker. It looks like it is for an audio system, not a PV system. Its just sad. PSA: Please don't use knock off or "audio style" breakers!

diysolarforum.com

I waited about 3h after the battery was fully charged, and it still didn't go into float mode. I agree with your emphatic assessment of this product. The BT-2 so far has not given me nearly as much grief as the other users are experiencing but if the charger cannot properly charge a LiFePO4 battery it's a serious issue. Will try to lower the boost charge time and the boost voltage as @Sgt Raven has suggested to see if that does any good.

 

[RandyP]

I waited about 3h after the battery was fully charged, and it still didn't go into float mode. I agree with your emphatic assessment of this product. The BT-2 so far has not given me nearly as much grief as the other users are experiencing but if the charger cannot properly charge a LiFePO4 battery it's a serious issue. Will try to lower the boost charge time and the boost voltage as @Sgt Raven has suggested to see if that does any good.

Are your LiFePO4 cells prismatic or cylindrical ?
Are you using the USER battery profile or the LITHIUM battery profile ?
Can you post a screen shot of your settings using the BT2 or Home app ?

 

[berndpfrommer]

Are your LiFePO4 cells prismatic or cylindrical ?
Are you using the USER battery profile or the LITHIUM battery profile ?
Can you post a screen shot of your settings using the BT2 or Home app ?

I'm using a pair of OhmMu Group 31 batteries which I believe are prismatic cells.

Manufacturer recommended settings:
Absorption: 14.4 to 14.6 volts
Float: 13.5-13.6 volts

I am feeding 15.8V into the alternator/starter battery from a converter which is pretty high but should not affect results (the charger also doesn't go into float mode when feeding from a real alternator with a voltage of 13.7).
I measured the resting voltage of the fully charged battery to be 13.67V

I tried both the USER (white light) and LITHIUM (blue light) profiles, but the test below is in USER mode.

Here are screen shots of my settings for test 1:
battery type: USER
boost voltage: 14.3V
float voltage: 13.3V
boost time: 10min

The current drops to strictly zero eventually, but the voltage stays near 14.3.

 

[berndpfrommer]

Here another test, again USER mode, this time with boost at 14.5 and float at 13.5 (battery manufacturer's recommended setting).
The graph of the current this time only captures the tail end. The current fluctuates between 0.1A and 0A, but stays increasingly longer at 0A. Not sure there is any meaning to it or if it's just noise. Eventually it does go strictly to zero.
Interesting that the BT-2 app says for battery status: "Close". Whatever that means.

 

[RandyP]

I would say from your post you know what you are doing and the data matches the statements you have made. I do not know why the Renogy DCC50S is not going to float. I think Renogy should replace it or refund your cost for it.
I was never satisfied with the DCC50S I played with for a year. Gave it away. Moved on to Victron and Sterling (Both high dollar, but they seem to work as advertised and explained in their manufacturer manuals). I'm a little happier now.

 

[max4296]

Here another test, again USER mode, this time with boost at 14.5 and float at 13.5 (battery manufacturer's recommended setting).
The graph of the current this time only captures the tail end. The current fluctuates between 0.1A and 0A, but stays increasingly longer at 0A. Not sure there is any meaning to it or if it's just noise. Eventually it does go strictly to zero.
Interesting that the BT-2 app says for battery status: "Close". Whatever that means.

Hi, have you had any luck with issue since your last post? I'm also currently dealing with perpetual "boost mode" on my DCC50s. The other issue I'm having with the controller is that once the battery is fully charged and the status light goes to green, it never transitions back to orange light no matter how low I run the battery -- it always indicates green for full battery.

After some back and forth with Renogy, I received a brand new replacement unit last week and it has the exact same issues! Was just on the phone with tech support and they suggested fiddling with my battery monitor, which I tried and it did not fix anything. Other than these two issues everything in my setup works perfectly -- very frustrating!

 

[berndpfrommer]

Hi, have you had any luck with issue since your last post? I'm also currently dealing with perpetual "boost mode" on my DCC50s. The other issue I'm having with the controller is that once the battery is fully charged and the status light goes to green, it never transitions back to orange light no matter how low I run the battery -- it always indicates green for full battery.

After some back and forth with Renogy, I received a brand new replacement unit last week and it has the exact same issues! Was just on the phone with tech support and they suggested fiddling with my battery monitor, which I tried and it did not fix anything. Other than these two issues everything in my setup works perfectly -- very frustrating!

Still the same problem with perpetual boost mode. Just came back from some more fiddling with the settings, using the BT-2 app. I'm gradually turning down the boost voltage to see what happens. I want to get to the point where it stops charging at 95%. The general rule is that you should not let the batteries sit at 100% charge for long time, so if I can get the charger to not charge all the way up, that may be an acceptable alternative to full charge, then float.

About the green light: yes, I've seen some strangeness with that, too, but eventually after a while it does show yellow (normal). I don't really care too much about the light so long as the charging works. Right now it doesn't.
I also posted about this on the Renogy forum (you need to get a login to see the responses). Got some configuration suggestions back with one guy claiming it works for him and several giving promising, but ultimately unsuccessful help.

 

[max4296]

Still the same problem with perpetual boost mode. Just came back from some more fiddling with the settings, using the BT-2 app. I'm gradually turning down the boost voltage to see what happens. I want to get to the point where it stops charging at 95%. The general rule is that you should not let the batteries sit at 100% charge for long time, so if I can get the charger to not charge all the way up, that may be an acceptable alternative to full charge, then float.

About the green light: yes, I've seen some strangeness with that, too, but eventually after a while it does show yellow (normal). I don't really care too much about the light so long as the charging works. Right now it doesn't.
I also posted about this on the Renogy forum (you need to get a login to see the responses). Got some configuration suggestions back with one guy claiming it works for him and several giving promising, but ultimately unsuccessful help.

Awesome, I may go down that route as well with custom settings through BT2. I'll let you know if there are any real solutions renogy tech support offers, although it increasingly seems like this is just a bug of this particular charger.

 

[DaPhatty]

Got really frustrated with the poor organization of the DCC50s manual and tossed together a table that shows the DCC50s Icons, their proper names, and their associated light codes, all in the proper order and on one page. Figured I'd share it here. Hopefully someone else finds this useful.