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Renogy DCC50S - Question

5K views 18 replies 6 participants last post by  OldDemps 
#1 · (Edited)
Question; If I'm using Renogy DCC50S DC to DC & MPPT controller, DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT

Which is better for battery / system monitoring on Input / output?

A Renogy 500A battery monitor - 500A Battery Monitor

OR

BT-2 blue tooth monitor? BT-2 Bluetooth Module

Why?

My other system components, all Renogy, 100AH AGM battery, single 100W flex solar panel on Van roof, DCC50S DC to DC & MPPT controller, 1000W 120V inverter. Small DC loads, LED lights, 12v cooler Etc. Application supports Weekend adventures only. Not full time vanlifer.

Thanks for your reply
 
#2 ·
Question; If I'm using Renogy DCC50S DC to DC & MPPT controller, DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT

Which is better for battery / system monitoring on Input / output?

A Renogy 500A battery monitor - 500A Battery Monitor

OR

BT-2 blue tooth monitor? BT-2 Bluetooth Module

Why?

My other system components, all Renogy, 100AH AGM battery, single 100W flex solar panel on Van roof, DCC50S DC to DC & MPPT controller, 1000W 120V inverter. Small DC loads, LED lights, 12v cooler Etc

Thanks for your reply
@Vanpackr posted a write up on the BT-2 on his website.
Renogy BT-2 Bluetooth Dongle for the DCC50S
Not sure if there is any benefit to the Renogy monitor since all your other stuff is Renogy, but FWIW the Victron battery monitor seem to be popular (and well liked) even by folks with systems that are not Victron based.
(I have no personal experience with any of these, just what I have learned from spending too much time on this forum)
 
#5 ·
The DCC50S charges your battery. The BT2 allows you to set a custom profile for the DCC50S. This is important if you are running lithium batteries as the default profile for lithium sucks. The monitor allows you to keep track of the amp hours pulled out of the battery.
 
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#6 ·
This is important if you are running lithium batteries as the default profile for lithium sucks.
Sorry to take this OT, but what are you basing this on? I didn't agonize over it, but I thought the defaults looked OK for my LiFePo4's. Maybe I should check that again?
 
#8 ·
Here's the table from the manual:

(I list a different model number in my signature below, but it's essentially the same thing)

152512
 
#13 ·
Interesting. I just watched very carefully as current tapered off while charging and I was thinking the opposite; that it was perhaps too low.

I'm also beginning to think that I'm not getting the full charge current when the unit heats up. More experimenting required on that front.

152519
 
#16 ·
for a 12V LFP battery "100% full" is 14.6V or 3.65V/cell The renogy settings look like they'll kill your battery if I'm reading that correctly. Usual recommendations for LFP are somewhere in the 14 - 14.4V boost charge and shutdown at no more than 14.6V.
 
#17 · (Edited)

It's going to depend a little on the brand. Here's an excerpt from the above linked page:

"For a 12V system, we really want to emphasize reaching 14.2V – 14.6V for bulk and absorption and float to be 13.6V or lower. "

(They do note multiple times that floating is not necessary or desirable, but that with some chargers this can't be shut off completely.)

Hence the 14.2 I'm seeing is on the low side. Frankly I'm not completely sure what they've meant by "shutdown voltage". Unless maybe if the output ever senses that voltage it won't charge - but it will never get that high unless something else is causing a fault.

There are effectively two stages for charging LiFePo4 batteries: 1. constant current (bulk), 2. constant voltage (absorbtion). When trying to accomplish these, feedback tells the charger what's happening with the battery. Entire books have been written on the subject, so this is an oversimplification.

A BMS between the cells and charger complicates things because it often requires higher voltages for balancing and/or have lower current capabilities than the cells. Internally the cell voltage is different than what's being applied to the terminals.
 
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