Renogy DC DC Charger w/ MPPT

Catastrofe · Jan 3, 2020

RandyP said:
The Renogy charger is cheaper. It also is physically bigger. The RedArc pigtails allow for a butt spliced sealed termination. Very clean and compact. No nuts to loosen up with vibration. No exposed termination points. No Maintenance required. Ideal for the 4Wheele drive community towing smaller camping trailers over rough terrain or just placed in the back of a 4Wheel vehicle with a second deep cycle battery to run the fridge and aux loads. The RedArc is rated for 9-32 v dc input, both solar and alternator input. The Renogy is rated Max Pv voltage 25v, conv. alt voltage 13.2-16v, smart alt 12-16v.

I'm sure either unit would serve 90% of potential buyers just fine.

RandyP · Jan 3, 2020

Remy1927 said:
Yes, although the how-to tests I found online didn't seem to apply to my truck. I seem to be having a pretty constant 14V+ coming in when I test it. I am driving a 2020 GMC sierra and from what I have found online it does have a smart alternator. It also has the auto stop/strart option, so obviously it wouldn't be putting out any voltage in that situation. I Just re-watched your video Will and you mentioned that it would be best to have the BVS hooked directly to the battery. I am wondering if the charger isn't getting a good read on the battery voltage and therefore isn't turning on because of it? I have 2 Valence U27-12XP batteries in parallel reading 13.43V.

13.4 v is a 99% SOC for a LiFePO4 battery. Perhaps the battery charger device sees no need to charge a fully charged battery.
From the install&operation Manual (see attachment):
The boost return voltage is listed as 13.2v, that might mean that once the battery is charged to 100 % SOC, the Renergy charger will not charge it again at boost voltage (14.4v) until the battery voltage drops to 13.2v. (13.2 v is a 70% SOC for LiFePO4 battery).

KG6S · Jan 3, 2020

Tezza said:
i been using one of these for the past 2 years with no issues, the main starter batteries are 24v its a dc-dc and mppt too.
house in the back is 12v. the have settings for lifepo4. take any voltage upto 50v an charge only 12v banks at upto 30amps
https://www.ringautomotive.com/en/product/RSCDC30

Exactly what I was thinking of doing. Provides nice failure proofing in lieu of a 24v DC-DC buck converter.

RandyP · Jan 3, 2020

Looks like the battery charging parameters for LI battery listed in the Remogy DCC50S Installation and Operations manual
Over Voltage disconnect: 16.4V
Over Voltage Recovery: 15V
Are NOT compatible with LiFePO4 battery acceptable charging specs.
Max charging voltage for aLiFePO4 battery is 14.6V, any charging voltage greater than that should be blocked by the battery BMS, or the battery would be ruined, scrap, toast.
I wonder if this is a Typo in the manual Tech Specs (last page of manual) ?

RandyP · Jan 3, 2020

The On-Line manual for the DCC50S has some different specs:
see the attachment.
The first three specs listed for LI(LFP) battery are all still excessive for LiFePO3 batteries.

Catastrofe · Jan 3, 2020

CTek is in the game as well with a 20amp version: https://www.ctek.com/au/products/vehicle/d250se

Remy1927 · Jan 3, 2020

RandyP said:
13.4 v is a 99% SOC for a LiFePO4 battery. Perhaps the battery charger device sees no need to charge a fully charged battery.
From the install&operation Manual (see attachment):
The boost return voltage is listed as 13.2v, that might mean that once the battery is charged to 100 % SOC, the Renergy charger will not charge it again at boost voltage (14.4v) until the battery voltage drops to 13.2v. (13.2 v is a 70% SOC for LiFePO4 battery).

Yeah I was wondering about that. So I put it under a load until the battery light turned yellow, still nothing. I just got off the phone with them. They are going to take it back and test it. Hopefully it's a defective unit, because I think I've run out of ways to trouble shoot this thing.

RandyP · Jan 3, 2020

Remy1927 said:
Yeah I was wondering about that. So I put it under a load until the battery light turned yellow, still nothing. I just got off the phone with them. They are going to take it back and test it. Hopefully it's a defective unit, because I think I've run out of ways to trouble shoot this thing.

What battery voltage (stabilized) did you discharge the battery to ? A yellow service battery indicator battery light is described as "battery voltage normal". A red service battery indicator light ON description is "battery under voltage". Red slow flashing indicated "battery over discharged".

I think you should discharge the battery until the service battery indicator is solid ON red (not flashing). Then try the the alternator charge or solar charge or both. If you are nervous while doing this, monitor the service battery voltage during the discharge with a DVM, insure the voltage does not drop below 12.0v (9% SOC).

If you have been living with lead acid battery performance for years, its hard to get past the idea(fact) that LiFePO4 batteries do not need to be charged to 100% state of charge every cycle or maintained at 100% SOC between charges. They will live longer if you run them at 80% - 20% SOC most of their life. LiFePO4 batteries also hold their charge at the same voltage for a long time if not loaded. Once the battery has 'settled' after charging, if all loads are removed from the battery, the settled voltage should not change much in a weeks time.

LiFePO4 batteries can be charged at 14.4 volts, but will settle to 13.6 volts fairly quickly after being charged to 100% SOC and the charging is stopped. If not loaded, they will maintain 13.6 for a long time.

RandyP · Jan 3, 2020

RandyP said:
The On-Line manual for the DCC50S has some different specs:
see the attachment.
The first three specs listed for LI(LFP) battery are all still excessive for LiFePO3 batteries.

Figured it out, the voltage specs are for the alternator/start battery, not the service battery (LI).

RandyP · Jan 3, 2020

RandyP said:
Looks like the battery charging parameters for LI battery listed in the Remogy DCC50S Installation and Operations manual
Over Voltage disconnect: 16.4V
Over Voltage Recovery: 15V
Are NOT compatible with LiFePO4 battery acceptable charging specs.
Max charging voltage for aLiFePO4 battery is 14.6V, any charging voltage greater than that should be blocked by the battery BMS, or the battery would be ruined, scrap, toast.
I wonder if this is a Typo in the manual Tech Specs (last page of manual) ?

Figured it out, the voltage specs are for the alternator/start battery, not the service battery (LI).

Remy1927 · Jan 3, 2020

RandyP said:
What battery voltage (stabilized) did you discharge the battery to ? A yellow service battery indicator battery light is described as "battery voltage normal". A red service battery indicator light ON description is "battery under voltage". Red slow flashing indicated "battery over discharged".

I think you should discharge the battery until the service battery indicator is solid ON red (not flashing). Then try the the alternator charge or solar charge or both. If you are nervous while doing this, monitor the service battery voltage during the discharge with a DVM, insure the voltage does not drop below 12.0v (9% SOC).

If you have been living with lead acid battery performance for years, its hard to get past the idea(fact) that LiFePO4 batteries do not need to be charged to 100% state of charge every cycle or maintained at 100% SOC between charges. They will live longer if you run them at 80% - 20% SOC most of their life. LiFePO4 batteries also hold their charge at the same voltage for a long time if not loaded. Once the battery has 'settled' after charging, if all loads are removed from the battery, the settled voltage should not change much in a weeks time.

LiFePO4 batteries can be charged at 14.4 volts, but will settle to 13.6 volts fairly quickly after being charged to 100% SOC and the charging is stopped. If not loaded, they will maintain 13.6 for a long time.

The battery light is solid green with a red flash occasionally, and as I said the batteries are at 13.4 so they can't be over-discharged. Also with a load on the battery it brings the voltage down to 12.1 which I believe should turn the charger on at least the techs at Renogy thought so. But you are right I should bring them down to solid red and see if it kicks on unfortunately I have a new issue. While trouble shooting I guess I over tightened the output terminal and snapped it. I don't know what this terminal is made out of but it isn't solid.

RandyP · Jan 3, 2020

Sorry to hear of the snapped off stud. Perhaps you return it to them, ask them to test it, perhaps they will just send you another one. Stud could be brass or SiBz, good conductor but no tensile strength. Bummer.

thedodgersonline · Jan 3, 2020

Catastrofe said:
No experience, but it's quite a bit less $$ than the Redarc 50 amp unit. I also like the fact that the unit has bare terminals whereas the Redarc has pigtails. IMHO, the bare terminals provide more flexibility for installation.

Hi
I have been using the RedArc for a number of years now. Have one under the hood - for the 2nd battery - and one in my slide on that charges 2 by 120aH AGM batteries. The one in the Slide On is about 7 years old (BMS15) and the one under the hood is a 1225D. I have traveled extensively around Australia - mainly on the outback roads - where heat is often over 50C and the corrugations are killers. The only issue I have with the RedArc is the low VoC from Solar. For this reason I have now added a Victron 75/15 to the slide on so I can use a decent size solar panel. In my Slide on I have 2 by 35L Engels and another Bushmaster Roadie 15L in the cabin of the ute. This along with water pumps / lights etc needs a fairly large solar panel to keep the batteries topped up.
Below are pics of my setup - small one when I am going solo and large Slide On when She Who Must Be Obeyed comes along.
Cannot recommend RedArc highly enough.
Regards

alex01 · Jan 14, 2020

Just read this and its great someone is making a full all in one solution which will solve the low temp charging issue for lifepo4 batteries. Glad this charger can sense low temp and stop charging without complicated external temp sensors and cut offs.

I guess the only caviet is the low voltage input for solar... sigh... 25V does seem very low.

RandyP · Jan 14, 2020

The complicated external temp sensor is included with the Remogy device and still has to be run to the battery and attached to the battery surface, the cut off temps are built into the battery charging profile you select to run the device and depend on the temp sensor input to the device.

lmwilco1 · Jan 14, 2020

RandyP said:
The complicated external temp sensor is included with the Remogy device and still has to be run to the battery and attached to the battery surface, the cut off temps are built into the battery charging profile you select to run the device and depend on the temp sensor input to the device.

The manual says that there is no temperature compensation for Lithium batteries so I am not sure there is a cutoff temp for them.

alex01 · Jan 14, 2020

In the manual it does say for lithium the charge is cut off below 1 degree C and resumes over 3 degree C

https://www.renogy.com/content/RBC50D1S-G1/RBC50D1S-G1-Manual.pdf

Checkout section 4.3

lmwilco1 · Jan 15, 2020

Thanks for pointing that out, I missed it when I read the manual.

RandyP · Jan 15, 2020

alex01 said:
....................................
I guess the only caviet is the low voltage input for solar... sigh... 25V does seem very low.

Depends on the solar panels you may already have, or plan to buy. If those panels were intended to charge a 12v battery system, the 25v max solar voltage is just right if you wire them in parallel.

Catastrofe · Jan 16, 2020

lmwilco1 said:
The manual says that there is no temperature compensation for Lithium batteries so I am not sure there is a cutoff temp for them.

Temperature compensation is related to the charging profile...the unit adjusts charging “speed” based on battery temp. None for lithium. This is independent of low and high temperature cutoff.
At least, that’s my interpretation...

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