[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

[brassmonkey001]

I have two Valence U27-12XP too ! Mad.

I'd recomend the Vitron 30A duel output smart charger....

It has dual isolated output, one for starter, one for leisure...

But you will need to add a Low temp charge disconect to shut off the Lifepo4s.....(either via a BMV712 + battery protect or any 3rd party solution.)

LTD discussion over hear.

Lithium Lifepo4 12v Batteries - - - Time For An Upgrade ? - - -

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Battery Chargers - How I Did It -

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Dellmassive`s -- "how I Done It" -- Thread

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I'm not so sure about the dual output charger, I gather you can't set the outputs to two different battery chemistries (LiFePO4 leisure battery and Lead Acid starter battery), you'd need to change settings to charge each type separately for maximum efficiency, although Justin on the Victron community pages reckons that "many LFP banks are perfectly happy at an FLA charge profile".

I understand how you have solved the low temp cutoff with the BMV712 in the other thread, and the low battery cutoff with a Battery Protect, but would the BMV712 also stop the IP22 charging at low temperature in that set up in the same way as it stops the MPPT charging? Or would it require a second Battery Protect wired in to stop the IP22 charging when cold?

 

[Markymark]

Out of curiosity what have you done with your old Redarc BCDC1240LV? Is it available to buy? My daughter about to get an old but virtually free Sprinter and a second hand Redarc might be a good investment in terms of battery maintenance for her rather than a SCR.

I think I’m going to give her my two AGM leisure batteries and the 240v charger as the fan noise does my head in as it is below my pillow. Then ask Travelvolts to install a new lithium battery and CTEK 240v charger. He has already fitted a Redarc BCDC1240D for me.

 

[brassmonkey001]

I'm not so sure about the dual output charger, I gather you can't set the outputs to two different battery chemistries (LiFePO4 leisure battery and Lead Acid starter battery), you'd need to change settings to charge each type separately for maximum efficiency, although Justin on the Victron community pages reckons that "many LFP banks are perfectly happy at an FLA charge profile".

I understand how you have solved the low temp cutoff with the BMV712 in the other thread, and the low battery cutoff with a Battery Protect, but would the BMV712 also stop the IP22 charging at low temperature in that set up in the same way as it stops the MPPT charging? Or would it require a second Battery Protect wired in to stop the IP22 charging when cold?

Having given it a bit more thought, if you connected all of your charging sources (MPPT, DC2DC and EHU charger) to one side of the Battery Protect and connected the BMV 712 Relay wires to the BP then wouldn't that do the lot? I.e. low & high voltage disconnect, and low & high temperature disconnect? There also appears to be relay settings for SoC as well within the BMV unit.
Would that work or am I missing something?

 

[Dellmassive]

I'm not so sure about the dual output charger, I gather you can't set the outputs to two different battery chemistries (LiFePO4 leisure battery and Lead Acid starter battery), you'd need to change settings to charge each type separately for maximum efficiency, although Justin on the Victron community pages reckons that "many LFP banks are perfectly happy at an FLA charge profile".

I understand how you have solved the low temp cutoff with the BMV712 in the other thread, and the low battery cutoff with a Battery Protect, but would the BMV712 also stop the IP22 charging at low temperature in that set up in the same way as it stops the MPPT charging? Or would it require a second Battery Protect wired in to stop the IP22 charging when cold?

in the original setup i had specced two "battery protects."

a 100A one for the main output from the battery, and a smaller 60A one to shut off the input charging side.

The MPPT has the ability to stop charging via the VE-Direct temperature data from the BMV712.

 

[Dellmassive]

Out of curiosity what have you done with your old Redarc BCDC1240LV? Is it available to buy? My daughter about to get an old but virtually free Sprinter and a second hand Redarc might be a good investment in terms of battery maintenance for her rather than a SCR.

I think I’m going to give her my two AGM leisure batteries and the 240v charger as the fan noise does my head in as it is below my pillow. Then ask Travelvolts to install a new lithium battery and CTEK 240v charger. He has already fitted a Redarc BCDC1240D for me.

ill be keeping it,

they are great for charging dis-similar batteries from a single larger charger . . .

it will sit inbetween a SLA AGM bank and LIFEPO4 battery pair

 

[Dellmassive]

Having given it a bit more thought, if you connected all of your charging sources (MPPT, DC2DC and EHU charger) to one side of the Battery Protect and connected the BMV 712 Relay wires to the BP then wouldn't that do the lot? I.e. low & high voltage disconnect, and low & high temperature disconnect? There also appears to be relay settings for SoC as well within the BMV unit.
Would that work or am I missing something?

Yes, i did come across that idea, . . . . . . .

But @travelvolts had reminded me that the Victron MPPT did not like having its main battery disconnected before the solar input was shut down, (possible internal damage)

also some DC-DC chargers do not like the batteries being disconnected...... (possible internal damage)

so the idea was to use the battery protect to disconnects the loads for "low volt battery protect"

To use the BMV712 temp via VE-direct to signal the MPPT to stop charging for solar LTD,

To use the BMV712 temp via onboard relay to interupt the DC-DC charger run/ignition signal.

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[brassmonkey001]

in the original setup i had specced two "battery protects."

a 100A one for the main output from the battery, and a smaller 60A one to shut off the input charging side.

I was wondering about different sized BPs but I was thinking the other way around because if you had for example a maximum load of 50A going out, but the batteries can take in a lot of charge, so if you had an EHU and solar, the combined current going in could be quite considerable depending on your setup? So a 65A BP on the output and a 100A BP on the input?

 

[brassmonkey001]

Yes, i did come across that idea, . . . . . . .

But @travelvolts had reminded me that the Victron MPPT did not like having its main battery disconnected before the solar input was shut down, (possible internal damage)

also some DC-DC chargers do not like the batteries being disconnected...... (possible internal damage)

so the idea was to use the battery protect to disconnects the loads for "low volt battery protect"

To use the BMV712 temp via VE-direct to signal the MPPT to stop charging for solar LTD,

To use the BMV712 temp via onboard relay to interupt the DC-DC charger run/ignition signal.

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Ah, yes, I hadn't considered the fact that charge controllers can be damaged when the battery is disconnected when still receiving power from the solar panels.
Bloody hell, it's not simple, is it? I just want my system set up so that nothing gets damaged, but it seems it's a bit of a minefield!
The way you have yours set up is a good compromise with getting overly complex, perhaps the answer is to just not connect the EHU charger unless you're sure the temperature isn't going to drop too low rather than over-complicating things?

 

[Dellmassive]

There is another option,

They do 12v heat mats that can sit under the battery, thermostat control and can keep the battery above freezing.

Low temp disconect can be tricky to implement with multiple charge sources.

Maybe you could put one of those temp controlled relay or BP on the EHU charger only...

And use a separate relay to switch the dc-dc off.

 

[brassmonkey001]

I've been looking into putting a heat pad under the batteries to keep them warm but it's not easy finding a low powered one. The trick is trying to balance how much power the mat consumes vs. how much power you can put back in. I haven't sat down and worked out the figures yet but I imagine a 100W pad on for 8 hours overnight is going to require a pretty sunny day to replenish what's been used.

 

[Dellmassive]

So far this autumn it's been below 5degC 4times..... yet not below 0degC.....

I'll keep monitoring...

 

[Dellmassive]

!!! HAS RENOGY JUST SOLVED ALL OUR PROBLEMS IN ONE UNIT !!!!

Heres a new solution to LTD with Lifepo4 Batteries:

A 50A DC-DC charger with built in MPPT,

That has a lithium profile WITH Low Temp Disconnect,

That will reverse charge the starter battery !!!!!

That has a IGNITION feed for smart alternator.

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DESCRIPTION
Renogy's DCC50S DC to DC MPPT on-board Battery Charger is designed to give you options! This multi-stage, multi-input battery charger can charge a service battery from an alternator connected to a starting battery or by utilizing solar panels connected directly to the unit. While your vehicle's alternator prioritizes your starting battery, this unit will allow your solar system to charge your service battery first! It's the smart way to keep yourself fully charged and off-grid longer! And with multi-stage charging and multi-chemistry functionality, Renogy's DC to DC MPPT Charger has you covered whether you're using Flooded, Gel, AGM, or Lithium batteries.

If you have any questions regarding this product, please call us at 1 (909) 287-7111 or email sales@renogy.com.

KEY FEATURES

• Designed to charge service batteries from two DC inputs—solar panels and alternator.
• Built-in Maximum Power Point Tracking (MPPT) to maximize the solar power.
• 3-phase charging profile (Bulk, Boost, and Float) ensures your service battery will be accurately charged at the correct voltage levels to 100%.
• Built-in Voltage Sensitive Relay (VSR) for easy setup with traditional alternators.
• Compatible with smart alternators (with variable output voltage).
• Trickle charges the starting battery via solar panels if the service battery is fully charged.
• Isolation of the starting battery and the service battery.
• Temperature and voltage compensation features prolong battery life and improve system performance.
• Smart Protection Features: battery isolation, over-voltage protection, battery temperature protection, over-current protection, overheat protection, reverse current protection, solar panel and alternator reverse polarity protection.
• Compatible with multiple battery types: AGM, GEL, Flooded, and Lithium.
• Compact with a sturdy design, it was built tough for all conditions.

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SPECIFICATIONS
System Voltage : 12VDC Battery Voltage Range : 9-16VDC
Maximum Charging Current : 50A (25A Alternator / 25A PV) Battery Type : SLA, GEL, FLD, LI, USER
Backup Battery Charging Mode : MPPT Charging Efficiency : Up to 97%
Max. Solar Input Voltage : 25V Maximum Solar Input Power : 660W
Alternator Input Voltage : Traditional Alternator: 13.2-16VDC Smart Alternator (Euro 6): 12-16VDC"

Maximum Alternator Input Power : 660W
Self-consumption : 60mA Operating Temperature Range : -22°F~149°F / ﹣35°C~65°C
Dimensions : 9.6 x 5.7 x 3.0 in / 244 x 146 x 77 mm Weight : 3.13 lbs / 1.42 kg

WARRANTY INFORMATION
Accessories 1-year material warranty


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some details from the install,

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DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT

https://www.renogy.com/content/RBC50D1S-G1/RRBC50D1S-G1-Manual.pdf

https://www.amazon.co.uk/Renogy-DC-..._1_3?keywords=renogy+dc&qid=1574256131&sr=8-3

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fwiw I've just gone on Amazon UK and grabbed one.

 

[Dellmassive]

post edited to show Victron 12/12/30 test results 3 weeks on : Dc-dc Charger (for Leisure Battery) -- How I Done It --

 

[Dellmassive]

You gotta love Amazon Prime . . . . . . . . .

Here it is - the Renogy 50A DC-DC + MPPT. (+LTD +starter reverse charge)

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its defiantly bigger than the Redarc and the Victron 12/12/30.....

we currently have the Victron 12/12/30 fitted, next us was the Redarc 1250D . . . . . but now this one?

which one to test next?





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DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT

https://uk.renogy.com/content/files/Specifications/RBC50D1S-G1-spec.pdf

https://uk.renogy.com/content/files/Manuals/RBC50D1S-G1-Manual.pdf

https://uk.renogy.com/content/files/Warranty.pdf

*********************************************

 

[Farnorthsurfer]

So the Renogy DCC50S has a voucher for 5% off on Amazon.co.uk just now so I have sprung for one. Cost £218.49.
Its going to be a while before I get it wired up but be good to work out where it will fit. Hopefully under the passenger seat along with a reasonable battery.
Look forward to any testing you might do @Dellmassive You got me into this
The combined MPPT and ability to charge the leisure battery and starter battery along with built in LTD sold it for me. Think I will start out with a resonably AGM and shift to Lithium when the prices fall.
The youtube review was very useful to learn how to set it up.

 

[Dellmassive]

@Long tall John said:
Don't want to pressure you as I know you're busy but did you get a definitive answer... do you get the full 50v if there is no solar charging connected? I do hope so especially as it's either 4 awg or 6 awg which is quite meaty... and I don't want to live with charging anxiety... lol


No official reply from Renogy yet . . .

But the install guide clearly states that you should use a 75A fuse on a 6awg or 4awg. . .

Dc-dc Charger (for Leisure Battery) -- How I Done It --

so going from that and the snippets from the Renogy forum im going to say it does 50A from alternator . . . .


the email I've sent them (twice now) asks for clarification:

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Hi guys

We seem to be having some confusion with this new product.
DCC50S 12V 50A DC-DC ON-BOARD BATTERY CHARGER WITH MPPT
https://www.renogy.com/dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt/
the spec mentions 25A from MPPT and 25A from alternator giving 50A max throughput…

but there is a mention of 50A throughput from alternator only . . . . ?

so please can you clarify these specs.
Is the MAX solar mppt 25A?
is the max alternator 25A or 50A?
what about if I connect any the below panels? . . . what split output will I get?
If the MAX alternator throughput is 50A? and I add 10A worth of solar? . . . will this work out to 10A solar + 40A alternator?
please can you clear up the below and if each line is correct or incorrect

0A solar mppt & 50A alt = 50A total output
5A solar mppt & 45A alt = 50A total output
10A solar mppt & 40A alt = 50A total output
20A solar mppt & 30A alt = 50A total output
25A solar mppt & 25A alt = 50A total output
30A solar mppt & 20A alt = 50A (or will it be limited to 25A solar & 25A alt?)
40A solar mppt & 10A alt = 50A (or will it be limited to 25A solar & 25A alt?)
Many thanks




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[Bryn23]

Hopefully you hear back from them regarding the input, as ideally you want more than 25ah from the alternator.

it’s also a big size difference between the renolgy and the redarc, keep up the good work testing these DC-DC’s, I’m sure a lot of people appreciate it

I ended up ordering a newer model of the Votronic triple charger 60/40/430 to replace the 30/20/250 model I am currently running, as I need faster charging For shorter drives between camps.

I’m also tempted to add another 240ah battery (same battery) to increase my capacity, although it would be fun to build a 12 cell, 540ah, with 180ah Calb Cells

but I’ll see how the current battery goes, now I will be able to charge faster

 

[Farnorthsurfer]

I am trying not to get hung up on the numbers but you boys are not making it easy

 

[Dellmassive]

@Long tall John said:
Don't want to pressure you as I know you're busy but did you get a definitive answer... do you get the full 50v if there is no solar charging connected? I do hope so especially as it's either 4 awg or 6 awg which is quite meaty... and I don't want to live with charging anxiety... lol


No official reply from Renogy yet . . .

But the install guide clearly states that you should use a 75A fuse on a 6awg or 4awg. . .

Dc-dc Charger (for Leisure Battery) -- How I Done It --

so going from that and the snippets from the Renogy forum im going to say it does 50A from alternator . . . .


the email I've sent them (twice now) asks for clarification:

**********************************************

Hi guys

We seem to be having some confusion with this new product.
DCC50S 12V 50A DC-DC ON-BOARD BATTERY CHARGER WITH MPPT
https://www.renogy.com/dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt/
the spec mentions 25A from MPPT and 25A from alternator giving 50A max throughput…

but there is a mention of 50A throughput from alternator only . . . . ?

so please can you clarify these specs.
Is the MAX solar mppt 25A?
is the max alternator 25A or 50A?
what about if I connect any the below panels? . . . what split output will I get?
If the MAX alternator throughput is 50A? and I add 10A worth of solar? . . . will this work out to 10A solar + 40A alternator?
please can you clear up the below and if each line is correct or incorrect

0A solar mppt & 50A alt = 50A total output
5A solar mppt & 45A alt = 50A total output
10A solar mppt & 40A alt = 50A total output
20A solar mppt & 30A alt = 50A total output
25A solar mppt & 25A alt = 50A total output
30A solar mppt & 20A alt = 50A (or will it be limited to 25A solar & 25A alt?)
40A solar mppt & 10A alt = 50A (or will it be limited to 25A solar & 25A alt?)
Many thanks




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Here we go . . . . . .

Here is the official word back from Renogy. (I had to read it a couple times before it sunk in)

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Hi Dellmassive...

Thank you for contacting Renogy.

The DCC50S will have 50a max current total. 25a from solar and 25a from the starter battery. If you only have 1 x 100w panel at 5a from the panels and alternator running it will still be a 25/25 split or in this case 5a/25a split (30a total). Even if you only have 2a coming from the panels the starter limit will still be 25a.

On their own, the starter battery is capable of sending 50a without solar and likewise the solar with 660w of input can send 50a to the batteries on its own.

If you have any further questions please let us know.

Thank you,
Matthew S. (Tech support)

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So basically it 50A or 600w from either solar or alternator as a single....

But.

As soon as you add both you go to 25a/25a split....

A bit confusing at first, I suppose internally there is 2 banks of 25A regulators.....with one power source connected it must feed both banks internally, but as soon as it detects power on both input sources it will split into two banks..... that would explain the readings they are giving....

I still think it's an impressive box.........

Now imagine having TWO of these boxes !!!!!! That would be 50a alternator and 50A solar, giving 100A total...... that's bad boy!

 

[Pauly]

but if you have solar connected you will always get something at the terminals effectively limiting yourself to 25A engine supply, i wonder if it would be worth fitting an isolator on the solar input so if you have flat batteries and need a fast charge (when its not sunny or your solar is nowhere near 600W) you can isolate them to allow the alt to have the full 50A ??