DC to DC charger / battery compatibility

[Miles]

Hello friends, I am about to build my first DC power system, using Renogy's DCC50S Battery Charger and a 60Ah Lifepo4 battery from Amped Outdoors, based on this blueprint: https://www.mobile-solarpower.com/simplified-400-watt-fewer-wires-and-alternator-charging.html (in this case no solar panel or inverter for now).

Quick question, I noticed the label on the battery says "Max current: 50A" I assume this refers to the max draw you can put on the battery, but does it also apply to charging current?

I remember in Will's review of the DCC50S that the charging current might have slightly exceeded 50A at times. Just want to make sure that wouldn't be a problem for this battery.

Also I assume that if I set the DCC50S to the Lithium battery setting, it will charge this battery properly, even though Amped Outdoors says never to use anything but the AC charger they sell.

 

[Master Dalor]

Hello. The renogy site says: Maximum Charging Current : 50A (25A Alternator / 25A PV)
amp outdoors says:
Nominal Voltage: 12V
Nominal Capacity: 60AH
Discharge Cut-Off: 10V
Charge Cut-Off: 14.65V
Charge Current: 50A Max
Cont. Discharge: 50A
Peak Discharge: 80A
But there are always lost amp in the cables and connectors, so you should never see the full amps on your battery.
If you see what renogy says, the alternator can give only 25 Amp.
I = P/V = 400W solar / 14.4V = 27.7777 Amp.
If you get 1000W per m square, that is only achievable in a laboratory, under special lights.
If we assume the controller is 90% efficient: 27.7777 Amp x 0.9 = 25 Amp.
So you could just come to maximum charge power when charging with alternator and solar together, but the controller will charge at constant current (maximum) when the battery is empty, until the battery voltage rises to the preset maximum of 3.65 volt per cell x4 for our case 14.6V or less like 14,4 to be conservative with the battery, than, the current given by the controller (the Amps) will diminish to almost 0 near the end of charge, this phase is named constant voltage.

 

[John Frum]

But there are always lost amp in the cables and connectors, so you should never see the full amps on your battery.

Voltage is lost not amps.

 

[Master Dalor]

Voltage is lost not amps.

Sure lost volts. sorry, thank you for the correction.
Anyways there is always something lost somewhere.

 

[Master Dalor]

Sure lost volts. sorry, thank you for the correction.
Anyways there is always something lost somewhere.

So Joey maybe You can rewrite my post with the correct answer to help our friend Miles?

 

[John Frum]

Quick question, I noticed the label on the battery says "Max current: 50A" I assume this refers to the max draw you can put on the battery, but does it also apply to charging current?

How many watts is your alternator rated for?
What battery chemistry are you planning for?
How many amp hours are you planning for?

I remember in Will's review of the DCC50S that the charging current might have slightly exceeded 50A at times. Just want to make sure that wouldn't be a problem for this battery.

Also I assume that if I set the DCC50S to the Lithium battery setting, it will charge this battery properly, even though Amped Outdoors says never to use anything but the AC charger they sell.

manual is https://www.renogy.com/content/RBC50D1S-G1/RBC50D1S-Manual.pdf
page 15 discusses wire sizes and fusing.
You can try the lithium profile but folks have been reporting problems with it.

Just use the correct wire sizes and over-current protection and all is good.

An alternate way to figure the cables and fuses is.

50 dc amps output * 1.1 charger efficiency = 55 input amps
55 * 1.25 fuse headroom = 68.75 fuse amps, call it 70 amps.
Plug that into the following calculator https://baymarinesupply.com/bosns_corner_wire_sizes
along with the system voltage which is 12 volts
and the round trip circuit length which will be 2x the length of your vehicle max.
That will tell you the awg wire you need to get <3% voltage drop.
Now check the ampacity table to make sure the wire specified exceeds the fuse amps.
Bo's yer uncle.

 

[Master Dalor]

How many watts is your alternator rated for?
What battery chemistry are you planning for?
How many amp hours are you planning for?



manual is https://www.renogy.com/content/RBC50D1S-G1/RBC50D1S-Manual.pdf
page 15 discusses wire sizes and fusing.
You can try the lithium profile but folks have been reporting problems with it.

Just use the correct wire sizes and over-current protection and all is good.

An alternate way to figure the cables and fuses is.

50 dc amps output * 1.1 charger efficiency = 55 input amps
55 * 1.25 fuse headroom = 68.75 fuse amps, call it 70 amps.
Plug that into the following calculator https://baymarinesupply.com/bosns_corner_wire_sizes
along with the system voltage which is 12 volts
and the round trip circuit length which will be 2x the length of your vehicle max.
That will tell you the awg wire you need to get <3% voltage drop.
Now check the ampacity table to make sure the wire specified exceeds the fuse amps.
Bo's yer uncle.

 

[Master Dalor]

Thanks Joey, or uncle Bo?
Do you think the alternator power is of any importance as the controller will only let 25A pass through? While the starting battery can deliver many hundreds amps?

 

[John Frum]

Thanks Joey, or uncle Bo?
Do you think the alternator power is of any importance as the controller will only let 25A pass through? While the starting battery can deliver many hundreds amps?

I think the dc2dc charger will pull the full 55 from the starter battery/alternator if there are no panels.

 

[Miles]

Hello. The renogy site says: Maximum Charging Current : 50A (25A Alternator / 25A PV)
amp outdoors says:
Nominal Voltage: 12V
Nominal Capacity: 60AH
Discharge Cut-Off: 10V
Charge Cut-Off: 14.65V
Charge Current: 50A Max
Cont. Discharge: 50A
Peak Discharge: 80A
But there are always lost amp in the cables and connectors, so you should never see the full amps on your battery.
If you see what renogy says, the alternator can give only 25 Amp.
I = P/V = 400W solar / 14.4V = 27.7777 Amp.
If you get 1000W per m square, that is only achievable in a laboratory, under special lights.
If we assume the controller is 90% efficient: 27.7777 Amp x 0.9 = 25 Amp.
So you could just come to maximum charge power when charging with alternator and solar together, but the controller will charge at constant current (maximum) when the battery is empty, until the battery voltage rises to the preset maximum of 3.65 volt per cell x4 for our case 14.6V or less like 14,4 to be conservative with the battery, than, the current given by the controller (the Amps) will diminish to almost 0 near the end of charge, this phase is named constant voltage.

Thanks @Master Dalor, this is super helpful. Sounds like I have nothing to worry about then.

 

[Miles]

How many watts is your alternator rated for?
What battery chemistry are you planning for?
How many amp hours are you planning for?



manual is https://www.renogy.com/content/RBC50D1S-G1/RBC50D1S-Manual.pdf
page 15 discusses wire sizes and fusing.
You can try the lithium profile but folks have been reporting problems with it.

Just use the correct wire sizes and over-current protection and all is good.

An alternate way to figure the cables and fuses is.

50 dc amps output * 1.1 charger efficiency = 55 input amps
55 * 1.25 fuse headroom = 68.75 fuse amps, call it 70 amps.
Plug that into the following calculator https://baymarinesupply.com/bosns_corner_wire_sizes
along with the system voltage which is 12 volts
and the round trip circuit length which will be 2x the length of your vehicle max.
That will tell you the awg wire you need to get <3% voltage drop.
Now check the ampacity table to make sure the wire specified exceeds the fuse amps.
Bo's yer uncle.

I believe the alternator for my 2011 Toyota Sienna is 150A, not sure about Watts. I currently have a 60Ah Lifepo4 battery, and am planning to add a 2nd one if I need more power.

I'm using Will's blueprint here for fuse and cable sizes: https://www.mobile-solarpower.com/simplified-400-watt-fewer-wires-and-alternator-charging.html

Sorry to hear there are mixed reviews about the lithium charging profile, that's slightly concerning. Do you have a link to read more about the issues people are reporting? Thanks!

 

[John Frum]

I believe the alternator for my 2011 Toyota Sienna is 150A, not sure about Watts. I currently have a 60Ah Lifepo4 battery, and am planning to add a 2nd one if I need more power.

I'm using Will's blueprint here for fuse and cable sizes: https://www.mobile-solarpower.com/simplified-400-watt-fewer-wires-and-alternator-charging.html

Charging a 60 amp hour lifepo4 battery is at 50 amps is fairly aggressive but not insane.
When you have 2 in parralel it will be better.

Sorry to hear there are mixed reviews about the lithium charging profile, that's slightly concerning. Do you have a link to read more about the issues people are reporting? Thanks!

Renogy DCC50S charging issue

Sorry if this post is in the wrong place. Just installed a new DCC50s in my van. Currently have x2 Renogy LiFePo batteries, connection from my solar panels, and connection from the starter battery/alternator. The batteries aren't charging when I set the DCC50s to LI battery type, but seem to...

diysolarforum.com

 

[John Frum]

Thanks Joey, or uncle Bo?
Do you think the alternator power is of any importance as the controller will only let 25A pass through? While the starting battery can deliver many hundreds amps?

The starting battery can but the alternator often can't.
Even if they are rated for 150 amps you need to look at the amps/rpm curve to see what the alternator can really do.
The peak amps are usually at rpm's higher than road speed.
Then you need to determine how much load the vehicle itself is drawing.
Worst case is an alternator at idle getting the life sucked out of it by a hungry battery and with very little cooling to make things even worse.

 

[Master Dalor]

The starting battery can but the alternator often can't.
Even if they are rated for 150 amps you need to look at the amps/rpm curve to see what the alternator can really do.
The peak amps are usually at rpm's higher than road speed.
Then you need to determine how much load the vehicle itself is drawing.
Worst case is an alternator at idle getting the life sucked out of it by a hungry battery and with very little cooling to make things even worse.

Yes, I just told about that in another post, I saw a video from victron where they burn a big alternator directly charging a lithium battery at engine idle speed, it burns because there is not enough cooling at low speed, there are systems managing the current pull to charge the utility battery. Miles could also put a voltmeter/ammeter to monitor his starting battery and solid state relay to cut the circuit at low engine speed.
I have that in back order on AliExpress: 12V Car Auto Double Battery Isolator Protector Dual Battery Controller Smart Battery Manager Automatic Charging And Power Off

 

[Master Dalor]

Well If you drive at noon in the desert, maybe you should put something on the pannels to cast a shadow, that will drastically reduce the power, and maybe also protect the pannels from to much heat, they don't like too much it seems. If you more batteries in parallel, they will accept more amp, but max current is not ideal, to protect the batteries, less current is better.

 

[Miles]

Well If you drive at noon in the desert, maybe you should put something on the pannels to cast a shadow, that will drastically reduce the power, and maybe also protect the pannels from to much heat, they don't like too much it seems. If you more batteries in parallel, they will accept more amp, but max current is not ideal, to protect the batteries, less current is better.

If it's true that this DC to DC charger will only draw 25A from the alternator to charge my house battery, that seems like a healthy balance for both the alternator and the battery, presumably less than what it is designed to crank into the starting battery in normal operation.

Perhaps when I add the solar panel I should also include the 2nd 60Ah battery so the existing battery doesn't get overwhelmed by the potential combined 50A of power.

 

[John Frum]

If it's true that this DC to DC charger will only draw 25A from the alternator to charge my house battery, that seems like a healthy balance for both the alternator and the battery, presumably less than what it is designed to crank into the starting battery in normal operation.

Its not true.

 

[Master Dalor]

I will use that in my van.

 

[Miles]

Its not true.

Gotcha. Looks like one of the reviewers on the Renogy site is saying the charger will pull 50A from the alternator if there is no solar panel attached. Once a solar panel is connected it will limit the alternator to 25A.

In that case perhaps a simple hack would be to connect a small folding panel to the unit, that I can deploy when I set up camp and the car's not running. Only use one power source at a time.

 

[John Frum]

Off topic, Is that an ES-333 ?