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Four 24v BYD's in a van

J

Jim_C

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Mar 8, 2020
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I have four, 4kw BYD 24v units that I want to install in my van. Connected in parallel to a 4K inverter.
I have Chargery BMS on each BYD. I also have low and high voltage relay disconnects.

Phase one is to use my 250 amp 12v alternator to charge the batteries. Phase 2 will be a second 24v alternator.

Can I use multiple Victron 12/24 DC to DC converters ( 20 amps each, want 4 in parallel ) for charging or do I need a 12/24 DC charger ?
Victron has a 15 amp 12 /24 charger and I'm not sure if multiple chargers can be put in parallel.

Thanks in advance.
 
Jim_C said:
Can I use multiple Victron 12/24 DC to DC converters ( 20 amps each, want 4 in parallel ) for charging or do I need a 12/24 DC charger ?
Click to expand...

No, you can't use the converters. They are made to convert a 24v battery down to 12v to run 12 volt devices.

You need a 12v-24v DC-DC boost charger. There's plenty of 12v-12v options, but I can't think of any commercially available boost charger...

I guess a cheap and easy option would be to run an inverter from the start battery/alternator (hot only when running) and use the 120v to power a mains charger.
 
The Victron converter that I was looking at converts 12vdc to 24vdc at 20 amps. The output voltage is adjustable 20-30 volts . I have seen lifepo4
batteries being charged with an adjustable power supply. I figured the converter would do the same. The output voltage is constant.
or. ??
 
Jim_C said:
The Victron converter that I was looking at converts 12vdc to 24vdc at 20 amps. The output voltage is adjustable 20-30 volts . I have seen lifepo4
batteries being charged with an adjustable power supply. I figured the converter would do the same. The output voltage is constant.
or. ??
Click to expand...
That could be used with a charge controller... feeding the voltage directly to the batteries wouldn’t be safe.
 
Supervstech said:
That could be used with a charge controller... feeding the voltage directly to the batteries wouldn’t be safe.
Click to expand...

Thanks for the reply. I hooked one up (dc to dc converter ). this am . There’s no regulation on the output current . It got real hot real fast . I don’t know much about solar . I’ll look to see how a charge controller works .
 
Jim_C said:
Thanks for the reply. I hooked one up (dc to dc converter ). this am . There’s no regulation on the output current . It got real hot real fast . I don’t know much about solar . I’ll look to see how a charge controller works .
Click to expand...

The 24v output from the converters won't be high enough voltage to run through a charge controller to charge a 24v battery. If the converters were 12 to 36 or 48v, then that 36 or 48v could be put through a charge controller designed for a 24v battery. The CC's need some voltage overhead.

But I think you may be asking too much of any converter to run at full capacity for any extended length of time.
 
SolarRat said:
The 24v output from the converters won't be high enough voltage to run through a charge controller to charge a 24v battery. If the converters were 12 to 36 or 48v, then that 36 or 48v could be put through a charge controller designed for a 24v battery. The CC's need some voltage overhead.

But I think you may be asking too much of any converter to run at full capacity for any extended length of time.
Click to expand...

Okay, makes since. Let me back up and ask this question. How best to charge 600ah 24vdc battery with 12vdc , 250 amp alternator. I’ll try that question here before starting another thread.
 
Jim_C said:
Okay, makes since. Let me back up and ask this question. How best to charge 600ah 24vdc battery with 12vdc , 250 amp alternator. I’ll try that question here before starting another thread.
Click to expand...

Something like this:

battlebornbatteries.com

Sterling Power Battery to Battery Charger 12V input to 24V output up to 70amps.

Click here to read more about this DC battery to battery charger and how it can help you get out there and stay out there!
battlebornbatteries.com battlebornbatteries.com

Make sure whatever model you chose can charge LFP batteries. That one will charge at 35 amps (24v). I'm not sure if they make bigger. Keep in mind that it's drawing 70 amps from your 12v alternator. Even with a 250a alternator, you don't want to push it's limits...most alternators are not meant for continuous draws anywhere near their max rating.

If your plan was to add a second 24v alternator now would be the time. Otherwise you're just throwing money away if this is only temporary.
 
Victron Orion TR 12/24 Dc to Dc smart charger is what you need for alternator charging. They can be paralleled for additional power.
 
Thanks for the replies. I went with two Sterlings for now. I really like the Victron but they are only 15 amps ( I think ).
 
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