12v bulk charger suggestions

[hwse]

I am looking for a way to decrease my generator run time for charging my 920Ah bank in my motorhome. I have a 10kw genset and a 2000w/100A Magnum inverter charger. I would like to find a relativly inexpensive charger to just add 100A - 200A of bulk when running the generator. My BMS will handle up to 400A of charge current. Ideally It would just produce CC until the bank hits somewhere around 13.6v and then shut off and let the Magnum finish off the top.

Any suggestions?

 

[time2roll]

PowerMax 120a $300 adjustable voltage

 

[hwse]

I remember reading something about using a high wattage PC power supply to charge LFP but never saw the particulars. I know of a PC recycler that sells used components very cheaply.
Anyone know how that works?

 

[Checkthisout]

I am looking for a way to decrease my generator run time for charging my 920Ah bank in my motorhome. I have a 10kw genset and a 2000w/100A Magnum inverter charger. I would like to find a relativly inexpensive charger to just add 100A - 200A of bulk when running the generator. My BMS will handle up to 400A of charge current. Ideally It would just produce CC until the bank hits somewhere around 13.6v and then shut off and let the Magnum finish off the top.

Any suggestions?

An RV battery charger like progressive dynamics etc..

 

[time2roll]

I remember reading something about using a high wattage PC power supply to charge LFP but never saw the particulars. I know of a PC recycler that sells used components very cheaply.
Anyone know how that works?

Voltage looks low for charging batteries. Does your buddy also modify them to adjust voltage?

https://www.oreilly.com/library/view/pc-hardware-in/059600513X/ch26s02s01.html

 

[hwse]

Voltage looks low for charging batteries. Does your buddy also modify them to adjust voltage?

https://www.oreilly.com/library/view/pc-hardware-in/059600513X/ch26s02s01.html

The Idea about using old power supplies was something that I read on a forum (so it has got to be true, right?)
I did not understand what the system was or even if it would work but thought I would see if anyone here had any insight.

 

[vvadym]

The Idea about using old power supplies was something that I read on a forum (so it has got to be true, right?)
I did not understand what the system was or even if it would work but thought I would see if anyone here had any insight.

Hi, have you moved forward with the computer power supply as a charger for the battery? I see extremely juicy offers like 50$ for 800W power supply with 12V/67A output on the local market.

 

[hwse]

I have not. I do not know enough about how the voltage is controlled to figure out how to adjust the regulated output voltage to make it work. I was hoping that someone on this site might have that knowledge.

 

[vvadym]

Appreciate it if someone would comment - is it possible to setup like using this controller or anything similar:

So up to 150$ (90$ inverter + up to 50$ power supply) for 60 A charger option.

 

[mikefitz]

The server power supply as shown in the diagram deliver 12 volts so assuming the MPPT needs an input voltage higher than battery volts to start working, then the system would not function. Not familiar with PowMr units but most MPPT need battery volts plus 4 to 5 volts to operate.
You can easily get the server power supply to generate about 13.8 volts without its overvolt protection being activated, this is enough to charge lithium to over 90% directly connected to the battery.
Its also possible after modification to connect two server supplies in series giving 24 volts that may be used as a MPPT input.
Since the internal parts of server power supplies operate at high voltages some experience in electrical systems is needed before attempting to modify these units.
An internet search will find information of the procedures necessary to convert these server power supplies.
Second hand server power supplies are available at low cost due to regular service replacements.
power supply

Mike

 

[hwse]

...
You can easily get the server power supply to generate about 13.8 volts without its overvolt protection being activated, this is enough to charge lithium to over 90% directly connected to the battery.
...

Mike

Thanks for the reply, Mike. You said that they server supply can supply 13.8v. What do you need to do to get that? What I am hoping for in this bulk charger is something that would put out significant amps up to about 13.6v - 13.8v. After that, my Magnum can finish off the charge. The power supply would only receive AC power from the generator.

 

[mikefitz]

You said that they server supply can supply 13.8v. What do you need to do to get that?

look on the internet for details on the server type you will be using. Although there is an adjustment pot the range is small, on the unit I use a resistor is added to change the output voltage. You also need to configure the control signals to command a start. However you cannot increase the voltage too much without the inbuilt overvolts protection shutting the unit down. Further investigation and changes could possibility modify this protection feature.

There are numerous videos and articles on the subject, here are some examples

Hacking HP Common Slot Power supplies - 12V@100A

I currently need a high power 12V power supply (to feed a Class-D amp, which in turn is going to provide an easily tuned source of ~60Hz pow...

colintd.blogspot.com

Mike

 

[vvadym]

The server power supply as shown in the diagram deliver 12 volts so assuming the MPPT needs an input voltage higher than battery volts to start working, then the system would not function. Not familiar with PowMr units but most MPPT need battery volts plus 4 to 5 volts to operate.
You can easily get the server power supply to generate about 13.8 volts without its overvolt protection being activated, this is enough to charge lithium to over 90% directly connected to the battery.
Its also possible after modification to connect two server supplies in series giving 24 volts that may be used as a MPPT input.
Since the internal parts of server power supplies operate at high voltages some experience in electrical systems is needed before attempting to modify these units.
An internet search will find information of the procedures necessary to convert these server power supplies.
Second hand server power supplies are available at low cost due to regular service replacements.
power supply

Mike

Awesome, thanks for so much going into details.
Well, from budget perspective in the range ~75A: two power supplies preferred + mppt controller costs are close to ~130-150$ but on the other hand POWERMAX PM3-75E for about 200-220$ will provide robust solution and still manageable price increase.
Would appreciate your suggestions on other power supply models recommendation)