charging 48v battery with 24volt input

[kpw]

Hi everyone,
I was wondering if it was possible to charge a 48v battery bank with a 24v dc generator. ( its from my old 24v system hoping to repurpose for 48v) Of course I could use a step up transformer but having trouble finding one that can handle 80 amps dc @ 24v thats cost appropriate.

Thinking Maybe using a micro hydro style charge controller? Does anyone know of a charge controller that can step up voltage?

Open to any other ideas

 

[Alphabavo]

What kind of generator?

 

[kpw]

What kind of generator?

Dewey military surplus 24v alternator generator diesel

 

[MisterSandals]

How about something like this? There are quite a few different input/output voltage flavors and amp choices:

Amazon.com

And parallel these units to get to 80 amp. Cost appropriate, i dunno.

 

[kpw]

How about something like this? There are quite a few different input/output voltage flavors and amp choices:

Amazon.com

And parallel these units to get to 80 amp. Cost appropriate, i dunno.

I was hoping to use most of the charge current available from the 24v generator. The options they have available look like i could only use 6 amps of the 80 amps available.. https://www.amazon.com/Victron-Energy-Orion-Tr-110-Watt-Converter/dp/B07DQ66PMS/?th=1
at $215 apiece would be to costly to parallel.
I think the generator cost me around $800

 

[kpw]

has anyone tried a DIY step up transformer?

 

[MichaelK]

Is it a single 48V Li battery, or is it a string of 6 or 12V batteries? In a pinch, you could disconnect the battery from the rest of the system, and charge each half one by one till fully charged. Assume that you'd need to charge each half to exactly the same voltage before reconnecting the two halves.

 

[740GLE]

Why not rehead the generator? You’d keep your losses to a minimum, and it’d be a great little project.

 

[kpw]

Is it a single 48V Li battery, or is it a string of 6 or 12V batteries? In a pinch, you could disconnect the battery from the rest of the system, and charge each half one by one till fully charged. Assume that you'd need to charge each half to exactly the same voltage before reconnecting the two halves.

Looking for a solution where i can just flip a switch and it works

 

[kpw]

Looking for a solution where i can just flip a switch and it works

its going to be charging 32 lipoe4 280 in 2x 16s

 

[kpw]

Why not rehead the generator? You’d keep your losses to a minimum, and it’d be a great little project.

Was thinking that might be a possabilty but the computer on the generator is 24v and does all the starting/ stopping/ timed charge, voltage adjustments, delay, and fuel pump prime and operation. starts with a single switch and was hoping to keep those perks

 

[The New JC777]

Looking for a solution where i can just flip a switch and it works

Make sure the Dewey is LFP compatible and programable to your cells as measured at your battery terminals.
To avoid the losses and expense of a DC to DC converter, you could do 2P8S x 2 battery giving you 1120 A/H @ 24vdc. You end up with the same Kwh battery, but with 2x the current flow requiring 2x wire size for the same distance run and a higher wire cost....but I bet you know this already. The up side, "just flip a switch".

 

[kpw]

Make sure the Dewey is LFP compatible and programable to your cells as measured at your battery terminals.
To avoid the losses and expense of a DC to DC converter, you could do 2P8S x 2 battery giving you 1120 A/H @ 24vdc. You end up with the same Kwh battery, but with 2x the current flow requiring 2x wire size for the same distance run and a higher wire cost....but I bet you know this already. The up side, "just flip a switch".

unfortunately my outback radian inverter is only compatible with 48v

 

[Bud Martin]

BTW, you will need higher than 48V to charge you 48V LiFePO4 pack.

 

[The New JC777]

unfortunately my outback radian inverter is only compatible with 48v

I had the same issue and wanted to go 48v in a mobile installation, but after following threads here, I went back to 24v for safety reasons. I will just sell the 48v AIO, take the loss, and add it to the cost of my education.

 

[MichaelK]

I had the same issue and wanted to go 48v in a mobile installation, but after following threads here, I went back to 24v for safety reasons. I will just sell the 48v AIO, take the loss, and add it to the cost of my education.

Reading this makes me feel quite sad. Going to 48V is not going to present you with life-threatening experiences. Stop listening to fear mongers!

 

[The New JC777]

Reading this makes me feel quite sad. Going to 48V is not going to present you with life-threatening experiences. Stop listening to fear mongers!

The general conclusions were; having 96+voc solar array connected to a 48V battery going down the road at highway speeds in a steel framed aluminum skinned trailer was just not a good idea. In a stationary system 48v is my choice. I would love to learn more, but don't want to pollute this thread.

 

[Tecnodave]

Hi everyone,
I was wondering if it was possible to charge a 48v battery bank with a 24v dc generator. ( its from my old 24v system hoping to repurpose for 48v) Of course I could use a step up transformer but having trouble finding one that can handle 80 amps dc @ 24v thats cost appropriate.

Thinking Maybe using a micro hydro style charge controller? Does anyone know of a charge controller that can step up voltage?

Open to any other ideas

Unfortunately for your situation a transformer is AC only, It is a dead short circuit at DC. Other than a very expensive DC to DC step up converter, this will be difficult.

Samlex does make DC to DC converters but at $300 USD, it may not make sense. Most DC to DC converters are to step down the voltage.

For a lithium battery you do not need a DC to DC battery charger like used for lead acid with 3 stages, just a simple DC to DC converter such as the Samlex IDC line or the fully isolated SDC line of converters.

The Samlex converters do have a voltage set point adjustment so it can be set for the exact voltage desired.

I use these on my 24 volt system to control voltage for my 12 volt devices, very reliable and low EMI/RFI especially with the fully isolated SDC line, very good for ham radio use as very low noise/EMI/RFI....“no birdies”

 

[740GLE]

Was thinking that might be a possabilty but the computer on the generator is 24v and does all the starting/ stopping/ timed charge, voltage adjustments, delay, and fuel pump prime and operation. starts with a single switch and was hoping to keep those perks

So with that being said, sounds like you need FLA of 24v of which this generator was designed for. Or unload the generator and find a different solution.

 

[DerpsyDoodler]

How about something like this? There are quite a few different input/output voltage flavors and amp choices:

Amazon.com

And parallel these units to get to 80 amp. Cost appropriate, i dunno.

the first ones listed are stepdown. Looks like the highest rated step-up 24-48 is $220 for 8.5a. That definitely does not seem cost effective.

Is there any way to replace a transformer on the generator and just have it generate 48v?