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charging 48v battery with 24volt input

kpw

New Member
Joined
May 7, 2021
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61
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
 
How about something like this? There are quite a few different input/output voltage flavors and amp choices:


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


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?
 
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?
The generator is DC........IT does not generate AC.......Transformers are AC.....NOT DC The only way to change voltage on DC is a inverter or buck-boost converter....or change the generator.....very expensive.
 
The generator is DC........IT does not generate AC.......Transformers are AC.....NOT DC The only way to change voltage on DC is a inverter or buck-boost converter....or change the generator.....very expensive.
So there is not component on an alternator that can be replaced/adjusted to produce a higher voltage?
 
AGAIN.....ITS NOT AN ALTERNATOR....ITS A DC GENERATOR...THIS IS NOT PRACTICABLE.......


An AC Generator or Alternator AC output can be changed to any voltage with a simple transformer

A DC Generator can be changed to a different voltage via a Inverter or buck-boost converter which chops the DC into AC.

A DC to DC converter converts the DC to AC with a buck-boost converter, buck converter, or boost converter which uses inductors and capacitors to make AC which is then transformed (via the inductor(s) and capacitor (s)) to the desired AC voltage which is then rectified back to DC

A DC to AC inverter first chops the DC input to AC which is run through a transformer to produce the required AC voltage. (very simplified)

Most common inverters operate at 50-60 Hz, buck converters, boost converters, and buck-boost converters typically operate at 25 khz. which requires much smaller inductors.

BOTH methods of changing the voltage involve inductors and capacitors to change the DC to AC

A good starter read on DC to DC conversion can be found at wikipedia : buck converters, boost converters, and buck-boost converters......read all three articles for a understanding of inductance/capacitive relationship in DC to DC conversion
 
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AGAIN.....ITS NOT AN ALTERNATOR....ITS A DC GENERATOR...THIS IS NOT PRACTICABLE......
I REALLY DONT HAVE A HARD TIME SEEING OR READING, BUT I'LL PRESUME YOUR CAPSLOCK IS BECAUSE YOU DO. SO WHAT IS THE DIFFERENCE BETWEEN A DC GENERATOR AND AN ALTERNATOR?
 
A DC generator produces DC directly

An Alternator produces AC which is then rectified to DC with diodes, Most common alternators are three phase AC at a variable frequency which is directly related to the r.p.m. of the Alternator.

An AC generator produces AC directly from the coils, the frequency of the AC is directly related to the shaft speed and the number of coils on the generator.... Common AC generators are 3600 r.p.m. or 1800 r.p.m. depending on the number of coils , 2 or 4 are most common

Honda Inverter generators are a hybird.....they are 3 phase alternator (AC) which is rectified to DC at about 80 volts which is then used to power the inverter to make the AC. So they are AC converted to DC then back to AC.

The advantage is frequency output is not directly coupled to the R.P.M. of the engine.....thus the inverter generators change speed to be more effecient which a AC generator cannot do as frequency is directly related to r.p.m.
the frequency of the alternator is directly related to the speed of the engine, the frequency of the inverter is derived from the logic in the alternator. They do not need to be the same.
 

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