Hi all,

I have two of these batteries: https://www.electricmotorsport.com/gbs-12v-4-cell-100ah-lifemnpo4.html. I've wired them in series to be 24v (I was told that 24v is better than 12). This is for a van conversion I'm doing with 24V solar panels. I need to get from 24v to 12v to run the LED lights, fan, fridge, water pump (pretty much everything is 12v). Is a converter the best way to get from 24 to 12 volts. Something like this: https://www.invertersupply.com/inde...MIyerv65WK6gIVER6tBh2S1Qu3EAYYASABEgKJ5vD_BwE.

The thing I don't understand is that this is rated for 5amps (60watts); I don't know how that equates with a 24v battery (200amp/hours) that I want to convert to 12.

Thanks much,

James

 

5amps (60watts) sounds a little skimpy for typical leisure loads. You likely will need something with a higher current capacity and power. Orion 24/12-70
https://www.victronenergy.com/uploa...DC-converters-high-power,-non-isolated-EN.pdf

A rough rule of thumb here is that the 12vdc load current requirements will be half that current load value at the 24vdc battery (100amp/hours because they are in series) supply .

 

If most of your stuff is 12V then make the whole system 12V not 24V. Not very efficient running 24V then converting it back down to 12V.

 

If most of your stuff is 12V then make the whole system 12V not 24V. Not very efficient running 24V then converting it back down to 12V.

Thanks, someone told me 24v was more efficient...and that I could additionally use more of the 24v solar panels. But I assume there are costs for converting energy back to 12v? Are there more efficient (or cheaper) methods than a converter; I assume one of those larger Orion converters will be pricey.

I'm trying to figure out the best way forward.

 

You need a controller between the photovoltiac cells and the battery. That usually also does the voltage conversion. Here is an example:
https://www.amazon.com/Controller-Battery-Intelligent-Regulator-Adjustable/dp/B072MMDY4F

 

Yes, I have this controller: https://www.renogy.com/rover-li-40-...MIlpTvuPuL6gIVAR-tBh1WXwDjEAQYASABEgK7J_D_BwE.

 

I have a 24vdc system using this controller. https://forum.allaboutcircuits.com/...c-controlled-battery-array.32879/post-1482098
You need about 50vdc from the solar panel array for it to operate normally (efficient MPPT) with at 24vdc energy bank.
https://forum.allaboutcircuits.com/...c-controlled-battery-array.32879/post-1513872

Each voltage conversion will lose (realistic numbers instead of what's printed on a datasheet) in the range of 3 to 8 percent of energy transferred so it's best to keep that at a minimum. At higher power, a 24vdc energy bank is typically more efficient than the equivalent 12vdc bank mainly from the reduction in IR losses with reasonable cable sizes and connections. Down converting to 12vdc will eat a large chuck of that advantage.

 

If your final needed output voltage is 12 volts, then use a 12 volt battery. Outputting to 24 volts and then downconverting to 12 volts will not be more efficient.

 

Okay, it sounds like 12v is the way to go. @nsaspook , is this for a van conversion or a house (if for a van, you must have 12v needs, how do you deal with those?) I also need to get a BMS for the batteries: since it seems like 12v is the way to go--this should fit my needs, right? : https://www.aliexpress.com/item/329...earchweb0_0,searchweb201602_,searchweb201603_