DCDC/AGM compatibility question

TJayTJay Registered Users Posts: 2
Hey guys. First post here. I hope I don’t embrace myself and or piss anyone off with my inexperience.:blush: 

Anyway I’m slowly building a battery bank to power a small camping fridge for short over night trips. At the moment I have two small 26Ah Odyssey AGMs which I plan on running in parallel (52Ah). I do have plans to get two more AGMs for a total of four (104Ah) in the future but for now it’s just the 2. That said I’m looking at the Redarch 25A BCDC to charge the 2 that I have now. However I just watched a video that said this charger is designed for a 75-200Ah bank. So my question is, will I damage my two paralleled 26Ah AGMs if I run this charger? 

Thanks in advance 


  • petertearaipetertearai Solar Expert Posts: 471 ✭✭✭✭
    Would not think a problem . But more of a problem will be mixing old and new batterys. 
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
  • TJayTJay Registered Users Posts: 2
    edited January 2022 #3
    Would not think a problem . But more of a problem will be mixing old and new batterys. 
    The age difference shouldn’t be all that big actually. My plan is to first run just the two to see how many hours of fridge run time I can get out of them. I expect to be disappointed.  At that point I’ll add the second two. I figure no more than a couple discharges between the two I have now and the two I’ll more than likely be adding. I’m not looking to go hard core off grid or anything. I’m more of a weekend warrior.  I figure if I can get by with just the two for what I’m doing I might as well save the money and put it towards a decent fridge. I didn’t know age played a factor though. Thanks for the heads up.  
  • Marc KurthMarc Kurth Solar Expert Posts: 1,029 ✭✭✭✭
    You need to check the Odyssey specs, but most AGM batteries in their class should not be charged at a higher rate than about 30% of their C/20 rating. So about 15 amps for your two batteries in parallel.
    What is the current draw of the refrigerator?
    Are the output (absorb and float) voltages of that charger correct for Odyssey?
    I always have more questions than answers. That's the nature of life.
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