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GlennWest

Dc/dc step down coverters

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Glenn, good question but I have no idea what "they" are talking about. I'm rusty as an engineer being so long retired, but believe the laws of physics still apply. Any black box device which converts DC of X volts to DC of Y Volts IS NOT 100% EFFICIENT there are heat losses, same as for Inverters or Chargers etc. I don't understand "never charge battery while hooked up"  

If I recall you are going to use a 24 or 48 volt system but need a DC to DC Converter to power up 12 VDC appliances. If so that's all well n good but as you know its NOT 100% efficient.

Perhaps ?? They mean when no load is applied to the devices output it doesn't draw any current from its input source ??? If so I like that !!

John T  Sorry I just don't understand what they are talking about

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Glen if you take it literally they dont want you putting power into battery bank while using the product. If this is what they mean it sure would not work well with a solar set up. I am unsure of your battery setup but if you are using 6 volt in series the first two will give you 12 volts.

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Oh, 48v lithium battery packs. I did not want to go Victron since I need at least 50 amps. Was going to get 60 amp unit. I would have to buy two and that price I can buy a lot of 12v batteries. That why wanting to try these Chinese units. 100.00 dollars so if it doesn't hold up not out of a lot. 

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2 hours ago, GlennWest said:

oh, found one that works while battery being charged with solar, wind,etc. Ordering that one.

Plus, Amazon has an excellent return policy, even for outside sellers.

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They all have a range of acceptable voltage. That maybe exceeded if it is charging voltage rather than battery voltage.

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I also think you are making a mistake here Glenn. Don't put unknown components in the middle of a very nice system.

 

\

 

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But the Orion unit is also a charger. Don't need that. All I need is a simple bulk converter. Could use my existing converter but it is inefficient compare to a dc/dc unithttps://www.amazon.com/HUAZHU-Converter-Step-Down-Module-Waterproof/dp/B07Z2NN95X/ref=mp_s_a_1_6?keywords=48v+to+12v+converter+60+amp&qid=1574454438&sr=8-6

Edited by GlennWest

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FROM the specs on the above linked converter:

"1. Can not used long time Under the MAX. LISTED LOAD POWER."  LOL.  Sounds like 'me love you long time'.

Don't waste your time on that cheap Chinese unit. Notice (as you mentioned) max input voltage is 50.  Your batteries at rest will be around 52v, even more  when they're being charged.

If need be you can parallel a couple Victrons.  Yeah, they're expensive, but there's a reason for that.

Edited by hemsteadc

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* Input Rated Voltage: DC 36V 48V 30-50V

Which one are you going to believe?

(original post edited to show 50)

Edited by hemsteadc

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I was referring to Victron line of 24 to 12 volt dc to dc converters. Forgot you were using 48. They are not chargers but can be used as a charger to charge a 12 volt pack from a 24. This is a 48 https://www.invertersupply.com/index.php?main_page=product_info&products_id=185548&gclid=Cj0KCQiAq97uBRCwARIsADTziyZiZIbbIKXI7gTH0gv4aZ6xiMWXEqvejggGhEbwkTrCujdYfQkdrnQaAtekEALw_wcB

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9 minutes ago, Daveh said:

I was referring to Victron line of 24 to 12 volt dc to dc converters. Forgot you were using 48. They are not chargers but can be used as a charger to charge a 12 volt pack from a 24. This is a 48 https://www.invertersupply.com/index.php?main_page=product_info&products_id=185548&gclid=Cj0KCQiAq97uBRCwARIsADTziyZiZIbbIKXI7gTH0gv4aZ6xiMWXEqvejggGhEbwkTrCujdYfQkdrnQaAtekEALw_wcB

sorry Dave but that is a 24v. Victron doesn't make a 60 amp unit. Would have to buy at least 2. 

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On 11/21/2019 at 10:16 AM, GlennWest said:

That why wanting to try these Chinese units. 100.00 dollars so if it doesn't hold up not out of a lot. 

.  ......what will it do to the batteries (FLA or Lithium) though?

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On 11/25/2019 at 1:42 AM, GlennWest said:

Oh, it will be fused

 

 

 

 

Does it controlcharing so the battery bank is not over/under charged?

FLA is bulk 4 stage bulk - absorb - float - standby - equalize (sometimes)

Lithium is 2 stage - bulk - float (cutoff after X minutes) with temp & voltage disconnects

 

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Just now, ALLOY said:

Does it controlcharing so the battery bank is not over/under charged?

FLA is bulk 4 stage bulk - absorb - float - standby - equalize (sometimes)

Lithium is 2 stage - bulk - float (cutoff after X minutes) with temp & voltage disconnects

 

Do What? It won't be charging anything. Simply suppling trailer with 12v from 48v. 

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To solve the problem of the large amperage draw of the slide motor I decided to just go with 2 battery banks. I have 620 watts of solar charging a couple GC-2s for my 12v needs. I mounted these panels on the side of my MH leaving the entire roof free for racking 9, 320w solar panels front to rear for my 48v system. This will charge a much larger 48v bank for my big inverter and 48v DC mini-split heat pump. 

Not only is this setup cheaper than a big 48-12v DC-DC inverter, but it provides additional energy storage as well as not suffering any inefficiency in the conversion process. Plus I have a small (600w) PSW 12v inverter that I use to power my entertainment center, computer and printer. It also serves as a back-up for minor 110v needs should the main 48v inverter go down. Also should the coach battery prove too weak to start my MH one day, these 2 GC-2 house batteries have enough starting amps to help start my coach. The coach manufacturer provided a dash mounted starter boost switch for this very purpose. I wouldn't lose this safety feature by eliminating my 12v house batteries. If I'm just using a limited amp (say 50 amp) DC-DC converter it may be powerful enough to work the slide, and start the generator, but not enough to start the engine in an emergency.

Chip

Edited by sushidog

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I don't have a motorhome though. No onboard generator, so no real need for 12v batteries. Slideouts are on 50 amp relays. 

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