Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

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Hardwarezone
Posts: 350
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

Mini dehumidifier cost about $16 online.
Most buyers incorrectly use at open space bathroom or bedroom , fully saturated in 1-2 days.

Visible silica gel beads go from orange , purple grape , greenish , pinkish , transparent.
The internal heater element runs about 3/4 the length , no heat injury to fingers as it feels like full boil egg.

On the first heating recharge session it took 5 hours to fully dry it back to bright orange.
For cool down it took 3 hours in the covered steel pot for cool until room temp.

First problem was this freshly recharged device too strong for the dry cabinet.
Running into the low 30s % RH , had to open the cabinet door a few times per day to exchange humid air in.
Lower isn't better , too low into 20% or less RH can cause adhesive / lubricant / paint coating to detach.

Next recharge sessions I tried heating 2.5 hour and it was sufficient. Cool down times remain fixed at 3 hour.
Cycle between 50% to 40% RH measured at the lowest corner of dry cabinet. The cabinet's built-in digital hygrometer takes reading at top which is 7% lower.


Charging in unwanted steel pot to insulate the heat
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green to bright orange after 5 hours
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cool down horizontally in the pot for 3 hours , put a pot lid to stop air exchange
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The heating session consume about 22 watt for most of the duration and gradually lower to 18 watt at 5 hour.
No auto-cutoff function.
Electronic dry cabinet runs at 3 watt normally to hit 45% RH and 0.5 watt when lowest setting to only run the hygrometer display.
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At this scenario I tried to simulate a storage tub holding a 6 inch SCT OTA (17.5cm diameter) , used a dummy 20cm diameter cylinder.
My green plastic tub's internal size cannot fit 8" SCT. With 6" SCT there may be 2 to 4cm leftover in Length.
Tub's edges are terrible with open gaps on the top lid as it wasn't designed to be airtight seal.

After 2 run ending at approximately 10-11 days each, I received a bigger airtight tub with silicone o-ring seal to test 3rd time.

Conclusion : normal tub lid unsuitable with air gap leak , viable low cost drybox or plastic bag solution if airtight.

green tub with gap at lid edges
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airtight tub , listed as 80L with 63.5cm external , I measured 53cm internal length.
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28% RH climb to 51% over 65 days
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Did another test on a cracked tub that I repaired , brand new fresh dehumidifier + 5 hours heat recharge
It drop to less than 10% RH overnight. Verified with digital and analog hygrometer , drop 65 to 25% rh within first 3 hours.
This is too dry and potentially cause damage.
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Hardwarezone
Posts: 350
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

From S____e online shopping platform , price vary widely as different seller like to chop carrot on the odd desperate buyer.

For local option can buy from the JiJi brand , airtight - big - affordable mid $20s , but the seal ring is EVA foam not silicone. I got rid of many eva foam stuff in my home since they start to breakdown little particles when nearly 10yr old.
Hardwarezone
Posts: 350
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

Updates after 5 months of usage of the airtight plastic tubs.
Works ok , bouncing between 40 to 50% RH. More usage = more recharge effort.

Bought the 40L Hercules tub from local brand Citylife. Available on shopping platform S____ and L_____
Not an advertisement post , I paid full price for my items.
Internal length 42cm x 31cm width. Bottom is flat without raised wheels so it get more support from the floor for heavier item.
Can stack ontop but cannot nest multiple within each other when unused storage. Vertical walls.
I recommend disassemble the silicone O-ring and wash everything with soapy water to remove any manufacturing oil.
Initially the O-ring tend to drop out , weeks after it's holding fine inside the groove.
4 side latches flip flop around block lid closure on single try , minor annoyance. 2 Bigger latches no issue.

Performance of this 40L tub is roughly the same as the above reviewed 80L tub , difference is November month much more rain than March-April.
Without opening the 40L tub , 25% climb to 40% RH takes 20 days.

Sold in 1 , 2 , 3 quantity. The 2pack is the most value. After stacking coupon and "app points" it's possible to get the Hercules 40L tub under $10 each.
I suggest skip the 26L smaller size unless you only use binoculars.

The $2 plastic hygrometer can be adjusted with a flat screwdriver at the rear opening. Take it out of a well referenced dry box and quickly adjust in 1 stroke. I received a few that were off by 15-25%.
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