Author Topic: Two Questions Tampering With Refrigerant and Battery Life  (Read 220 times)

Richard

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Two Questions Tampering With Refrigerant and Battery Life
« on: April 09, 2018, 11:36:37 am »


Question
 The technician added "some gas" last week. I did not have any data so it was added just based on the feeling. Then 3 days ago I connected an ammeter and saw it 5.3 amps (I did not know what it was before) . I also observed ice on the return tube just after insulation. This was typical sign of overcharged gas based on your info. So yesterday I disharged "some" amount of gas. The amp went down to 4.3 and the compressor is not running non stop any more which was my problem. And after several hours, the main compartment was at 6 C.

I had an issue with my battery charger now it was fixed, maybe this was another problem independent from the fridge. Anyway it is good idea to check the batteries' capacity. Can you pls give some details about the test, what to measure how to measure and how to evaluate the results?

Answer
I find it is generally a big mistake to have anyone tamper with refrigerant or even connect gauges to one of these small compressors. Non destructive testing must be done first to confirm that refrigerant is or is not a problem. Amperage draw and where there is frost and confirmation that compressor is actually running is all that is needed to evaluate refrigerant quantity and flow.

I do not know what your original problem was or what unit you have but it sounds like a Danfoss BD compressor amperage range.  For anyone to help you we need to know who made this system and compressor model number and age.. If this is a variable speed Danfoss compressor air or water cooled? There are inherent problems with each type system and each manufacturers designs are different.  Amperage draw is always predictable within a given range if speed size of compressor are known.

As to battery capacity it varies with age, charging rates and total of amps through put over time. When purchased a battery it will have a diminishing amp-hour capacity over time. The rate of battery amp-hr capacity loss can be measured in how quickly it is recharged or how quickly it discharges with a fixed load. An inexpensive new group 27 deep cycle wet cell battery will lose 70% of its amp-hrs in use on a charter boat in 26 weeks if used as the house battery. The more expensive the battery we should expect and do get more daily discharges. If you remove less than 30% amp-hrs of a fully charged battery daily you will greatly extend its life. Abuse a battery you shorten its life. Battery age alone shortens its amp-hr life.

There are several ways to test how much capacity is lost in a battery.
1. Using a standard automobile 100 amp load tester that is available from parts stores is one way to evaluate a battery. Harbor Freight has them for around $30. If a fully charged battery will carry 100 amps for 5 to 10 seconds while needle stays in the green it is still good but this test will not confirm available remaining amp-hr capacity.
2. Battery voltage and length of time to recharge at a given amperage will tell you when batteries need to be replaced.
3. There are Invertors that have a low voltage cut out that can be used to test remaining battery life/capacity. When testing 12 volt refrigerator stress on battery life connected to shore power I used a Heart inverters test procedure and an old electric 110 volt clock and two 60 watt light bulbs. With inverter connected to a fully charged 12 volt battery and two 60 watt bulbs and analog clock set to 12:00 was their recommended test. When power was applied both lights and clock where operating. When DC voltage at inverter reached a low of 12 volts it shut down with clock showing hours. Using 120 watts consumed per hour from bulbs and inverter clock running time service life of battery can be determined.