This is a question not a statement. I am seeking clarification about the designation of THE LONGEST LASTING capacitors for my old 55-amp WhiffCo. 3, actually 1 stage converter.First of all I WANT IT TO BE FIXED VOLTAGE. 13.6 for my use is fine.But true to form when my laptop blew up it took information with it about replacing capacitors with PANASONIC ESD capacitors.In my new-to-me 5-lb NEWARK catalog I found a category for "Low ESD Panasonic capacitors rated at 10,000 hours at 105 c operation" Are these the longest lasting I can use or is there an even "better" grade?With the Mega's in the charger I have an alternate. I won't need higher voltage from the WhiffCo. Instead I will isolate the output with yet another monster Schottky rectifier set and drop voltage from 13.6 to 13.3, and with DO-5 silicon rectifiers voltage can drop to the high thirteens. But a repeat of the diagram for the unit showing which resistor to replace (I'll do it with pot) would be a constant temptation.Caps fail over time. Holes get punched electronically in the wraps. I am considering a full-on capacitor replacement - every last one in the unit. Is there anything else that could be upgraded? I can purchase upgrade transistors for instance. A ziploc emergency repair kit. I'll do an audit of the components and make sure I have enough spares. Where I haunt, a "resistor" is placed in handcuffs.This time answers get copied to Microsoft word then stored on USB flash memory.

Interesting. Been in electronics since about 1954 and never thought much about how long capacitors last. They do fail and get replaced when they fail. Never replaced them before they fail. I guess having a supply on hand is a good idea. Seems to me a capacitor that is guaranteed to last 10,000 hours is a little over 1 year. I just changed out a cap in a piece of equipment I bought new in 1992. That is 23 years. I do agree when it failed there was down time. So guess I don't understand your logic changing out them out before they fail. BTW Mouser electronics does sell parts with mil specs etc.

I believe those specs are worded as to reflect hours of operation at 105c which I will try to avoid. Mil-Spec is a guarantee that the device will perform as spec'ced and has an elaborately recorded history from where the raw material originated all the way forward to who tied the twine on the packing box.My concern is this: A failed component leading to failure of related components such as inductors that I will not have.So, I'm way the hell and gone down here and an inductor blows. Peruse the catalog. Choose an inductor for three dollars. It ships via DHL for seventy two dollars. It must pass through Mexican Customs. "Product Of Far East!" they declare. 400% tax added and if I do not beg the vendor to HIDE the DHL shipping charge or the customs people will tax the entire amount. DHL collects the tax. I spend thirty five dollars to drive back and forth from DHL. A hundred plus dollars, a two and a half week wait, a three hour journey to DHL all for a three dollar inductor. WAIT! I forgot the cost of the phone call...!Life down here is different. When there is nothing, when something breaks you learn to live without it. With a CPAP ir BiPAP machine and a power outage things get serious. In a power outage no lights, no fan, no AC no boob-tube, unless batteries or a generator are used and the nearest fuel is a 72 mile round trip. This gives a person whole new outlook on what kind of stuff to buy and how to take care of it. Solar panels in triple canopy rain forest? Life, ordinary existence down here is more challenging than most north of the border boondocking camping trips.

WyoTraveler wrote:Interesting. Been in electronics since about 1954 and never thought much about how long capacitors last. They do fail and get replaced when they fail. Never replaced them before they fail. I guess having a supply on hand is a good idea. Seems to me a capacitor that is guaranteed to last 10,000 hours is a little over 1 year. I just changed out a cap in a piece of equipment I bought new in 1992. That is 23 years. I do agree when it failed there was down time. So guess I don't understand your logic changing out them out before they fail. BTW Mouser electronics does sell parts with mil specs etc.Caps failing was a pretty popular and easy repair for many TVs I serviced in the 1980s-2,000.. So they can and do fail..Fast forward to modern day switching power supplies, these guys can and will eat caps for breakfast, lunch and dinner if you use standard caps due to the high frequency and high voltage spikes they endure with switchers.Low ESR caps are a definite requirement and yes 105C should be fine under most conditions.If you are concerned about "life" you could move up to the next available voltage rating provided it will physically fit. This will give you some additional headroom to work with.

When my Meanwell rsp-500-15 fails, it will be a sad day. I've grown extrmemely fond of it.To forestall that day, I have greatly increased ventilation and heatsinking adjacent to the transistors on casing exterior.I thought that most here consider the Wfco to be a failure waiting to happen, and a battery murderer until that point.

It is a fixed voltage power supply. Nothing more nothing less. It feeds a Lifeline and I can rely on it for maintaining the battery while under supervision. I now have so many Meanwells, Cheapos, and Mega's it isn't funny. But the Whiff's 55 ampere capability intrigues me. When I want to zap the battery I'll use the BORG at 14.4. volts, timed for X minutes. When the BORG is resting the float can maintain 13.2 (temp 30+C) or whatever I choose. When the Spirit goes months at a time out of service in Guatemala I'll connect a cheapo under-hood, and dial in 13.4 volts. The 1 Quetzal local bus and 20 Quetzal cross-lake water taxi is too much to resist. Panajachel is tourist city +. Start off with Eggs Benedict at Al Chisme, and fake it from there.I just do not like WRONG charging settings forced on me. The day I do not have 10-seconds free to check the batteries is the day I cash it all in.At both Las Pe?as and Santiago, my main daily duty will be playing Green Acres with gardens. Raising baby cucumbers for GENUINE kosher dill pickles, cantaloupes, monster radishes and yellow USA corn for tender corn on the cob. My last cantaloupe planting in a 10X14' area yielded 304 fruit, the heaviest weighing almost 2 kg. Stretching heavy commercial fishing nets in a giant X across the garden 8' tall, did the trick. The vines climbed up and down the net. The area is rife with honey bees.But all this is no fun when the lights go out. I have a pair of Endless breeze fans and a NOOK to keep me busy at night. In the tropics there is zero twilight. It goes from light to black in nothing flat. High power UV lighting in the bedroom and bathroom to find scorpions in a flash of green. On/On switches between LED and UV. These lights have found and doomed more than 100 scorpions. Get a wall full of scorpions at night and bring a couple of hens. The roosters follow. To them it's like a trip to Tony Roma's. There are on the other hand no "alacranes" at the lake.Here where I am presently, there are six-inch long scorpions called "Emperor Scorpions". Fat. The curved barb on the tail measures 1/4" in length. Locals call them alacranes de mamá.Yep. I need reliable batteries, chargers and LED lighting. South of the border IS without question, "The School of Hard Knocks".

100% Of The Capacitors Turn-Around In My Old WhiffCo.

35 Replies

LScamper
Explorer
Aug 19, 2015
MEXICOWOANDERER wrote:
" I have a 330uf 450vac axial cap ready to install across the output."

I'm not sure I understand. Are you planning to connect the 330uf cap on the output from hot to neutral? If so why, seems like a bad idea.
MEXICOWANDERER
Explorer
Aug 19, 2015
Is it my imagination that when I have replaced capacitors with the next-step voltage same uf they "seem" to operate significantly cooler?

On an extremely different note if I am successful in changing 100% of the caps I am going to install a suppressor board on the incoming line voltage. Gas discharge tube and multiple MOVS and TVSs. I have a 330uf 450vac axial cap ready to install across the output.

All this would be ridiculous - a total waste for a WifCo up there but down here is a different story. No one answered my question about an alternative brand that uses premium capacitors, so I have to assume that none of them are using capacitors of anything but "just get by" grade.

I crunched some numbers last night but without drawing a graph the numbers are hard to potray. Looks like the unit -may- end up maxxing out 12-hours a week 80% 15-17 hours a week. My Harbor Fright charger runs cool full output so it's getting a pair of Schottky rectifiers plus an environmentally sealed 25-amp breaker, suppressor system, 5Kuf cap, all new switches and an Intermatic 2 hour timer and tiny 50 mm 18-volt fan. That unit has got a World-beater transformer in it -even full load for hours it never seems to get > 50c. Also getting a set of Analog gauges. This will be for my son-in-law. A Shumacher 10-amp manual charger costs 215 dollars down here and they are rare. Wheeled chargers cost 300+ dollars and are Hwang Ho garbage. In Guat city who knows? But I will upgrade what I have. I need to find high reliability manual reset breakers for everything looks like they will be Klixon marine toogles. Ouch- pricey. But its either this or let 900 dollars worth of AGM Lifelines rot.
KJINTF
Explorer
Aug 19, 2015
Yes indeed that one looks like it might be bad, could be maybe? - Suggest you replace them both plus the one I draw attention to below and you will be good to go for a long time to come. On second look your main input fuse is toast! that cap might be the issue however suggest you check out the FET's before applying power unless you want fire and flame. Your unit looks similar to several I have seen that got plugged into a 240Vac source - not a good result the input side caps go up in smoke the FET's short etc......

Mex

I have found that the 10ufd cap to the left of the bleeder resisters on the small vertical PCB there in the corner has been a major failure item. A low ESR cap is required in that location.

To answer your question - None I'm aware of NOT even the highly promoted PD series which uses the lowest cost caps they can source - seen dozens of them most with Cap problems

Additionally replace the smaller one on the main PCB board right by those hot bleeder resisters
Chris_Bryant
Explorer II
Aug 19, 2015
I don't know- this one looks bad:

OT- the first sound system I ran was all Altec- a pair of A-7 "Voice of the Theater" cabinets, 4 of the cut down A-7 style cabinets, Altec 1220 mixer, a few Altec amps- 50 watt tube models, IIRC. This was ~1974-75.
MEXICOWANDERER
Explorer
Aug 18, 2015
What is the harm in substituting Panasonic capacitors that are rated for 10,000 hours @ 105c? I have installed (2) higher CFM ball bearing fans on the unit, and it is open frame unenclosed. Failure is not an option nor are multiples of converters as Mexican and Guatemalan Customs officers seem to have el beeg problem with spare electronics.
KJINTF
Explorer
Aug 18, 2015
Sal,

I believe you nailed it - I too believe most converters are not run near their max for more than a very short duration. Most converters run two large caps on the input stage in parallel after the full wave bridge rectifier. Guess it's lower cost to get two smaller ones than one large one and might be easier to get in the space requirements.

From what I have seen much of the time it's a heat related issue that destroys the components. The high failure items are mechanical as in the fan stops after getting full of dust and dirt and it's only a matter of time before the unit dies from excessive heat.

Sure hate to see folks toss good converters / inverters / electronic devices in the trash when normally in less than 30 minutes they can be as good as new for very low cost.
Salvo
Explorer
Aug 18, 2015
I'm surprised you haven't found more defective input caps. If you're pulling max current, those caps work hard. This is a peak charge circuit. That means the capacitor ripple current is very high. Charging current is limited to the peaks of the ac sine wave.

Say you got a converter delivering 1000W. You think the ac current is:

I = 1000W / 120V = 8.3A rms, or 11.8A peak

However, the peak current is considerably greater than 11.8A due to the power factor of perhaps 0.7.

Peak current is actually about 11.8A / 0.7 = 16.8A (or more).

Perhaps the reason you're not seeing more input cap failures is because most supplies don't operate at max power too often. The PD never gets to max power.

KJINTF wrote:
Very seriously doubt if the primary side large 820ufd @250Vdc caps will cause you any grief. They should be rated 200Vdc or higher since the peak value of the 120Vac RMS voltage is what is applied to them which is typically 170Vdc.

Many of the units have 450Vdc rating to accompany the 240Vac market.

I have had well over a hundred converters apart for repairs and only found the primary side filter caps bad in less than 5 units. They are used in a simple filtration application where ESR is of limited concern.
MEXICOWANDERER
Explorer
Aug 18, 2015
Alas the BK meter is at home! Endless thank you's for setting me on the right track. Will see about feasibility of upgrading to Panasonic and one level higher voltage if the radial lead spacing is not too different.
KJINTF
Explorer
Aug 18, 2015
Very seriously doubt if the primary side large 820ufd @250Vdc caps will cause you any grief. They should be rated 200Vdc or higher since the peak value of the 120Vac RMS voltage is what is applied to them which is typically 170Vdc.

Many of the units have 450Vdc rating to accompany the 240Vac market.

I have had well over a hundred converters apart for repairs and only found the primary side filter caps bad in less than 5 units. They are used in a simple filtration application where ESR is of limited concern.

Suggest you get your ESR/Cap Value meter out and test the 10ufd and 22ufd caps in the feedback loop of the switching circuit they are the typical failure items.
MEXICOWANDERER
Explorer
Aug 18, 2015
I repeatedly claim the Samsung Galaxy is smarter than I am and you just proved the point, thank you for the tip!