Weird D problem.

[mikesantor]

So I have a sst90 3D mag that is direct drive with the flex dimming board. For this set up I purchased 3 new NiMh Tenergy cells with a 4 bay titanium smart charger. I charged the cells once about 2 months ago. I have used the Mag MAYBE 6 times for no more than 1 minute at a time. So say a total of 6 minutes on the new cells. When I went to pick up the mag today to mess with it it was very dim. So I took the cells out and put them in the charger. 2 cells showed empty and 1 cell showed completely full.

I guess I have 2 questions. What would make (3x) 10k Mah cells only last a measly 6 minutes and what would make 2 cells drain and one cell stay full?

This is my first run with NiMh cells and Im a little confused. Thanks in advance!

 

[jayflash]

I'll begin the guessing game with questions. Is your charger an MD-3000 and do you know all four bays properly charge other cells from past experience? What's the state of the fourth cell or wasn't it also charged? Is it possible the "full" cell, of the three, really isn't full? Has it been fully discharged to be certain and the voltage monitored?

Those new cells probably need a break-in cycle and a couple conditioning cycles, if that hasn't been done, but two of them could also be bad; at this point it's hard to guess. If your light has a high parasitic drain while off and two of the new cells aren't up to normal capacity yet, the "good" cell may appear to be full.

You may have already done good diagnostics, but not knowing your level of experience, we need more info to be of further help. Others may have other ideas. Get back to us and we'll probably be able to fix your problems. The CPF has many good techs and experienced builders.

 

[mikesantor]

I'll begin the guessing game with questions. Is your charger an MD-3000 and do you know all four bays properly charge other cells from past experience?

Yes, that is the charger. I purchased 4 new batteries. Placed all 4 on the charger at the same time and they were all full basically at the same time. within about a minute of each other.

What's the state of the fourth cell or wasn't it also charged?

I just grabbed the 4th cell that has not been used that was initially charged with all the others. It has been stored in a rubbermaid tote. I just threw it on the charger and it is reading dead. :shrug:

Is it possible the "full" cell, of the three, really isn't full? Has it been fully discharged to be certain and the voltage monitored?

It is always possible that the charger is saying it is full but it is not. I meant to mention this but About 3 months ago my DMM took a 12'' fall and that was that. Since I am not big into electronics I have not purchased another one but I am planing on it. The first thing i thought of was checking the voltage on the "full" cell...

Those new cells probably need a break-in cycle and a couple conditioning cycles, if that hasn't been done, but two of them could also be bad; at this point it's hard to guess. If your light has a high parasitic drain while off and two of the new cells aren't up to normal capacity yet, the "good" cell may appear to be full.

You may have already done good diagnostics, but not knowing your level of experience

Low to low medium.

 

[jayflash]

First off, spend $20 on a new meter; it will save you far more in time and is useful for your car, testing wiring continuity, house AC and, of course, your lights and batteries. But for now ... more questions.

Roughly how long does it take to charge the D cells and how many charge/discharge cycles do they now have -- only two? If those cells have a capacity of about 8000mAh, it'll take over 6 hours for a full charge once fully broken in. Your charger supplies ~1600 - 1800 mAh per hour and charging is less than 100% efficient. A fully charged voltage check would be helpful. I'm concerned about that 4th cell. Are these regular or "LSD" cells?

You may want to open your DMM and look for a loose connection or broken solder pad. Even cheap meters can take a beating sometimes and simple things can go wrong. Closely inspect all wires and parts on the PCB. Without a meter it's hard to go much further, but let's try.

 

[mikesantor]

Roughly how long does it take to charge the D cells and how many charge/discharge cycles do they now have -- only two?

When I first got the cells they were half charged and took about 4 hours to charge. I charged them that first time and they have been in my mag ever since. Besides the one that sat in the tote that is now dead. So technically 3. One from the factory I guess, One from when I first received them and the one charge they are getting right now.

If those cells have a capacity of about 8000mAh, it'll take over 6 hours for a full charge once fully broken in. Your charger supplies ~1600 - 1800 mAh per hour and charging is less than 100% efficient. A fully charged voltage check would be helpful. I'm concerned about that 4th cell. Are these regular or "LSD" cells?

Regular cells. This is the actual kit that I purchased:

http://www.batteryjunction.com/combo-md3000-4d.html

You may want to open your DMM and look for a loose connection or broken solder pad. Even cheap meters can take a beating sometimes and simple things can go wrong. Closely inspect all wires and parts on the PCB. Without a meter it's hard to go much further, but let's try.

I actually tossed mine. Just last night I was online looking for a decent DMM for under 25 bucks. I may just go pull the trigger on a cheap craftsman so I can get some solid answers on whats going on.

Thanks for all the help so far Jay!

 

[jayflash]

I've got two Craftsman meters $10 & $20, each, on sale and they're close to the accuracy of my Fluke 112.

I'm on my second MD-3000 due to failure of the first one. Except for the CR123 cells, I haven't had good luck with Titanium cells, but things change and yours may only need to be well broken in. Maybe contact BJ to let them know of your problem so you don't run out of warranty time, should those cells prove to be bad. They indicate 14 - 16 hours to charge those cells.

After fully charging the four D cells, unplug the charger and then reconnect and press the discharge button on the side of the charger. All four slots should begin to indicate the discharge cycle in the display. Sometimes it takes several attempts to get all four bays to do the same thing, as the charger can be touchy. Maybe yours works more easily than mine.

Number your cells and try writing the charge and discharge times for each one. At a discharge rate of 200mA it'll take 50 hours for 10Ah to be discharged. That very low discharge rate is actually good and helps to better "form" your cells. With luck, your Titaniums will gain capacity and not self-discharge too quickly. Given the results others have had, you may find yourself returning the cells. Good luck.

 

[jayflash]

I just read another thread in this forum that the high end Tenergy D cells were supposed to be quite good. I'm not familiar with the brand's nomenclature or how those compare to your cells. My concern is the short shelf-life, which I don't think is related to being "broken in" or "fully formed", which does affect capacity. Perhaps some of our experts will weigh in.

 

[357mag1]

I would suspect your MD-3000. Mine recently died and started the process by not fully charging individual channels. Even the bad D cell batteries out there perform better than what you mentioned.

Good luck with getting Battery Junction to help you. They didn't want anything to do with my problems because I waited to contact them just past 90 days. After buying tons of stuff from them I was treated like a thorn in the side.

Wish you well and if you happen to be local (Chesapeake, VA) I can lend you some assistance.

 

[jayflash]

I had an even less savory experience than 357. It's unfortunate that BJ has no clue how much I've, since, spent elsewhere. Good quality and good CS ranks higher with me than a few % difference in price. Total cost of a product is sometimes beyond the initial price.

 

[mikesantor]

I hear you Jay. I would definatly spend more money with a company that cares. I have had 2 issues with lighthound with products. BOTH times it was no questions asked, priority mailed new products to my door. LH is AWESOME. They have my business for life.

Back to the Charger. The Ds have been discharging for 2 days now. Im going to leave them on one more night. Im going to run pick up a DMM tomorrow morning. I feel like a bum putting it off. I literally have a sears hardware within WALKING distance of my house... I should have some more info tomorrow when I get the DMM.

 

[jayflash]

I've also been pleased with LH.

If you haven't gotten your DMM yet, look for one with a 10 or 20 amp range along with mA & even uA, if possible. The lowest current ranges are good for checking parasitic drain and are more accurate at low current. I like lighted displays, but those usually cost more.

A full 48 hours will be almost 10Ah, the cell's advertised capacity. Using your meter you can check the actual discharge current for each bay. With a little practice you can press a probe on the negative end of the cell while pulling the movable charger contact back with the other. My MD-3000 shows 200mA for each one. The charger seems to be less consistent with charging, but I'm now using a transient protected UPS for my chargers. Brief power interruptions and spikes have occasionally reset or altered charging on other chargers.

 

[mikesantor]

Thanks for all the suggestions Jay.

The sears by my house had no DMMs at all. It was kind of weird. At this point I was getting impatient so I went to another store accross the street and purchased a sperry DM-6400. from what I understand, it is not super high quality but it will do for now.

So I got my batteries sitting here that have been discharging for 3 days now.

Battery 1 reads 1.24v
Battery 2 reads 1.37v
Battery 3 reads 1.38v
Battery 4 reads 1.35v

???

 

[jayflash]

If your Sperry has current measuring capability select a range good for several hundred milliamps. Unless the charger is way off or your meter is inaccurate, you should measure a drain of about 200mA. Three days, as in 72 hours? 72 X .2A + ~14Ah, which is more than the cell's rating.