Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

Re: Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

Steven Lake wrote: »

Huh, looks like the Tenergy might be worth investing in for some NIMH cells.

i agree. any hams try these in their hts yet?

edit to add-it seems in my looking around for these batteries i had found that the same company offers up a 10 battery smart charger at a reasonable price.
http://www.sears.com/tenergy-combo-t-6988-smart-10-channel/p-SPM10929494216?prdNo=4&blockNo=4&blockType=G4

Re: Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

niel wrote: »

i agree. any hams try these in their hts yet?

Yes, but do you really need LSD low-self discharge in an HT application? (That is what the Centura Tenergy's and Sanyo Eneloops are) If you intend to use your rig within a week or two at the most, you may be better off with standard nimh. Both standard and LSD cells have about the same self-discharge rate within a week or so. Beyond that timeframe, the LSD hold their charge longer.

The desire for LSD cells is long-term storage - something you probably don't want to do with an HT that is used regularly, so the benefit of LSD is lost. By using standard nimh and using them more frequently, you can up the capacity, BUT you still want a quality cell. Powerex AA's fit that bill for standard nimh. (The same guys that make the excellent Maha/Powerex line of chargers) They also make Imedions, which are the LSD versions, and personally I find the quality-control to be quite good compared to many others.

Also be aware that most AA packs are intended for alkaline which have a very high-impedance so they are unlikely to cause immediate personal damage if shorted. Nimh cells with their inherent low impedance are another story, and will dump a huge amount of current in a short period of time if shorted, and with AA packs typically unfused, you are risking a personal safety issue. However many still use LSD eneloops due to them having a higher-voltage under load, so you may get more life out of the radio if used on high-power, whereas with others, you are stuck using low-power from the start due to the voltage drop.

Also beware of irreputable dealers dumping new-old stock that is many years old with drying electrolyte / internal oxidation. One reason I stick with Thomas Distributing. An analyzer/charger like an MH-C9000 is a great investment, and possibly the only one I know of that will give you an internal impedance reading to help determine the health of a cell, rather than just an idiot-light and a refusal to charge. (tip - one-time only impedance check at the beginning of charge: 1.6 = good cell, 1.8 middle aged, 2.0+ old / EOL)

Going small with nimh should be done with the same care we take with our larger solar battery banks - pick a reputable distributor, get fresh stock, and recognize marketing techniques and buzzwords intended to sway the unwary un-savvy consumer. A trip to Candlepower forums has much more detailed reviews than can be talked about here.

Re: Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

i use the lsd types in my ht with an add on aa battery pack. i may use the crap out of it one week and the next 3 months it may sit. (after full charge of course) normal nimh batteries will still self discharge a good deal of their power even in a few weeks and one never knows when one will need to use it in a hurry.

Re: Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

It all depends on how serious you want / need to be with your nimh application. The analogy would be would a Sam's Club battery be better than a Rolls-Surrette? Are you following the proper charging alogorithm to get the most out of them?

Unfortunately, the nimh world is a mess unless one takes it to the next level, which most consumers don't have time or patience for. You have good batteries with bad chargers, bad batteries with good chargers, price deals that dump new-old stock, varying quality among manufacturer's own offerings... Ugh. Energizer recently updated their line of batteries both normal and lsd as of 2010, but for some, they may still be swearing at their aging stock of pre-2010 cells. Again, CPF or Candlepower forums has the lowdown.

Generally, cells made in Japan are of higher quality than those made elsewhere, but there are exceptions. It may not matter much in a non-critical application, and if the cost of replacement is not an issue.

Avoid smart chargers that charge in pairs. Charging each cell individually is the enthusiast's choice. Unfortunately, even Sanyo Eneloops come with chargers that charge in pairs, unless you look specifically for those that charge individually. Maha/Powerex is one of a few that actually charge nimh correctly. There are others like Sony etc, but you have to dig deep into their specs to make sure.

Let's put it this way - a Tenergy on a good charger is a much better deal than a Sanyo Eneloop on a cheap drugstore charger. Much like you wouldn't want to charge an expensive Rolls-Surrette with a random automobile battery charger.

Re: Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

Oops - sorry Niel - I got my models crossed between the 6988 and the 9688 (lately redesigned as a TN190-4 <grin>

However between the two the 9688 does the better job. Why? To accurately detect a negative delta-v, one should be applying at least 0.5C, otherwise there is the risk that it will be missed and the charger will have to rely on a safety backup such as a timer. In Maha's case, they also monitor overall voltage and temp.

The 10-bay 6988 only provides 800ma charge current to AA's, and that is a little bit low to meet the 0.5C recommendation for delta-v detection for larger cells. Ie, a 2600mah rated cell should be receiving 1300ma of current to get that good delta-v. The saving grace is that many cells are over-rated in capacity, even after a few break-in cycles. That alone is one reason I use an MH-C9000 analyzer among other tests, such as user-displayed internal impedance.

The 9688 / TN190-4 provides 1.3A of charge current to AA's, and that helps provide a more accurate delta-v. 500ma for AAA's is especially useful for detecting delta-v, and if missed those smaller batts can heat up rather rapidly while waiting for a safety timer to kick in.

So unless you need 10 bays at a time, I actually prefer Tenergy's universal 4-bay 9688 / TN190-4 as they too allow for DC input charging and better overall specs. For some this is splitting hairs in non-critical applications where one just buys more batteries sooner than later. Battery geeks like me will tend to gravitate to Maha/Powerex, LaCrosse and the like.

What it boils down to is that Sanyo Eneloops are like high quality AGM's that hold a higher voltage under load, can accept rapid charge and discharge easily, and maintain that performance very well over their cycled lifespan. Others may come close. An analyzer like a Maha MH-C9000 can help weed out marketing from reality and let one make their own decisions. Toss in a West-Mountain Radio CBA-IV analyzer if you really want to go there.

Cheap chargers vs Maha or LaCrosse - this is akin to the difference between an online inexpensive charge controller, and something like a Morningstar, Stecca etc. Both work, it is just a matter of how precise and durable one wants to be.

Re: Tenergy NIMH brutally honest about technology VS Panasonic Eneloope

That can be done too, and have a backup charger in case you desire to upgrade. But be sure to choose a reputable dealer who is not dumping new/old stock from 5 years ago. Again, the Maha analyzer with impedance measurement capabilities can inform you if you got, um dumped on with a deal too good to be true.

Eneloops have been around long enough now that I see old stock-dumping at times, even counterfeits, so be careful out there.

From a solar perspective, Eneloop or not, one big advantage to LSD cells is that due to their very low internal impedance, they don't get as hot during charge as a non-lsd cell does - given a decent charger. This can give one a little more temperature headroom if they are charging via solar outside (shaded!) in hot climes. Not that I recommend this, as I do a two-step DC charging process from one large AGM to all my nimh charging setups later when convenient, but for the gizmos that charge directly in a device in the sun, the LSD's are a bit more robust under those elevated temperatures. And of course, some manufacturer's can withstand this better than others. A Maha analyzer will help you keep an eye on this with the impedance measurements, as a cell may have plenty of cycles left on it, but with temperature abuse, the impedance will start rising from cooking the electrolyte. (For enthusiasts one of the first things they do is note the impedance of the cells they just purchased to track it further down the line...)