Olympus BLM-1

The Olympus BLM-1 was not opened since, due to it's cost, should it fail within warranty it would be quite expensive to replace. It seems reasonable to assume, though, that the cells and control/protection circuitry are adequate and the capacity test confirms that the cells are up to standard.

The capacity test shows just a bit under 1500mAh. I have no doubt that at the normal discharge rate used for cell capacity rating this would turn in a 1600+mAh performance. Over-discharge protection cut in at 4.5 volts for over-discharge protection of Lithium-Ion cells, this is quite satisfactory. The duration and shape of the discharge curve is strikingly identical to that of the Energizer OM-1 and this leads me to believe that if I did open it up I would find the same good quality pair of Panasonic cells (or equivalents) inside and a similar (if not perhaps the same) control board.

Of note is the short-circuit protection. During hook up I managed to unwittingly short the cell with a pair of pliers causing a just a few small sparks to be emitted briefly. After a short spell in the charger to top up the pack all was well and no ill effects were observed. Short circuit protection does work after all! This is a solid, workmanlike performance from Olympus, and their packs carry a warranty as well which you could actually rely on. This result places the Olympus BLM-1 in second equal position with the Energizer OM-1 for capacity.

It is difficult to rate this pack. On pure performance and protection grounds it warrants a 'Highly Recommended' but the street price goes against it. In the UK it is over three times the price of the UNiROSS which has extra capacity and it is almost exactly three times the price of the Energizer which has the same capacity, and both of these have the same level of protection and control circuitry and equivalent build quality. No doubt the differential is equally great around the world whatever the actual prices are compared to the UK. The Olympus BLM-1 has nothing extra to offer over these two packs but the high price means it is marked down accordingly.

PS-BLM1 (7DayShop.com)

The control and protection circuitry is not on the at battery ends as in some cells, but is on a PCB sandwiched between the cells and the bottom of the pack. This is a good location for the temperature control. There is no indication of the manufacturers of the actual cells.

The control board incorporates a battery voltage monitor IC (U1) which does certainly cut the pack off completely at about 5.6 volts thus protecting it from over-discharge. I could not tell if it protects against over-volts in the charger. The voltage monitor U1 controls what I believe to be a MOSFET power pack (U2) in a latched mode so once off it stays off. An LRDP260 polyfuse is incorporated (2.6 amps) for protection against short circuits. Charge control is via R6 which I believe to be a real thermistor. Although it has no markings I could see (another clue - normal resistors are marked) the rate of change of value with temperature is quite high, far more so than would be expected of a normal resistor.

Capacity test shows around 1000mAh or so. I should point out that I discharged this cell at around 0.5C instead of 0.1C (i.e. 750mA or so rather than 150mA) for an accelerated time curve. Manufacturers capacities are usually stated at 0.1C discharge rate so I have no problem believing this would achieve it's rated 1300mAh, and probably a bit more. The curve shown covers around 90 minutes. In summary, this one is good in my books and will be going into service (or would if I hadn't hacked it apart lol).

Update: a re-test at 0.15C (as the other cells, see note at foot of page) produced a useful capacity increase to 1139mAh so I have up-rated this one to it's proper 1300mAh or so rating, and as such it does represent good value for the money and is the best of the 'low-cost' clones.

WT-BLM1 (SterlingTek.com)

For lack of a model number I have called this the WT-BLM1. As with the others, the circuitry is not at the at battery ends, but is on a PCB sandwiched between the cells and the bottom of the pack. This is a good location for the temperature controlled charge gut-off. Compared to the PS-BLM-1 the circuit board is flimsy, as is the whole case assembly. The cell welds are fewer and poorer, the metal straps thinner and narrower. There is no indication of the manufacturer of the actual cells however they are recent and clearly marked as 1300mAh, I am astonished that this battery can be marked as a 1560mAh item, and to sell it as a 1700mAh item is just laughable, not to mention deceitful.

The control board incorporates an SE666 battery voltage monitor IC as in the PS-BLM1 which is supposed to cut the pack off completely at about 5.6 volts thus protecting the cells from over-discharge - mine didn't! The voltage monitor controls what I believe to be a MOSFET power switch to cut off the cells to prevent over-discharge. On this pack, this failed completely, the voltage oscillating between 5.4 and 4.8 volts for a few seconds then continuing to discharge until manually cut off by me at 3 volts. A second test later confirmed this to be completely non-functional. There is no polyfuse, or any other type I can identify, therefore no protection at all against short circuits and potential venting or explosion. Charge control is via an ordinary 10K resistor rather than a proper thermistor.

The capacity test shows just over 1200mAh. Please note the disclaimer at the bottom of the page. I have no problem believing this would achieve the cell's rated 1300mAh but to suggest that these are 1700mAh (or even 1560mAh) is just a joke. The discharge curve covers around 405 minutes. In summary, this is one to avoid at all costs. Construction is poor, charge control is poor, protection is non-existent and over-discharge protection is questionable (failed totally on my sample). If you want to buy at this price level, get the PS-BLM1 instead, it lacks a few mAh capacity compared to the WT-BLM1 but more than makes up for it in other areas.

Energizer OM-1

As before, the circuitry is not at the at battery ends, but is on a PCB sandwiched between the cells and the bottom of the pack. This is a good location for the temperature controlled charge cut-off. This pack contains the same quite satisfactory control board as the PS-BLM-1 tested earlier. The label is not very elegant but the case is robust, the cell welds are proper four-spot ones and the metal straps are a good width and thickness.

The cells are quality items manufactured by Panasonic and are confirmed as rated at 1500mAh and in addition are confirmed as UL approved. The discharge test confirmed them as quality items well up to spec. The control board incorporates a battery voltage monitor IC as in the PS-BLM1 which cuts the pack off completely thus protecting the cells from over-discharge - this one operated at about 4.2 volts which is lower than I would like but is far better than nothing. An LRD260 polyfuse for protection against short circuits is fitted, this is rated at about 2.6 amps. Charge control is via a proper thermistor, R6 on the PCB.

The capacity test shows just a bit under 1500mAh, see disclaimer at the end of the page. In normal usage I would imagine they could fairly be rated as anywhere between 1650 to 1750mAH. The discharge curve covers almost 8 hours!

In summary, this is a quality act despite the somewhat tacky and un-informative label. Construction is good, charge control is good, protection is good and over-discharge protection works fine. Now, granted you could get 2 PS-BLM1 packs from 7DayShop.com instead and have change, and have in total about 2400mAh on tap so why buy the OM-1? Well, two reasons: first, all other things being equal, packs are about cells, cells and cells. Here you have a pair of quality cells from the Matsushita stable, rather than the PS-BLM1's 'no-name' brand. Secondly, the Energizers carry a 2-year warranty so if they flake out after 3 months you have a chance of replacements. With the PS-BLM-1's you are in the hands of your supplier. Of course, as with all things YMMV.

Available in the UK at around £26GBP compared to the Olympus original at £68GBP this one will now become by main standby battery (at least, if I can manage to glue it back together lol). Highly recommended!

Hahnel HL-M1

The Hahnel HL-M1 was one of the first clones I bought since their web site carried this reassuring text and I really wanted to get the same level of quality and protection as the Olympus original: "A built-in microprocessor safeguards the cells by limiting maximum voltage and by protecting against deep discharge, short circuit and overload." I was a little disappointed to find that it was marked up as a 1400mAh pack, but as a standby backup not too concerned. As Hahnel is a manufacturer of known repute and confirms the level of protection available I have not opened this pack for inspection as it would seem unnecessary.

The capacity test shows just under 1400mAh. See disclaimer at the end of the page. This is a good solid 1400mAh performance with a little left over. Over-discharge protection cut in at about 5.6 volts, just about ideal for protection of Lithium-Ion cells. Of note is the fact that the Hahnel web site lists the HL-M1 currently as 1500mAh capacity, unfortunately I can't see from the picture if the pack is actually marked as such.

This is a good, solid, workmanlike performance from Hahnel, and their packs seem to carry a two year warranty as well. This places the HL-M1 third in the series so far, the Energizer OM-1 is a better buy at the same price and quality but with significant extra capacity and the UNiROSS absolutely smokes it with the same quality and protection but even more capacity and (in the UK at least) a significantly lower price.

Stop press: while this version has been marked down for capacity, it has been confirmed that the current version being sold is a full 1500mAh capacity.

UNiROSS VB104295

As with all the others the the circuitry is sandwiched between the cells and the bottom of the pack. This is a good location for the temperature controlled charge cut-off. The VB104295 uses the same control board as the Energizer OM-1 tested earlier which was awarded a 'Highly Recommended'. Just as in the OM-1 the label is not very elegant but the case is robust, the cell welds are good four-spot ones and the battery straps are a good width and thickness. The cells are manufactured by Panasonic and are confirmed as rated at 1500mAh and in addition are confirmed as UL approved. The discharge test shows that they are quality items well up to, and indeed above, spec.

The control board incorporates a battery voltage monitor IC which cuts the pack off completely thus protecting the cells from over-discharge. My sample operated at 4.29 volts. This is lower than I would like, but quite acceptable. An LRD260 polyfuse for protection against short circuits is fitted. This is rated at about 2.6 amps. Charge control is via a proper thermistor, R6 on the PCB.

The capacity test shows 1494mAh. As before, see disclaimer at the foot of the page. This is an extremely good performance and a testament to the generous rating of these cells. In normal usage I would imagine they could fairly be rated as anywhere between 1700 to 1800mAH. The discharge curve covers 8 hours! If this reads similar to the OM-1 test, that is because apart from the label, and slightly higher capacity, the UNiROSS is identical in all respects to the Energizer pack. Same cells, same control board. I surmise from this that they are both sourced from the same OEM manufacturer, a not uncommon practice. Notwithstanding that, in summary, this is a quality act despite the somewhat tacky label. Construction is good, charge control is good, short circuit protection is good and the over-discharge protection works quite well. Again, the UNiROSS pack carries a 2-year warranty for peace of mind.

Available in the UK at around £20 compared to the OM-1 at around £26 and the Olympus original at £68 this one will take the place of the OM-1 to become my main standby battery. At £6 cheaper than the Energizer and with extra capacity this has to earn a 'Very Highly Recommended'!

'WinTop' PS-BLM1 (NOTE: This battery is NOT made by Olympus)

Having a fake Olympus label, I have termed this one the 'WinTop' BLM1 after the control board. Unlike the others the the circuitry is not sandwiched between the cells and the bottom of the pack but is carried at the end of the cells. This is not a good location for the temperature controlled charge cut-off as it relies on the temperature of most of the whole pack to rise in order to cut off. The very thin control board (by WinTop) carries the usual control chip and FET switch but has no short circuit protection fuse. The label is a bit of a concern - it is clearly designed to give the impression that this battery is made by Olympus when it is not. The case is flimsier than most of the rest and the cell welds leave a lot to be desired. The battery straps are tissue thin, I didn't have to use cutters on them I just tugged! The cells are a pair of flat sandwich-construction types with no identifying marks whatsoever to indicate either capacity or manufacturer.

The control board battery voltage monitor IC did cut the pack off completely thus protecting the cells from over-discharge. My sample operated consistently at 5.5 volts. This is higher than many, but quite acceptable. Again, there is no polyfuse for protection against short circuits, a lamentable omission. The charge control device is not a proper thermistor but just a resistor on the end-mounted PCB.

The sample tested was kindly donated by UK-Kev, an E-1 owner in the UK, after about a year of use, withdrawn due to a breakage in one of the plastic contact separators. The capacity test though shows only about 800mAh, a poor performance after only a year of use and only 20 charge cycles. The discharge curve struggled to cover 4 hours! One has to wonder if it ever produced anything near the rated 1500mAh. As before, see disclaimer at the foot of the page. I have not added this to the summary as it seems unfair to compare a pack with a year of use with new cells so I have just shown the discharge curve.

Update 12 April 2007: thanks to Tim the Grey, who has donated another sample of this make of pack to the cause, I have been able to examine another one of these and find the same poor control board, the same unmarked low-quality prismatic cells (rectangular) and again, despite only 8-10 months of light use and 25-30 charge cycles this one has collapsed completely, not only has the overcharge circuitry failed, the over-discharge circuitry has gone as well and as you can see in the last discharge curve it just falls off a cliff and doesn't cut off at all. The cells have just given up totally.

In summary, this is a cheap and tacky product with a deliberately misleading label. It is shipped in a virtually identical box to the genuine Olympus article with 'Olympus' instructions and is a clear attempt at counterfeit with a dreadful quality copy product. Construction is poor, charge control is average, short circuit protection is non-existent although the over-discharge protection does work (edit: but not always). As to warranty, it will depend on the seller but typically those selling these types of product aren't too bothered about after-sales service.

Available on the Internet very cheaply (and no wonder) there are better third-party cheap packs to be had than this one. This sample was obtained from an eBAY store operated by 'kinmobile' and is the worst one yet tested. Another one to avoid!

e-Film (Delkin) BLM1

The control circuitry is not sandwiched between the cells and the bottom of the pack but is carried at the end of the cells. This is not a good location for the temperature controlled charge cut-off as it relies on the temperature of most of the whole pack to rise in order to cut off. The very thin control board by Weton (who also make the control board for the Sterling Tek WT-BLM1) carries the usual control chip and FET switch but again has no short circuit protection fuse, nor does it have a proper thermistor to limit maximum charge. The case is fairly flimsy and the cell welds leave a lot to be desired. The battery straps are quite thin and not very wide. The cells are a pair of unidentifiable types with no clear markings to indicate either capacity or manufacturer.

On the discharge test the control board battery voltage monitor IC did eventually cut the pack off completely but it clearly had some problems switching the pack off as the expanded discharge graph shows. It eventually operated at about 3.65 volts. This is quite low, and gives questionable protection for the pack. As with many lowest-cost packs there is no polyfuse for protection against short circuits, a lamentable omission. The charge control device is not a proper thermistor but just a resistor on the end-mounted PCB. Conceivably this along with the poor low-voltage cutoff and problems in that area led to the premature failure.

The samples tested were kindly donated by an E-1 owner in the US, after only about a year of use and only about 30/40 charge cycles each. Bought for around $US16 each one has failed completely and will not charge and one has become severely reduced in capacity. The discharge test shows only about 400mAh, a poor performance after only a year of use and only 30-40 charge cycles. Whether these ever produced anything near the rated 1500mAh is questionable. As before, see disclaimer at the foot of the page. I have not added this to the summary as it is not sensible to compare a pack with a year of use to new cells so I have just shown the discharge curve.

In summary, this is a cheap, low quality product and seems unreliable as well as short-lived. Construction is poor, charge control is average, short circuit protection is non-existent and the over-discharge protection seems to have problems. Another one to avoid!

Cb Clone BLM1

As the maker is unidentified I have called this the 'Cb' clone after the logo in the bottom left corner. As in the WinTop clone the control circuitry is not sandwiched between the cells and the bottom of the pack but is carried at the end of the cells. This is not a normally a good location for the charge cut-off circuitry as it relies on the temperature of most of the whole pack to rise in order to cut off the charge however in this pack the temperature control is remote and extends into the pack under the cells a little way. This is better than nothing but it would have been better had it been a proper temperature sensitive thermistor and not just an ordinary resistor. Conceivably poor charge control caused by this has been responsible for the premature failure. The control board (again by WinTop) carries the usual control chip and FET switch but appears to have no short circuit protection at all. The case is very flimsy and the cell welds are a bit hap-hazard . The battery straps are quite thin and not very wide but where they exist are slightly heavier duty than, for example the WinTop. The straps at the front are non-existent, being replaced by a couple of jumper wires. These are soldered onto the pack terminals which are fixed to the cell case with melted plastic posts rather than being riveted to the control board - a most unsatisfactory arrangement. The pair of DLG18490 cells appear to be of Chinese manufacture and are clearly rated at 1250 mAh. For a pack labelled as 1700 mAh this is absolutely laughable and flagrantly misleading.

The discharge test shows it struggling to reach 950mAh and this after only about 8-10 months light use with 20-25 charge cycles. This is not surprising given the dubious quality of the low-rated cells used.

The sample shown was kindly donated by an Tim the Grey (many thanks, Tim). All images with E-1 and 14-54mm.

In summary, this is another cheap, low quality product and seems as unreliable as it is short-lived. Construction is poor at best, charge control is average and short circuit protection is non-existent. Even taking it's low cost into account it is difficult to see how such an poor quality sort-lived product can be more attractive than some of the low cost quality clones which are available such as the UNiROSS, the Hahnel and the Energizer. This one definitely joins the 'avoid at all costs' group!

Conclusions

In summary, it is clear that price alone is NO guide to the capacity or safety level of a particular pack. One of the cheapest (7DayShop) packs had a perfectly good control board and quite acceptable build quality but was let down badly by very low-capacity no-name cells. A slightly more expensive pack (Sterling Tek) had no real protection at all, much poorer build quality and was grossly under-performing compared to the pack markings and the (different) advertised rating. Fortunately, it is clear that good quality cells with adequate control and protection circuitry can be obtained far cheaper than the Olympus original and in some cases - the UNiROSS being a case in point - can equal and exceed it in all areas of build quality, warranty, capacity and protection.

Overall results as follows:

Overall winner - UNiROSS VB104295

Second place - Energizer OM-1
Third place - Olympus BLM-1
Fourth Place - Hahnel HL-M1 (note 1, 2)

Best capacity - UNiROSS VB104295
Best value for money - 7DayShop PS-BLM1

AVOID AT ALL COSTS

Sterling Tek WT-BLM1 (note 2)
'WinTop' PS-BLM1 'Olympus' clone
e-Film (Delkin) PS-BLM1
'Cb' BLM1 clone

In concluding this series, I hope this has provided everyone with some useful information on which to base purchasing decisions for replacement and backup battery packs. I would also comment that I do find it rather puzzling that something as critical to the real-world usage of a digital camera as the power system goes almost completely un-remarked by the various worthy review sites - perhaps this will change in the future?

Note 1 - the Hahnel has recently been up-rated to 1500mAh and I have no doubt would perform to it's specifications and this would likely give it third place over the Olympus.
Note 2 - operations like 7DayShop and Sterling Tek source packs from all over - the same 'own label' pack available in a few months time might have completely different internals.

Disclaimer: I must stress that I discharge packs at around 0.15C instead of 0.1C (i.e. 180mA or so rather than 150mA) for a slightly accelerated time curve. Manufacturers capacities are usually stated at 0.1C discharge rate so the capacities shown here are less than might be otherwise achieved, however perhaps more fairly reflect the more aggressive everyday use these packs experience in a modern digital SLR camera.