rechargeable batteries

[mrg198]

I've run Sennheiser EW G2 mics on Varta Charge 'n' Go batteries with great success before. Managed at least 6hrs reliably and they really do take 15 mins to charge fully from flat. Sadly I bought a set of 4 with charger to test and after great success I tried to buy more but they seem to be impossible to get hold of. I don't know why. I've tried uniross quick (supposedly 15 mins) charge batteries before but the batteries seem to be their standard rechargables which a) took 45 mins before the charger switched off and b) didn't appear to have been fully charged in that time so didn't last very long.

 

If anyone knows where I can get more of the varta charge n go range or knows why they seem to be hard to find please let me know!

 

Michael

[Noizeboy]

Might be worth having a fiddle around with the settings on the Mic, because if the built in compressor is working overtime the batteries will run flat very quickly.

[paulears]

er.... you're saying that the compressor has an effect on battery life? On what premise do you base this on?

[GridGirl]

We're using rechargeables in our Sennheisers at the moment (couldn't tell you exactly which ones - although 100 series rings a bell?) and having absolutely no problems at all with them. The mics are on for 3 1/2 hours, they're 1.2v batteries and have had zero issues with them. Matinee days we do use non-rechargeables for the first show, as we can't get the batteries charged up between shows, but for the single-show days it works fine for us.

[JMackenzie]

The terminal voltage of the batteries shouldn't matter with the G2s - they step up whatever voltage they're presented with to a higher level to power the electronics. As the voltage drops, the current draw simply increases. They output a constant RF power level until the battery is absolutely dead.

The battery monitoring circuitry may be a little misleading because of the lower voltage, but it shouldn't affect any other aspect of operation.

 

Having said all that, I've not actually tried it but would be quite happy to run a few rechargables down in the interests of science :blink:

 

Well Shez, this is exactly what I thought, and I am so glad you have brought it up.

I have been using rechargeables in my G2's for a long time now, with no problems. I also use 800mah AAA' s in my sk1220's, again with no problem.

I wish the Sk1220's had a battery indicator, it is quite handy to have some sort of reference point.

I also use rechargeable pp3's in my condensor's , only because my phantom power has packed up in my mixer.

I use the same rechageable pp3's in my Audio Technica hand helds, but I only have 180mah types.

I find that they dont last very long, but will normally make it through a 3hr show.

The most interesting thing I have done in this feild ,is the purchase of an "Eco charger" which recharges normal alkaline disposables, and this is proving very useful.

I can recharge AA , AAA, D and C cells, at least ten times ---probably more. The only problem I have with this is that they recommend that you charge them before they go down too far. When placed in the charger, it analyses the cells, then gives a time reading for the charge, which does give you an indication of their state. It also rejects cells that are too far gone to charge.

I am starting to use this now, just so I know I have 1.5 volts when I need it.

Does anyone else use this type of charger?

The ecocharger is slow, but can sit happilly all day and night doing this. Some batteries take 20 hrs or so to complete, but seem like new when you take them off it.

I am glad I have found someone who does use rechargeables.Apart from the environmental aspects, it does reduce costs if on a tight budget , like in a school.

[Matt Riley]

As a church, we use sony nimh rechargeables. they're charged and then used from 9am till about 1pm. Generally don't go down to below half charge on the indicators.

 

Personally I wouldn't even think of it for doing shows where my reputation depends on it.

 

M

[safetyman]

My experience of using AA Nimh rechargeable batteries is as follows:

 

BATTERIES

 

Version A - high capacity around 2,850 mah

 

Version B - medium capacity hybrid around 2,100 mah

 

Version A - initially charges up to the rated capacity for the first few charges, then drops down to 60-70 % on a full charge. Takes a very long time to charge-up from flat and does not hold its charge for more than a short period. Constant discharge when not in use.

 

Version B - initially charges up to the rated capacity and keeps its charge. Very low constant discharge( still @ 80% after 6 months ). Charges up much quicker due to lower capacity and because it retains any left-over capacity between charges. Only needs topping up between charges.

 

CHARGERS

 

Most chargers only charge either 2 or 4 batteries( cells ) at a time and take a long time to do so as they slow charge to allow all the voltage levels to synchronise on the way up. Fast chargers aim to charge same number of batteries in a shorter time, and do so but at the expense of shortening the life of the batteries due to overcharge. Both the above types of charger do not charge the cells individually and neither do they take account of the state of charge in the individual cells = under charge of some, and overcharge of other cells within the same pack of 2 or 4

 

Technoline BL 700 intelligent charger. There are others on the market in/for specialist applications but they cost a whole lot more ( £ 100 + ). This one cost £ 27.99 inc vat & delivery from www.batterylogic.co.uk( see the website for full details ). It will charge 1,2,3, or 4 of either AA or AAA cells, or a mixture of both in any order or configuration. It does this individually, under individual control of each of the four single sections, giving a constant readout on the lcd screen to tell you what its doing. It charges at 200, 500 or 700 mah and also discharges at 100 mah, together with cell refresh( cycling the cells ) up to 20 times automatically.Individual cells are, therefore always fully charged at their max capacity, and faulty cells are easily identified and can be discarded.

 

UNIROSS HYBRIO AA CELLS

 

I now use these exclusively( 4 ) in my flashgun which I use to photograph shownights and mobile discos. They hold their charge very well between charges, give me up to 400 flashes per charge( indoors ) and recharge very quickly( sse above ). They cost £ 7.99 for 4 AA, £ 5.99 for 4 AAA from batterylogic, who also do small plastic carriers for 4 AA @ £1 each making it very easy to transport/store packs of batteries .

 

While the above rechargeable cells are still only rated @ 1.2 volts per cell, as opposed to 1.5 volts for the Alkaline disposable variety, they have a vastly superior capacity and ampage output. You either gets volts or amps, but not both so, as long as your mics and other appliances will work at the lower voltages, no problem.

 

Apart from being a satisfied customer, I have no connection with the above company. My experience is based on running radio controlled electric models over the last 10-15 years as well as photography over the last 30 years, together with a relation who uses keyboards on battery power( 6 x AA ) for his live quartet street gigs and now can run for several hours with no problems.

 

Cheers

[DangerousMark]

Hmmm personally going on the maths I'd stick with the non-rechargables unless you're worried about the (small) environmental impact the extra heavy-metal and chemical waste you're generating is going to have...

 

Been a long time user of rechargable batteries for many things, and the weakest part of the whole arrangement is the human element. You do need to be very disciplined in making sure the dead ones get recharged, ensuring they've charged properly, you have sufficient charge available before starting a task, etc. Whereas standard alkalines you can just pop out of a bubble pack and be good to go in moments. If it's actually for a money generating thing, the fact that it costs a couple hundred pounds a year more to power the kit, but it is more reliable and easier to set up, may be worth it vs the initial higher outlay of rechargables, then the hassle and potential unreliability that you exchange for the dirt-cheap recharges. Plus, the charge leakage in storage, which I've found to be a bigger problem now I've become more of a light user.

 

Good NiMH cells in kit that's designed for / is able to cope with them will easily outlast almost any Alkalines, and give the "photo life" type Lithium cells a run for their money. Even good NiCads will challenge poor alkalines - the "standard" batteries don't have that great a charge capacity, they just have a much more consistent voltage curve and higher nominal voltage which means they both seem to last a bit longer, and go from "dying" to "dead" at a lower speed in more exacting devices.

(NB Fresh alkalines are about 1.6v, and it's when they dip significantly below 1.5 that things start to fail, but some things like torches and speakers will put up a fight til about 1.1v; Rechargables start out 1.3-1.4v and it's game over by 1.2v because they then start to drop off quite hard, something to do with internal resistance? The Lithium type may not even be entirely safe for some electronics if you are using several in series, as they start out at about 1.72v on my multimeter - but they do run for absolute yonks with a flat Alkaline-type charge/voltage curve)

 

Quite happy to use them in my camera as I'll get many hundreds of shots out of them, and it's entirely on me when the time comes to switch them out for the fresh set in my pocket. But if it was for presentation purposes I might think again just because there is that occasional unreliability - a slightly older battery may not charge properly one time, or an unintentional part-charge may reduce the capacity. An annoyance when it means you have to stop halfway through a run of photos; critical if it takes a mic offline. And the camera quite often won't work if I've left it sitting awhile in the drawer, as the batteries have leaked charge.

Mind you if you do take care to look after them, most rechargables you throw away will be because the plastic jacket has taken too many knocks and fallen off.

 

I think the super-fast charge ones may have disappeared from the market for the same reason that the "recharge your alkalines!" things have never captured a great deal of market segment: they're not that reliable, are a touch dangerous and can ruin the batteries' life. (Conjecture but part based on fact and experience). The only alkaline recharger I ever owned, bought in a haze of "this is such a great idea!" was taken back a couple weeks later, the plastic pockmarked with spilt electrolyte. I figured spending the refunded purchase price on fresh batteries was a much better idea than trying to extend the ones I already had.... the ones that did charge only had a fraction of their original life, took ages to actually juice up, often wouldn't charge a second time, and some actually split. Despite it having an electronic readout and claims of all manner of safeguards. Similarly, given how hot the Nickel (cadmium and metal hydride) batteries tend to come out of my 2 hour (big white rectangle thing) and 3-ish hour (wall wart) electronically-controlled fast chargers, and that even doing that rather than using the alternate trickle mode seems to have killed a couple of them (of the charger's own brand!), I'd want a bundled pair of tongs to handle 15-minute ones with! Saw it in the Argos catalogue ... was tempted ... then thought "aw hell no".

 

Your mileage may vary but even in the name of elf & safety the Procells are probably yer best bet 'til we start getting AA-shaped Li-Ion-Polymer cells, which can actually stand up to high speed charging a bit more effectively.

(even so my laptop and phone still tend to need at least 2.5h for a 5% -> 100% charge, with a "shaped" current input if you use a power meter to check them, and come out of it just a bit warm)

 

edit: re the IBS link ... I think I'll be rigging up a thing to test my batteries under load from now on, unless the multimeter already does that (which I doubt)...

[AndyL]

I also use 800mah AAA' s in my sk1220's, again with no problem.

I wish the Sk1220's had a battery indicator, it is quite handy to have some sort of reference point.

 

What's an Sk1220 ? Do you mean the venerable >15years old SK 2012's? We keep telling Ofcom that radio mics last more than 10 years! :** laughs out loud **:

 

Might be worth having a fiddle around with the settings on the Mic, because if the built in compressor is working overtime the batteries will run flat very quickly.

er.... you're saying that the compressor has an effect on battery life? On what premise do you base this on?

 

I can promise you that there are no settings whatsoever on a G2 transmitter that will have any effect on the battery life, apart from the off switch! (and the phantom power switch on the SKP 500 G2 - exception that proves the rule) It really doesn't matter how hard the compander is working. Radio mics use FM, not AM!

 

As Shez has already explained, battery terminal voltage does not affect the performance of a G2 transmitter - until it reaches the point where it stops altogether - because there is a DC-DC converter built in to squeeze the batteries dry. On the earlier "G1" evolution wireless transmitters which used 9V batteries there was no DC-DC converter and the low batt warning triggered at around 7.2V, which was the nominal terminal voltage of many NiCd rechargeable batteries in the 9V 'PP3' style package.

 

The G2 300 & 500 series are designed to work with Sennheiser BA 2015 NiMh battery packs. The BA 2015 battery pack has a tab on it which tells the transmitter that a re-chargeable pack has been inserted and the battery monitoring is adapted accordingly. If you just insert ordinary re-chargeables they will work fine, but the battery monitoring circuit won't know so you might get misleading readings. Once you know how long your particular cells will give you in the TX's you can make allowances accordingly. :)

[safetyman]

Yes, there is always the human element to contend with.........!

 

However, until affordable li-ion cells arrive, it is perfectly possible to use Nimh Hybrio cells as long as you use that charger, or chargers to make sure that each individual cell is fully charged. Oh, by the way Nicads/Nimh's etc all need to reach a temperature on charge of approx 10 degrees above ambient( say 30 degrees) before they are fully charged.

The point I was making was that the new hybrio cells, if suitably charged are ideal for this type of application due to low self discharge. However the best way of achieving this is to have ,say, two/three of these chargers at home in the workshop and enough cells to be able to take with you fully charged for each gig. Because of low self discharge you charge them all up between gigs, and they stay fully charged for at least 1 month @ 100 %, so only those used are topped-up. As long as you rotate the packs regularly, so they all get used, then no problem.

 

In the future we will see Lithium based cells of AA size with a 2-3 amp capacity, able to take a 3 amp charge and with a 1.75-2.00 volt rating. Great, but then if you forget to charge them, or use the wrong charger.