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Scuba Forum / UK Scuba / August 2004NiCad Cells for UK D8R Battery Pack
Batteries in the standard D8R battery pack are 4000 mAh sanyo Nicads. A mate has a tired pack, so we are looking to replace the cells with these 5500 mAh cells http://tinyurl.com/5q8tk Q1. Will the standard charger charge these larger capacity cells without problem (though obviously over a pro rata longer charging period)? Q2. Does anyone know of a significantly better deal on 5500mAh (or bigger) tagged D cells than the £43 odd that Maplins will want for 8 off? Availability and delivery is an issue as the pack needs to be ready for the weekend. Thanks David >Q1. Will the standard charger charge these larger capacity cells >without problem (though obviously over a pro rata longer charging >period)? I guess so, the same charger does my 1800 and 2300 AA's as you say, it takes a bit longer. >Q2. Does anyone know of a significantly better deal on 5500mAh (or >bigger) tagged D cells than the £43 odd that Maplins will want for 8 >off? Availability and delivery is an issue as the pack needs to be >ready for the weekend. I got some 9000MAH size D from a place in Broughton Astley, over the counter: specialist battery warehouse. If you're heading for Stoney Stanton it's only 3 miles away. Don't know if that helps? >>Q1. Will the standard charger charge these larger capacity cells >>without problem (though obviously over a pro rata longer charging >>period)? >> >I guess so, the same charger does my 1800 and 2300 AA's as you say, it >takes a bit longer. Nod. >>Q2. Does anyone know of a significantly better deal on 5500mAh (or >>bigger) tagged D cells than the £43 odd that Maplins will want for 8 >>off? Availability and delivery is an issue as the pack needs to be >>ready for the weekend. > >I got some 9000MAH size D (*?!!!** WTF ???? 9000mAh Checks. NIMH, not NICD! >from a place in Broughton Astley, over the >counter: specialist battery warehouse. Google suggests it was these people - http://www.multicell.co.uk/index.htm >If you're heading for Stoney >Stanton it's only 3 miles away. Don't know if that helps? All roads eventuallylead to Stoney!! Thanks David >>I got some 9000MAH size D > > (*?!!!** WTF ???? 9000mAh > Checks. > NIMH, not NICD! They'd be no problem in the torch, just the charger that might not like them - but then its maybe worth getting a different charger to do the NiMH anyway if you use the torch a lot? David >>>I got some 9000MAH size D >> [quoted text clipped - 7 lines] > >David The idea was to get a mates torch running again, without spending the approx £90 some LDSs want for a new genuine UK battery pack. He has recently replaced the charger, so will probably not want the extra expense of a set of NIMH and associated charger. The 5500s from Maplin should be a useful enough upgrade over the original 4000s. Thanks David >>>> I got some 9000MAH size D >>> [quoted text clipped - 18 lines] > > David I've just bought 4 x 4500mAh to replace the pack in my UK C4R. Ordered Saturday, delivered Monday morning. Tagged D 9000mAh are on offer at ?6.50 each. Charging those with the standard charger may be an epic event! http://www.powerstoredirect.co.uk/x2200.html HTH Paul > Batteries in the standard D8R battery pack are 4000 mAh sanyo Nicads. > [quoted text clipped - 13 lines] > > David I'm not sure why anyone would use nicads these days when Ni-Mh are so much better? I've thrown my Nicads out long time ago. Adam >I'm not sure why anyone would use nicads these days when Ni-Mh are so much better? >I've thrown my Nicads out long time ago. > >Adam Is it possible to use the same charger for NiMH as NiCad? I had thought the NiMH demanded something a standard cheapy NiCad charger would not supply, thus stuck with the existing battery technology. David > Is it possible to use the same charger for NiMH as NiCad? I had > thought the NiMH demanded something a standard cheapy NiCad charger > would not supply, thus stuck with the existing battery technology. AIUI (and I may be wrong) a *standard* NiCad charger will charge Li-MH just fine, the problem is with the 'fast' or 'rapid' NiCad chargers. Apparently Li-MH need to be trickle charged and can't cope with the aggressive quick-charge that NiCad can. Hope that makes sense. My 9000MAh D's need 14 hours at 900MA. hth > >I'm not sure why anyone would use nicads these days when Ni-Mh are so much better? > >I've thrown my Nicads out long time ago. [quoted text clipped - 6 lines] > > David NiCad and NiMH need pretty much identical charging regimes so you can use the same charger. Lead Acid has totally different requirements NiCad are still popular in power tools. They are more robust tham NiMH and can take a lot more abusive use. Also NiCads last around 1000 full cycles but NiMH last around 500. Pays your money etc.. Nick > NiCad and NiMH need pretty much identical charging regimes so you can > use the same charger. Lead Acid has totally different requirements Typically yes, but not quite. Please see for instance: http://www.greenbatteries.com/documents/Battery_Charger_FAQ.htm > NiCad are still popular in power tools. They are more robust tham > NiMH and can take a lot more abusive use. Also NiCads last around > 1000 full cycles but NiMH last around 500. Pays your money etc.. AFAIK, the main real difference is the discharge current capacity. NiCd can take larger discharge currents, hence are more applicable to powertools where you need as much ompf as possible. BTW, I just upgraded my Omersub Technolight from what must have been NiCd cells (counting backwards from burn times), to NiMH cells (4/3A sized 4000mAh Sanyo's), and the burn times increased very nicely. There is a noticable "overdrain" though. I was runing the test with a 35W bulb, and after the lighgt went off I let it be for a while, and then tested again. It came back up real bright and all. With the NiCd once it discharged, it was pretty drained. This suggests that the NiCd had a flatter discharge curve than the current pack. I am yet to see what happens to the battery pack with a 50W bulb (4.2A dischage current, i.e. 1.05C of the cells, as this is already beyond the recommended optimal range. /Marcin >> NiCad and NiMH need pretty much identical charging regimes so you can >> use the same charger. Lead Acid has totally different requirements > > Typically yes, but not quite. Please see for instance: > > http://www.greenbatteries.com/documents/Battery_Charger_FAQ.htm Marcin Excellent link, all my questions answered. Thanks. David > >I'm not sure why anyone would use nicads these days when Ni-Mh are so much better? > >I've thrown my Nicads out long time ago. [quoted text clipped - 6 lines] > > David NiMH chargers are readily available. But I charge my C Mi-Mh batteries in a Nicad timed charger. This works fine if you only partially discharge the cells--the Nicad charger than provides roughly the amount of charge to fully recharge the cells. You can also put the Ni-Mh batteries in for two cycles and take them out when they start getting too warm. Adam The difference in using higher capacity batteries is simple. If you have a charger that states the charging time is 14h (for 4000mAh) then its likely the charge current is 286 mA. for a 1C charge rate. (battery capacity in mAh / Time to charge as stated on the charger) If you put 5500 mAh batteries in, the charge current will remain the same, the charge time will extend to 19 hours as the charger is set for a constant current. If you really want a long burn time www.eurobatteries.co.uk do a tagged 'D' cell @ 9000 mAh this would take you charger 31 hours to complete the charge but it would last all weekend! The bog standard chargers can shorten the life of the battery if they are left on longer than recommended, also part charging the battery will have some effect on the chemistry, some call it the memory effect. The best chargers will discharge to 1V per cell and then fast charge to a known cut off point, the battery is not fully charged at this point, good chargers will then pulse te battery for about 15 mins bring it up to full charge and then trickle charge ( at C/20 to C/30 ) until the battery is removed for use. Hope this helps . > Batteries in the standard D8R battery pack are 4000 mAh sanyo Nicads. > [quoted text clipped - 13 lines] > > David >The difference in using higher capacity batteries is simple. > >If you have a charger that states the charging time is 14h (for 4000mAh) >then its likely the charge current is 286 mA. for a 1C charge rate. (battery >capacity in mAh / Time to charge as stated on the charger) Wrong. You need to put in 140% of what you get out due to battery efficiency. Charge current will be about 400mA for 14 hours (C/10). >If you put 5500 mAh batteries in, the charge current will remain the same, >the charge time will extend to 19 hours as the charger is set for a constant >current. Right answer for the wrong reasons!! Pete S. |
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