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stefuel

When you have a device that is designed for using NiCad batteries and has it's own internal slow charger, what would happen if you swap out the batteries with NiMH batteries? I have read in a couple of places that they require a special charger. Is that just to get you to buy their charger?
The device is a touch panel that sits in a cradle and slow charges when not in use. Both the NiCad and NiMH batteries are 1.2 volts each. Thanks,

virusc · Joined: 11 Apr 2007 Posts: 358 Location: Massachusetts

the charge cycles and sensors are different from what I was told and if you attempt to charge a NiMH in a NiCad charger it will destroy the battery. Some NiMH chargers can charge NiCad though.

Sparky015 · Posted: Mon Dec 06, 2010 8:36 pm Post subject:

different chemical properties, different charging voltage and amperage conditions. Definitely not compatible unless the charger says it can handle both technologies as VirusC points out. You need a charger that can sense the battery you put in it so it can apply the appropriate charge cycle. Sometimes they make the charger backwards compatible, but don't expect your older NiCad charger to be able to handle NiMH.

stefuel · Posted: Mon Dec 06, 2010 11:32 pm Post subject:

Been doing a bit of reading on the subject. NiCD battery chargers that charge for a spacific time will under charge them but not likely to harm them. Fast chargers if unattended can hurt the batteries. A trickle charger like what I have should not harm the batteries but will take a long time to charge them.

Elaine Benes · Joined: 25 Apr 2006 Posts: 1416

I have an old Philips colorimeter that used to have a NiCad battery pack. The original batteries died unceremoniously, so I replaced them with NiMh and haven't experienced any problems with them charging in the device, using its built in charge system, whatever that is...just my experience of course...

**Curt Palme** · Posted: Tue Dec 07, 2010 3:12 am Post subject:

I thought it was the other way around. NiMh use a far higher charging current than NiCads, so putting NiCads into a NiMh charger will kill them. I know the Roomba forums sell NiMh batteries to replace the Nicads and no mods need to be done, the battery drops right in place of the NiCad one.

cinema mad · Joined: 25 Nov 2009 Posts: 219

Fast Charging NiMh is better for the Cell as in longer life expectancy and requires A different charging method compared to NiCad & usually offer High AH/M amps compared to Nicad but dont perform as well for High current drawing devices..

NiCad work better for high Current devices but have A memory Affect so require total discharging for optimum performance..

Lith-ion can only be charged A set amount of times due to potential rupter so come with built in safety,they dont like heat/High curent draw .. http://en.wikipedia.org/wiki/Lithium-ion_battery..

Hope this helps..

virusc · Joined: 11 Apr 2007 Posts: 358 Location: Massachusetts

are you replacing the battery sealed cells themselves or the entire enclosed pack with multicells? I would just replace with NiCad and be done with it. Cheap and no risk. Is is Crestron? Did you search on ebay for replacement kit yet? often they are available from China from the same factories as they were the OEM and are dirt cheap if it is a common pack.

stefuel · Posted: Tue Dec 07, 2010 10:32 pm Post subject:

stefuel · Posted: Wed Dec 08, 2010 1:06 pm Post subject:

In searching around the Crestron web site I noticed that the ST/STX 1550 and 1700 touch panels batteries have been upgraded from NiCads to NiMH's. The TP's when now new come with a different docking station part number but also state that the old docking station/charger will work when replacing the batteries in a older 1550 or 1700 that came with NiCads.
Those are 4 cell packs as well as the ones in a STX-3500C. The 3500 just uses two packs.

virusc · Joined: 11 Apr 2007 Posts: 358 Location: Massachusetts

I would recommend calling crestron support or speaking with a crestron dealer if you have access to either regarding the replacement of NiCads to NiMH. I would be somewhat concerned that the batteries could leak from overcharging and possibly damage you panel. I have a 1550c and bought a new pack for like $5 off ebay to replace my well worn one. My panel is always on and I put in back in the dock frequently so I'm not sure that I would actually need NiMH.

stefuel · Posted: Fri Dec 10, 2010 11:25 am Post subject:

Well I ordered 8 NiMH batteries. I don't know the design of the charging circuit but it does say in the panels owners manual that leaving it plugged into a power source (cresnet or wall wart) "will not harm the batteries" so it must have a peak voltage or temp limit incorporated for protection. When charging via cresnet connection, it is trickle charge only.
I'll just keep an eye on it and see what happens Wink

stefuel · Posted: Sat Dec 11, 2010 12:18 pm Post subject:

I'm a little confused about battery/battery pack ratings. Crestron lists the original (4)"pack" as being 2800 mAh. Does that mean that each battery is 700 mAh or does the mAh stay the same only the voltage is increased in a pack? I ask because the single c size cells ratings range from 2500-3500 mAh for NiCads and 3500-9000 mAh for NiMh cells.