H/H VHF batteries

single

single

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I have just found my old hand held vhf so thought i would charge it.Anyway charged all night and it lasts less than two mins!! Just opened the case and it contains x8 AA batteries but all thats on them is 'made in Japan'.Question is can i put any rechargeable AAs in or is it more scientific with the charger output and if i do is it a simple case of soldering them as they came out or are there any precautions?
 
You'll probably find there's some sort of sensor in there too. Be sure to include that. Ideally go for NiMH, rather than NiCd, and get tagged cells as they're easier to solder.
 
Yes, They are most probably NiCd, which can be interchanged with NiMH. The charger circuit should have a temperature sensor next to the batteries which will switch off if they go over 40 or 50 degrees Celcius.
 
Look for relacements with a decent capacity too. It is probably that those are only 800mAh or similar - you should be able to get 1200mAh or higher now, which would give you up to 50% longer duration.
 
The charger for NiMH has a much more sensitive end of charge detector than that for NiCd (to get technical, the voltage depression for NiMH at end of charge is 10 times smaller than that for NiCd). If your charger was not designed for both, you risk overcharging and damaging the NiMH cells.

What output current does your charger say on it?
 
pteron said:
The charger for NiMH has a much more sensitive end of charge detector than that for NiCd (to get technical, the voltage depression for NiMH at end of charge is 10 times smaller than that for NiCd). If your charger was not designed for both, you risk overcharging and damaging the NiMH cells.

What output current does your charger say on it?
Click to expand...
Looked at the charger and just says the input but nothing else apart from 'charge 5hrs'
 
I did just this for my Garmin VHF - I took the pack apart and replaced the cells with new NiCads - worked fine.

NiMH would probably be okay too but NiCad is a safer choice, and good enough for what I need
 
single said:
Looked at the charger and just says the input but nothing else apart from 'charge 5hrs'
Click to expand...

Unfortunately, a 5 hour charge is likely to be above the trickle charge limit of NiMH.

Which radio is it? Do they claim a NiCd or MiMH battery pack?
 
It really would help to know what radio. Is it by any chance an ancient SMR/Sealab type.... quite literally nearly half the size of a house brick! ??

If so or something similar it won't have any form of fancy charging control. Just replace the AA cells. Although tagged cells are the 'proper' way way to go, it's much cheaper just to use ordinary NiMH cells from the likes of ALDI/LIDL. Most are now around 2100mAHr. Solder quickly with powerful iron. With the original charger, a full charge will take much longer --- ideally measure the charge current and work out the appropriate time.
 
As said NiMh batteries should be fine considering there are 8 of them giving a 10v pack.
I got from China recently a little Cree torch it will take 1X AA battery however you can get and I did a lithium ion battery which while looking exactly like an AA is 4 volts. Although it is written on the battery it could be disastrous to fit these.
Anyway back to NiMh you can get them at 3000mAH which would be a huge improvement over the original if they were only 800mAH and therefor the charger will take longer to charge them. Indeed the fast charger may well be OK for normal slow charge/indefinite but I would not leave the batteries on charge for more than 10 hrs or so if I were you.
good luck olewill
 
pteron said:
The charger for NiMH has a much more sensitive end of charge detector than that for NiCd (to get technical, the voltage depression for NiMH at end of charge is 10 times smaller than that for NiCd). If your charger was not designed for both, you risk overcharging and damaging the NiMH cells.

What output current does your charger say on it?
Click to expand...

Very true.
I would replace with high cap NiCads. They hold their charge longer than Ni metal hydrides too. Nicads are very under rated.
 
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