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 Post subject: rechargeable 9 volt batteries
PostPosted: May Thu 02, 2019 2:59 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
I was looking at 9 volt rechargeable batteries and I found lithiunm batteries but the charger only puts out 8 volts and I want to make 90 volts out of 10 of them. What would you recommend for a rechargeable 9 volt battery thanks.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Thu 02, 2019 3:03 pm 
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Joined: Apr Wed 03, 2019 6:41 pm
Posts: 96
Location: Raleigh, NC
NiCd and NiMH cells produce less volts than carbon-zinc and alcaline batteries. use 11 batteries instead of 10.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Thu 02, 2019 3:25 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
the batteries I am looking at are lithium is that okay to use 11 of them?


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Thu 02, 2019 4:23 pm 
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Joined: Feb Wed 27, 2019 9:51 pm
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Location: Medford, Or.
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...Lithium, or lithium ion? Surely they must be lithium, like for smoke alarms. I'd say just use 10 of those


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Thu 02, 2019 5:49 pm 
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Joined: Feb Wed 07, 2018 6:52 pm
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Location: Stone Mountain, GA
Lithium batts run 3.1-4.1V with an average of around 3.6. Two batts in the 9V is 7.2 and will finish charging at 8.2V or so. Three batts in a 9V will be way too high.

NiMH/NiCad batts are about the same charged voltage. Probably adding a 7th cell would have reduced capacity due to needing smaller batts. I used them for a while and they were near useless as they self discharged and had much less capacity than regular 9V's.

You need a special charger for each type (although a CC/CV bench supply can do lithium if they are not over discharged.)

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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Fri 03, 2019 5:59 am 
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Posts: 32745
Location: SoCal, 91387
Timmy1 wrote:
I was looking at 9 volt rechargeable batteries and I found lithiunm batteries but the charger only puts out 8 volts and I want to make 90 volts out of 10 of them. What would you recommend for a rechargeable 9 volt battery thanks.

What were you going to use the 90 volts for? If it's for the plate supply in a radio, 67-1/2 volts is normally sufficient unless you want to rattle the windows, so anything more than that should be adequate.

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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Fri 03, 2019 12:59 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8700
Location: Long Island
Consider how you are going to charge these batteries. Each type calls for a charging profile suitable for its chemistry; with Li-ion a proper charger designed for that kind of battery is absolutely necessary not just to secure maximum life but to prevent overheating. NiCads are the least demanding, requiring only a DC power supply and current limiting means. NiMH can be charged similarly but will last longer if charged with a device that applies the correct charging cycle.

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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Fri 03, 2019 1:10 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
the person who is selling the battteries is also selling a charger and I bought it also. thanks.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Sat 04, 2019 2:22 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1529
Location: Phoenix, Arizona
I use a box of 9 volt batteries for B+ on an old Grebe radio. I soldered a jumper on each to the next as opposed to snapping them together. I tapped in at about 18 volts for the 22 1/2 detector. The voltage is not critical.

If you use rechargeable Lithium batteries you need a controlled charger otherwise the batteries can catch fire and explode. Most battery packs used in tools and laptops have a circuit board inside to control the charge and discharge.

If you are using NiCad put a small light bulb in series as a current limiter to charge them.

Jim


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Mon 06, 2019 3:02 pm 
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Joined: Jun Mon 12, 2017 8:17 pm
Posts: 49
HI, I'm with Jim, that is what I use for a portable. they last longer than you think.
the problem with lithium batteries is that if they are brought below their thresh hold voltage (about 3 volts) they will normally die.
Rich


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Mon 06, 2019 5:39 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
If I use 10 lithium in a radio how can I tell when the battery is getting below 3 volts.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Mon 06, 2019 6:18 pm 
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Joined: Apr Wed 03, 2019 6:41 pm
Posts: 96
Location: Raleigh, NC
That's 3 volts per cell. You can buy voltage monitors cheap. They're used a bunch in the radio control hobby where lipo batteries are used extensively.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Mon 06, 2019 7:17 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
that is good to know but for me I can't see to read the monitors I have to figure out another way.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Mon 06, 2019 7:24 pm 
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Joined: Apr Wed 03, 2019 6:41 pm
Posts: 96
Location: Raleigh, NC
Most have buzzers.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Mon 06, 2019 8:53 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
so I just use one and hook it to 1 of the 9 volts and where can I get one.


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 Post subject: Re: rechargeable 9 volt batteries
PostPosted: May Thu 09, 2019 5:04 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 592
Location: Lagrangeville New York 12540
I was looking online and they don't have one for one lithium 9 volt battery.


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