# Hams, battery thought on VX-7R



## Wilsonite (Jan 7, 2006)

I know there are a few radio operators out there, wondering if any of you have a VX-7R, and if you have the 2 AA adapter for it? Is the case designed to be watertight as the original Li-Ion pack? Thinking of getting the 2 AA pack and stuffing 14500 Li-Ions in it so I can keep spares in the vehicle. Anyone tried this?


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## BobVA (Jan 7, 2006)

I've got the VX-5. The AA case for that has the same gasket around it that the LiIon pack has, so it would seem to have the same water resistance when attached to the radio. It's clearly not water resistant when not on the radio.

Let us know if you try the 14500's. 

Cheers,
Bob


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## John N (Jan 8, 2006)

I also have a VX-5 and have a couple of comments about the FBA-23 (2xAA) battery holder. Note sure if the VX-7 uses the same adapter or not..

1) While it does have a gasket, it is fairly easy to dislodge it. If you do so, it can easily get lost. Use care to maintain the water resistance.

2) I think it has a step-up regulator circuit. Bumps it up to 4.5V if I recall correctly.

3) IIRC, transmit power is restricted (to .5W?) while using the AA battery pack.

-john


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## redcar (Jan 9, 2006)

I also have the VX-5R. Great setup for listening or scanning. Almost useless for transmit (on the AA pack that is, otherwise nice rig on the lithium-ion). I too look forward to hearing how the 14500's work out. My AA pack fits pretty snug and use it a lot.

The AA pack for the FT-50 uses 4 batteries and while still weak is not as laughable. 

I ended up getting an Icom T2H (6 watts). 8 AA's gives some respectable juice. I usually use some MAHA's AA's with like 2.2Ah ratings if I have a heads up. I think those batteries have an even higher rating than that now.

good luck, Red


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## Mike Painter (Jan 9, 2006)

Interesting idea. I went through several ideas, including building a 12 NiMh pack. Then bought a cheap SLA with cables for jump starting your car and two 12 volt sockets.
I realized that if I was going to have to use it a lot I'd want a lot of power available.

I know that I can have it on for 15 hours or so with fairly heavy transmit use at least six of those hours and light use the rest of the time. 

Keep us informed.


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## Wilsonite (Jan 13, 2006)

Well, I just ordered some 14500s, and a protection circuit. Need to call up Burghardt's to get the AA adapter... Will update when goodies arrive...


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## philiphb (Jan 13, 2006)

I've have the VX-7RB for quite awhile. I used it during TOPOFF3 the DHS Drill here in CT last year. The battery case for the AA's is not up to the task, I had two back-up Li batteries (one from my VXA-700). There is not enough power in the AA case for full power extended transmitting. Nice to fool around with but not for ARES use.

W1PHB CT ARES Area 4 Training Officer:devil:


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## bluecrow76 (May 16, 2007)

Time to wake up an old thread...

Did anything ever come of this?

I accidentally left some alkalines in my FBA-23 2AA battery case once... they leaked all over and I had to disassemble the case to clean it. There is a step up circuit in there. I've been toying with the idea of using 14500's in it and removing the step up circuit to see if I could get the full transmit power. Haven't had the time to do it yet, or the guts for that matter. I guess the first step would be to manually connect (alligator clips, magents, etc.) two 14500 to the contacts on the radio and see if it lets me transmit using anything other than 0.5W. Will return and report.... after we move into our new house... we're closing on Thursday! Yeah!


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## John N (May 16, 2007)

I haven't done anything about it, but I posted a query to the Yahoo Groups YAESUVX5 mailing list regarding building a pack from 123A cells. Here is a response from Gary N. that you might find helpful:



> I understand what you want to do, and why you want to do it. I use CR123As everyday, and they're great! I 'll confess to lining up three 123's in front of my FNB-23 and trying to dream up some way of doing this.
> 
> There are some important things you need to be VERY AWARE of regarding CR123A Lithium primary cells.
> 
> ...



-john


Gary N: I tried to email you asking if it was OK to post this, but the email you posted on the list bounced. If you don't want this posted for some reason email or PM me and I'll remove it. Thanks. -john


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## Rogue_monkey (May 16, 2007)

I just got back from my monthly ham meeting and a comment was made about this very thing. 

find out the price to replace the original battery pack. 
Now in 5 to 10 years when they don't make the battery pack and your still using your nice radio that you really like and don't want to give up. Having the AA adapter around really makes sense now. Its a cheap investment that you won't regret no matter how much you use it right now and weather it is totally what you want now. It will come in handy sometime. sooner or later.

thats my 2 cents.


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## download (May 17, 2007)

I cut & place some old plastic parts with epoxy like this, connecting 2 protected li-ion (~1700mAh) in serial serve me several yrs already. Enjoy


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## Daniel_sk (Oct 20, 2007)

I would like to bring this thread back to life :candle:.

Did anyone try to build an external battery pack for the VX-7R? Will it work (not like the 2x AA, that doesn't provide full power for transmission)? How could it be connected? (maybe with use of the 2x AA pack and wires running from it to an external battery?)

I have been thinking about getting the VX-7R for a year now,because it's the only good handheld that can transmit on the 6 meter band that I know of. But I need to have the ability to run it on an external battery pack (higher capacity, less expensive, easy to replace)..


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## Daniel_sk (Oct 24, 2007)

Anyone? 

Would two 186500 batteries work? The voltage would be the same, higher capacity and much cheaper. I know, they are probably too big for the radio, but I could place them inside the rucksack and connect them to the VX-7R with wires (with help of an empty 2x AA adapter).


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## Screehopper (Oct 24, 2007)

That's one of the reasons that kept be away from getting the VX-7R. I have a FT-60R instead which has a AA adapter that holds 6 AA's. That way I get the full 5-watt output when the need comes during emergency communications use.


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## John N (Nov 24, 2007)

Daniel_sk said:


> Anyone?
> 
> Would two 186500 batteries work? The voltage would be the same, higher capacity and much cheaper. I know, they are probably too big for the radio, but I could place them inside the rucksack and connect them to the VX-7R with wires (with help of an empty 2x AA adapter).



Snip from an above quote (referring to 2x3v cells, not 18650s): 


> The voltage with two cells would only be 6V, which really isn't enough for full 5W output. The radio's going to be ramping the PA down, I'm guessing the around 3W. Three cells would be 9V, and the forward drop across the diode would bring this down to around 8.4V; the same as a fully charged OEM Yaesu battery.
> 
> There's no problem with putting 12V-16V into the battery contacts in the battery compartment of the radio. The EXTPWR circuit feeds the radio along the same pathway, and when charging the OEM batteries on the radio, pulses of up to 12V are present there.



Based on this quote, it seems that 2x18650 would power the radio, but might not at full power. Seems like 3x18650 would be better.

That said, it isn't clear to me if there is any discharge protection, so protected cells are probably in order. 

It also isn't clear that you would want to charge two or three lithium ion cells in series without something specially designed for it, so I'd be inclined not to attempt to charge the cells with the radio.

-john


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## Daniel_sk (Nov 24, 2007)

John, thanks for your reply.
I think I read somewhere that there are 2 lion cells inside the original Yaesu VX-7R battery. Someone replaced his old lion cells with new ones and it worked. I'll try to find that post (it was on a Ham forum).
There is a circuit inside the original battery (probably protection and charging circuit).

A single LiON cell has 4.1-4.2V (not sure, please correct me) when fully charged. Two of them would be 8.4V, exactly as on the original Yaesu battery.
That's why I believe that two 18650 would work at full power and would extend the operating time of the VX-7R.
They wouldn't fit the radio of course, but could be placed externally, in a small pack. One could use an old Yaesu battery, remove the old cells and make a wire running out of it, to the external battery pack.

Safety first - protected batteries from AW and a special charger for lion battery packs are a must of course.


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## John N (Nov 30, 2007)

AFAIK 18650s are 3.7v.

But, I checked my VX-5 lithium-ion battery pack (FNB-58LI) and it is rated at 7.2V @ 1100mAh, not the 8.4V from the quote. This does suggest that 2x18650 probably would be a drop in replacement for the OEM battery pack.

-john


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## fieldops (Dec 1, 2007)

The VX-7R is usually rated at 7.4v at 1400mah (new ones). I found it is also true that the batteries labeled 7.2 work fine as well. They both come up to 8.3 or 8.4v. I wish I could get a hold of the oem that makes the actual battery housings. Then I'd have parts for years. My ARES district would love it. If not, I guess I'll just assume  that I'll have newer technology radios available for my use in the time the batteries become unavailable. 

73 Frank WQ1O
Cape and Islands ARES DEC


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## Daniel_sk (Jan 30, 2008)

If anyone is interested, I found pictures of a FNB-80Li battery taken apart. 








(pictures made by member ws8e, http://groups.yahoo.com/group/VX-7R)


The case can be opened by prying. I have one dead battery at home, but I am waiting for the special tri-wing screwdriver to remove the three screws (the screwdriver can be bought for $0.95 shipped from dealextreme). 
It looks like 18500 LiOn batteries? Maybe they could be replaced. 
And if not, then I can at least remove the old batteries and run a cable out of the case (through one of the three screw holes), so I can power it up on a external Li-ion pack.

Woudln't it be great if they made a 2x CR123A battery case? Primary CR123A could deliver enough power for full transmit. But some sort of a step-up transformer would be needed to get the 6V to 7.4-8.4V... This could be a good backup...

I'll let you know if I manage to get the box apart without much damage.


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## Greebe (Jul 8, 2012)

I am bringing back this really old thread because we never got answers as if this could be done. I found this thread because I too was thinking of taking a FBA-23 AA pack and using it with 3.6V 14500 lithium-ion rechargeable batteries. It was said in this post that there is a step up circuit in the FBA-23 AA pack, but it would seem that if you bypassed this you should be fine. However you would only be able to get 7.2V and around 900mAh with two 14500.

It was mentioned in this post that people thought the batteries in the FNB-80Li were 18650, but those would be longer than the battery pack so I don't believe that would work.

One option might be two protected 17500 cells from Battery Junction that are rated at 1300mAh. With two in series, this would give us the 7.4V 1300mAh like the original FNB-80Li Li-ion packs. This might be an option by just slightly modifying the FBA-23 AA pack.

So did anyone ever try anything?

Thanks,
Greebe


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## zoulas (Jul 23, 2012)

Interesting ideas. I have the vx-5-6-and 7. Love the whole series. Replacement bateries on ebay are 35 bucks. Many not be a bad idea to keep a spare in the car. You get much lower transmit power with AA's. Also, the desktop charger is a great investment.


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## SomeDude4744 (Aug 10, 2012)

Post Removed


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