Topic: POWER in Mobile Go-Packs.

[MrGClips]

Hi Crowd!

I've checked out a couple of very interesting clips about "Mobile Go Packs". Various sizes, configurations and complexity in backpack or hard-case solutions.

What got me curious was that I saw it time and again that pretty powerful mobile radios (50W or even higher) have been operated from those portable 12V, 7Amp batteries. HOW is that even possible, when such radios would draw almost twice the Amp power to run on full capacity?

I'm sure many of you have such "go-pack" emergency portable setups, so please, talk about them a bit to make us, newbies, understand it better.

The idea is so cool, I myself could imagine putting a mini-system like that together, but I just don't understand what is necessary (beside the radio and a power supply) for a simple system, and how can those full-sized powerful mobile radios even work on those relatively small-power portable batteries?

I mean, on the same token, one could just hook up a bunch of rechargeable AAs to come up to the 12Volt/7Amp power output as those portable batteries and run a radio like that? I seriously doubt it would work! ... or would it?

I just don't understand the whole thing. Please, someone explain it in a way that newbies can understand and maybe even build their own little back-pack systems.

THANK YOU!

 

[MTS2000des]

A 50 watt mobile radio can easily run off a 12v 7A/h gel battery, just for not very long.

The average 50 watt mobile draws 9-12 amps max.
The A/H rating equates to capacity, not current output capability as you typically see in a linear or switching DC power supply.

In other words, your 50 watt radio will drain a small battery after transmitting for more than a few minutes.

Personally, I would operate such a radio at a lower power setting, most ham rigs will run at 5 or 10 watts with a lower TX current drain, usually 5amps or less, which gives you more transmit time.

And not to mention, any 50 watt radio should be operated with an antenna away from people, always follow proper RF exposure guidelines.

 

[N0IU]

IMHO, I think a lot of these "go kits" (or whatever you want to call them) are built simply as an academic exercise. By this I mean that they assemble what they seem to think will be the necessary components to put some sort of amateur radio station on the air outside of the comfort of their own home without any idea of what their "go kit" will actually be used for.

There is a huge push in amateur radio to get people involved because of this notion, "When all else fails, amateur radio gets through". There is no question at all regarding the value of amateur radio in the case of a true emergency but truth be told, there really aren't that many emergencies where there is a significant loss or breakdown of commercial communications systems.

But back to the topic, you are absolutely correct in recognizing the fact that without power to run your station, these "go kits" are useless. If you are really honestly serious about operating "off grid" for extended periods of time, this will require the use of a deep-cycle battery that can do the job. But keep in mind that it won't be cheap and it won't be light.

This is not an endorsement for this company or their products (even though I have used many of them over the years), but West Mountain Radio has really put a lot of thought into this issue and has several products specifically made for this application: West Mountain Radio - DC Power Models.

For example, the battery box with the Super PWRGate (used to keep the battery charged when you are on commercial power) and RigRunner (used to distribute the power) all in a nice box costs $250. Add to that the 73 A/H deep-cycle gel battery which costs $235. So here you have a system that will supply adequate power for an extended period of time (depending on what power level you use) that costs almost $500 that will probably weighs over 55 lbs.

So before you put together your own version of a "go kit", ask yourself exactly what you plan to do with it?

 

[prcguy]

Gel Cell batteries have a couple of problems for portable operation, weight and voltage sag. Many of them will be in the mid 11v range for much of their discharge cycle, dipping lower on transmit and some radios have trouble with that.

The best batteries for portable operation were the A123 Systems 12V7 packs, which run about 13.5v for most of their discharge and at 5AH for each pack. The cells in these packs are capable of producing 140 amps continuous discharge for the two strings of internal cells in parallel (per mfr spec), but the internal wiring and 30A fuse limit you to about 30A max. These packs are housed in a 12V 7AH size container and which a fraction of what a 7AH gel cell weighs. You can also parallel these batteries forever to get the AH rating you need. Each pack had a built in cell balancer so you don't need a charger, just apply about 14V and they charge and balance themselves. They also have a low voltage cutoff to protect the cells. Each pack was rated for minimum 7,000 charge/discharge cycles, which will last a very, very long time.

I've used a single 5AH 12V7 pack to run a 100w HF radio in the field for several years now and it gives me a couple of hours of play time per charge and I've never run it dead yet. The reason you get so much time from a 5AH battery is your receive to transmit ratio is usually small and my HF transceiver only draws about 190ma on receive. These have the same cells as the packs sold by Buddipole but those need a special charger, have no low voltage cutoff and cost more.

Unfortunately A123 Systems has gone somewhere and these are not available at the moment. There are similar batteries available but the ultimate current capability and charge/discharge cycles are less and rated about 2,000 cycles, which will still last quite awhile.

Here are a couple of examples of similar batteries that have built in cell balancing and you can parallel them for lots of capaciy. These also weigh a fraction of a similar size gel cell.

12V 7Ah LiFePO4 Rechargeable Battery Dakota Lithium CR1207 | eBay

K2 Energy 12V 7Ah LiFePO4 Battery for CATV Systems Robotics E Bikes USA SHIP | eBay
prcguy

 

[prcguy]

Follow up, looks like A123 Systems sold some of their product line to NEC and here is a link to these fantastic batteries:NEC Energy Solutions ALM 12V7
prcguy

 

[ramal121]

Gel Cell batteries have a couple of problems for portable operation, weight and voltage sag. Many of them will be in the mid 11v range for much of their discharge cycle, dipping lower on transmit and some radios have trouble with that.

The best batteries for portable operation were the A123 Systems 12V7 packs, which run about 13.5v for most of their discharge and at 5AH for each pack. The cells in these packs are capable of producing 140 amps continuous discharge for the two strings of internal cells in parallel (per mfr spec), but the internal wiring and 30A fuse limit you to about 30A max. These packs are housed in a 12V 7AH size container and which a fraction of what a 7AH gel cell weighs. You can also parallel these batteries forever to get the AH rating you need. Each pack had a built in cell balancer so you don't need a charger, just apply about 14V and they charge and balance themselves. They also have a low voltage cutoff to protect the cells. Each pack was rated for minimum 7,000 charge/discharge cycles, which will last a very, very long time.

I've used a single 5AH 12V7 pack to run a 100w HF radio in the field for several years now and it gives me a couple of hours of play time per charge and I've never run it dead yet. The reason you get so much time from a 5AH battery is your receive to transmit ratio is usually small and my HF transceiver only draws about 190ma on receive. These have the same cells as the packs sold by Buddipole but those need a special charger, have no low voltage cutoff and cost more.

Unfortunately A123 Systems has gone somewhere and these are not available at the moment. There are similar batteries available but the ultimate current capability and charge/discharge cycles are less and rated about 2,000 cycles, which will still last quite awhile.

Here are a couple of examples of similar batteries that have built in cell balancing and you can parallel them for lots of capaciy. These also weigh a fraction of a similar size gel cell.

12V 7Ah LiFePO4 Rechargeable Battery Dakota Lithium CR1207 | eBay

K2 Energy 12V 7Ah LiFePO4 Battery for CATV Systems Robotics E Bikes USA SHIP | eBay
prcguy

Voltage sag does indeed eat into the usable capacity of a battery system. As another solution you could use a 12 volt to 12 volt buck/boost regulator to provide a constant voltage to your equipment. The small loss in efficiency by using one is offset by the ability to squeeze every bit of capacity out of whatever battery you choose and still provide power to your radios that they are happy with.

Using one at a solar repeater site and has helped a bunch when daylight hours are minimal.

 

[MrGClips]

I agree that this is more like an experiment and definitely not a long-term solution, but I find the concept of a mid-range lightweight "take it with you" pack itself interesting. Like the bigger brother of an HT.

So, if I wanted to build such a lightweight "Go-Pack" rig, what would I need?
- A mini light-weight maximum 25w radio with a whip antenna.
- A small and lightweight 12V battery, at least 4-5A minimum, 6-7A recommended? (weight is the issue)
- Small and simple power regulator between the battery and the radio to keep the 12V feed constant? (if necessary)
- A small digital Volt reader for monitoring maybe? (if necessary)
- A power switch connected to the battery? (if necessary)
- Some sort of a folding-type easy to pack solar panel to recharge the battery? (if necessary)
- Connectors, cables, cigarette lighter adapter, 12V-to-5V converter and USB adapters to use the solar panel and/or the battery for charging other devices as well, maybe?

I really don't know this stuff, so I'm just a "noob" theorizing here.

The whole thing should be very lightweight to make it useful and portable with as few as possible components to save space, cut down on weight and simplify things, otherwise it makes no sense. BUT (!!!) if there are small-sized fitting components for such a pack, then it could be useful and fun, too!

 

[MrGClips]

I've found these super-lightweight Lithium Polymer batteries from Trace! Even the biggest unit weighs only 1,250 grams, less than 1.5 pounds! Wow! That is so cool!

The prices, however, are pretty steep:
- 12 Volts 8 Amp $160-
- 12 Volts 10 Amp $200-
- 12 Volts 14 Amp $235-
- 12 Volts 22 Amp $305-

LINK: http://www.tracerpower.com/tracer-lithium-polymer-battery-packs.html

These battery packs maintain constant 12V till the end, no fluctuations, which would extend the actual usability of a radio as well, compared to regular batteries. And I guess, the voltage regulator could be eliminated also.

I've read an article about this same experiment where the regular lead-acid 12V/7Ah battery on 20W output provided just short of 1 hour operation. That is absolutely horrible!

With a couple of these larger 22Ah Lithium Polymer units, even a full-day operation could be achieved, especially if they are constantly being recharged by a solar panel. Very interesting!

 

[cmdrwill]

And most ham radios are not very efficient on lower power TX.

 

[prcguy]

The Trace batteries do not have much current capability, the 4AH version is only rated at 4A continous output where the A123 Systems 5AH pack will do 23A continuous output for the regular version and 45A for the HP version. The Trace is only rated at 300 charge/discharge cycles where A123 is over 7,000 and the A123 clones are a good 2,000 cycles.

I just noticed Trace uses LiPo cells, which can turn into hand grenades or road flares where the LIFeO4 cells in the other batteries are among the safest available.
prcguy

I've found these super-lightweight Lithium Polymer batteries from Trace! Even the biggest unit weighs only 1,250 grams, less than 1.5 pounds! Wow! That is so cool!

The prices, however, are pretty steep:
- 12 Volts 8 Amp $160-
- 12 Volts 10 Amp $200-
- 12 Volts 14 Amp $235-
- 12 Volts 22 Amp $305-

LINK: TracerPower.com Tracer Lithium Polymer Battery Packs

These battery packs maintain constant 12V till the end, no fluctuations, which would extend the actual usability of a radio as well, compared to regular batteries. And I guess, the voltage regulator could be eliminated also.

I've read an article about this same experiment where the regular lead-acid 12V/7Ah battery on 20W output provided just short of 1 hour operation. That is absolutely horrible!

With a couple of these larger 22Ah Lithium Polymer units, even a full-day operation could be achieved, especially if they are constantly being recharged by a solar panel. Very interesting!

 

[MrGClips]

The Trace batteries do not have much current capability, the 4AH version is only rated at 4A continous output where the A123 Systems 5AH pack will do 23A continuous output for the regular version and 45A for the HP version. The Trace is only rated at 300 charge/discharge cycles where A123 is over 7,000 and the A123 clones are a good 2,000 cycles.

I just noticed Trace uses LiPo cells, which can turn into hand grenades or road flares where the LIFeO4 cells in the other batteries are among the safest available.
prcguy

Thank you for all that info, I'll definitely look into it, because weight, performance and reliability are just as important considerations as safety! I prefer not to get anything blown up by accident.

 

[Thayne]

I gotta agree 100% with pcrguy. I bought one of those batteries and it is great. It was probably not so great from a cost viewpoint because I have only used my setup casually, but it consists of a smallish plastic craftsman toolbox which contains the battery, 2 older model Kenwood mobiles, (VHF, UHF) with a way to charge either from a vehicle 12V or 120 AC using an old Kenwood 15VAC charger with a few 25 amp rectifiers I had laying around, & a small murata 0-18 V digital voltmeter. The mobiles can easily be slid out and the antenna connectors 1 each SO239, BNC,& N are mounted thru the lid. I have just used the vehicle mounted antennas when getting on the ham bands, but plan on being able to perhaps attach antennas directly to the box. (with the exception of the lower freqs.)

 

[prcguy]

And I agree the A123 Systems 12V7 batteries are not cheap, but once you have one you keep finding great uses for them.

After being amazed dozens of times at how long it powers a 100w SSB rig in the field I put it to use with a 12V air compressor that draws a ton of current to raise a 42ft Will-Burt pneumatic mast in the field. Then I use it with a 12V water pump to water the garden with wasted water collected in a rain barrel (we have to get creative with water here in So Cal). Then I plug in a solar panel and charge it with this neat snap on solar charger and power distribution block: BatPac Solar | Hardened Power Systems

This power distribution block and voltmeter by Hardened Power Systems comes with or without the solar charger and can be the center of a simple grab and go radio system. It fits on top of common 7AH size gel cell batteries and also fits the A123 12V7 with a little coaching.
prcguy

I gotta agree 100% with pcrguy. I bought one of those batteries and it is great. It was probably not so great from a cost viewpoint because I have only used my setup casually, but it consists of a smallish plastic craftsman toolbox which contains the battery, 2 older model Kenwood mobiles, (VHF, UHF) with a way to charge either from a vehicle 12V or 120 AC using an old Kenwood 15VAC charger with a few 25 amp rectifiers I had laying around, & a small murata 0-18 V digital voltmeter. The mobiles can easily be slid out and the antenna connectors 1 each SO239, BNC,& N are mounted thru the lid. I have just used the vehicle mounted antennas when getting on the ham bands, but plan on being able to perhaps attach antennas directly to the box. (with the exception of the lower freqs.)

 

[MrGClips]

Follow up, looks like A123 Systems sold some of their product line to NEC and here is a link to these fantastic batteries:NEC Energy Solutions ALM 12V7
prcguy

Yes, I searched for "A123 Systems" but they're gone, and so is the "ALM 12V7" batteries. But I've found the new ones! Here is the direct link with all specs and info: https://www.neces.com/products-services/battery-systems/alm-lithium-ion-battery-systems/alm-12v7/

Amazon links below:
- ALM12V7s: http://www.amazon.com/ALM-12V7s-Lithium-Ion-Battery-Module/dp/B0170FNZLI
- ALM12V7s HP: http://www.amazon.com/ALM-12V7s-Lithium-Ion-Battery-Module/dp/B0170HRUQM

They look incredibly good on paper and barely weigh over 2 pounds? Is that correct? WOW! But then why does Amazon indicate 11 pound shipping weight? I don't get it. Also, their "Nominal Capacity" is listed as ONLY 5Ah. That seems VERY low. I'm a bit confused.

 

[prcguy]

Yes the 12V7 pack is rated at 5AH but the internal cells can produce tremendous amounts of current to feed high power radios on transmit. The internal 26650 cells are rated at 3.3V @ 2.5AH and can put out 70A continuous current. The 12V7 pack has eight of these in a four series, two parallel configuration to give about 13.2V @ 5AH.

As I mentioned before, not counting the fuse and internal wiring, the internal battery configuration is rated at 140A continuous discharge but of course with 5AH rating it would be used up quickly. A typical 100W HF SSB radio draws around 8A average current on transmit and a 40-50W FM radio draws about the same. I'm getting several hours of casual conversation use on a 100W HF radio with just one 5AH 12V7 battery, so they are quite useful even running high power.

One battery would not suffice for a portable go box in a net control situation but it will certainly allow hams to communicate in emergency situations with no other power available. I think a go box should have more capability than 5AH and the 12V7 packs are a great building block for that.
prcguy

Yes, I searched for "A123 Systems" but they're gone, and so is the "ALM 12V7" batteries. But I've found the new ones! Here is the direct link with all specs and info: https://www.neces.com/products-services/battery-systems/alm-lithium-ion-battery-systems/alm-12v7/

Amazon links below:
- ALM12V7s: http://www.amazon.com/ALM-12V7s-Lithium-Ion-Battery-Module/dp/B0170FNZLI
- ALM12V7s HP: http://www.amazon.com/ALM-12V7s-Lithium-Ion-Battery-Module/dp/B0170HRUQM

They look incredibly good on paper and barely weigh over 2 pounds? Is that correct? WOW! But then why does Amazon indicate 11 pound shipping weight? I don't get it. Also, their "Nominal Capacity" is listed as ONLY 5Ah. That seems VERY low. I'm a bit confused.