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mkothe
super member

Reged: 03/08/07

Loc: Boston, MA

Am I overthinking power tanks?
#5602123 - 01/02/13 11:05 PM

Hi,

My apologies for starting another thread about power tanks, but all these threads about how to maintain them to avoid having them lose capacity, and the various instructions on how to build better devices from marine or wheelchair batteries have made me somewhat reluctant to consider a serious goto telescope. I have a Nexstar 102 SLT which I am powering with an AC adapter for now, but if I were to get something more involved, I would like to be independent of outlets.

Unfortunately I get to observe only infrequently (less than once per month). I am looking for something that I would not have to remember to recharge every few weeks, and then remember to take off the charger after a few hours. I also would like to avoid having to become an electrical engineer and fiddle with a voltmeter to track how the battery is performing. OK, I guess I could get a voltmeter just for checking, but some of the instructions for maintaining the charge sound more involved than I would like.

Is there a solution that would allow me to plug the unit in and forget about it until needed? Maybe the battery tender devices I saw recommended, or something different than the power tank? I won't have a lot of equipment to power (I'm thinking of a Nexstar 6/8SE, maybe some dew strips and possibly a USB charger for the iPad).

I would like to avoid having to build something myself, unless it is easy and would be a substantial improvement over what is available at reasonable cost. The wheelchair battery setups sound promising in that they seem to last forever, but I don't want this to turn into a project, and also would like to avoid something that might be too unwieldy (weight, size, lots of cables etc.).

Maybe I'm getting the wrong impression and power tanks are more user-friendly than it sounds from these threads? Please keep in mind that I would use the unit fairly infrequently, so maybe that changes the situation and makes a power tank a poor choice and I should consider a different solution? Something without lead/acid batteries?

Thanks for listening and any advice,
Michael

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CJK
professor emeritus

Reged: 12/05/12

Loc: Scenic SE TN

Re: Am I overthinking power tanks? new

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[Re: mkothe]
#5602138 - 01/02/13 11:16 PM

The type of situation you're describing is pretty much the same as that faced by many boat, RV, and motorcycle owners. A good quality, deep cycle battery connected to a multi-stage charger (such as a Battery Tender) is pretty much a "set it and forget it" solution. If you don't need a huge amount of capacity, one of the jump start thingies or the power tanks is fine, but throw away the wall wart and use a Battery Tender Jr. To charge it instead.

I'm an R/C car and aircraft guy, and I've just finished building a battery power system for my astronomical endeavors -- I need to write up the details to post here, but I'm procrastinating -- and trust me, the key to a happy battery is a quality charger.

-- Chris

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RTLR 12
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[Re: CJK]
#5602312 - 01/03/13 02:46 AM

There are some, many actually, jump packs that have 'smart charging'. You have to read the description to find the ones that do not need to be unplugged after charging and can be left plugged in all the time. I have some Vectors (Black and Decker), Schumacher's and Duracell's that all have smart charging. There are many more brands out there too and with them you don't need to buy an additional charger to maintain them.

Stan

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Tom and Beth
Carpal Tunnel

Reged: 01/08/07

Loc: Tucson, AZ

Re: Am I overthinking power tanks? new

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[Re: mkothe]
#5602340 - 01/03/13 04:19 AM

Like Chris said; Battery Tender.

I have a wheel chair battery hooked to mine, and it's connected with a "goof resistant" plug. The battery is maintained at the proper charge, and when it's time to use it, 15 seconds max to disconnect from the charger.

All you have to do is remember to spend 15 seconds to reconnect when you get home

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Ira
Carpal Tunnel

Reged: 08/22/10

Loc: Mitzpe Ramon, Israel

Re: Am I overthinking power tanks? new

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[Re: Tom and Beth]
#5602429 - 01/03/13 07:01 AM

My AstroTec power tank is plug and play. Never had a problem with it. I do unplug it after it indicates a full charge. That's it.

/Ira

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Midnight Dan
Postmaster

Reged: 01/23/08

Loc: Hilton, NY, Yellow Zone (Bortl...

Re: Am I overthinking power tanks? new

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[Re: Ira]
#5602451 - 01/03/13 07:27 AM

Hi Michael:

You can get automotive jump start units that have smart chargers in them so you can leave them plugged in all the time without risk of overcharging. That should be all you need.

Another option to consider is a NiMH battery pack. MUCH smaller and lighter than a lead-acid jump starter, and you can also get them with smart chargers ... but not built-in. The advantage of these is you can usually find a place to velcro them to your mount, and they add very little to overall weight of your system so you don't have another item to haul out with you.

Here's a picture of a 2-pound NiMH battery pack that I have velcroed to the base of my 8SE. I get 4-5 hours of usage per charge, powering my SE mount as well as 2 dew heaters.

It does take a little wiring up because you have to make a cable to fit your particular mount. Here's where I got the battery pack. http://www.onlybatterypacks.com/showitem.asp?ItemID=11075.37
The same site sells a variety of smart chargers. I just got the cheapest one, even though its a fairly slow charger:
http://www.onlybatterypacks.com/showitem.asp?ItemID=11862.12

-Dan

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hamdul
super member

Reged: 06/23/09

Loc: Litchfield NH, USA

Re: Am I overthinking power tanks? new

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[Re: Midnight Dan]
#5602627 - 01/03/13 09:50 AM

Hi Michael,
I have a Schumacher XP 500 Which I got at Walmart (On Line) I think it was around $35.00. It has that feature of leaving it plugged in and not overcharging. It has worked flawlessly for me. As a former Bostonian I have to ask, Where do you observe from, certainly not the city?
Fred

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hamdul
super member

Reged: 06/23/09

Loc: Litchfield NH, USA

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[Re: hamdul]
#5602630 - 01/03/13 09:53 AM

P.S. Michael
My Schumacher also has a USB port connection
Fred

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Al Canarelli
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Reged: 12/06/07

Loc: Central New Jersey

Re: Am I overthinking power tanks? new

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[Re: hamdul]
#5602738 - 01/03/13 11:00 AM

I've always owned power tanks (usually 17 amp size) and enjoy their compact size, weight and the convenience they offer. I learned only recently that when they no longer accept a charge, it's not always a battery problem but rather frequently can be a wall charger problem. (I wonder how many power tanks I gave up on when the culprit was only a faulty wall charger.)

Nevertheless, the last time one of my power tanks would not take a charge from the wall charger ( Celestron 17 amp unit), I used an automotive charger instead. I connected the alligator clips of the charger directly to the alligator clips of the power tank ( red to red, black to black) and let it charge for a few hours. About 4 hours later it was fully charged. I did this months ago and the power tank is holding up as though it was brand new. Btw, the wall charger still will not charge the power tank.

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cliff mygatt
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Reged: 01/27/09

Loc: Kitsap County, WA

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[Re: Al Canarelli]
#5602929 - 01/03/13 12:41 PM

Michael, I use a 12 Volt RV/Marine Deep Cycle battery in a standard plastic battery box with two 3 plug cigarette lighter adapters attached to the top. I charge it with a standard Craftsman battery charger before I take it for star parties and it lasts the 4 days of these events. I store it with my telescope accssories in the garage when not in use. It provides all the power I need with room for future use such as a laptop or CCD camera. Simple, affordable and easy to handle. Good Luck!

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skybsd
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Reged: 02/01/08

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[Re: mkothe]
#5603026 - 01/03/13 01:38 PM

Hello,
Have a look at the Kendrick Astro Power Packs.

Rather excellent quality, and helpful customer service.

Hope that helps..,

Regards,

skybsd

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oo_void
sage

Reged: 11/13/09

Loc: San Francisco, CA

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[Re: skybsd]
#5603037 - 01/03/13 01:44 PM

Yet another one of these. Power Tanks and Jump Starters are typically designed for a short, quick burst of power, not a constant draw. The best bet is a deep cycle marine battery and a cheap battery box with 12v connector built it. Add a Battery Tender, Jr. and you're set. If I can put such a system together, anyone can

.

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mkothe
super member

Reged: 03/08/07

Loc: Boston, MA

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[Re: oo_void]
#5603825 - 01/03/13 10:39 PM

Thanks for all the input! I think I'll go with one of the power packs with built in smart charger to keep it simple for now. I like that they are one-hand portable and self-contained. The Schumacher sounds like a good option. The Amazon reviews on that one were mixed, but the price is right, and with the endorsement from Fred, I'm willing to give it a try.

Fred, I am in West Roxbury, so the skies are not great, but a bit better than right in Boston.

Michael

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derangedhermit
sage

Reged: 10/07/09

Loc: D/FW, TX

Re: Am I overthinking power tanks? new

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[Re: mkothe]
#5605532 - 01/04/13 08:30 PM

My only suggestion (request, actually) is that you rethink leaving the charger attached to AC power all the time. Most units, e.g. the Schumacher "automatic" one referred to earlier, tell you in the User's Manual under "How to Charge" to *unplug the unit from the wall when charging is completed*. Battery chargers left plugged in and unattended have started a lot of fires in people's garages and homes.

I can promise you that having your house burn down is a life-changing event.

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RTLR 12
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Reged: 12/04/08

Loc: Capistrano Beach, Ca

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[Re: derangedhermit]
#5605651 - 01/04/13 10:07 PM

This is what it says in my Schumacher User's manual...

The GREEN LED will light when the battery has reached full charge. This could take up to 72 hours, due to the age and condition of the battery. The charger will automatically go into maintain mode and maintain the battery at full charge without damaging it.

Stan

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derangedhermit
sage

Reged: 10/07/09

Loc: D/FW, TX

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[Re: RTLR 12]
#5605819 - 01/05/13 12:15 AM

I went to the web site and d/l'd the XP400/XP500 pdf.
web page
Maybe it would be good to read the manual for a specific model before any purchase.

IMHO it is better to figure out some way to remember to plug the charger in for an hour or two at least once a month, and leave it unplugged the rest of the time.

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hamdul
super member

Reged: 06/23/09

Loc: Litchfield NH, USA

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[Re: derangedhermit]
#5606197 - 01/05/13 09:34 AM

I agree, "It would be good to read the manual' And the manual CLEARLY states "The green LED will light When the battery has reached full charge. This could take up to 72 hours due to the age and condition of the Battery. The charger will automatically go into maintain mode and maintain the battery at full charge WITHOUT DAMAGING IT."
As I read it the references alluded to in the previous posts are for when the battery is being charged by the automobile battery not from house current.
Fred

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panhard
It's All Good

Reged: 01/20/08

Loc: Markham Ontario Canada

Re: Am I overthinking power tanks? new

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[Re: hamdul]
#5606250 - 01/05/13 10:20 AM

Here is what I use to charge batteries. It does all my batteries. Also when storing a battery, don't put it on the ground or on concrete floor. charger.

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RTLR 12
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Reged: 12/04/08

Loc: Capistrano Beach, Ca

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[Re: panhard]
#5606285 - 01/05/13 10:36 AM

Quote:

... don't put it on the ground or on concrete floor.

That is an old wives tale.

Stan

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EdTheEdge
Pooh-Bah

Reged: 04/10/09

Loc: Lomita, CA

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[Re: RTLR 12]
#5608477 - 01/06/13 02:08 PM

I probably shouldn't say this for fear of jinxing myself. But my Celestron 17AH powertank has been one of my most dependable pieces of equipment. It even outlasted my Battery Defender which just quit on me 2 months ago. I have replaced the Battery Defender with a Battery Tender Jr which is working OK but takes more time to recharge (all) of my batteries. I have never used the Power Tank's included charger. My Power Tank has given me flawless performance for almost 4 years now.

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RTLR 12
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Reged: 12/04/08

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[Re: EdTheEdge]
#5608574 - 01/06/13 02:50 PM

Battery Tender JR only charges at a rate of .75 amps. Slow to charge, but easy on the battery.

Stan

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Smittty692k4
scholastic sledgehammer

Reged: 07/05/11

Loc: East Bernard, TX

Re: Am I overthinking power tanks? new

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[Re: EdTheEdge]
#5609973 - 01/07/13 11:12 AM

Hiya Michael,

Instead of a bettery tender, I would recommend the Schumacher XP2260 power tank. ou can buy it at walart in the automotive section.

I also use the 102 SLT and a Nexstar 8SE (with dew strips)

Just wanted to throw this out there. And if you have a problem, its only Walmart, exchange it right. HAHA

Digital battery display
Non-overcharging (If you forget, it wont ruin the battery)
2 AC ports
2 Cig lighter ports
USB port

Plus extras. Been using my 2 for a year and half. No issues.

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zippeee
sage

Reged: 12/27/10

Loc: Alberta, Canada

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[Re: Smittty692k4]
#5610248 - 01/07/13 01:27 PM

I read somewhere that the Battery Tender Jr. gets really hot (hotter than you'd feel comfortable with leaving it plugged in and unattended), can anyone confirm this? I'd like to replace my 12v charger (a very nice, standard auto/RV one) with a low power BT of some sort.

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Paul G
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[Re: zippeee]
#5610339 - 01/07/13 02:32 PM

Quote:

I read somewhere that the Battery Tender Jr. gets really hot (hotter than you'd feel comfortable with leaving it plugged in and unattended), can anyone confirm this? I'd like to replace my 12v charger (a very nice, standard auto/RV one) with a low power BT of some sort.

Mine hasn't after years of use. I use Optima blue top dual purpose marine batteries and Optima tech support recommended Battery Tender, Jr. It has worked very well for me.

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EdTheEdge
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Reged: 04/10/09

Loc: Lomita, CA

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[Re: Paul G]
#5611805 - 01/08/13 11:46 AM

I leave mine plugged in almost 24/7 charging my cars and/or my power tank. It does not get hot.

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ponz
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Reged: 07/18/12

Loc: Kansas City, MO

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[Re: zippeee]
#5611959 - 01/08/13 01:31 PM

Quote:

I read somewhere that the Battery Tender Jr. gets really hot (hotter than you'd feel comfortable with leaving it plugged in and unattended), can anyone confirm this? I'd like to replace my 12v charger (a very nice, standard auto/RV one) with a low power BT of some sort.

I've been using the (same) Battery Tender Jr for several YEARS on my motorcycle batteries and haven't had on problem.

Ponz

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Doug Culbertson
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Reged: 01/06/05

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[Re: ponz]
#5611973 - 01/08/13 01:41 PM

Quote:

Quote:

I read somewhere that the Battery Tender Jr. gets really hot (hotter than you'd feel comfortable with leaving it plugged in and unattended), can anyone confirm this? I'd like to replace my 12v charger (a very nice, standard auto/RV one) with a low power BT of some sort.

I've been using the (same) Battery Tender Jr for several YEARS on my motorcycle batteries and haven't had on problem.

Ponz

+1 I also use it for my 7AH gel cells that I use on my Starmaster, and often forget to disconnect them for days at a time. No problems at all.

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CJK
professor emeritus

Reged: 12/05/12

Loc: Scenic SE TN

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[Re: ponz]
#5612004 - 01/08/13 02:00 PM

Quote:

I've been using the (same) Battery Tender Jr for several YEARS on my motorcycle batteries and haven't had on problem.

Ponz

Doh! Meant to do that back in December when it got too cold to ride!

-- Chris

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bobmarleyou812
sage

Reged: 01/18/08

Loc: CA

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[Re: CJK]
#5616294 - 01/10/13 09:24 PM

Am I overthinking power tanks?

YES

I have the PSX thing that Costco sells. I can run my scope all night and still have enough juice to put 40 psi in my tire and jump my truck in the morning.

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jrbarnett
Eyepiece Hooligan

Reged: 02/28/06

Loc: Petaluma, CA

Re: Am I overthinking power tanks? new

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[Re: skybsd]
#5617635 - 01/11/13 05:35 PM

I think the pricing is way, way too high per AH on the KAIs.

You can get a 66AH Optima Blue deep cycle battery for a couple hundred bucks, a DC plug socket splitter for $10, and a battery Tender Jr. for $17, and have greater capacity in a smaller size than the $950 KAI Titan.

I have a small 7AH KAI pack. Overpriced. It uses a cheap, 7.5AH gel cell like you can buy off eBay for $17. I view the KAI solutions as being for those who are afraid of batteries and clamps. You're paying *a lot* to hide the battery inside of something.

- Jim

Edited by jrbarnett (01/11/13 05:52 PM)

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RealSorin
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Reged: 10/22/12

Loc: Seattle, WA

Re: Am I overthinking power tanks? new

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[Re: jrbarnett]
#5630248 - 01/18/13 04:50 PM

I've been trying to understand the battery options and this is a helpful thread. One question I've been pondering in particular: why aren't there many light/compact and plug and play options? I'm looking at this from a consumer electronics perspective where the battery technologies are clearly available, but there don't seem to be many options suitable for driving a telescope.

The PowerTank is heavy and has the issue that the battery really isn't designed for a low draw, or plug and forget charging (without a different charger).

I can across the Goal Zero Sherpa 120, which while expensive, seems like it would work great for a night of observing, and weighs about 4 lbs (lithium iron phosphate cells).

I guess I'm just wondering if there are better solutions I'm not seeing, if this is a gap in the market that people are content to engineer their own personal solutions for, or if nobody else really sees this as a gap?

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Steve Daniel
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Reged: 06/03/12

Loc: Austin, TX

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[Re: RealSorin]
#5630283 - 01/18/13 05:23 PM

I'm loving this one: http://www.amazon.com/gp/product/B002CG001E/ref=wms_ohs_product

It will power my Celestron CPC800 all night. I leave it plugged in all the time. Looks like it's no longer available, but there's a 1800 mAh model, which would be about the same as the Celestron pack, I think.

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Ricky
Carpal Tunnel

Reged: 09/09/03

Loc: Nor Cal

Re: Am I overthinking power tanks? new

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[Re: Steve Daniel]
#5630464 - 01/18/13 07:29 PM

I'm using a bioenno 12v 12ah lifepo4 battery. It is relatively expensive but its a very safe lithium battery, can be deep cycled well below 50% capacity without damage, is extremely compact in size and weight, and if properly cared for is capable of 2000+ recharge cycles. I've been using it for a couple of weeks now and so far so good...time will tell.

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RTLR 12
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Reged: 12/04/08

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Re: Am I overthinking power tanks? new

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[Re: Ricky]
#5630926 - 01/19/13 12:56 AM

Ricky,

How much is "...relatively expensive..."

Stan

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skinnyonce
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Reged: 03/23/11

Loc: ohio

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[Re: RTLR 12]
#5631041 - 01/19/13 04:41 AM

115 $ expensive

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RTLR 12
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Reged: 12/04/08

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[Re: skinnyonce]
#5631116 - 01/19/13 07:33 AM

Wow,

Maybe I'll just stick to something like this...

http://www.batteryspec.com/cgi-bin/cart.cgi?action=link&product=300

Stan

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Ricky
Carpal Tunnel

Reged: 09/09/03

Loc: Nor Cal

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[Re: RTLR 12]
#5631325 - 01/19/13 10:59 AM

Expensive at the start but my batt should last for many years.

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EdTheEdge
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Reged: 04/10/09

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[Re: RTLR 12]
#5631868 - 01/19/13 05:01 PM

Quote:

Wow,

Maybe I'll just stick to something like this...

http://www.batteryspec.com/cgi-bin/cart.cgi?action=link&product=300

Stan

That does look temptingly promising!

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