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Power Tank 7ah question - Dual batteries

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#1 ben2112

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Posted 13 February 2013 - 02:51 PM

I got a power tank as part of a kit with my 8SE. No surprise, it was messed up. The flashlight switch on top wouldn't work. So I called Celestron and they are sending me a brand new one and didn't want the old one back. I am wondering if the battery is good in the broke unit, if I could use it in parallel with the new one and double my capacity.

#2 GlennLeDrew

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Posted 13 February 2013 - 05:33 PM

In the main, I should think so, at least if the condition of the old battery is reasonably decent. If the old one has been rather deeply discharged at some point, or gone through many charge/discharge cycles, it will probably impact current capacity of the pair in parallel.

Hopefully someone better versed in the technology of batteries will chime in...

#3 starrancher

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Posted 13 February 2013 - 06:00 PM

Yep , the battery bank is only as good as its weakest link . Id start with two new ones . Actually , for about 60 bucks , you could get a 35 ah unit . Be like 5 times the reserve of the OE power tank batt .

#4 ben2112

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Posted 13 February 2013 - 07:14 PM

The powertank was never used. When I got it, I plugged it in for about 3 to 4hrs. When I turned on the flashlight on the front (the small one), it flashed on for about a second or two. Then when I went to plug it back in to finish charging, the red light wont come on and nothing works. I took it apart to check the charge of the battery, but for some reason, I can't find my multimeter. UGH!! :mad: Oh well, I'll just see about getting another multimeter next payday. The one I had was 15 years old.

But if this battery is still good, I'll just use both until they die and then upgrade down the road..

Edit: Well, the batter has a charge. I found my circuit checker. It lights up the test light. So that is a good sign. I wonder if I could use a 10amp car battery charger.

#5 GlennLeDrew

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Posted 13 February 2013 - 07:43 PM

For gel cells you need a rather more gentle charger than a 10 amp job made for car batteries. The charger that came with your power tank should suffice, although charging times will double (if you decide to bank two 7Ah batteries in parallel.)

#6 ben2112

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Posted 13 February 2013 - 07:47 PM

For gel cells you need a rather more gentle charger than a 10 amp job made for car batteries. The charger that came with your power tank should suffice, although charging times will double (if you decide to bank two 7Ah batteries in parallel.)


Thanks. I didn't want to mess up the battery. When the new Powertank arrives, I'll connect the other battery up and let it charge overnight.

#7 Phil Sherman

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Posted 13 February 2013 - 09:36 PM

... I took it apart to check the charge of the battery, but for some reason, I can't find my multimeter. UGH!! ....


Check your magazines and newspaper ads for a Harbor Freight Tools ad. They often give away multimeters as a gift with any purchase. If you want to purchase the meter, they're available from $4 to $7 for their house brand.

I've made a $0.79 purchase and obtained a free meter.

Phil

#8 ben2112

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Posted 13 February 2013 - 10:11 PM

... I took it apart to check the charge of the battery, but for some reason, I can't find my multimeter. UGH!! ....


Check your magazines and newspaper ads for a Harbor Freight Tools ad. They often give away multimeters as a gift with any purchase. If you want to purchase the meter, they're available from $4 to $7 for their house brand.

I've made a $0.79 purchase and obtained a free meter.

Phil


Cool idea.. Our Harbor Freight is close to my office. I'll just swing by there at lunch tomorrow. Thanks for the tip.

#9 DaveJ

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Posted 14 February 2013 - 08:16 AM

Cool idea.. Our Harbor Freight is close to my office. I'll just swing by there at lunch tomorrow. Thanks for the tip.


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