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-   -   Lithium battery? (http://www.performers.net/forums/showthread.php?t=17514)

Magic Brian 05-01-12 03:39 PM

Lithium battery?
 
I bought this lithium battery to run my AER compact 60 (http://www.ebay.com/itm/300693372295...84.m1497.l2649) but I couldn't even get enough power out of it to turn on my inverter. I took it to an electronics guy and he seems to think that it's not putting out the 9800mAh. Not sure why it's not working or what to do. When I test it, it shows that it's putting out 12volts. I'm looking for something lighter than the two 12v 7Ah bricks that I currently have. Any thoughts?

gav 05-11-12 05:24 PM

I find it highly unlikely that your battery can put out 9.8 amps. I think they have severely over rated it.
I looked on Aer web site and see that the compact 60 watt now uses 2 x 6volt 12 ah batteries.
If yours is 2 x 12volt 7 ah, that either means it was running on 12 volts with 14 amps at it's disposal or it was running on 24 volts with 7 amps.

Either way, I think you've been had with your battery purchase.
Your average lithium batteries aren't particularly good at handling sudden increases in power draw as you might get with a D class amplifier such as the AER.
You might want to consider a t class amp that draws less power.
Take a look here at what they have to offer and check out their forum for good advice.
http://www.41hz.com/forums/content.p...T-Tripath-amps

Magic Brian 05-12-12 08:51 AM

Hey Gav,
Thanks for the info. I'm not using the mobile version. I'm using the powered version, smaller and lighter. I've got the two batteries so one the first runs out after a couple of shows I have a back-up. The plan was not to have two batteries but I've had power issues lately with relying on one.
As for the lithium battery, I've done some research since my post and this is what I learned:
The way the power capability is measured is in C's. A C is the Amp-hour capacity divided by 1 hour. So the C of a 2Ah battery is 2A. The amount of current a battery 'likes' to have drawn from it is measured in C. The higher the C the more current you can draw from the battery without exhausting it prematurely. Lead acid batteries can have very high C values (10C or higher) , and lithium ion cells have very low ones typically around 1C some can get up to 10C.
What that would mean is that my 9.8amp battery drained quite quickly as it tried to power my inverter. I guess that's what you get for $40!
I'm not really in the market for a new amp since I just got the AER last year. I'll just have to cart around extra batteries for a while, or spend a lot more than $40 on a battery.

gav 05-14-12 12:25 PM

I totally missed that you were using an inverter in your first post. I'll blame my one bad eye for that.
Inverters use(waste) a lot of power and where possible it's best to avoid using them to power an amp. Is the mobile AER that much heavier than your amp plus the 2 batteries plus battery charger and inverter ?

Magic Brian 05-17-12 12:50 PM

Not sure about the weight difference but it is smaller and can fit in the overhead of even small planes. I didn't think I'd need to buy two batteries for it. I was hoping just the one would do but after a year of use, the battery does not hold it's charge as long so I got the other one as back up. At least I can distribute all the extra weight amongst my bags!
I'll live with this one for a while and look for other solutions. Maybe someday the price of a good lithium battery will go down...


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