# MaxAmps Life batteries



## XXX-Steve (Oct 23, 2008)

Technically, these aren't really LiPo batteries, but I thought this should go here since I haven't seen any discussion for them. Has anyone had a chance to use one of these yet? They're still pretty new, but apparently they've been in use quite a bit already.

I like the fact that you don't have to worry about using them with a low voltage cut-off, having them catch fire or explode. Aside from that, they can sit as long as a LiPo, but you don't need to cycle them to keep the cells fresh as would be the case with NiMH. Not to mention, these reportedly last four times longer than LiPos. The only drawback I'm seeing is that they're slightly weaker. Still though, for racing where you're not always going to need that extra punch, I think these are going to be a lot more convenient.

I'm still sort of confused about what kind of charger you would need to charge these. I've read people using a regular LiPo charger, a Li-ion charger, and so on. Some say they're fine charging that way and some say otherwise.

Thoughts?


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## hankster (Jan 1, 1998)

From the MaxAmps web site:

The new 4500mah 6.6V pack can be safely charged extremely fast using our Hyperion line of balance chargers under the LiFePO4/A123 setting.

All they are is A123 cells which have been around for quite some time. A pack is only 6.6 volts which is a lot less then a NiMh or LiPo pack.


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## XXX-Steve (Oct 23, 2008)

Well, purchasing one would be out of the question if I would have to buy a new charger for it.

Based on the application though, they look like a decent battery even with less voltage. I've seen a few videos with cars running them and they're flying.


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## nutz4rc (Oct 14, 2003)

The voltage, amperage, use, draw, type of motor, racing surface all play a part in the usefullness of the battery. Oval carpet racing is high drain on a battery where offroad stock class is low drain. Performance, run time, and longevity of the battery will all be impacted by these issues. 

Before buying, I would try to find someone with actual experience using them. I know when we started running 1 Cell Lipos in Legends rather than the old traditional 4 cell NiCads, we had to make major gearing changes to achieve the same performance. There are always trade offs to be made.


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## Promatchracer (Sep 28, 2001)

Nutz Can you PM or Email some info on the 1cell lipo legends 
I want to try that this year at my track 
Thanks


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## speeddaddy (Feb 19, 2005)

Researchers have developed a new advanced Lithium Ion battery that will allow mobile phone and laptop computers to be fully charged in seconds. Electric car batteries may be charged in as little as five minutes, removing one of the main barriers to wider uptake of EVs. Solar and wind power generation could also benefit as better batteries could be used to store surplus energy.

MIT researchers Byoungwoo Kang & Gerbrand Ceder have discovered a way to make a lithium iron phosphate (LiFePO4) battery charge and discharge about as fast as a supercapacitor. In a typical lithium ion cell when a current is applied to charge the cell, lithium ions move away from the cathode compound and are trapped at the anode storage medium. When the battery discharges producing current, those ions travel back to the cathode medium and in so doing produce current flow.

Speed of charging in typical lithium-ion cells is slowed by virtue of the fact that it takes time for the lithium ion to move off the cathode material. Various techniques have been tried to increase that speed including the nanoparticle doping strategy that A123 Systems uses.

The scientists noted that lithium iron phosphate forms a lattice that creates small tunnels through which the lithium ions flow, but that although the cathode seemed ideal it still took some time for those ions to travel. The novel solution they devised was to create a lithium phosphate glassy surface to coat these tunnels. This glassy surface acts as a speedway that rapidly transports the lithium ions on and off the cathode.

Extremely high rates can be achieved, at a 200C rate (corresponding to an 18 second total discharge) more than 100mAh g can be achieved, and a capacity of 60mAh g is obtained at a 400C rate (9 sec to full discharge). Such discharge rates are two orders of magnitude larger than those used in today’s lithium ion batteries. Typical power rates for lithium ion battery materials are in the range of 0.5 to 2 kW/kg. The specific power observed for the modified LiFePO4 (170kWkg at a 400C rate and 90kWkg at a 200C rate) is two orders of magnitude higher. At this point the researchers have only tested the cells to 50 cycles but have noted no degradation. They have made a small prototype cell which can be fully charged in 10 to 20 seconds, compared with six minutes for cells made in the standard way.

This new ability to charge and discharge lithium-ion batteries within seconds blurs the distinction between batteries and ultracapacitors. Besides being able to charge one’s cellphone in seconds, this will have a major impact on electric cars. If electric grid power was available, an electric car with a 15kWh battery could be charged in five minutes. This would require the delivery of 180 kw of energy in that time frame.

Two companies have already licensed the technology one of which includes A123 Systems. Because it involves a new approach to manufacturing lithium-ion battery materials, rather than a new material, it could be ready within two to three years


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## Heatseeker (Sep 8, 2006)

I got the Green Series Life 4500 2S2P 6.6V to run in a stock Slash and it is performing great. Ran it for 17 minutes with no noticeable drop in power. The 6.6 VS. 7.4 25C 5100 definitely has slightly less power. Less tire spin led to faster lap times but it couldn't provide enough oomph to clear a double that I could clear with the 7.4 LiPo. Worry free running and charging can't be beat. I'm sure gearing changes could compensate. I'll be getting the receiver packs that are available soon.


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## XXX-Steve (Oct 23, 2008)

I noticed last night that my charger will charge these, so I might be considering getting one. What about the 6750 pack? It's still only 6.6V, but do you think the extra mah would give it a bit more power?


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## Heatseeker (Sep 8, 2006)

XXX-Steve said:


> I noticed last night that my charger will charge these, so I might be considering getting one. What about the 6750 pack? It's still only 6.6V, but do you think the extra mah would give it a bit more power?


30C Constant(202.5 amps) VS 30C Constant(135 amps) will deliver more power, I believe, and at 6750 longer run time. I would say yes to your question. I probably should have gotten the 6750 but I was was the first at our track to try it so I saved a few bucks just in case it wouldn't work too well. My mistake.


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