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Blue Angel, Champion
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Larger batteries can supply more power than smaller ones. For the snowblower to operate at maximum power it requires two batteries of a minimum 4Ah. Smaller batteries will definitely work, but the snowblower will not offer as much peak power output and will have shorter run times.
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A 2.5 ah battery vs a 4 or 5 means the cells will basically have to provide 2x the output. There are series and parallel battery cell arrays.
Sure run time is determined by ah, but ah in this case also determines the maximum power draw from the battery.
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I have 7.5 AH and 2.5 AH for mower and trimmer, both of which work wonderfully.Want to look at snowblower.Will both of these fit into snowblower and any idea how much time I would get from them or should I really get the 5.0 batteries to power the snowblower?
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Oregon Mike, Champion
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Amp draw is power draw at the measured time which calculates to KW or power requirements.
The 5ah and 4 ah have 2 parallel circuits both 56v. So think of it this way. If you use two 2.5 ah batteries, that is the same as using 1 5ah battery. Using two 5ah batteries is like using 4 2.5ah batteries.
I don't mean just the math here. The two 2.5 would experience a 1000 watt power draw which is roughly 19 amps (using 54v as a reference) that is a crazy amount of power draw from a single stack of cells. The two 5ah would experience half of this.
As amp draw increases in a battery, it's internal resistance goes up which leads to heat and inefficiency. Keeping the amp draw in a lithuim cell is critical to it lasting a long time.
Plus for the extra 100.00 you get 450.00 worth of batteries. I wouldn't recommend spending slightly less for such a huge difference in value.
Voltage drop even in the 5ah battery at 20amps is alot. I've measured nearly 5v using my home made tools that run off of ego batteries.
Let's just say that 2000 watts is alot to pull from two 5 ah batteries alone. Expecting a cell bank to do double that will lead to battery failure, but I'm pretty sure that the blower accommodates this in the circuit. I've used one 5ah and one 2ah and the 2ah goes red pretty fast due to the huge amp draw
Clear as mud?
Don't just think of ah as run time, ah means run time, but in this case ah means 1, 2, or 3 internal cell banks per battery to divide the amp(not amp hours) requirements
2ah,2.5ah = 1 bank (1p)
4ah,5ah = 2 banks (2p) or 2 internal 56v batteries per battery
6ah, 7.5 ah = 3 banks(3p) or 3 internal 56v batteries per battery
Blue Angel, Champion
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4Ah and 5Ah = 28 cells (2P)
7.5Ah = 42 cells (3P)
Each “P” represents a string of 14 cells in series giving 56V.
The more cells you have to spread the load over, the less the voltage drop for a given load, the more power output potential.
With two 2.5Ah batteries I’d be concerned more about power output than run time for small driveways. That plow pile at the end of the driveway is really tough to move, and as Jacob pointed out, for a 20% increase in price you guarantee the machine will have the proper power output.
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szwoopp, Champion
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This is how Milwaukee’s RedLithium higher capacity (XC) lithium ion battery packs can deliver a performance boost over compact battery packs, and why Makita’s heavier duty LXT tools must be powered by high capacity battery packs and not their compact ones.
It’s not just about runtime. Higher capacity battery packs can deliver power via additional channels. Liion batteries can be damaged by overdrawing current from them, so modern battery packs have safety measures in place. If a tool wants to draw more current than it should, control circuitry will shut the tool off until it cools down or the load is reduced.
If you have twice as many cells to draw current from, there’s going to be greater room to operate.
Let’s say a 2.0Ah battery pack is limited such that continuous current flow cannot exceed 1.0A in order to protect the cells. Theoretically, a 4.0Ah battery pack could be designed where each grouping of cells are set to deliver a maximum continuous current of 1.0Ah. With the two groupings coupled together in parallel, the battery pack could then support a maximum current draw of 2.0A.
But you’re not going to see battery packs advertised as delivering 100% more power than smaller samevoltage packs. Ignoring realworld engineering limitations that govern battery pack designs (such as heat buildup), power tools are not designed to be able to handle 100% more power.
Realistically, if a compact battery pack has a maximum continuous current draw of 1.0A, a higher performing extended capacity battery pack might be designed where it can support a maximum current draw of 1.2A or so. These numbers are all for example purposes. Realistic shutoff limits are likely quite a bit higher.
If a power tool doesn’t draw the extra power extended capacity packs can provide, total runtime is further extended. Since battery cells in parallel share the total load, losses (such as those due to heating) could be reduced. Thus, greater efficiency could enable doublecapacity battery packs to deliver more than double the runtime.
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