Why a min of a 4.0AH battery for the snow blower?

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Why do you recommend a 4.0AH battery for one of the batteries in the snow blower? AH means length of run time. Not power output. I have two 2.5AH batteries and not a big area to snowblow. Wouldn't that be fine? The output power should be the same with a 2.0AH battery vs a 7.5AH battery. The blower just shouldn't run as long. Right?
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David Groner

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Posted 11 months ago

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Donjacke

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Im the owner of a leaf blower with a 2.5 battery and a lawn mower and snow blower, both with 7.5 batteries..The products with the larger batteries have prongs that are set apart differently than the leaf blower. The snow blower battery release also is different. That account for the difference in recommended battery size.
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Oregon Mike, Champion

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Donjacke, the battery to tool interface on all batteries and tools is the same. No differences in size or spacing where the battery connects to the tool including the prongs (terminal) area. Also, the battery latch area on the batteries is the same on all batteries too. Perhaps how the latch mechanism operates on the tool is different, but the battery's latching area is the same on all batteries. As BA says, it just comes down to ah for the snowblower. More is better for it.
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Donjacke

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Thanks your reply. Always good to get more product info, especially where battery compatibility is concerned. My 2.5 battery seemed like it wouldn't align properly with my lawn mower or snow blower. Good to know that the only issue would be power, not alignment.
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Blue Angel, Champion

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Official Response
Any size battery will work in any tool. The primary difference with battery size is run time.

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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TK

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Go get a tank of 85% ethanol. Drive until you are near empty. Write down the miles driven. Go get a tank of straight gas. Write down the miles driven. Quite a difference... Energy density..
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Jacob, Champion

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It causes too much stress on the smaller batteries. Also a larger voltage drop
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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Joe C

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This reply was created from a merged topic originally titled batteries.

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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Jacob, Champion

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For the extra 100 for two 5ah batteries, I would say get the kit. The price of the bare tool is rediculous. It's roughly the same price to buy a blower with two 5ah batteries as it is to just buy the batteries. Trust me here, buy the kit.
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David Groner

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I'm still not understanding this. If I had one 5AH battery at 56V in the blower vs. if I had two 2.5AH batteries at 56V. Isn't the draw of power exactly the same? Wouldn't the blower be drawing the same amount of current say 5 minutes into snow blowing in either scenario?   Lets put it this way, if this snow blower could take 4 2.5AH batteries plugged into it, or one 10AH battery....and the voltage in both scenarios is 56V....wouldn't they last the same length of time?  
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Oregon Mike, Champion

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I keep wondering the same thing since the manual sort of implies all of the current is available so maybe it shouldn't matter if there is a large difference between the batteries, but without really understanding the theory of operation of the dual battery system in the snowblower it is a bit hard to understand why Ego doesn't recommend any battery combination. Jacob tried to explain, and I understand what he's saying, but not how that determines why the batteries shouldn't be so mismatched current-wise. Seems it comes down to how the battery cells are assembled and how they can deliver their current based on how they are assembled, but it would also be nice to know how the snowblower uses that current.
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David Groner

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Well it'd just be interesting to know. I usually get about 3-5 inches of lighter, dry snow at a time. So reading about people using the blower with two 5AH batteries on 6" of wet snow for over an hour and 25% power remaining appears it would be overkill for my needs. I'm rarely out there 20 minutes on a corded electric 110V 13.5A 18" blower. I'm just tired of the cord. But the only other power tool I have or need is EGO's weed whacker which uses the 2.5AH battery..and I have two of those. And the second battery was overkill for my needs. 
(Edited)
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Jacob, Champion

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Amp hours is power over time which can be calculated to kwh with voltage, then to horsepower
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
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Blue Angel, Champion

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2Ah and 2.5Ah = 14 cells (1P)
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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David Groner

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I bought my Snowblower without the batteries, and threw in my existing charged two 2.5AH batteries today. A pretty good test because it was existing, packed, iced snow in a long driveway/sidewalk. It did just fine which was surprising because this snow basically compacted and became icy after several days of sitting. So I should be fine with a fresh amount of 4-5" of dry snow (what we normally get up here in the mtns per snowfall). Thanks for the answer guys. I'll update if it changes this winter. 
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Jacob, Champion

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So you saved 100.00 and didn't get 450.00 worth of batteries. Should have gotten it with batteries and sold them on eBay for 150 each. And then 50 for the charger.
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szwoopp, Champion

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Should have gotten it with the batteries and enjoyed the POWER!
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David Groner

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I think it has great power as is. I got the blower w no batteries on Ebay, no tax, for $479. If I bought it at home depot w 2 batteries, it would have been $650 w tax. so I actually saved $170. If I ever need a 5.0AH battery, it currently costs around $110 on Ebay. The way I look at it I "wasted" the opportunity to make $50 on Ebay after shipping costs and Ebay's cut. (I give no value to the charger because chargers are a dime a dozen on there). 
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Jacob, Champion

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But you got it without a warranty.
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David Groner

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Well finally a good test. Today we got 8" of mtn snow. Mostly dry powder. Used the two 2.5AH batteries and it completed 150' of pickup truck/car width with an additional 30' of 4ft width of walkway before it died. I have two standard chargers, and the two batteries. So, I'll be able to complete a final 1/3 of my driveway in about 50 minutes when both batteries are recharged. I don't see the downside of this setup yet! And yes, it had plenty of power or "umph" to blow the snow while at a normal walking pace.
(Edited)
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Blue Angel, Champion

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Awesome, glad to hear it’s working well!
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Paul Christenson

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Power tool battery packs are not so simple where 4.0Ah = 2.0Ah times two. Yes, a 4.0Ah battery pack has twice as many battery cells as a 2.0Ah pack, but the circuitry and controls are usually different.

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. Li-ion 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 same-voltage packs. Ignoring real-world 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 shut-off 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 double-capacity battery packs to deliver more than double the runtime.


(Edited)

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