4Ah vs 5Ah batteries

[knighty]

2x4ah would just be an 8ah wouldn't it?
Ie, the 2x 5ah will still give you a longer total run time

yes., but.....

the batteries have C rate (I think it was mentioned earlier)

*normally* they measure the Ah capacity while draining it at 10% of capacity, so drain a 4ah battery at 0.4amps and a 5ah at 0.5amps.... see how long it lasts and that's your Ah capacity

but... if you drain it slower it lasts longer and if you drain it faster it doesen't last as long.... because of the efficiency in the battery chemistry turning "chemicals into electric" (short version)

there's also a bit of recovery time, where it takes time to convert "chemicals to electric" - if you pull power out faster than it the battery can keep up the battery will run out of power quickly... but then recover a bit later on when you're not using it

it's a bit like starting an old car on a cold morning, you crank and crank, you can feel it slowing down and the battery start to die... so you stop for a moment and give it a rest.... suddenly it's cranking fast again! (as the battery recovers a bit)


if you're draining them fast/hard you'll lose a lot of potential capacity

if you drain them slow (say half as fast because there's two of them) they last a lot longer

 

[Turbo]

I would suggest to MaffF that he is using his mower beyond its capabilities. It is designed to cut short grass regularly, not cutting strong grass.

At the rate you are draining the batteries you will very shortly wear the batteries out, resulting in a very expensive bill to replace them! Makita LXT drill batteries are designed to be charged only a certain amount of times before the built in electronics deem they are worn out & prevent you charging it any more. This life will be shortened by using regularly it in high drain situations like yours!

I would suggest you need to use a petrol mower until your grass is easier to control. For around £150 you can buy a basic petrol mower to do your job, about the same as the cost of 2 5Ah LXT batteries plus you can sell the mower on & get some of your money back!

As to the original question 4 vs 5Ah batteries. In theory they should last 25% longer, the cells inside are 25% larger capacity but due to losses in the system you are unlikely to get 25% more out.
Where a 5Ah gains is in producing better torque in items like grinders, nut guns, etc. I have noticed on my LXT nut gun that by swapping from a 4 to a 5Ah battery I can sometimes remove a bolt that the 4Ah wouldn't shift. Likewise the LXT grinder is gutless on a 3Ah battery but great on a 4 or 5Ah. This extra oomph is usually maintained until the battery is nearly drained.
On your mower the 5Ah would give the cells an easier life but not a lot of extra run time, certainly not 25%.

 

[MattF]

I would suggest to MaffF that he is using his mower beyond its capabilities. It is designed to cut short grass regularly, not cutting strong grass.

You would be incorrect. I chose a mower which is quite capable of any task I need it for.

The fact I may need higher amperage batteries, & that my current batteries are already a few year old, have done a lot of work, & may nowadays not be in peak condition, is a different matter entirely.

 

[J1nx]

You would be incorrect. I chose a mower which is quite capable of any task I need it for.

The fact I may need higher amperage batteries, & that my current batteries are already a few year old, have done a lot of work, & may nowadays not be in peak condition, is a different matter entirely.

I have the same mower but I tend to put my 6Ah batteries in, i think they give a noticeable improvement but even a pair of fives will do the front lawn (500ish m2) no problem without switching over to the second bank. Nowadays I only use the Makita if it’s long/wet and the robot can’t cope so it’s not as if it’s only the easy maintenance cuts….

I even tow the wheel barrow back to the compost heap with it after.

 

[MattF]

They're quite a good mower, aren't they. Is that the area you cut with yours? That's an impressive size area.

 

[J1nx]

They're quite a good mower, aren't they. Is that the area you cut with yours? That's an impressive size area.

You can probably see about 400m2 there, I use it on two smaller lawns and the driveway verge, probably double the photo. The back garden is much bigger, that gets the John Deere.
Its a decent mower, I had the Bosch one previously but it’s like a child’s toy in comparion..

 

[MattF]

You'd say a pair of 6Ah batteries are a worthwhile investment for it then?

 

[J1nx]

Yes, I definitely notice the difference. The premium for 6Ah has all but disappeared now in £/Ah. I wait for the deals but I think it was about £280 (70each) for 4 from fastfix, might of been by their eBay store with one of those eBay offers thinking about it.
Claw a small amount back by charging all my batteries with the 12v chargers from my sheds solar panels. Not a big saving on electric but filling the John Deere and 4 cans to keep me going was £40 of petrol this weekend.

 

[MattF]

Looking at current prices, around £176 for 2 seems about the cheapest price. Sounds like they may be worth that though, for the faffing they'll save.

I have been thinking at least one of my current 4Ah batteries may be on its last legs. Seems to drain more quickly than the others.

 

[Prajna]

One advantage with more Ah is fewer cycles. All battery systems have a limited cycle life, so with a bigger battery you need to recharge it less often and it should result in a longer lifetime than a smaller battery charged more frequently.

 

[MattF]

A pair of 6Ah have arrived today, so I'll be testing those out Saturday. Sod's law the grass has barely grown this week.

 

[hotponyshoes]

One advantage with more Ah is fewer cycles. All battery systems have a limited cycle life, so with a bigger battery you need to recharge it less often and it should result in a longer lifetime than a smaller battery charged more frequently.

This might well make sense,
But the bigger battries can be a lot more expensive in the first place.
It might be worth buying a bigger battery for a low power tool just for this reason though.
Personally, it's not something I can justify due to the price of them.
For the day job I use 3 or 4ah for the cordless drills, they last maybe 2 or 3 weeks each between charges.
I use 8ah's for the angle grinder and they all get charged daily (so 5 or 6 times a week)
The warranty on them is 3yrs or 1000 charged cycles so I pretty much write them off over the 3yrs.
I might get away with using 2x 12ah rather than 3x8ah but they would still need charging daily so probably won't last any longer and, at the moment, the 12's are bigger/heavier than the 8's and 2 of them cost more than 3x8's anyway.

 

[hotponyshoes]

Just had a quick look on the bosch website at the procore's.

Currently, the 8.0ah is the cheapest £/ah.

Ie, it's cheaper to buy 1x 8ah than 2x4ah
Which you would expect as there is only one case/control board/etc

However, it's also cheaper to buy 3x8ah than it is to buy 2x12ah.

OK, you will have to swap & charge batteries 1/3 more often so (unless like me you will be charging them once a day anyway) it muggy make sense to pay a bit extra for the 12ah and reduce the number of charge cycles and extend the life of it, but, if I dropped one or left it out in the rain or one drops dead out of warranty then I would rather it was one of 3 cheaper ones instead of 1 of 2 expensive ones

 

[MattF]

Most of the time it's either convenience else cost related, with batteries. With the Bosch batteries, I've mainly gone with 5Ah ones simply for cost reasons. I've got one 2Ah for weight reasons. Not got any procore as I can't justify that cost when they're not actually earning money, or necessity. Compromise usualky kicks in somewhere, with batteries.

I've stumped up for these 2 Makitas for convenience. The 4Ah's do appear somewhat tired & at their limit for the task. They'll still do fine for the hand tools though.

Just need to keep smelling salts to hand until the "feeling faint at the cost" episodes subside.

 

[hotponyshoes]

Most of the time it's either convenience else cost related, with batteries. With the Bosch batteries, I've mainly gone with 5Ah ones simply for cost reasons. I've got one 2Ah for weight reasons. Not got any procore as I can't justify that cost when they're not actually earning money, or necessity. Compromise usualky kicks in somewhere, with batteries.

I've stumped up for these 2 Makitas for convenience. The 4Ah's do appear somewhat tired & at their limit for the task. They'll still do fine for the hand tools though.

Just need to keep smelling salts to hand until the "feeling faint at the cost" episodes subside.

The procore only really show their worth in the higher power stuff like angle grinders/saws/heat guns/etc
If you need something equivalent to mains power then they are great but expensive otherwise.

Although, the 4ah procore is probably less than 2/3 of the size/weight of a regular 5ah so I do like using them in the drills even though they offer no proformance increase

 

[eLuSiVeMiTe]

Most of the time it's either convenience else cost related, with batteries. With the Bosch batteries, I've mainly gone with 5Ah ones simply for cost reasons. I've got one 2Ah for weight reasons. Not got any procore as I can't justify that cost when they're not actually earning money, or necessity. Compromise usualky kicks in somewhere, with batteries.

I've stumped up for these 2 Makitas for convenience. The 4Ah's do appear somewhat tired & at their limit for the task. They'll still do fine for the hand tools though.

Just need to keep smelling salts to hand until the "feeling faint at the cost" episodes subside.

Could be worse

Flexvolt 6ah and 9ah

 

[Turbo]

The warranty on them is 3yrs or 1000 charged cycles so I pretty much write them off over the 3yrs.

Most manufacturers don't give a warranty on their batteries, so good luck getting them to honour this!

 

[PhillipM]

A lot of those small tool batteries have a lot in the controller these days and they even talk to the tool to negotiate voltage and max currents on a few of the more recent ones - I bet they've had a simple charge/discharge counter in there for years.

 

[cr500dom]

Just had this through the door, 2x5ah batteries, move on the rest with your older 4ah

 

[Turbo]

View attachment 346732
Just had this through the door, 2x5ah batteries, move on the rest with your older 4ah

Remember to add vat!

Comes to £139.99 which is still a great deal - basically you're buying the batteries & getting the drill & charger free!

I got this deal a few months ago & the drill gave up in a puff of smoke upon its second use! Took it back to Screwfix, they sent it for 'repair' & got it back 2 weeks later. I've been using it regularly since & so far so good!