Realative AH

[electric.mike]

Ime sure in my recent reading of the forum some one said a modern battery for a given AH has more juice than an old SLA but i cant find it now.
Are they equivalent if not is it possible to say how much difference there is.

Thanks

 

[trex]

you want to google up Peukert effect. Essentially, SLA is more affected by Peukert effect than Li -ion. So you get more miles out of Li-ion for the same capacity in AH if the average draw is more than 4A-5A, below that, the difference is not significant.

 

[flecc]

As laid down by Peukert's Law, the ability of a battery to deliver all it's charge content depends on the discharge rate, the higher the discharge, the lower the amount that can be used. SLA batteries suffer quite severely from this, so in a high discharge application like an e-bike motor, as little as under 60% of the nominal Ah can be used to drive the bike. Lithium batteries are not so severely affected but can still suffer.

Some while ago A to B magazine tested an e-bike with a lithium 36 volt 10 Ah nominal battery at different rates. Used gently they were able to draw the whole 10 Ah, but at the other extreme of full throttle all the time, they were only able to draw a little over 7 Ah. That was an early lithium battery however, todays are rather better.

N.B. Crossed with Trex's post while typing.
.

 

[electric.mike]

So if i read this right the modern battery has the ability in most circumstances to give you more of its stored power when fitted to an Ebike than an SLA could.
So next could i expect a 36 volt 10AH modern battery on 24 kg bike to match the range of a 36volt 15AH SLA on my 38kg Powabyke.

I know these questions are akin to how long is a piece of string so only looking for an approximation answer.

Thanks

 

[Deleted member 4366]

It should beat it easily.

 

[electric.mike]

Thanks folks for the answers,just giving some thought to things before i spend any money

 

[Alan Quay]

Rule of thumb (in electric bike applications) is that SLA is about 50% of the quoted Ah rating, which is normally the 20h rate.

So your 15Ah SLA pack will be closer to 7.5Ah equivalent to a modern Li-ion pack. It might even be as low as 6Ah.

Hope that helps.

 

[electric.mike]

Rule of thumb (in electric bike applications) is that SLA is about 50% of the quoted Ah rating, which is normally the 20h rate.

So your 15Ah SLA pack will be closer to 7.5Ah equivalent to a modern Li-ion pack. It might even be as low as 6Ah.

Hope that helps.

Thanks,the one ime thinking about is the 36v 10AH so i would be well in then.

 

[Deleted member 4366]

You have to have a battery that can supply enough current too. The bikes with SLA batteries often have powerful motors which take 20 amps or more, which is too much for a standard lithium-ion battery. Perhaps if you tell us a bit more about your bike, we can advise you.

 

[D8ve]

The other factor is discharge ratios. A sealed lead battery will have a very short lifespan if it is run down to 20 percent charged. The plates get distorted and other things happen.
A modern lithium can provide 99 percent and show no negative affects not even memory effect.
It's complex and has lots of chemistry and maths involved but lithium is great as well as lightweight too.

 

[electric.mike]

You have to have a battery that can supply enough current too. The bikes with SLA batteries often have powerful motors which take 20 amps or more, which is too much for a standard lithium-ion battery. Perhaps if you tell us a bit more about your bike, we can advise you.

Think my careless rambling may have mislead you,my intention is to re battery the the old powabyke euro with SLA,then run it for a while,first to see if i enjoy it as much as i used to second to see if that combination gives me the range i want.
The question about equivalent modern battery's and bike weights was to see what replacement Ebike would be a sensible ,my hobby fund has been seriously depleted in the last 18 months buying new photography gear and when your retired it doesn't get replaced as quickly.
With my envisaged use and avoiding towing a trailer i have the Woosh Sirocco in mind as a replacement.
Thanks
Mike

 

[jimmyhackers]

if you buy a 10ah lipo or li ion to replace a 10ah sla. youll see a range and performance increase. more so in torque/accleration and less so top speed.

the bike will weigh less which adds to performance in handling/brake efficiency.

sadly the price is nearly 3 to 4 times as much.

however, the battery (if properly mantained) should outlast sla batteries 3 to 4 times so in the long run you save money.

i use sla becuase i have them (for silly cheap charity shop price) and they work so far wonderfully. new they would of cost 120 quid, an equivilant ah lipo is 3-400 quid plus. i dont have that money (am saving for one). but if i did i would get one.