Battery life

guerney

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One would chang lvc & hvc, typically for 80% DOD for a 36v set up would be 33.6v & 40.2 v. 90% DOD approx. 36v & 41v .
Would connecting four of these in series and stepping up to 42V, be a bad idea? Otherwise 25.74kg is a tad heavy...


 
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WheezyRider

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Would connecting four of these in series and stepping up to 36V, be a bad idea?


Not a great idea. Your 20A controller would need >800W, meaning the current needing to go into the booster would be >60A for a 12V battery. I think that booster is rated at 40A max. Better to have a 24V system.
 
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soundwave

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DSC_0297_03.JPG

i need more robots :p
 

Nealh

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One can't mix battery chemistries, those Eve prismatic cells have to be clamped/compressed together to prevent them expanding . They are more suited for a static solar use or a larger static positioned ev use.
For bike use just too heavy and at 105ah way too much capacity a 48v LFP would be 5000wh & 30kg in weight.

These might be good for a battery build 35a continuous.
PALO 3.2V 7200mAh 32700 LiFePO4 Rechargeable Battery 35A Continuous Discharge Maximum 55A High power battery+DIY Nickel sheets| | - AliExpress
 
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soundwave

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guerney

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guerney

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One can't mix battery chemistries, those Eve prismatic cells have to be clamped/compressed together to prevent them expanding . They are more suited for a static solar use or a larger static positioned ev use.
For bike use just too heavy and at 105ah way too much capacity a 48v LFP would be 5000wh & 30kg in weight.

These might be good for a battery build 35a continuous.
PALO 3.2V 7200mAh 32700 LiFePO4 Rechargeable Battery 35A Continuous Discharge Maximum 55A High power battery+DIY Nickel sheets| | - AliExpress
According to this reviewer, this 12 x only weighs 1.78kg + BMS. What effective AH could he expect from this LiFePO4 pack?

"There was doubt in one 3.9V battery. But after the charge and discharge (IMAX b6acv2) became normal 3.6-3.28 volts. Measured internal resistance, 7 mom Milli OM
accumulated a capacity of about 6900 mAh.

Not 3.9volt a 3.09 Volt slightly wrong."







 
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WheezyRider

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One can't mix battery chemistries, those Eve prismatic cells have to be clamped/compressed together to prevent them expanding . They are more suited for a static solar use or a larger static positioned ev use.
For bike use just too heavy and at 105ah way too much capacity a 48v LFP would be 5000wh & 30kg in weight.

These might be good for a battery build 35a continuous.
PALO 3.2V 7200mAh 32700 LiFePO4 Rechargeable Battery 35A Continuous Discharge Maximum 55A High power battery+DIY Nickel sheets| | - AliExpress
Have you got a reference where it says the Eve cells need to be clamped to stop them from expanding? I recently bought some of these to make a battery for solar use, so it would be good to know what needs to be done with them.
 

Nealh

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They are prismatic so basically a soft cell pack, the casing is only thin ali sheet. Poor grade or fakes will swell also as they warm the sides can expand ,bow a little . Keeping under light compression is recommended.
They are popular for diy solar use and camper van use , quite a lot of films on utube.

This geeky guy explains swelling
LFP Cell Compression || The What Why How & Very Important Considerations || Step-By Step Tutorial - YouTube

These guys I quite like and explain things quite well.
Very Detailed Beginners Guide To Building A Custom DIY LiFePO4 Battery - YouTube

Building a Custom 48v LiFePO4 Battery - YouTube
 
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flecc

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This is what I was referring to:

I've read that long before and it is suspect in two ways. Firstly there's disagreement in many quarters, particularly on the proportions of particulate sizes. Quantitatively it is even greater nonsense as I've pointed out.

Secondly it is being used as propaganda against electric cars which is even more silly. The smoothness of the transmission and braking witn e-drive and regenerative deceleration means less tyre wear. The article admits as much, saying that aggressive driving is worst. The wear is worst with changes in transmitted thrust, giving the e-car with no gear changes a big advantage, especially in comparison with modern automatics with as many as 8 gears changing up and down all the time.

And it's often coupled with the other sniping against e-cars, the even sillier claim that the brake pad particulates are as bad as with ic cars. Since most of their routine braking is done by motor regeneration that is obviously untrue.

Newspapers are always looking to stir up controversy and e-cars are a popular one with their readership who love their gas-guzzlers. Ignore it, e-cars, vans, buses and trucks are coming in ever faster now and they will make a big difference for our health and environment. They will cause there to be far fewer cars on the roads anyway, another very desirable benefit.

Newspapers on the other hand will only increase the increasingly prevalent mental illness as they cause ever more needless worrying over non-issues.
.
 

WheezyRider

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From what I've seen from reports from rental and taxi fleets, tyre wear rates with EVs and ICE cars are slightly worse to similar. Yes there is regenerative breaking with EVs, but under heavy breaking, not all the energy can be absorbed and so brakes are still needed and will generate particulates (hence a reduction, but not an elimination). It makes sense to look at these sources of pollution when tail pipe emissions of particulates from modern ICE vehicles is falling and EVs are being introduced.


This isn't to say that EVs are evil, the point is they are not a panacea for the solution of the environmental, economic and social costs associated with motor vehicles.

For me, I just can't get excited about EVs. When I was 12, I thought they were great and would solve everything, but then I grew up.

We have to reduce the number of motor vehicles on the road, whatever their power source.
 
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Bikes4two

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Wow. What the devil was that radar system? :oops:
It was the Marconi made radar type 909 used to guide the Seadart Missiles found in the Type 42 (Sheffield Class) destroyer. The radar beam could in good sea conditions track a one metre square test target to in excess of 70 miles - when I say 'track', that's knowing it's postion within +/- 10 metres iirc - the best I ever got was something like 80 miles on a good day.

The radar beam was a hazard to health and the directional aerial system had a dedicated mechanical system of cam operated switches to ensure the beam did not irradiate crew on the upper deck and it was not allowed to opearate in harbour or when steaming close to other vessels.

This was early 80's technology - no microprocessors even - mainly TTL logic and discrete components - I learnt a lot in my 2 years in that ship but of course it's old hat now.

Oops - sorry for thread/topic drift.......................
49746
 

Nealh

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According to this reviewer, this 12 x only weighs 1.78kg + BMS. What effective AH could he expect from this LiFePO4 pack?

"There was doubt in one 3.9V battery. But after the charge and discharge (IMAX b6acv2) became normal 3.6-3.28 volts. Measured internal resistance, 7 mom Milli OM
accumulated a capacity of about 6900 mAh.

Not 3.9volt a 3.09 Volt slightly wrong."





Another cell over rated and nowhere near the specs , 5500mah max it seems if one is lucky.
 
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guerney

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For me, I just can't get excited about EVs. When I was 12, I thought they were great and would solve everything, but then I grew up.
I hoped we'd all be floating about in vehicles levitated magnetically by now. In theory magnetic braking could tear out your eyes, no brake pads required (but eyeballs may need seatbelts).
 

guerney

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Another cell over rated and nowhere near the specs , 5500mah max it seems if one is lucky.
I do like the idea of these larger 32700 cells: more capacity in a smaller pack, and fewer cells overall lowers the odds of battery pack failure. In general, are packs made with cheap LifepO4 cells, less likely to fail than cheap lithium ion batteries?
 

georgehenry

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I made one of my quite regular journeys to go shopping in near by Guildford and noted where changes in the journey effected the rate of my battery consumption.

I do like to get some exercise from riding, and one of the great attributes of my Yamaha motored Haibike is that there appears to no drag when you cycle with no assist and it is pleasant to ride in that way. So the first mile was with no assist up a gentle gradient trying to hold 12mph and get the heart and blood pumping.

Some low assist was then required to allow me to recover while I continued up a slightly steeper gradient country road to get me to the entrance to my first track. Downhill so no assist required and quite a steep challenging track at the top with a section that has to be done right or tragedy could follow, but immense fun. This gets me down into the valley and eventually on the towpath of The River Wey. Once on the River no assist is the order of the day. So 4.4 miles of my journey was mostly off road using very little assist and therefore battery. 3% battery used.

Riding away from the towpath involves a steep little section of tarmac track then tiny lane using bottom gear and low assist. Then onto a busy road to mix it with the impatient traffic where I have found going a reasonable speed (20mph +or-) combined with a bright flashing rear light and assertive but not overly aggressive riding away from the curb is your friend. With some stopping and starting at traffic lights. This style of riding took me to my chosen store and back to Guildford Railway Station. So this 3 mile section riding quicker used 12% of my battery.

I got the train from Guildford back to Godalming. Then no assist on the half of a mile to another shop.

Then a blast up a steep hill back to my house using middle assist on the hill that used 11% of my battery in 1.2 miles.

So the rate of consumption and predicted range for each of my riding styles on this ride if used to consume a full battery would give very different results.

I rode 9.1 miles in total ridden using 26% of my full battery. So my varied riding styles would give me a 35 mile range on my old 400Wh battery

However if I had continued consuming my battery as I did on the first 4.4 mile section my battery would have had a total improbable potential range 146 miles.

The second 3 mile section where I was riding faster mixing it with the traffic on the road would have meant my battery would have a total range ridden in the same way of 25 miles.

The blast up the hill home style using middle assist would have used my full battery in 10.9 miles.
 
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flecc

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We have to reduce the number of motor vehicles on the road, whatever their power source.
Fully agreed, but what is so good about e-cars now is that they will be doing just that. It is clearly the policy of governments and the motor industry now they have woken up. Just look at the facts:

We are not going to get cheap normal e-cars, despite all the previous promises. In fact quite the opposite is happening, they are getting far more expensive and far beyond most wallets.

Why? Here's the answers.

The car industry is fed up with loss making small cars. You probably know that every original Mini ever made was at a loss and the same has long been true of all small cars. The industry has only ever made its profits from the premium up market models. That is why GM withdrew from Europe and why they virtually gave away Vauxhall and Opel brands to PSA (Peugeot-Citroen). Following that Ford announced they were also considering pulling out of Europe.

So now they've all come to their senses they are not repeating the mistake with e-cars so have sharply increased their prices and are eliminating cheaper models. They won't lose anything by doing that, they'll just be working less hard for the same or more profitability. When I bought my Leaf in 2018 the cheapest option was £22,000. They discontinued that and are now ending all Leaf models next year. The replacement is the Ariya model which for a reasonable spec starts around £37,000 with the premium model at £47,000. There's very few e-cars under £35k now and they are disappearing fast.

The mass of the public who have been buying new IC cars for from £8k to well under £20k just won't be able to afford those very high e-car prices, especially as the western world is getting poorer due to climate change measures and political trends.

And governments are willingly assisting by removing the e-car subsidies. No more £5000 grant to buy an e-car. No more £500 grant to buy a home charging point. No more free VED (road tax) from 2025. And the killer now is that electricity is just as dear as ic fuel for running a car.

As unfair and socially undesirable as it might seem, e-cars will be mainly for the minority privileged, so as ic car sales are banned and older ones wear out or suffer enforced scrappage, there will be far fewer cars left on the roads. I'd forecast at least a halving eventually.

In this country cycling won't be the big winner though, it will be public transport as London has already shown.
.
 
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