Understanding the battery - for beginners

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Nagaman
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Understanding the battery - for beginners

Post by Nagaman »

The UK MG ZS EV and MG5 owners group podcast.....explained that there are 108 cells with a maximum charge of 4.2V and the maximum total voltage is 450 for a fully balanced charge state ..ie 108 X 4.2 (4.166666) which equates to being fully balanced - (450V).
As I understand it. ......(there are experts here who can correct me).....if a column of cells fall significantly then all the other ones are reduced to that same level.......?
Is it that that particular level is determined by the location of one cell, an accumulated reduction or a combination or am I completely wrong yet again ?
antiscab
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Re: Understanding the battery - for beginners

Post by antiscab »

Nagaman wrote: Tue, 16 Feb 2021, 07:37 The UK MG ZS EV and MG5 owners group podcast.....explained that there are 108 cells with a maximum charge of 4.2V and the maximum total voltage is 450 for a fully balanced charge state ..ie 108 X 4.2 (4.166666) which equates to being fully balanced - (450V).
As I understand it. ......(there are experts here who can correct me).....if a column of cells fall significantly then all the other ones are reduced to that same level.......?
Is it that that particular level is determined by the location of one cell, an accumulated reduction or a combination or am I completely wrong yet again ?
Balancing generally takes charge out of the fuller cells to bring their voltage down to the lowest cell
If there is a wide variation, likely an error code will come up, as cells don't just fall significantly compared to the rest unless something is wrong
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells
Nagaman
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Re: Understanding the battery - for beginners

Post by Nagaman »

antiscab wrote: Tue, 16 Feb 2021, 09:20 Balancing generally takes charge out of the fuller cells to bring their voltage down to the lowest cell
If there is a wide variation, likely an error code will come up, as cells don't just fall significantly compared to the rest unless something is wrong
Is the battery button (beside KERS) of some practical use, because I heard someone suggesting that it was a useless device...?
Last edited by rhills on Tue, 16 Feb 2021, 23:02, edited 1 time in total.
Reason: Edited to fix quote tag
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KlinkPC
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Re: Understanding the battery - for beginners

Post by KlinkPC »

From the manual:
The driver can toggle the BATTERY switch in the centre
console forwards or backwards to display the remaining
distance available on the current battery charge. The data
will be displayed for a few seconds in the message centre
in the instrument pack and then extinguish.
FyKnight
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Re: Understanding the battery - for beginners

Post by FyKnight »

However it always displays the remaining distance (guess) in the bottom left of the dashboard display anyway. So yes the battery toggle is pretty useless. When held down it just shows the same information in bigger numbers.

It'd be great if it would display the percentage charged somewhere, however that is only displayed while it is actually charging — when distance is not! I try to divide the remaining distance by 263 in my head... not very easy (oh yes, there is an 8-blip charge state indicator beneath the instantaneous power gauge, but that is pretty rough and hard to convert into a percentage too)

While we are on battery indicator gripes (I believe it's a called guess-o-meter, right?): As soon as you turn on the fan, even with no aircon and on the lowest fan speed, it reduces the remaining distance (guess) by quite a lot. Something like 263 to 220 km. If you then turn the aircon on and the fan to full speed, it doesn't reduce any further. You can get a better idea of how much power these auxiliary systems are drawing with the electrical stats display (go three screens down using the button on the steering wheel). It shows the current drawn from the battery. With the car stopped and just the fan on it's 0 or 1 amp, with the aircon it's 2 or 3 amps.

Edit: actually I checked and distance *is* displayed while charging, whoops.
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