charging to 100%

[GaryMG4]

I tried a scheduled charge today in response to another members thread, it stopped at the allotted time as it should. As it was at 78% I decided to restart the charge as as the PV was still dumping 3+kwh into the grid and thought it might as well go into the car. It stopped at the 80% I was surprised a hour later to see the green lights on and although it was still at 80% and charging at 0.1kw on the app. So I guess it was balancing at that point. I presume its the same as my r/c lipos where the soc is derived from the pack voltage (12.6=100% 11.6=40%), they charge at the set rate until close to 100% then it drops very low whilst balancing. The LiFe (LFP equivalent) operate at different voltage ranges, don't self discharge much, can remain fully charged for a long time without degradation, but cannot with deliver or receive as much current as LiPo.

 

[PeteC]

An earlier post showed a balance charge at 80% SOC for my Trophy holding 7kW for the charge and then dropping straight down. @Rolfe asked if that was normal and I said that I guessed so but it seems I was wrong as I've since done a balance charge at 100% SOC and had the following outcome. It held 7.4kW all the way to first showing 100% SOC in the app and then after a short while dropped to around 5kW for a bit before dropping right down.

I have no idea why it is a different outcome at the two percentages or if this will be what it always does! I only know this is what happened as I'm away from home and the Connected Kerb charger I'm using supplies these charging graphs.

 

[Tig170]

... but what is this telling us?, should we be charing to 100% or not?

 

[Rolfe]

Thanks PeteC, that's interesting. I don't see my SR doing that, but having said that, I've never really watched it on a type 2 charger, only on the granny charger when it sits at about 1.86 Kw then drops straight to 20 watts.

I think we should do what MG tell us to do with our respective batteries. That is charge the SR right up whenever we like, but for the LR treat 80% as "full" unless we're going to need the whole range the next day - plus (if there aren't enough long trips for it to happen anyway) take it up to 100% once a month and drive it down to 80% or less the next day.

Maybe there are other ways to squeeze an extra two days of life out of a battery, or to make it last yet another year after the car has already fallen to bits round it, but these recommendations have been formulated by people thinking about the balance between looking after the battery and the convenience of the driver. It is possible to overthink this.

 

[PeteC]

Agreed. When I had the i3 I charged it to 100% all the time as it had such a small battery and short range. It was 8 years old when I sold it and it still had more than 85% of it's original range, so I'm not worrying too much about what happens.

I've charged the MG up to 100% this time as I'm driving back to England tomorrow, so I took the opportunity to do a balance charge.

 

[tsedge]

... but what is this telling us?, should we be charing to 100% or not?

Why wouldn't you follow MG's guidelines anyway?