battery deterioration

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,850
2,763
Winchester
Our Bosch 400wh battery is showing signs deterioration. Maybe not unreasonable after 8 years (we got the bike 2nd hand about 2 years old about 6 years ago), around 6000 miles.
Hard to tell, I'd say it was down to somewhere around 60%.

Once deterioration starts to be significant is there likely to be a point of sudden collapse, or is the curve much smoother?
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
7,004
3,240
Telford
In my experience, it doesn't collapse, but it starts accelerating downwards. I notice the saggyness more than the capacity, but Bosch might be a bit different because the motor works at 24v from the 36v battery.
 
  • Informative
Reactions: sjpt

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,850
2,763
Winchester
Thanks. I did have one indication of sagginess the other day. It was still claiming 5 miles range and cut out; Sport (3/4) on a significant but not that steep hill. I'm keeping an eye on it, and also keep checking for not quite as silly as normal prices on a replacement. Winstanley at £440 for a 400wh look my best bet at the moment.
 

guerney

Esteemed Pedelecer
Sep 7, 2021
11,531
3,277
Winstanley at £440 for a 400wh look my best bet at the moment.
Is this it? £279.99 plus £7.50 delivery, allegedly brand new, no charger:

 

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,850
2,763
Winchester

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,850
2,763
Winchester
Just got an email from Merlin to say the Bosch 500wh rack battery is back in stock at £349.
I'd forgotten I'd asked to be informed.
That seems a very reasonable price, and they do well on trustpilot, so I've ordered it.
I'll be happy if it keeps the Motus on the road for another 8 years; and if I'm on the road to ride it.

The Winstanley 400wh one at £439 was due in yesterday, but is now showing overdue. I'm glad I didn't go for it.
 

egroover

Esteemed Pedelecer
Aug 12, 2016
1,050
635
57
UK
Just got an email from Merlin to say the Bosch 500wh rack battery is back in stock at £349.
I'd forgotten I'd asked to be informed.
That seems a very reasonable price, and they do well on trustpilot, so I've ordered it.
I'll be happy if it keeps the Motus on the road for another 8 years; and if I'm on the road to ride it.

The Winstanley 400wh one at £439 was due in yesterday, but is now showing overdue. I'm glad I didn't go for it.
Result, great price !
 
  • Like
Reactions: sjpt

soundwave

Esteemed Pedelecer
May 23, 2015
16,994
6,536
when my original batt 400w gave out a few years ago it got down to say 50% and from there it fell off a cliff
 
  • Informative
Reactions: sjpt

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,850
2,763
Winchester
when my original batt 400w gave out a few years ago it got down to say 50% and from there it fell off a cliff
Yes, my combined concern that they were coming more difficult to find at all, plus the possibility of sudden decline, and the good Merlin price, made my final decision easy.

I thought for some reason you were still on your original battery, which seemed miraculous considering how long you've had the bike and how you ride it.
 

soundwave

Esteemed Pedelecer
May 23, 2015
16,994
6,536
i got 2 more batts but i can confirm that the new smart batts do not work on the older motors even if you change the connector ;)

i gave my old batt to peter and he gave it to the guy that now can recell the bloody things so my old 400w batt might still be out there just with new cells :p
 
Last edited: