How much battery sag is too much for a 3 year old battery?

[Ghost1951]

Throttle doesn't deliver any hill climbing at all when set to "Speed" control (that parameter as set in your post#115). Climbed all hills, albeit slowly on "Current" control. I'll switch it back, then probably disconnect the throttle - not needed because PAS is fast activating and powerful enough for most situations.

Yes - there are several out of date settings charts that are still posted. I tried current mode. It never pulled more than about 200 watts even though current in PAS 0 was set to 15 amps. I think the bike always got to 6kph before the slow start ended, so it lacked the strong and useful 'spurt' I used to get with the full power, unlimited speed throttle that came with original settings.

All moot now, though since I have taken the throttle off the bike and taped up the socket. I don't need it and it would save any discussions with confused enforcement person.

You certainly did solve the limit to 6KPH thing though.

 

[guerney]

You certainly did solve the limit to 6KPH thing though.

Partly - the KT style legal throttle doesn't appear to be possible for the BBS01B. The moment I'm certain some flavour of open source firmware replacement is compatible, I'll consider overwriting. I've got a spare controller, but won't take daft risks. Controllers aren't usually free.

 

[Ghost1951]

On the question of how much life there is in this over three year old battery of mine.

I'd say now that I was quite wrong to suspect it was on its way out. That said, I don't think it would qualify as a high drain type, but run lightly, it seems to have a pretty good range.

After 31 miles today and yesterday, riding it at a low PAS level, which means it is generally working at about 130 watts to the motor, the resting voltage is 36.5v when I stop the bike. This probably means that it is a bit more than half empty, so the range is probably over 50 miles. I don't think it was any better than that when I first got it. Back then I did run it forty five miles until voltage drop on slopes cut the power and I had to ride it under leg power alone. It is always problematic to compare two rides on different terrain and maybe different amounts of rider effort, but the battery seems not to have suffered much in its lifetime so far so I won't be sourcing another one this year, or maybe next.

 

[Biker44]

My bafang BBS01 has spent more time in the garage than on the road over the last three years. It has done about 2000 miles and has been kept charged when not in use. After 24 miles of riding around the hilly locale, the resting voltage of the 10s 6p Sanyo battery was 35 volts. Using 250 watts up a slope the battery sagged to 34 volts. Drawing 500 watts it sagged to 32 volts.Given a short break either by me doing the work or switching it off for a minute the voltage returned to 35 volts off load, 34 volts on a 250 watt load and 32 volts when pulling 500 watts. Obviously, it isn't new, so it is expected that some performance penalty arises.

My experience (three e-cycles) has been that 3 years is about the limit. This covers both the aluminium Extrusion type (2010/2012 vintage) and a Gazelle Bosch PowerBank (failed in 2.5 years, though a question mark over whether it was truly 2017 vintage).
When they go, its quite quickly (the Bosch battery very suddenly, presumably in the BMS)
There doesn't seem there is much you can do to improve this.

 

[Nealh]

My pair of 14.5ah Dolphins ex Woosh celled 29E's are now in their 10th year , both still capable and used for power on my centrifuge honey extractor . I use them lightly now and only draw 4.2a max but they will see me at least another three or four years.

 

[Ghost1951]

My pair of 14.5ah Dolphins ex Woosh celled 29E's are now in their 10th year , both still capable and used for power on my centrifuge honey extractor . I use them lightly now and only draw 4.2a max but they will see me at least another three or four years.

I think the best information on battery life, favours taking care of them properly. You have obviously done that with a battery that lasted ten years at good capacity.

The big killers of batteries are their owners, and their big sins are:

• Leaving fully discharged batteries in the shed and not charging them for months.
• Keeping fully charged batteries right up to the limit (4.2 volts per cell group) and not using them.
• Using fast chargers which can heat the batteries way beyond their normal limits.
• Pulling excessive current from batteries not specified for that level of output.

There are probably more than that, but those are not uncommon forms of battery abuse.

I was reading around this subject this afternoon and advice seems to suggest that if you want a battery to last a really long time, don't take it to a high state of charge all the time. Obviously that has no downside on say a single cell setup like your phone, but in a series charged battery of multiple cell packs like an e-bike battery, the simple BMS systems we have, need to get to a full charge so they can balance the cell groups up. So this point about not fully charging them, to get a longer cycle life, is not perfect.

EV cars are, so I understand, set up not to go to the maximum charge ever, but they have far more sophisticated charging and balancing arrangements, so they don't get out of balance because they are not charged the same way as a cheap e-bike battery.

 

[Nealh]

Fully charging to 4.2v per cell isn't an issue , it is the leaving them at that level for prolonged periods without use.
All my batteries are fully balance charged a few hours before use.