Which is the lesser of two evils?

[Fordulike]

It's time to replace my aging battery, powering my BBS02. This one is at the top of my short list, with the LG HG2 cells:

https://em3ev.com/shop/em3ev-48v-13s5p-jumbo-shark-ebike-battery/?currency=GBP

Now I have read up on the benefits of charging to 90% to be kinder to the cells, and EMV3ev offers a charger that does exactly this.
Unfortunately, it is a 5A charger, and we all know that faster charging kills cells quicker. But on the other hand, charging cells to 100% isn't good either!

So the question is, should I buy the regular 2A charger that charges to 100%, or the 5A charger that can charge to 90%?

 

[vfr400]

You can only charge to 90% if you have a special BMS that doesn't use top-balancing. Be careful!

 

[Fordulike]

You can only charge to 90% if you have a special BMS that doesn't use top-balancing. Be careful!

It appears to use a smart BMS, this is the blurb on their website:

"We use a high tech, fully programmable Smart BMS, which is rated for genuine 40A continuous plus, with a programmable over-current trip set to >60A (which is ample for the intended application). With our BMS you can view various battery data, such as: cell voltage levels, temperature, instantaneous charge/discharge current, capacity (genuine SOC, measured Ah and remaining Ah), data log, error indication (on matching LED panel) and it all links to your phone with a continually updated and improved App. Our BMS balances during charging (when charging and when at >50% charge) and therefore doesn’t require a full charge in order to balance. Auto power off function, auto power on and with a pre-charge function (no sparks, so long as the battery is powered off when linked to the controller)"

 

[Fordulike]

@vfr400 Would you be more concerned about charging amps, or charging to 100%?

 

[wheeliepete]

I wouldn't worry too much about charging that pack at 5 amps, being 5P, it's only 1 amp per cell. Paul at EM3EV has put alot of work into his battery development over the last couple of years and are prob. one of the best built and safest around. If I didn't build my own packs, I would buy from him, no question. He also has a technician in the UK, should you have any problems. From the spec of the BMS, it has the ability to balance charge the pack at any voltage over 50%.

 

[wheeliepete]

Have you considered 52v?

 

[Fordulike]

Have you considered 52v?

I did, but am happy with 48v. The voltage sag on my current battery is the problem. Great for the first few miles, but the sag takes the edge off the performance after that.

 

[vfr400]

I think 5 amps should be Ok. From what you extracted from the listing, that battery is OK for partial charging. Is it expensive? My thoughts are that I'd only charge at 5 amps if I needed to. I'm doubtful whether spending all the extra on the charger and battery will give you a return on your investment. A cheapo battery and charger lasts about three years, by which time there's normally better cells, so you want to change the battery anyway. That's just my thoughts, not based on any real facts.