homeless in ca.

I just got an e-bike. It's fun to ride but range is not yet sufficient to make this a daily driver.

I purchased an additional battery identical to the one that came with the bike. And I'll probably get another one asap. Links are below. The batteries are 36V10.4Ah. The charger that came with the bike is 2A.

I work as a tech and do service calls that sometimes take 30 minutes to an hour. I'd like to get a couple of "fast" chargers to bulk charge my batteries during those stops.I'd still use the 2A charger at home.

If there is a "smart charger" that could lower the output as battery voltage increases that would be even better. But I saw some 4A chargers for $20. I'm tempted to go ahead and order 3 of them and do the bulk charging manuallly.

I'd also like to know if it's possible to charge two or three batteries with one charger. Since in my case the batteries are identical.


https://www.princessauto.com/en/20-i...t/PA0008925406

https://www.princessauto.com/en/20-i...t/PA0008907644

2old

Most "experts" state that batteries are stressed by fast charging. Accordingly, charging at 2 amps probably is optimal, and higher rates probably will decrease battery life. Check the literature to determine how much.

Doc_Wui

Your 36V10,2AH battery probably has 40 cells, arranged in a 10x4 array. In battery talk, that's 10S-4P for 10 series groups and 4 parallel cells per group.

With a 2A charger, each cell gets 0.5A in charge current. You would have to look at the spec sheet for the max charge current, but I "think" most commercial cells would be fine at 1.0A. My biggest charger though is 3A, and that's actually 2.7A actual current. I chose it over a 4A or 5A charger because my experience is that the 5.5mm connector will overheat at 4A,

Some of my batteries use RCA XLR microphone plugs for charger connectors, These won't melt.

gregf83 

They don't really have to be 'smart' to do that. All lithium chargers will start with a constant current until the battery voltage reaches about 4.2V/cell. After that the voltage will be held constant and the charge current will gradually taper down. The charger should shut off when the charge current drops below a fixed threshold, typically around 5% or so of the capacity - in your case around .5A.

homeless in ca.

I've always heard that fast charging is fine as long as you don't go over 80% of the battery's full capacity. The Luna charger puts out 5A but switches off when the battery reaches 80%. Or they can switch to a lower amp setting if you want a full charge.

In my case I don't want to spend hundreds of dollars on smart chargers if I can do the same thing manually with a timer. I'll just check the voltage and if the battery is 50% then I can safely add 3 amps and set the timer for 45 minutes.

mclewis1

I think using a timer with basic chargers is a good simple solution, but you do need to "know" your particular batteries. Even with a timer I would also keep a close eye on the charge state of the batteries using a multimeter or more preferably an inexpensive inline voltage and amperage monitor.

The Luna advanced charger simply gives you the choice of 80, 90, or 100% charges (there's no default) at various amperage rates (1-5amps). While many question the build quality of the Luna units I've been pleased with mine for about a year now. My 52v battery is rated to be able to be charged at up to 8 amps so the occasional fast charge at 5 amps is fine ... but I normally just charge my battery to 90% at 2 amps.

MNebiker

Her is a link I found on the Luna web site regarding battery charging that may help:

https://www.electricbike.com/ebike-battery-longevity/

Calsun

The faster a battery is charged the fewer charge cycles it is likely to accept. Best bet is to get a second battery if you really need more range or perhaps consider using your legs to pedal so the motor is drawing less from the battery. Every e-bike I have looked at had a range variance of 100%, or 50 miles little pedaling but 100 miles if the rider's legs did most of the work.

Lithium battery chargers will usually provide maximum charge rates until the battery has a SOC of around 50% and then taper off. I don't know if the brick type transformers are that sophisticated and this is probably why they tend to be low output 2 amp ones. You will also shorten the useful life of a lithium battery if you draw it down to 50% or higher SOC and then recharge it. Batteries are rated for a given number of charge cycles and not amount of recharge per cycle. A battery that is recharged when it is at 20% SOC is likely to last longer than one recharged when it is at 60% SOC as the latter will be recharged more times per mile traveled.

KPREN

I regularly fast charge at 5 amps even to a 100% state. I have about 300 cycles so far. If the battery does not get hot no problem Once in a while I slow charge. I have two 2 amp chargers. a 5 amp charger and a 15 amp charger.

My 5 amp charger is the Luna charger. I have charged both 52 Volt and 48 volt with the same charger on a trip. I just open the case and use a small screw driver to change the pot voltage between 58.8 volts and 54.6 volts. .