Should I top up my battery before a ride?

[Jeff McD]

No. But you can simply calculate the time when you need it to switch off to have desired % of charge.

Can you please be so kind as to describe how to calculate this? Don't ride bike every day. For example if I finish ride at 28% battery left how do I calculate time needed to charge it up to 50-60% so I can set an alarm to remind me to turn it off? Tanks, eh?

 

[salko]

Can you please be so kind as to describe how to calculate this? Don't ride bike every day. For example if I finish ride at 28% battery left how do I calculate time needed to charge it up to 50-60% so I can set an alarm to remind me to turn it off? Tanks, eh?

Here is a calculation example for 700Wh battery and 4A charger:
If you ride home with 13% and want to charge to 75%, there is 62% difference. Charging speed is around 22%/hour (only for about first 80-85%). So 62÷22 = 2,82 hours = 2 hours 49 minutes ... this is time needed and you will have it charged to approx. 75%

 

[MattyB]

First off not having a go and making out to be any kind of expert but a couple of things from your post. I don't understand the point of when you say you charge only charge up to 75% if these batteries are like any other modern day battery don't they get a memory and get used to being charged to only that point of which you always charge, giving the optimum use of the battery a shorter life span and not getting the full 100% use of the life of the battery.

No, Li ion batteries have no memory effect. As long as you do not leave the pack at an elevated SOC (>4V/cell) for more than 24 hours there is no difference between charging in 4x small bursts from 75% vs a full charge from 0%.

...Another point of don't regularly discharge to below 20%, why? Ok don't constantly let your battery get to 0% when out riding every time, but the manufacturers give you that other 20% for a reason. So are you saying if you are out on a ride and see you have 25% left you are going to head home with that 5% battery to not get into the remaining 20%? seems daft in my opinion. The batteries have been built to get the full use out of them, Ok we all need to be careful of how we look after them ie like you say don't charge straight after a ride and don't leave discharged for long periods, but use them how they were meant to be used and developed by Shimano/Bosch etc, for longer rides in the saddle.

On this point you are correct. It's true that deep discharge (generally anything below 3-3.1V/cell) of lithium packs will damage them, but the onboard BMS will display that the battery is at 0% well above the point at which cell damage occurs. Bosch and Shimano engineers have told me exactly that F2F at the Bike Show, and it makes complete sense...

Gradual Battery Degradation - EMTB Forums

 

[OldGoatMTB]

Here is a calculation example for 700Wh battery and 4A charger:
If you ride home with 13% and want to charge to 75%, there is 62% difference. Charging speed is around 22%/hour (only for about first 80-85%). So 62÷22 = 2,82 hours = 2 hours 49 minutes ... this is time needed and you will have it charged to 75%

I agree with your math, but I believe that I charged my 504w battery from 0-100% in around 4 hours, so I don't think the 22%/hour figure could be accurate. I have not collected a lot of date on this (though I would like to see a lot of date on this) and sometimes have a fuzzy memory.

 

[salko]

I said my example is for 700Wh battery and 4A charger. For your battery you have to measure charging speed simple by charging it for exactly 1 hour and check for how much % charge increased...

 

[KennyB]

Levo 4 amp charger output voltage is 42 volts current is 4 amps. Power (Watts) = current x voltage (W=VI) so 168 Watts. Charge for 1 hour that gives 168 Wh, approx 22% of a 700 Wh battery and about 33% of a 500 Wh battery. As noted above, at about 80%, the BMS halves the output to about 11% (and 17%).
Of course all this is for a Levo 2019/20. Double these times for a 2 amp charger.

 

[mak]

Honestly all this is a bit over my head, with a full charge I can get several rides out of my bike ( 635 wh bosch) 18miles/ 10 miles/ 12 miles 10 miles etc, all small rides and at the end of that little list ( 50 miles) there's still 20% left .

I wouldn't dream of sticking the thing on charge with a good ride left in the battery unless I new I needed to do a bit of an epic.

Maybe I'm wrong but I thought the less charge cycles you apply to a battery the better

 

[MrBrownstone]

Maybe I'm wrong but I thought the less charge cycles you apply to a battery the better

No, the more charge cycles that you apply to the battery the better. Means yer riding more.?

 

[KennyB]

Bit of a misunderstanding of charge cycles. Charging from, say 50% to 75% is not a charge cycle. Doing it 4 times is.

 

[Jeff McD]

Mucho thanks to salko and KennyB. Perfect clarity.

 

[moiralabrecque03]

I'm definitely a B type of person. I do like to look after my gear.

That is a big difference in cycles between fully charged an 80%.

I have had a look at that article but I'll dig in further.

So...
- Always fully charging isn't best practice for longevity of the battery even with daily use.
- Only fully charge if you need to for a big ride.
- Never leave your stormi merchandise battery low at astroworld for any length of time.
- If the battery is going to be out of use for a while, store with around 60% charge.

My smart power monitor plug arrived today ?

Thanks for all the info an thoughts.

It seems that batteries don't like being under stress and need time to settle after changing and riding.

please tell more about this!

 

[Swissrider]

Most of my rides use most of my battery, so I tend to charge it up fully after each ride, ready for the next one. To charge to say 80% is tricky as after a ride I would have to remember to go out to my shed and turn the charger off and how would I know exactly when to go and turn it off? Too soon and it is undercharged, too late and it’s fully charged. Also, if I charge it to 80% I’ve got to go and charge the bike for about 40mins for a typical ride, by which time my mates have left. Over the winter when I can’t ride because there is too much snow I do discharge to 60% and store the battery indoors. Finally, although I know not to leave it fully charged, how does one discharge a battery, other than going out in the pissing rain, which is why I’m not using the bike!

 

[flash]

I think some of you are over complicating this a bit. It's great to take care of your batteries. They're expensive and they'll last longer if you do. But there's no need to be obsessive about it by measuring charger rates. You don't even have access to the full charge cycle of the battery as the BMS is making sure you can't hit 100% or zero% charge. Unless that fails you have inbuilt charge safety in the system. All you need is to be in the ball park.

Here's what I do. If the battery has two or three bars at the end of a ride I leave it in a warm place and charge it to 100% the night before my next ride. If my battery is in the red or has one bar I charge it for 40 mins per bar (to about 3 bars out of 5) using a cheap AC timer and then finish charging it to 100% the night before the ride. I don't charge in extreme cold or heat.

Then I go ride the bike.

It's great to know about battery optimisation but your batteries are fine for short term storage anywhere between 30 and 80%. Only bother for closer to 60% for longer term storage. Topping up the night before the ride really isn't the end of the earth. Close is good enough.

Gordon

 

[Akemtb]

When I get home from a ride I plug the battery in, then next day or whenever I get around to it I'll unplug it.
I think it's best to have the battery full charged a all times, internal chips monitor battery health and lot of other stuff.
Like someone early stated, don't overthink it.
When I sold my Bulls Monster with Bosch Gen 3 the battery had about 80 full charge cycles and 100% charging capacity.

 

[Swissrider]

What is the difference between battery health and the ability of battery to hold charge. After two years and about 2500k my battery shows 95% health and charges to about 97% (never 100% anymore)?

 

[flash]

What is the difference between battery health and the ability of battery to hold charge. After two years and about 2500k my battery shows 95% health and charges to about 97% (never 100% anymore)?

The 97% figure is well within the margin of error. You might be getting 100% (or 93-92---) and it's just misreporting. 95% health after two years is excellent.

Gordon

 

[Philly G]

I've been leaving my Bosch battery for at least an hour after my ride, then charging to 100%. I disconnect the charger fairly promptly. It then sits for a week before I go for my next ride. Is this considered too long an interval? Should I instead charge to 60%, then top up to 100% the night before my next ride? I know for long term storage the battery should be kept at 60% but I thought a week wouldn't matter

 

[flash]

I've been leaving my Bosch battery for at least an hour after my ride, then charging to 100%. I disconnect the charger fairly promptly. It then sits for a week before I go for my next ride. Is this considered too long an interval? Should I instead charge to 60%, then top up to 100% the night before my next ride? I know for long term storage the battery should be kept at 60% but I thought a week wouldn't matter

Ideally, no, you wouldn't leave your battery fully charged for that long. Best practice would be to charge to 40-70% and then top it up the night before a ride. Batteries prefer not to be stored with a high or low SOC (state of charge) for more than 12-24 hours.

However, occasionally we all do have to leave our batteries fully charged for some reason. Either it rains cats and dogs or something comes up and we can't ride when planned. Don't panic it'll survive fine for a week or two. It's also worth noting that you NEVER get your battery to either 0% or 100% charge. The BMS won't let you do that. The 0-100% we see is the usable charge that the manufacturer sets, not the actual battery capacity at maximum or minimum. So there's some saftey margin already built in to the system.

I would definitely avoid months though.

If I have one (maybe two) bars left after a ride I give it a bit of charge using a cheap timer. If (two) three or four bars I just leave it until the night before I ride and plug it in as part of my getting ready process for the next morning.

Gordon

 

[Philly G]

Ideally, no, you wouldn't leave your battery fully charged for that long. Best practice would be to charge to 40-70% and then top it up the night before a ride. Batteries prefer not to be stored with a high or low SOC (state of charge) for more than 12-24 hours.

However, occasionally we all do have to leave our batteries fully charged for some reason. Either it rains cats and dogs or something comes up and we can't ride when planned. Don't panic it'll survive fine for a week or two. It's also worth noting that you NEVER get your battery to either 0% or 100% charge. The BMS won't let you do that. The 0-100% we see is the usable charge that the manufacturer sets, not the actual battery capacity at maximum or minimum. So there's some saftey margin already built in to the system.

I would definitely avoid months though.

If I have one (maybe two) bars left after a ride I give it a bit of charge using a cheap timer. If (two) three or four bars I just leave it until the night before I ride and plug it in as part of my getting ready process for the next morning.

Gordon

Great, I'll start doing things differently, I do want to look after it the best I can. These things aren't cheap after all.

 

[OldGoatMTB]

I rarely charge mine fully, only if I'm looking at a very full day of riding with lots of climbing or several days of riding without the chance to charge up. I'll usually charge to 80-90%. My battery has been through 21 charge cycles and is still at 100% health (whatever that really means!)