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Unreliable range at low charge/cold temp

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mrj
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 mrj
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I've done about 400miles (600km) and about 10 charges. Bike is stored outside so the battery is cold in the morning (5-10'C now in the UK). This has happened twice in succession now:

Bike says it has 18-20% charge, and about 12 miles range (on setting 2). Good enough to get to work and back (which is a 9 mile round trip). It also said this the night before so I didn't take the battery out for a charge. So I start my journey. Range plummets in the next 20 minutes and when I get to work I am worried. 1st time it was 7 miles, today it was 2 miles.

The first time I took the battery indoors for 4 hours so it warmed up. On the return journey it started at 7 miles range, and was STILL 7 when I got home!

Today I panicked and got my wife to bring the charger to work. I really couldn't risk the "2 miles" being the truth.

Both times I have also seen occasional error 94 (power cable fault). Today, while this was showing, and with 5% charge flashing, full power returned for a bit!

I'm just reporting this in case anyone else sees it, and as a warning not to trust the range below 20%. Now I'm going to charge when I get this low, rather than at 10%.

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socomods
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pretty much standard for lithium tbh, cold temps reduces the voltage and available charge - i try to avoid riding mine below 10C if i can; and avoiding going below 20% is def a good idea, for battery life if nothing else - going below 20% and in the cold, is def a risk

 

the battery warranty is extensive enough for you to not worry to much about charging it regularly (based on years (3 for TS) and distance, rather than number of charges), no need to wait until its almost dead, charge it between rides as much as possible (during day and at end of the day) - the old issue with recharge memory no longer exists in lithium batteries, so you won't damage it by charging it regularly like this

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mrj
 mrj
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@socomods Thanks for the tips!

Mine is out the front of the house so charging means hefting the battery out so I do it as infrequently as I can get away with! And I commute on it every day so rain/shine warm/cold. That or a bicycle. I definitely need to charge at 20% rather than pushing it though. I have a feeling its good to do the occasional deep discharge though? That's why I was pushing it to 10%, but its obviously too risky.

 

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socomods
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lugging the battery around is a pain initially, you do get used to it though (i carry mine upto 2nd floor at home and 3rd floor at work, no lifts, so i know the struggle 😅)

 

deep discharge is not actually good for lithium, it causes crystals to form in the cells, which will grow the more you do it, at best these reduce efficiency, at worst they can  the grow enough to pierce layers in the cells and explode (not very likely with good cells, but possible)

 

Partial discharge is always best option when available, it will extend your battery life significantly

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alexaraducristian
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As @socomods says, don't risk to damage your battery discharging it so low.

Lithium-Ion batteries don't have memory, so it's perfectly fine to charge it from 30%, or 50%, or 60%... up to whatever percent you want, but recommend to not charge it more than 80% too often. Full charge to 100% once every 2-3 month is recomended to balance all internal batteries.

I always calculate the distance I plan to do and try to charge my battery to keep it around 50%. By example 12km is my commute to/back work. I need 1.3%/km, so ~16% of battery. Therefore before leaving I charge it to 60% and I arrive back home with 44%.

If I plan to have a longer journey, like 50-60km, then of course I charge to 90% or even 100%. It's perfectly fine as long as I start immediatly to ride, so I don't keep the battery at 100% for some days.

I ride at 5-15° for the moment and works fine, I don't feel I loose too much distance. Actually I have my TC since November last year, so never had the chance to ride it at 25° =))

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mrj
 mrj
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@alexaraducristian

I always charge over night so it is always to 100%. Oh well. I'm at work at the moment so I can't remember what voltage the charger says (i.e. if its 100% or a bit less). UK charger.

I got my TCMax just before Christmas, so looking forwards to exceeding 55mph (90kph) in the summer! Its definitely more lively on the mornings when the battery has been nice and warm indoors all night.

 

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socomods
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it is worth noting that the original Soco TS battery already under charges, so taking it to 100% is fine - it isn't actually reaching 100%, the BMS shuts off charging before 100% 

 

difficultto get exact numbers, but i believe it charges to <70V (based on controller 70V restriction) or 4.12V per cell, rather than 4.2V max charge

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alexaraducristian
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@socomods my charger is charging to maximum. It's written on the sticker 71.4V, so 4.2V/cell.

I know some chargers have 69.7V output (especially in UK, Ireland, probable because of more strict warranty) which mean 4.1V/cell and the lifetime is doubled.

But unfortunetely I have to approximate when to stop the charging. By example I leave it ~1 hour for a 15-20%. Anyway I would like to have more control and looking for a cycle satiator charger, but it's not yet in my budget.

 

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