48v10ah Battery Charging Guidelines

[Vipermn]

 Hi everyone!
I have a few questions about the MP4 48v10ah battery and charger:

Are there any special conditions or guidelines to consider when recharging?
Are things like environmental temperature, battery temperature, remaining charge, charging current important ?
Is it okay to discharge the battery completely as in running the motor until it won't go anymore and then charge it?.
Is it bad to charge the battery after short rides when the battery still has 50% to 85% charge remaining?
Is it okay to leave the charger plugged into the battery all the time with the charger on even after battery is charged?
Is it possible to connect a fully charged 48v10ah battery with a fully charged 48v8ah battery in parallel to increase distance?
Is the standard charger for the 48v10ah battery from GM sufficient to charge a 48v10ah battery AND a 48v8ah battery wired in parallel?
 
thx

[e-lmer]

All information below is from my experience, I offer these statements as is, as with e-bikes, YMMV.

Are there any special conditions or guidelines to consider when recharging?

LiFePO4 battery packs are very robust, but the remember, this is a very powerful
package, a short can start fires quite easily.

Are things like environmental temperature, battery temperature, remaining charge, charging current important ?

The environmental limits are in the battery specs online, but in general if your puppy would not like it your battery would not.

Is it okay to discharge the battery completely as in running the motor until it won't go anymore and then charge it?.

Yes, one time, but do not disconnect the battery and reconnect it.  The lower voltage
could be detected as a 36V pack by some controllers, and that would allow you to discharge your cells below the minimum cut-off voltage, damaging the cells.

Is it bad to charge the battery after short rides when the battery still has 50% to 85% charge remaining?

Some say that the charging cycles of a battery are per charge, not per Watt/Hour.
I say the risk of damage from turning on a low battery are greater than the risk of (possibly) shortened life.

Is it okay to leave the charger plugged into the battery all the time with the charger on even after battery is charged?

While I do this sometimes, I can't recommend leaving a fire hazard plugged in unattended.  So my answer is no it's not ok.

Is it possible to connect a fully charged 48v10ah battery with a fully charged 48v8ah battery in parallel to increase distance?

Kind of, but I don't suggest it.  When you first connect them you are going to have
potentially different charging voltages and a short between them until they equalize.
I have used a 12 V lamp to get the batteries to the same voltage in my experiments, but this turned out to be a royal pain.
It turned out to be easier to call the 8AH battery a spare that you swap in when the 10AH battery reaches it's cutoff voltage.

Hope that answers your questions.
Elmer
Is the standard charger for the 48v10ah battery from GM sufficient to charge a 48v10ah battery AND a 48v8ah battery wired in parallel?

[Flipseth]

I have found this site helpful on battery questions.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

As far as the parallel question as long as they are the same voltage then it will increase the ah 10+8 = 18ah.
I would use a volt meter to check voltage.
As far as charging it would be faster to charge them separately and with there intended charger.

Please correct me if I am wrong, thanks
Phill

edit> I would agree with e-lmer and use the 8ah pack as a spare and swap out instead of wire in parallel.

[Bikemad]

To save time I am simply going to add my replies to Elmer's from his earlier post.
(My replies are in Blue)

All information below is from my experience, I offer these statements as is, as with e-bikes, YMMV.

Are there any special conditions or guidelines to consider when recharging?

LiFePO4 battery packs are very robust, but the remember, this is a very powerful package, a short can start fires quite easily.
Do not use your charger in rain or damp conditions and always make sure that the cooling fan and vents are not obstructed.

Are things like environmental temperature, battery temperature, remaining charge, charging current important ?

The environmental limits are in the battery specs online, but in general if your puppy would not like it your battery would not.
Do not attempt to recharge your battery in sub zero temperatures, bring it indoors and allow it to warm up a bit before charging.

Is it okay to discharge the battery completely as in running the motor until it won't go anymore and then charge it?.

Yes, one time, but do not disconnect the battery and reconnect it.  The lower voltage could be detected as a 36V pack by some controllers, and that would allow you to discharge your cells below the minimum cut-off voltage, damaging the cells.
The GM batteries have their own built in BMS and do not rely on the controller's low voltage cut-off for protection.
Your battery should have a longer life expectancy if you don't regularly discharge it completely.
If it is fully discharged, always charge it back up to at least 40% capacity as soon as possible, if you don't want to fully charge it.

Is it bad to charge the battery after short rides when the battery still has 50% to 85% charge remaining?

Some say that the charging cycles of a battery are per charge, not per Watt/Hour.
I say the risk of damage from turning on a low battery are greater than the risk of (possibly) shortened life.
It is better for the battery to only be partially discharged to 50% and recharged every day than it is for it to be completely discharged over two consecutive days and then recharged.

Is it okay to leave the charger plugged into the battery all the time with the charger on even after battery is charged?

While I do this sometimes, I can't recommend leaving a fire hazard plugged in unattended.  So my answer is no it's not ok.
If everything is working as it should, the battery charging will automatically cut off when the charging voltage is achieved and the current draw then falls below a pre-set level, therefore it should only be possible for the battery to become overcharged if the constant voltage function of the charger fails to operate.
Most charger failures I have come across typically result in either a current reduction or a total loss of charge current, and would therefore not overcharge or harm the battery.

Is it possible to connect a fully charged 48v10ah battery with a fully charged 48v8ah battery in parallel to increase distance?

Kind of, but I don't suggest it.  When you first connect them you are going to have potentially different charging voltages and a short between them until they equalize.
I have used a 12 V lamp to get the batteries to the same voltage in my experiments, but this turned out to be a royal pain.
It turned out to be easier to call the 8AH battery a spare that you swap in when the 10AH battery reaches it's cutoff voltage.
As long as the two batteries are the same voltage and are both identical chemistry (LiMn, LiPo or LiFePO₄) they should both be at a very similar voltage when fully charged.
As Elmer already mentioned, it is very important to ensure the batteries are both at a similar voltage (I would suggest that up to 1V difference would be acceptable).
If you are going to carry both batteries on your bike, connecting them both together in parallel would be the obvious thing to do as it will give a slightly better range than using them one at a time because they would both be sharing the load when connected in parallel. This means that each battery is operating under less load while still delivering the same total amount of current (which reduces the voltage drop) resulting in greater power and efficiency which should allow you to travel further.

Hope that answers your questions.
Elmer

Is the standard charger for the 48v10ah battery from GM sufficient to charge a 48v10ah battery AND a 48v8ah battery wired in parallel?

Provided the batteries are identical voltages and chemistries the GM charger should be able to charge them both simultaneously, but it will take a lot longer to charge (at least 80% extra charging time would be required to charge both batteries).
The three amp charger supplied with the GM battery would take at least 6 hours to fully charge both batteries (18Ah) up to 58.4V after being completely discharged.

Alan
 

[Vipermn]

 :)thanks for the info