What would be best for our batteries?

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turok
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What would be best for our batteries?

I have a question, but I don't know if anyone can answer this completely.

In EV's I'm a novice, but I understand the basics of electronics.

The manual I received with my V states that it is ok (or is it safe?)to plug/unplug the charging cord whenever you want.
It even says that you will benefit even from short charges & topping off.
Apparently the BMS will take care of it?

But I wonder what effect it will have on a long term due to the "memory effect" on batteries.

I, e.g., have only a few km to commute, so if I wish I could go through a whole week before I have to recharge.
My gut tells me I should only recharge when "as empty as possible" (no deep discharge though)
But when I read certain threads, my gut feeling may be wrong? Some people would still recharge every day ("topping off")?

Can anyone enlighten me?
Does anyone know what the BMS does (if anything) to keep up the shape of the pack?

Turok

myvectrix2008
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Re: What would be best for our batteries?

I am no good with electrics, but it is my understanding that Ni-MH batteries do not suffer from the memory effect like Ni-Cad cells do. I would have thought that every once in a while it would be good to wait until the cells are low on charge, say 1 or 2 bars, and give it a full recharge including equalization.

HarryS
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Re: What would be best for our batteries?

I drive 15 miles each way to work and the battery is just about half empty. I can make a roundtrip with only 1-2 miles to spare. I am charging twice daily on each side of the commute. I did call Vectrix and ask the about their recommendation and they recommended that I charge unless I have no opportunity to do so.

qmprius
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Re: What would be best for our batteries?

Hello.
My english is limited. Sorry
My Vectrix has about 2500 Km. now; I do about 5-7 trips of 20-25 km each week and I recharge when i retour to home (some days I do 2 charges) with about 8 bars in the battery level indicator. A technician of my dealer recommended me than about 20 partial charges I do a full discharge (when the red battery icon lights) and then a full charge. So the software recalibrates the 0 bar indicator correctly, (and I think also the little memory effect than the Ni-MH batterys hads is resetted).
(To do the full discharge I need do some km. circulating near home, so I can retour without trouble). To simplify the process I do a full discharge/charge cicle each 500 km.
Regards from Granada (Spain).

siai47
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Re: What would be best for our batteries?

Heat is one of the things that impacts battery life more then anything for a NiMH battery. The battery builds up a lot of heat during the final phases of the charge and discharge cycle. When charging, you should set a timer to start the charger so that the charge finishes (or is close to finishing) when you are ready to ride. Otherwise, energy put into the battery near the end of the charge phase will continue to be disapiated as heat, shortening the life of the battery. On the discharge side, as the energy stored in the battery is used up, internal resistance increases causing the battery to heat internally instead of delivering energy to the motor. You need to reduce the rate at which current is delivered from the battery (slow down) to reduce the internal heating. In a perfect world, the battery would normally not be fully charged (execpt for equalization cycles) nor fully discharged. Plan your charge cycles and ride duration to minimize these effects as much as possible.

RaDy
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Re: What would be best for our batteries?

After all the different point of views that you will get from Official Vectrix Technicians, Battery experts, info from Wikipedia and V for voltage, you will reach to the conclusion that you are far more lost than when you started.At least thats what has happened to me, so i have decided to wait untill there is more experience on the Vectrix batteries and for the moment simply recharge when you need to.
I do a comute of around 55km a day from Monday to Friday.I end my trip with hardly 4 to 5 bars and i recharge my Vec every night from 04:00 in the morning to 09:00 (controlled with a timer) but i leave abit later so can actually leave it abit more if it needs to(which it nearly never does so).
I now have 2600Kms on the Vec and i bought it in Feb 09. When i did my first check up they told me that i had a very good Battery life expectancy due to the info that they recovered from my bike (I dont know if they just said it to make me happy or its true).
The only thing that i think you should avoid is to let the battery heat up too much because of use or charging. For example when i start my commute in the morning the bike has rested between 1 and 2 hours before it stopped charging(giving it time to cool down) then i do 27Kms and it cools down for 5 or 6 hours, then i reach back home and it cools down again before programed charging starts at 04:00. The least you charge discharge, the better but never letting the bike discharge to less than 5 bars or so.
Hope you can make out something.
Rag

avronw
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Re: What would be best for our batteries?

This is not intended for a Vectrix, but I felt provides a good overview of battery care and is an extract from the Segway manual. It raises a few points that I have seen debated a few times here, so may be a good guide for most of us novices.

Battery Care (PDF)

Anderson
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Re: What would be best for our batteries?

Evidently in long periods of inactivity it's better to leave the scooter at a 40% state of charge and NOT fully charged ( I don't know this for a fact but I think it's correct and if it is true then it's very counter intuitive );

What does work is to leave the scooter in 40% SOC and then do a full charge just before it is needed again. And even then it might not charge fully the first time around after a long period of inactivity.

The serious risk associated with inactivity periods is that it is very likely that one of the 102 cells has a significantly increased self discharge rate compared to the others. This cell will be damaged further when the unexpectedly low range forces continuing riding or rather crawling along. Reverse charging is a likely result of this and can destroy the cell in very short order.

Several shallow discharges followed by full recharging each time are needed after a long period of inactivity, just like when you get a new Vectrix which has not been used in months.

I would suggest C/15 charging for 2hrs for the first day, and another hour for each day of inactivity in the first week, then another hour for each further week to a maximum of 20hrs at C/15.

Although if you plan to leave it for over two months or more I would fully charge it with expectations it would loose most of it's charge over that time so it wouldn't completely run down.

You can read the full post here; http://visforvoltage.org/forum/5260-topping-charge
post #11

Mik
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Re: What would be best for our batteries?

My advice is now different, and hopefully better!

I did not know back then that the Vectrix MC is "permanently on" and that 7mA are constantly draining out of the battery.

Doesn't sound like much, but do the maths:

0.007A x 24hrs x30days = 5.04Ah !!!

The Vectrix drains 1/6th of it's nominal battery capacity per month due to this alone!

The self-discharge of NiMH cells is in addition to this.

So you are probably better off storing the Vectrix fully charged, because you are not really "storing" the battery, but rather you are slowly discharging it!

The advice to store at 40% SOC came form Battery University and is probably correct for NiMH cells (including Vectrix cells) if they are stored without any current drain.

I might of course be wrong again...

This information may be used entirely at your own risk.

There is always a way if there is no other way!

jethro
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Re: What would be best for our batteries?

The batteries on a Vectrix "like" to be charged at every opportunity and the newer software requires as deep a discharge as possible on a regular basis to be effective - you will notice a difference in range on most bikes.

Extended storage should be done with the battery fully charged and a top up charge done every three months at the most.

If your Vectrix is not in daily use eg. sat/sun charge it on the friday so it is fully charged on saturday as if you charge sunday the batteries will self discharge during the week.

The cells used on the Vectrix were originally used in a marine application and will last over ten years if looked after.

edited to add missing info

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