Battery heat opinion?

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Todd
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Battery heat opinion?

I don't think this is normal... opinions?

Took the bike to town today and it was 14C/58F ambient.

Battery started 8C at 136V
Rode 9.9 miles battery to 126V, charged at Kroger 32 min till charge stopped, 15C 138V
Rode till red light - 13.5 miles, 23.4 miles total 21C 124V
Set 30 min delay on charge, at the end of charge it was 24C.

So after 23 miles and 2 charge cycles the batteries went from 8C to 24C with 14C/58F ambient.

Seems like a lot of heating to me for not a lot of miles.

Long before I got the red light the bike would not accelerate normally, as much as 4 miles before the red.

Can you tell from the above info if it may be just imbalance, cells going bad, or is this normal?

I have not been riding the bike a lot with the cooler weather but I did take it out couple days ago for a short ride. I know the batteries self discharge when sitting. Interestingly Matt, tech from Vectrix, told me to compensate for the sitting just turn the bike on once a week and roll it back and forth then plug it in to charge and it would keep the battery up. Had not heard about rolling it back and forth before.

Todd

AndY1
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Re: Battery heat opinion?

That depends on how you rode the bike. If you pushed it hard (70+kmh), it's normal. Your second charge took place at 14°C ambient, so it's normal for the battery to heat up from 8°C to 15°C, because the ambient air actually added heating to the battery.
Then, if you rode it hard until red and then did a full charge from red, it's normal for the full charge to heat the battery up to 24°C. In fact, that is the ideal battery temperature.

The Laird
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Re: Battery heat opinion?

Hi Todd,

You are quite right , that is a LOT of heating.

9 miles to 126Volts, sounds like you either traveled at full throttle all of the way or started out with a half empty/full battery.

The 32 minute charge at Kroger would definitely have warmed the battery up, but not by more than a few degrees (2 or 3 I would expect). That half hour charge would have put in about 5Ah (on your almost empty battery) and the ride back, 13.5 miles, would have used a further 10 to 12 Ah.

The lack of power prior to the end of the ride indicates a lack of battery voltage. The high temperatures at the end of the ride indicates cell reversal. If you had the use of the diagnostic programme and CanBus adapter, you would almost certainly have seen one or two of the battery modules showing high temperatures whilst other modules would have been much cooler.

This temperature difference is simply a manifestation of severe imbalance (resulting in cell reversal) or of faulty cells.

The reason that the temperature rises after use (whilst standing idle) is that the heat is generated within the cell and it takes time to reach the sensors. The delay can be anything up to an hour or two for the temperature to stabilise throughout the module(s). I know this from experience,

Your best action here is to NOT to take it down to the red light. Instead, keep an eye on the battery volts and temp whilst riding (I can do this in three to five seconds whilst on the move). When the temperature begins to rise the cells are struggling. Aim to complete your journey with as little temp rise as possible.

Ideally, your battery requires a total strip down, replacement of any faulty cells (all of those which are bulged are damaged/well stressed and should be replaced plus any which are electrically faulty/short circuit). The cells all then need equalising. And then you are back in good shape.

Equalising by overcharging is basically the cause of the bulged cells and I am still testing an alternative method of equalising which does less or no damage. I am not there with that one yet but will publish system and results when available.

Until we have a viable equalising system, I suggest that you just treat it gently to prevent further damage.

Best wishes and good luck

The Laird.

mikemitbike
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Re: Battery heat opinion?

I don't think this is normal... opinions?

Long before I got the red light the bike would not accelerate normally, as much as 4 miles before the red.

I have not been riding the bike a lot with the cooler weather but I did take it out couple days ago for a short ride.

Todd

Hi Todd,
as the others wrote how fast /agressive did you ride? I´m afraid a lack of power with fast rising temperature
is very often a bad cell. My own experience.

Because of the different selfdischargerate and the overheating during the EQ charges, I charge 3 times a week when
the bike is not in use. so you have only CC with 3 Amps for a shorter chargingtime instead of CP with 10 Amps and
a longer charging time which will stress the cells with a low selfdischarge-rate because of the overcharge.

Greetings Mike

Todd
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Re: Battery heat opinion?

Of course and I should have stated, I rode the bike very gently the first 20 miles as I usually do. Easy starts, coast downs to stop. My trip on Sunday was probably 35 - 40 mph average in a rural area, about 10 miles at 30 - 35 and ten at 40 - 45 with 1 short section for about a mile of 55. Last 4 miles were around my subdivision and more spirited, stop and go with a lot of acceleration to bring the red light on.

I have owned EVs for years and currently have an Insight with 220k and I still get 70 mph average so I have learned to conserve energy when I want to, which is most of the time.

Todd

AndY1
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Re: Battery heat opinion?

Spirited stop and go with a lot of acceleration will heat up your battery. More than faster speeds.

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