Newbie Questions for 2008 VX-1

Are you using disk brakes instead of using regen braking, or are you avoiding excessive acceleration and speed, therefore reducing the need to brake?

From an efficiency point of view, any braking is wasted energy. Regen braking wastes less energy, but only if your battery can handle the high charge current.

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If you have cells with high internal resistance, then they could end up very hot with regen braking. Then, they remain hot after riding.

A hot cell has a drastically increased self discharge rate. It even produces more heat due to the self-discharge in progress.

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My earlier suggestion http://visforvoltage.org/forum/11409-battery-temperature-reaches-39-40-c-after-full-charge-beginning-end-my-beloved-nimh-vect#co... to do a gentle deep discharge was meant to ensure that the possibility of voltage depression has been dealt with. Deep discharges should not be a regular occurrence. Don't do the slow discharge with a hot battery, the whole charge and discharge cycle should be as cool as possible.

I just had an unusual experience...charged mine from 126v on timer for two hours. I just happened to look at 1.5hours....was up to 151v and temp had gone up 5 degrees. Was still charging at 10 on the tacho.

I've never seen it (voltage) go up so high before.....and perfect timing, because now i'm going for a 30km ride.

The voltage will stay up for a couple of days, but after a few charges, a full charge only gets me up to 135V-136V, not quite enough to get me the 12 miles to work. Should I schedule in a weekly ride to run down to 123V-124V, get a light, and charge from 0 bars to keep my voltage up for the week? Mind you, throughout the process the temperature stays down below 35°C.

Any thoughts?

I find exactly the same thing. Very annoying software issue, obviously. The fix for me is to red light it.

An update:

I've been quite diligent on the charging regimen, making sure to stay out of the 3A phase to avoid overheating. I haven't seen temps over 40°C in over 5 weeks. I still have range issues, which I hope to address when I have a few weeks break and buy some replacement cells.

Here's the current phenomena, and I'm wondering if anyone has input: I will get the red battery light every now and then at about 123V-124V. I charge to about 13 bars and disconnect the charger to avoid overheating. I'm actually looking good with about 140V-142V at the start of a ride, with 130V at the end. The voltage will stay up for a couple of days, but after a few charges, a full charge only gets me up to 135V-136V, not quite enough to get me the 12 miles to work. Should I schedule in a weekly ride to run down to 123V-124V, get a light, and charge from 0 bars to keep my voltage up for the week? Mind you, throughout the process the temperature stays down below 35°C.

Any thoughts?

Sounds like your battery has a much higher self-discharge rate than what the software is expecting.

The Lairds software would fix your problem and possibly increase the range.

I've been quite diligent on the charging regimen, making sure to stay out of the 3A phase to avoid overheating. I haven't seen temps over 40°C in over 5 weeks. I still have range issues, which I hope to address when I have a few weeks break and buy some replacement cells.

Here's the current phenomena, and I'm wondering if anyone has input: I will get the red battery light every now and then at about 123V-124V. I charge to about 13 bars and disconnect the charger to avoid overheating. I'm actually looking good with about 140V-142V at the start of a ride, with 130V at the end. The voltage will stay up for a couple of days, but after a few charges, a full charge only gets me up to 135V-136V, not quite enough to get me the 12 miles to work. Should I schedule in a weekly ride to run down to 123V-124V, get a light, and charge from 0 bars to keep my voltage up for the week? Mind you, throughout the process the temperature stays down below 35°C.

Any thoughts?

The 3A charge at the end is very important to keep up with the self discharge....don't skip it

The best charging regimen is to use a timer, so the charge process completes immediately before riding

The problem is nimh batteries have the highest self discharge rate when they are warm or at high state of charge.
Minimise the amount of time the battery is at a high state of charge and the self discharge correction becomes accurate.

142V is only around 80% charged, while 140V is only 60% (roughly), 136V is closer to 40%

Loading The Laird's firmware is also a good idea, mainly because it reduces the heat up near the end of charge by charging at a lower rate.

Matt

Can someone send me a link for the Laird's software, along with directions/necessary hardware? Is it difficult to do?

Best is to start with reading this thread:

http://visforvoltage.org/forum/12321-latest-may-2012-software-instructions