Thanks Myles. I would have liked to have been able to see the PakTrakr readings while the voltage was up.
Do you think that because I didn't run the batteries down when leaving the harbor the batteries were full and would have had more resistance to current?
If I motor for a short time, say 2 or 3 minutes, then turn the charger on the amps into the batteries drops to 0 in less than a minute. I'm guessing this a function of the "smart" charger sensing no need for charging. Is this because there is more resistance due to the fully charged battery bank?
If this is the case could we all be getting paltry regen numbers because our battery banks are not drawn down low enough when we are checking?
Mike, have you checked regen at a low SOC?
Mark
Santa Cruz
--- In electricboats@yahoogroups.com, "Myles Twete" <matwete@...> wrote:
>
> I'm not familiar with the controller settings required for regen, but it may
> be that with the motor in forward and with "miniscule throttle" and a
> following wind, the controller could have been charging the batteries up for
> some time until you switched it to neutral. Assuming flooded cells, at
> 54.89v, that's 2.29v/cell, or 6.86v/battery. Fully charged batteries will
> typically be 2.14v/cell or 6.42v/battery or 51.36v. In your case, you saw
> 51.7v when in Neutral, which is about right for a fully charged pack.
> According to charging curves, even a C/40 charge rate (or less) could cause
> 2.29v/cell, hence for T105 batteries, even less than 5-amp charging rate can
> cause such voltage rises. I have some 15v/6a charging 'bricks' (laptop
> power supplies) that I've used to occasionally equalize series pairs of
> T105's on my electric car. I attached this setup after the normal series
> charger completes its charge. And at 6amps, the batteries will reach
> 2.5v/cell.
>
>
>
> In your case, you may have had well under 5amps of regen charge current,
> then when you switched to Neutral, no more regen was taking place and the
> battery voltage relaxed to 2.15v/cell or so.
>
>
>
> In case this helps-
>
>
>
> -Myles Twete, Portland, Or.
>
>
>
> From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
> On Behalf Of acsarfkram
> Sent: Sunday, April 24, 2011 6:47 PM
> To: electricboats@yahoogroups.com
> Subject: [Electric Boats] regen
>
>
>
>
>
> I had something interesting happen today. I was trying to get some numbers
> on regeneration with the Watt Meter that I mounted at the helm. I was not
> able to see any amps recorded. I'm thinking the Turnigy Watt Meter might not
> be sensitive enough to detect low amps. But with the motor in forward and a
> miniscule amount of throttle I noticed that the volts were reading 54.89.
> That seemed odd so I shifted into neutral and after a a few minutes the
> battery voltage was 51.7. Something is going on. The bank was used for only
> 2 minutes at the start of the day - there was a nice 12 knot wind over the
> starboard stern on the way out of the Harbor. Great day, at one point
> surfing down a wave I saw 9.1 knots on the GPS!
>
> Mark
> Santa Cruz
>
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