Hi Matt,
I always assumed that the pre-charge resistor was to reduce switch arcing, not necessarily to protect the controller. I could be wrong about that. Might want to check with the controller mfr.
Jim
--- In electricboats@yahoogroups.com, matt elder <mattelderca@...> wrote:
>
> Thanks for the reply.
> On the charger, the connections were directly to the batteries, the entire
> controller and batteries were in the same box.
> Anyway, the caps don't really need to be connected all week as the boat sits and
> charges. The precharge is really to stop the big inrush from playing on the
> controller, I don;t feel comfortable with it, but it could just be me.
> Your comment on running without precharge is a good one. I thought of that and I
> am not against it. My switch is heavy enough for sure, and as I said I'm not
> worried about it, just the controller. I will say that even at 24 V the inrush
> to the controller is significant!
> I guess I was just looking for confirmation the controller should stand up to it
> fine. They seem to survive the golf cart world OK, and I imagine there's plenty
> of abuse going on in that field.
>
> The charge controller, batteries and PV panels were upgraded this season as
> well, so charging should improve anyway.
> For now I'll wait until power up and play with it then, I'll run without
> precharge and think about more.
>
> Happy sailing!
>
> mattelderca
>
>
>
>
> ________________________________
> From: luv2bsailin <luv2bsailin@...>
> To: electricboats@yahoogroups.com
> Sent: Wed, April 13, 2011 6:32:42 PM
> Subject: [Electric Boats] Re: Question on precharge for controller
>
>
> Interesting question. Not sure exactly what's going on with the solar charger,
> but you might try a different connection point that's closer to the batteries.
> The diode thing you suggested might work too, as might a higher resistance value
> for the pre-charge resistor. Your comment about charging the caps being
> unnecessary doesn't make sense to me. I think that's the whole point of having
> the pre-charge resistor in the first place - to keep the controller's filter
> caps charged all the time so you don't arc the power switch every time you turn
> it on.
> You can get away with no pre-charge resistor if your switch is hefty enough.
> I've run Alltrax controllers for several years on a couple different boats
> without using pre-charge resistors. There is a significant "pop" when I turn on
> the main cutoff, which is one of those big round marine battery switches, rated
> at 3 or 400 amps. With such a beefy switch I think it will take hundreds of
> cycles for it to erode away enough contact material to make a difference.
> Switching it quickly probably helps a little too. I'm using 48V, your 24V system
> should produce even less arcing.
> I say try it without the resistor and see if the charging situation improves.
> That would also confirm your theory about the caps being the culprit.
> Let us know what you find out.
> Jim
>
> --- In electricboats@yahoogroups.com, "mattelderca" <mattelderca@> wrote:
> >
> > Good day all,
> > I've been away from this group for a while but I see some of the regular people
> >are still around.
> > I have a bit of a puzzle that I just can't seem to resolve in my head.
> > It is in regards to precharge of my Curtis type controller and I was wondering
> >if someone here may have a simple answer.
> >
> > Here is the setup,
> > 24 volt solar charged pontoon boat with twin MinnKota's controlled by a Hyundai
> >golf cart controller. ( similar to a Curtis)
> > I have a manual battery disconnect (newly added), key switch for the controller
> >on, and reversing contactors after the controller.
> >
> > Previously I had no battery disconnect so the precharge was done once when the
> >batteries were connected. It served me fine for the last 6 years, but I was
> >always a bit concerned that I had no emergency off.
> > We don't need to debate that.
> >
> > One other problem that came up with this setup was the fact that the capacitors
> >held the voltage high and fooled the solar charge controller into thinking the
> >batteries were charged. They were, just not fully topped off.
> >
> > Now I am re wiring my controller and have added the manual battery disconnect
> >switch. I know I should have a precharge resistor across that disconnect but I
> >don't want the charge controller to "see" that the caps are connected. I could
> >add a switch to the resistor but that throws another thing to think about before
> >turning on the power.
> >
> > I have gone over a few possible wiring schemes but wondered what some others
> >may have done and what issues they may have had.
> > My final thought is to have a diode in series with the resistor thinking this
> >may keep the caps and batteries separated enough so the charge controller isn't
> >effected. This would keep the caps charged all the time as well, which is not
> >necessary. I would like a scheme that would keep the controller completely out
> >of the circuit until the main disconnect is turned on. But I can't think of an
> >idiot proof way of doing it.
> >
> >
> > Got any suggestions?
> >
>
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