Windlass causing unusal drop in voltage

[matt_unique]

Napoleon is back in the water and looking great! During my shakedown cruise for this season I noticed when I engaged the windlass, with engines running, it would drop my voltage to the point where it would reset my GPS/Radar system (this has never happened before).

Using a multimeter I checked the voltage at the applicable bats. With engines off my house reads 12.49 volts, stb start bat reads the same, and the port start reads 12.6 volts. Of course only the house and stb start powers my windlass and electronics (I always have my stb bat switch set to 'Both' with engines running).

I have a paper schematic of the back of my windlass switch. The leads on the side are DC 'in' and the leads at the bottom of the switch are DC 'out' leading to the windlass. I checked the voltage on the DC 'in' leads on the windlass switch and the loss is only .09 volts from the bat. I tested the loss at the DC 'in' leads on my main fuse panel behind the helm and it reads a bit more of a drop - .14. Said another way, the wiring leading to my windlass switch is more efficient than the wiring leading to my main fuse panel. That to me rules out problems from my bat to the windlass switch.

With engines running - the DC 'in' on the windlass switch reads 14.43 volts. With the windlass engaged, the DC out on the windlass switch reads 11.72 volts. I don't know if that is within the correct parameters.

Based on what I think I know so far - by all means chime in and correct me if I'm mistaken - the problem is either the switch itself (perhaps someone else knows the acceptable voltage drop with switch engaged?), the wiring leading from the switch to the windlass, the wiring contacts on the windlass, or the windlass itself. There must be some corrosion or a loose contact between the switch and the windlass leading to high resistance.

Thanks for the suggestions.

--Matt

[Will-C]

Matt,
I would get an amperage meter on the leads going to the windlass. Check for amperage under load going to the windlass. I would try to find out what was normal full load amperage and see if you are in that range If the problem is in the windless which causes excessive amperage load that might be drawing down your voltage a little because of the extra load. You could also test the windless by jumping out the switch momentarily. Many have recommended using a contactor (a relay made to handle larger amperage loads) That way the switch just switches power to the contactor's coils and the contactor's contacts switch the heavier load going to the windlass which reduces the load on the switch making the up and down switch last a lot longer. Better yet score on a replacement switch which can't be all that bad to have in stock. Checking the new switch using a multimeter set to ohm's would show you what normal resistance is on a good switch a higher ohm reading on the old switch would indicate that the switch contacts are deteriorated or deteriorating.
D.D.

[B~C]

time for new batteries or a good charging. A fully charged battery should read 12.6 & that reading really doesn't mean much. A old tired battery can read 12.6 but not have enough capacity to hold a suitable voltage while loaded. A bad, or corroded connection, would cause reduced amperage draw and less of a voltage drop at the battery. Batteries just hate sitting around, the plates get sulfide crystals on them and it causes them to loose capacity

here's a test for you, watch your battery voltage as you load the battery (starter, windlass, or, better yet a load tester) if the voltage just drops (below 9.6 is somewhat the standard) your battery needs help, watch what the voltage does after the load is removed. If the voltage climbs back up to 12.6 the battery is worn out and needs replacing. If the voltage does not go back up & stays on the low side, it may just need to be charged up good and retested

march on down to wallyworld and pungle up the dough for a new set of batteries

another thought, your voltage is low so your windlass will try to draw more amps due to low rpm (cemf) and is trying to produce the same wattage

[Chris]

If your batteries are only reading 12.49 volts they are not in good condition. My guess is that deteriorating batteries are the cause of your sudden problem.

[ghone]

I am with Ken and Chris if you have original 5 year old batteries they are likely done. My new windlass install from Lewmar came with a contactor( relay) as the setups pushing loads through the toggle were proving problematic. Joe (sea wolf) gave a good generic relay cole Hersee 24450 a while back or get one made by your windlass manufacturer. It keeps the heavy loads off your toggle switch so will perform better. Good luck. George

[B~C]

that relay is a good addition to the circuit, I gots to get me one. we've had a few toggle switches fail...as in short ...on the work boat windlassssss.....it aint cool when you're sitting at the dock and the anchor starts to deploy or spool up on it's own

[BrentB]

Bad batteries and/or poor connections are my first thoughts

Many places like WalMart and Sam's Club, and auto parts stores will perform a detailed analysis on batteries including a load test and provide a printout for free and also willing to sell you replacements.

I thought I had a bad auto battery but after testing the battery was fine but the battery cable bolt was cracked and needed to be replaced.

[Sea Wolf]

Here are those schematic diagrams mentioned above:

They're for a Cole-Hersee 24450 relay, but the principle is the same with various types of 12v reversing polarity DC contactors.





Joe.