Small spark when I connect the batteries on the 002?

[Silverbulletsmith]

I have noticed that I get a small spark at the battery terminal when I touch the the cable to them. The spark is smaller when I touch them together rapidly repeatedly, and noticeably bigger when I give it a few seconds between touches.

Testing current between cable and terminal shows 0.00/0.01a with the Fluke 77, which strikes me as odd, I do get the same spark when I touch the test leads.

My best guess is a capacitor somewhere in the charging circuit leaking.

Anybody seen this?

 

[dependable]

I have the same thing in my latest 003. I was thinking it was related to jammed shut of solenoid, which tends to stick in off position, but have not verified that yet. Please post what you find out.

 

[doghead]

Mine did that too.

I added a battery disconnect for when it's not in use. It also has a solargizer on it.

It has been working fine like this.

 

[Speddmon]

I have noticed that I get a small spark at the battery terminal when I touch the the cable to them. The spark is smaller when I touch them together rapidly repeatedly, and noticeably bigger when I give it a few seconds between touches.

Testing current between cable and terminal shows 0.00/0.01a with the Fluke 77, which strikes me as odd, I do get the same spark when I touch the test leads.

My best guess is a capacitor somewhere in the charging circuit leaking.

Anybody seen this?

Yes, there is a capacitor located at the voltage regulator, and yes it probably is going bad. Quite a common thing for a lot of people, and covered a few times.. Unless your machine quit charging, leave the batteries hooked up and forget about it

 

[Triple Jim]

It would be normal to get a small spark when first connecting the battery, as the 50μF capacitor charges, even if it's not leaky. Doing it again a few seconds later shouldn't make the spark because the capacitor should already be charged. Ten milliamps will take months to significantly discharge the battery, but a disconnect is always a good idea.

 

[PeterD]

A good capacitor will draw current as it charges. The only acceptable test for the above perceived problem is to put an ammeter in series with the battery lead and measure long term current after any capacitors have charged.

 

[Silverbulletsmith]

Well, I assume the most likely cause is a cap that has deteriorated (aged) to the point of internal leakage. I see Dependable and Doghead have the same behavior.
I've read up on the Solargizer and I see it's pretty universally highly thought of. That, along with a disconnect switch, aughtta hold me 'till I get around to finding that cap and replacing it.

Thanks, guys!

 

[Ktighe]

I have two MEP-002a's and they both do exactly as Silverbulletsmith describes. They have good batteries but after three months of no use they become drained. (Yes I know I shouldn't let them sit for three months). When I put a Volt Amp Ohm between the terminal and battery and it reads 2.6 mA.
I discovered that removing the fuse stops the current drain, so that's my solution for now. Is it possible that this is just they way they are?

 

[glcaines]

For what it's worth, my MEP-003a doesn't spark when I connect the battery cables. I just checked again to confirm. I keep a Soneil Model 2404SX1 charger on mine continuously to keep the batteries charged and in good condition. I have two more I keep on my two deuces. Great little chargers.

 

[Isaac-1]

A couple of more points of comparison, my MEP-002a does spark, and my MEP-003a does not

 

[Triple Jim]

I've seen it with my 003A, but it's a capacitor charging kind of thing. One spark, and then if you disconnect and reconnect, you don't get another one. I don't know of anything that should be drawing a few mA continuously. I guess you could leave the meter connected and disconnect things until it drops to zero to find the cause.

 

[Ray70]

I've got 3 MEP-002A's and all 3 spark when connecting the batteries. I've always assumed it was a leaky cap on the regulator like others mentioned. My solution was to get $6 battery disconnect terminals ( battery terminal with a green knob on it) from Harbor freight and install on the wire connecting the 2 batteries together. I've also wondered if you had 1 battery that was starting to go bad, if it ( I assume it would) would pull down the other good battery if they were left connected together. I believe the TM actually says to pull off the battery wires if the unit will sit for more than a month.

 

[swbradley1]

Leaking or not when you hook up the battery to a fully discharged capacitor you will usually see a spark. (Depends on V and C)

Based on the observed current of 10mA and assuming 24VDC that gives us a pure R of 2,400 Ohms. Tau(Time in seconds for 63%))= R*C (C is in Farads) so we have 2400*.000050 = .12S

In a perfect world you should see one spark and if let it sit for more than a quarter of a second it would be fully charged and pulling the batteries off and putting them back on would never exhibit a spark. But if the cap is discharging faster then you would.

I like using some of my old high school electronics stuff.

 

[Triple Jim]

You're assuming the 2,400 ohms is in series with the capacitor, but if the 10 mA is constant, it's not.

 

[ctfjr]

You're assuming the 2,400 ohms is in series with the capacitor, but if the 10 mA is constant, it's not.

ftw

The 'leakage' is in effect a resistor in parallel with a 'perfect' capacitor - if this current is all due to leakage.