Smart Charger Voltage 15.9 volts ? (VEC1093DBD)

Got it. Last time I missed the two rear screws that were hidden by the bottom cover.

Any hints on getting the strain relief off the charging cables?

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Channel locks solved the strain relief problem. After all that I wasn't able to get any numbers of that diode to see if its the temp sensor. There was another similar looking diode on the output side of the fan. The raised diode was on the input side.


I was hoping for some kind of adjustment on the board, but I didn't see any trim pots.


I'll have to wait and see what tech support says before doing anything more drastic.
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The handle has screws in it --no need to cut the grip. ISTR the bottom cover for the storage bin comes off first then the upper half. Don't force anything, it all comes apart ok. Note there are little screws and big screws and where each size goes for putting it back together.

BFL13 wrote:
You could put the battery in the hallway on a mat or something that didn't matter. IMO you need to check it at room temperature as your baseline.

If we're talking about a short test just to see what voltage it tries to charge at I could do that. I can't leave it on for any period of time. It will stink up the house with fumes.

BFL13 wrote:

I took mine apart to get at the fan. It just has a lot of screws to undo, not complicated. Easier with a magnetic screwdriver with those screws down in their holes.

I'll have to look again. Maybe I missed something. I got the bottom partially apart by removing all the screws on the back. The power cord going from the lower section to upper section stopped me. It seemed like to get the top half apart you needed to remove the rubber grip on the handle (cut it off) and it wasn't clear what was holding the upper case together(with the fan in it). I thought it might have been glued.

BFL13 wrote:
Not much you can do with anything in there though.

I expect the temp sensor is in there. I think it wold be better to replace it with a potentiometer or an external temp sensor. This may be it, I can't think of any other reason for it to be up in the air like that vs close to the circuit board, and when I put a 250 watt light up against the case in front of it the voltage goes down:

You could put the battery in the hallway on a mat or something that didn't matter. IMO you need to check it at room temperature as your baseline.

I took mine apart to get at the fan. It just has a lot of screws to undo, not complicated. Easier with a magnetic screwdriver with those screws down in their holes. Not much you can do with anything in there though.

I can't bring the battery into the house - too much of a chance of making a mess.

I can tell you that the temp compensation has nothing to do with the battery temp.

I was charging a battery in the basement ~55 degrees and the battery was warm to the touch - at least 80 degrees, probably more. The acid was bubbling very hard. This thing was still going along at 15.2 volts.

I assume that if this thing is working properly that there would be minimal bubbling at any stage of the process.

I sent an email the the importer, we'll see what happens there.


Has anyone taken one of these apart yet - for example to replace the fan?

I'd like to know how to get it apart without breaking anything or cutting off the rubber grip if that's possible.

I don't think the sensor would be near the fan. The unit gets quite warm inside when it is running and that is what the fan is for.

Ideally, the temp sensor would be in the neg clamp so it goes on the neg batt post. But then, the instructions say to put the neg clamp on the frame when the batt is neg frame grounded (to prevent sparks) so that wouldn't help.

I still recommend leaving the batt and the charger at 72ish for several hours and then see what it does for your baseline, then decide if it is working right or not.

BFL13 wrote:

OP, I suggest you put the charger in the house at more like 72F and a battery and wait till everything warms up for a goodly time, then try it out to see what its own voltage says and also what your other meter on the batts says to confirm. It may still be in shock from all those temp changes all of a sudden. Or not. If it is busted, there might be a warranty. Mine works ok and so do many others'

It responds to temp changed pretty quickly. I tested it with a 250 watt light. The temp sensor must be near the fan. If I heat it up with a 250 watt light I can get the voltage to drop. Remove the light and it goes back up. Heating up the battery terminals with the light does nothing. Warming the charger with the light in other locations does nothing as well.

That's where I got the table which I saved/printed. From one of the many Marks :)

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26670835

OP, I suggest you put the charger in the house at more like 72F and a battery and wait till everything warms up for a goodly time, then try it out to see what its own voltage says and also what your other meter on the batts says to confirm. It may still be in shock from all those temp changes all of a sudden. Or not. If it is busted, there might be a warranty. Mine works ok and so do many others'

I can handle disconnecting the battery for charging as long as this thing isn't going to over cook them.


I was surprised to see such a high voltage since this charger seems to be so coveted on this forum and it has a features for jump starting a car and presumably charging in place.

We already established that, at least in cold weather, there's a risk to trailer electronics. I suspect that a similar risk occurs with a car/truck. I'd hate to fry the computer as a result of charging a low battery on a cold winter morning.

BFL13 wrote:

mrekim wrote:

BFL13 wrote:
It should be around 14.8 at 68F.

If you have somehow hit Equalize (green light flashing) by poking a pin in the hole for that, then it would go into the 15s (15.7v nominal for Equalize.)

Nope, it's not in equalize.

I went and got an IR temp meter. I was off the temp in the basement. I shot the battery and the charger and got 55-56 degrees. Doe that seem more reasonable for a regular cycle?

The table I have for equivalents to 14.7v at 77F is that at 55F it would be 14.99v. So it may not be that far out of whack, but at the high end of whatever its +/- margin of error is?

I have not done a calibration check on mine but it certainly does the temp comp. It will go over 16v in Equalize in cold temps.

I agree with BFL.

I have a Schumacher SC-12000A multistage Speed Charger. When charging a battery outside in cold weather my charger would peek out at 16.1 volts in cold temperatures of 10 to 20F. This would be the last portion of charging when the battery is above 95% SOC. The amps would drop to 2 amps and tapering while the voltage held the peak to shut-off. If temperatures were closer to 32F the peak would be around 15.5 volts. The charger never allowed the battery to overheat. Last winter BFL had a post were we had some graphs of different charging profiles done in cold weather.

This portable chargers were not meant to be used similar to the chargers installed in RV's. If charging batteries installed in RV's the batteries should be on "disconnect" to protect electronics in the RV circuits.

My model of charger was a heavier duty version compared to the the BD (Vector) 3-stage charger. It was generally used in the racing industry. They discontinued this model which was the largest multi-stage portable in their line. I suspect some people may have used it in ways that could have damaged electronics in a circuit.