Batboard

Does anyone have any experiance with Deltona "battery tenders"? We have had one go out in a fire engine in the county, and are wondering if the problem it has is common. The charger is marked as part number 022-0082-E1, it is rated at 20 amps @ 12 VDC, and came off of an E-One truck. Four power MOSFETs on the board inside failed (catastrophically). I haven't done any in depth investigation yet, and am wondering if anyone has seen this before and knows what caused the FETs to fail.

Hello Ryan,

I think your Deltona Battery Tender is manufactured by Deltran in China. Deltran's headquarters, engineering and service support groups are located in Deland, Florida. Here's the web site:

http://www.batterytender.com/

Deltran claims their products are protected against direct shorts on the output circuitry. In your case I think your Battery Tender took an "Induction Surge" and there's a remote possibility that the Power FETs were not protected by the clamping Diodes on the printed circuit board. This surge would be very similar to not having a diode across a relay coil as the voltage field collapses then sending a voltage "spike" back to a transistor and blowing the device.

Depending on the age of your Battery Tender, having a 2 year Warranty, you may want to contact and "alert" the supplier and/or manufacture of this failure.

Dan

Thanks for the info, Dan. We're already aware of most of what you posted, but your assesment of the possible cause of the failure is new info. In fact, I'll go you one further on the location of their "headquarters" in Deland. The same number is listed for both Deltran, and a day-care service! Maybe the kids build the chargers between naps? Either way, the marks on two of the legs of all four of the FETs that look like where they were arced over definately support your theory of a possible surge. Doesn't look like anything else was damaged, though, and the FETs are less than $2.00 each, so we'll probably try repairing it. BTW, the unit is over two years old, so the warrenty is gone.


Oh, and one other thing, I don't go by my first name, but my middle name, Brett. Thanks for the reply!

Hello Brett,

I had one other thought about how the Battery Tender is being (possibly improperly) used and the saying is, "A picture is worth a thousand words but being at the Fire House when the employees connect or disconnect the Battery Tender might provide the key problem why this unit blew all four FETs simultaneous." FETs in general can't handle Surge or Spike Currents being applied through them and turn into three legged fuses.

The root cause could be a possibility factoring in the human being who connects and disconnects the Battery Tender's cables from the E-One Vehicle's Battery in a hurry, who didn't remove or shut off the 121V AC Primary Power to the Tender unit. Even though the Battery Tenders provide 12V DC @ 20 Amperes to the Batteries, when quickly disconnected, they can produce sparking and voltage arcing between the charger and the load.

I would check all the Diodes for leakage or opens although you've stated that the remaining components appear to be okay. I read somewhere that these Deltran Battery Tenders are Microprocessor driven. This makes me wonder if the "Microprocessor" has an input or output problem. Not having access to Deltran's schematics puts me at a disadvantage trying to guess how these units were designed. Thank goodness the FET devices aren't too expensive when purchasing and replacing them,

Dan

Dan, I will double-check, but I don't think the batteries were ever disconnected/reconnected before the charger went out, unless you are talking about the battery master switch, which the charger is not ran through. The last time I saw something like this was in the 72v to 12v converter board in a locomotive Spectra. The shortline I used to work for would send a few a month to the shop with the converter board flashed over, and we couldn't figure out what was happening to them. We finally started to keep better records of what was going on, and it turned out that every time the mechanics had to jump off a locomotive, there was another burnt converter board. Started disconnecting the radio before jumping one off, and the problem went away.

Thanks for the replies, and I'll try to do a little more investigating on this end.