Dan,

Following our conversation yesterday about warranty coverage for the four Deltran Power Tender Plus chargers that I sent back, I visited your website at batterytender.com to look at the product documentation available there. Based on that information, as explained below, I cannot agree that these chargers were misused in any way. I have also included two photos showing the location of the chargers.

From the notes I jotted down during our conversation, the claim of misuse was made on a few different points. These were misuse due to:

¥ improper battery size (batteries are too large for the charger)
¥ long operation times (due to battery size, demanding application)
¥ high charger temperature (ventilation)
¥ excessive ambient temperature (inadequate ventilation)

Before I go over these points, I'd like to state again that as far as I could tell, the chargers themselves were not damaged. The fuse holders attached to the chargers melted, which created a high resistance connection to the battery and caused the chargers to no longer charge the batteries properly, though to varying degrees depending on the charger. I cannot see how this could be due to anything but either material defect or flawed workmanship in the fuse holder, i.e. bad crimp connections that overheated.

From http://batterytender.com/product_info.php?products_id=7:

"¥ Charges both flooded & sealed maintenance free lead acid batteries.
 ¥ Charges any size (capacity) lead acid battery."

Clearly, it states here that the Power Tender Plus is suitable for charging any capacity lead acid battery. I am using each charger to charge one 92Ah sealed lead acid battery. From the Product_Instructions_LWOB.pdf:

"Some large automotive or marine, deep cycle type batteries may take more than 24 hours to fully recharge."

I typically discharge the batteries no further than 50% DOD, and the chargers go to the float charge in about 12 hours. Nothing in the product documentation backs your claim of misuse due to improper battery size, nor does it state that this is an excessively long charge time.

As for the high charger temperature, the Product_Info_LWOB.pdf document states that the maximum operating temperature is 50C, typical. This would be approximately 122F. From the Installation_LWOB.pdf:

"Caution -- It is possible that part of the charger outer case may reach as high as 70C (158F) during normal operation..."

I don't have the equipment to accurately measure the outside case temperature on the chargers, but I regularly check them by holding my hand on the case surface after they have been charging for several hours. They do get quite warm, but hardly more than 50C, and never close to 70C--I wouldn't be able to hold my hand on the charger without getting burned. The installation document also states that 70C may be attained during normal operation, and does not say that this indicates inadequate ventilation, or that it constitutes misuse. From this, I feel that I am well within the operating temperatures outlined by Deltran.

Because the problem is with the fuse holder, and not the charger itself, you stated that this may be due to very high ambient temperature, causing the fuse holder to overheat. As you can see from the photos, the fuse holders are not touching the charger case, and so the ambient air temperature would have to be raised to the point that the fuse holder could no longer handle the charger supplied current of 6A. Excessive current is not the cause, as the fuses have not blown. (I did attempt to remove one of the fuses from the melted holder which caused the fuse casing to come apart.) You stated that these fuse holders are rated at 20A. I don't have information on that particular fuse holder, but for a fuse holder that is rated at 20A to melt at 6A would require a huge increase of ambient temperature, something that is not happening inside the car or under the hood--the temperature inside the car is not more than a few degrees warmer during charging than the outside air temperature.

The Deltran documentation makes it clear to me that despite the demanding nature of this application, it does not constitute misuse of the charger, and further, because of the kind of failure, that the cause is either with the materials or workmanship used in the construction of the fuse holder. I am disappointed that a charger "backed by the reputation of the undisputed battery charger industry leader, DELTRAN" is not backed by better warranty support.

If these chargers will not be replaced, please let me know in writing the reason(s) these chargers are not covered, and return them as soon as possible.

Regards,