Trickydicky1 Posted March 3, 2019 Share Posted March 3, 2019 In my m/h charger unit the fuse marked up as engine battery keeps melting but not blowing.any idea what’s wrong..thanks Link to comment Share on other sites More sharing options...
sshortcircuit Posted March 3, 2019 Share Posted March 3, 2019 Bad connection by fuse holder. Replace fuse holder and most importantly use good quality fuses, not cheapos. Link to comment Share on other sites More sharing options...
aandncaravan Posted March 3, 2019 Share Posted March 3, 2019 Trickydicky1 - 2019-03-03 12:46 PM In my m/h charger unit the fuse marked up as engine battery keeps melting but not blowing.any idea what’s wrong..thanks Assuming the fuses are quality items and the correct value, repeat melting of a fuse usually means the fuse is passing current right near it's limit. Enough to generate heat to melt the plastic, but not enough current to melt the metal 'fuse' strip. Typically that might indicate that the Starter battery is either drawing too much current when charging on mains or that the habitation battery is tired and drawing more current than designed from the Alternator. Obviously any faults in the wiring, connections, etc could also be an issue. Maybe think about getting both batteries 'Capacity' tested (not drop tested) and check along the cable for poor connectivity, all the way battery to battery, including the battery clamps themselves. Have you had issues with the batteries discharging? Have you added a second battery or installed AGM batteries that can pull twice as much current through the wiring from the alternator? Some information on the motorhome and Electronics installed for the charging systems might be useful in providing a better diagnosis? Link to comment Share on other sites More sharing options...
plwsm2000 Posted March 3, 2019 Share Posted March 3, 2019 There is a big difference in the quality of "pound shop" fuses and branded ones from a decent manufacturer such as Littelfuse, MTA etc. The cheap fuses are often made from a plastic with a lower melting point. I wouldn't trust the current rating of them either. Even a branded fuse will get quite warm at higher currents. According to Littelfuse data sheets for ATOF fuses [url=] http://www.farnell.com/datasheets/1897221.pdf [/url], a typical 20A fuse drops nearly 0.1V when run close to its rating. This is about 2 watts which is quite high for a small size. The other thing to be careful about is the fuse holder and how many times you change the fuse. These parts don't last forever if mistreated. Link to comment Share on other sites More sharing options...
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