ProNautic Battery Charger Install Problem

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WayWeGo
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ProNautic Battery Charger Install Problem

Post by WayWeGo »

When I installed a ProNautic 1230P battery charger in our boat, I made a logical but poor component choice that could have resulted in a fire!

The instructions call for a 40A fuse at the battery, but I could only find a fuse holder rated for 30A at any of the local chandleries. With the boat in the water, dead batteries and a bilge full of water, I bought it along with a 30A fuse and planned to upgrade them if the fuse ever blew. My thought was that a fuse holder rated for 30 with a 30A fuse was marginal as per the instructions, but the only risk was blowing a fuse and the batteries not charging. Boy was I wrong!

Fast forward five years and I noticed that one of my batteries was not charged and the charger was not doing anything about it. Upon inspection, I found that the connection between the battery and the charger was broken, and the cause was the fuse/holder had melted! On the side that was not charging, the fuse holder and fuse crumbled into dust in my hands when I tried to take it apart.
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Re: ProMNautic Battery Charger Install Problem

Post by WayWeGo »

When I inspected the other battery's fuse, I found that it had also overheated.
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Re: ProMNautic Battery Charger Install Problem

Post by WayWeGo »

Since these were not cheap no-name fuse holders, I contact Blue Sea Systems tech support to see what they thought the cause might be. My concern was that this was not a random failure because it happened to both sides and with the 30A fuses not blowing, I had not exceeded the design criteria.

After some discussion, we concluded that while the fuse holders and fuses are rated for a maximum of 30A, they are unable to handle the heat generated by a sustained 30A of current over a longer time. Blue Sea Systems generously upgraded me to some of their significantly more expensive MAXI fuse blocks at no additional cost to me. These are capable of a maximum current of 80A, so plenty of excess capacity for my application. The install was a little more complicated, but I am happy with how it turned out and impressed by how Blue Sea Systems stood behind their product.
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Re: ProNautic Battery Charger Install Problem

Post by BobCT »

Wow, that’s scary. During my repower, I added fuses to the charging circuit which I never had before (also the same charger). I used MRBF style fuses but only because I called Pronautic or I might have done the same.

But, I thought the fuses had to be within 6” of the positive battery terminal? I have three banks and added one to each battery on the positive posts. Each one connects to the feed coming from the charger.

Are yours serving this purpose or in addition to the battery end(s)? If the output of each fuse (from your MAXI blocks) just connects to the battery then that section of wire is essentially unprotected.

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Re: ProNautic Battery Charger Install Problem

Post by WayWeGo »

Bob, that is a good point to mention. The MRBF fuses would not fit into my battery boxes so I went with the MAXI ones instead. While not obvious from the photo, the fuses are about a foot from the battery terminals.

ABYC E-11 recommends that the fuse be within 7" of the battery. Since this was not easy without some significant changes, I got as close as practical.
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Re: ProNautic Battery Charger Install Problem

Post by BobCT »

Got it, sometimes the physical constraints on a boat make the decision for you. I was able to rotate my fuses on the battery studs so they cleared the battery cover.

This is a relatively newer ABYC requirement (charger fusing at ea battery) and probably a good idea for everyone to consider doing. It’s a quick rainy day project.


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Re: ProNautic Battery Charger Install Problem

Post by Boppy »

Great post! I have been using MRBF for years, but I had room in the old battery boxes for them. When I went over to LFP for the house bank I still used MRBF but installed a pos and neg buss bar and attached them to the pos side of that. I don’t use or need battery boxes for the LFP because there is no acid to worry about or out-gassing either. I do have hold-downs for them, however. Glad Blue Seas helped you out. I used the same battery charger as you for years, but switched over to a Victron one after the battery bank changeover this year, which is mostly charged via solar panels at anchor, and alternator under power.
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