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intaudiom asked

Wiring for IP22 charger on a narrowboat

Hi All...I have an elderly narrowboat fitted with four Halfords HLB681 leisure batteries connected in parallel and one Yuasa YBX3096 starter battery....normally these are charged by the boat’s alternator, but I’m going to be hooked up to shore power for a few months and not running the engine...I have acquired an IP22 3 output 20A charger to charge the batteries (I don’t have solar power) but the manual merely says “connect the charger to the battery, or batteries”....would I be right in thinking I connect one output to the starter battery and one to the four parallel leisure batteries?...but what gauge wire, and do I need a fuse in each positive connection, and if so what rating?....charger will be mounted approx one metre from the batteries...any help/advice gratefully received!

bluesmart ip22
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2 Answers
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sdowney717 answered ·

So you have 2 battery 'banks' then, one 8 or 10 gauge wire to the starting battery, and one 8 or 10 gauge wire to the 4 other paralleled batteries. Each bank output can do a full 20 amps, but the total of all 3 bank outputs wont exceed 20 amps. Example, starter bank may draw 5 amps, and the other 4 batteries together draw 15, 5+15 =20 amps total. I did not fuse my charger, I thought it's output was regulated? But I understand since one end is connected to a massive battery, if the wires short out, they would melt and burn if not fused. So the fuse should be used. Fuse for the ampacity of the wire gauge you use, fuses protect the wire, not the equipment. 10 gauge is a 30 amp wire, so a 30 amp fuse. Fuse should be slow blow style is what I think, but likely you will end up using a typical automotive plastic spade style fuse and fuse holder. Another idea is use a 30 amp DC breaker.

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sdowney717 answered ·

Installing a Marine Battery Charger | BoatUS

Fuse used here attaches direct to battery terminal. I might be interested in doing a fuse too.

Mine is an old boat from 1970, and chargers were never fused on it AFAIK.

My charger wire attaches to the back of the 3 way switches to the always on lug which is an extension of the battery lug, I suppose those wires could be moved down to the battery if long enough, OR, I could fuse right off the switch lug.

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