Anchor windlass battery question

[biscuit]

I am about to fit an electric windlass: 700w, with total cable length about 16m : the installation tables indicate that 25sqmm (4 AWG) main cable should be OK. I wonder if my present "leisure" battery, rated 85 amp hrs will be sufficient, (always used with the engine running) or do I need to change it to something bigger?

 

[Red Admiral]

I am about to fit an electric windlass: 700w, with total cable length about 16m : the installation tables indicate that 25sqmm (4 AWG) main cable should be OK. I wonder if my present "leisure" battery, rated 85 amp hrs will be sufficient, (always used with the engine running) or do I need to change it to something bigger?

Depends on alternator output. Your windlass under load will take about 60 amps. If you have, say, a 50 amp alternator and run the engine at not less than 2000 rpm you should be OK. Your alternator belt needs to be in good shape and properly tensioned.

On my boat with 1000 watt windlass I used 36 sq.mm. welding cable and, once engine is charging, parallel the two existing batteries. Had no problems.

 

[SHUG]

In the auto business, the standard cable for 60A is 8.5mm.sq. That is of course for short runs so your 25mm.sq sounds adequate. It sounds a lot more but it is just less than twice the diameter