As­saulted Bat­tery

When it comes to se­cure bat­tery in­stal­la­tions, ac­cepted in­dus­try stan­dards might fail to con­sider real-world con­di­tions. BY STEVE D’AN­TO­NIO

Cruising World - - Contents - Monthly Main­te­nance by Steve D’an­to­nio

Bat­ter­ies must be tightly se­cured at sea.

The bow was en­veloped by yet another azure wave, and like all the oth­ers, it ex­ploded into a plume of snow-white briny mist, stop­ping our for­ward mo­tion. We were above the Arc­tic Cir­cle, far from any sort of as­sis­tance, and I thought for the hun­dredth time: I won­der how the bat­ter­ies are do­ing? Are they se­cure? Are the ca­bles tight? Is any­thing chaf­ing? Th­ese are the sorts of things I think about while on watch.

It’s not of­ten I differ with the well-es­tab­lished guide­lines set forth by the Amer­i­can Boat and Yacht Coun­cil (ABYC). The mat­ter of bat­tery in­stal­la­tion is one of a hand­ful of ex­cep­tions. Among other things, the stan­dard re­gard­ing bat­tery in­stal­la­tions details the amount a bat­tery is al­lowed to move af­ter it’s been in­stalled: “Bat­ter­ies, as in­stalled, shall be re­strained to not move more than one inch in any di­rec­tion when a pulling force of twice the bat­tery weight is ap­plied through the center of grav­ity of the bat­tery as fol­lows: ver­ti­cally for a du­ra­tion of one minute, and hor­i­zon­tally and par­al­lel to the boat’s cen­ter­line, for a du­ra­tion of one minute fore and one minute aft, and hor­i­zon­tally and per­pen­dic­u­lar to the boat’s cen­ter­line for a du­ra­tion of one minute to star­board and one minute to port.”

In the scheme of things, given this sort of lat­i­tude for move­ment, just about any piece of equip­ment — par­tic­u­larly items as heavy as a bat­tery — will even­tu­ally come to grief. If a bat­tery moves with ev­ery wave the ves­sel en­coun­ters — we’re talk­ing hun­dreds, or thou­sands, of times in a given pas­sage — the stress im­parted to the bat­tery, and the po­ten­tial for chafe or the loos­en­ing of ca­bles and con­nec­tions, is very real in­deed.

Based on my ex­pe­ri­ence in both the boat­yard and at sea, my pref­er­ence is for the com­plete im­mo­bi­liza­tion of bat­ter­ies. This can be ac­com­plished with a clamp-type strong back ar­range­ment, or heavy ratch­et­ing straps us­ing stain­less-steel buck­les. For­get the wimpy ny­lon strap with a plas­tic buckle; while fine for a run­about or ten­der, it is sim­ply in­ad­e­quate for large bat­ter­ies in seago­ing ves­sels. Com­plete im­mo­bi­liza­tion of bat­ter­ies be­comes more chal­leng­ing when they are in­stalled in boxes, par­tic­u­larly if the box is over­size, as so many are.

Con­trary to pop­u­lar be­lief, com­pli­ance with ABYC Stan­dards does not man­date that bat­ter­ies be in­stalled in boxes. In fact, un­less they are of the flooded va­ri­ety, I’d ar­gue bat­ter­ies are bet­ter off with­out boxes; elim­i­nat­ing them of­fers bet­ter ven­ti­la­tion and makes reg­u­lar in­spec­tion far easier and thus far more likely. Once again, the stan­dards state: “Pro­vi­sion shall be made to con­tain in­ci­den­tal leak­age and spillage of elec­trolyte. Note: Con­sid­er­a­tion should be given to: 1. the type of bat­tery in­stalled (e.g., liq­uid elec­trolyte or im­mo­bi­lized elec­trolyte); 2. the boat in which the bat­tery is in­stalled (e.g., an­gles of heel for sail­boats, and ac­cel­er­a­tions for power­boats).” It makes lit­tle sense, there­fore, to in­stall a gel or AGM bat­tery in a box, since leak­age is es­sen­tially impossible. Flooded bat­ter­ies, of course, do ben­e­fit from 100 per­cent con­tain­ment, since they are prone to leak­age and oc­ca­sion­ally ex­plode.

Fas­ten­ers used to se­cure bat­tery boxes or trays must not be in­stalled in an area where they might come into con­tact with spilled elec­trolyte; i.e., they can­not be in­side the box, mak­ing a fur­ther case for an ex­ter­nal clamp or strap ar­range­ment. Ad­di­tion­ally, un­less th­ese are through-bolts (most of the fas­ten­ers used for bat­tery in­stal­la­tions I en­counter are tap­ping screws), it’s likely the in­stal­la­tion will fail to meet the above­men­tioned static load test.

Fi­nally, where bat­ter­ies are in­stalled in boxes, us­ing the com­mon shoe­box-lid de­sign, the apex of the lid must be vented to al­low hy­dro­gen gas to escape. This ap­plies to sealed AGM and gel bat­ter­ies as well; un­der over­charge con­di­tions, th­ese can vent hy­dro­gen gas. Bat­ter­ies that are poorly se­cured are more likely to suf­fer from loose and arc­ing con­nec­tions. Add that to a de­sign whose boxes fail to vent hy­dro­gen, and you have an ex­plo­sion in the mak­ing.

Steve D’an­to­nio of­fers ser­vices for boat own­ers and buy­ers through Steve D’an­to­nio Ma­rine Con­sult­ing (steved­marinecon­sult­ing.com).

Bat­tery boxes are es­pe­cially well-suited to flooded bat­tery in­stal­la­tions (left); how­ever, the shoe­box-like lid must not form an en­ve­lope in which hy­dro­gen gas can be cap­tured. Bat­ter­ies must be se­cure and com­pletely im­mo­bi­lized, and their pos­i­tive ter­mi­nals must be in­su­lated. This in­stal­la­tion (center) cov­ers all those bases. A fid­dle or frame around a bat­tery bank (right) can serve two pur­poses: to con­tain elec­trolyte and to keep the bat­ter­ies sta­ble.

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