Do you disconnect your battery before charging it with a Battery Tender?

[MrMoose]

I just bought a Battery Tender and I'd like to use it from time to time to top-up the boat batteries. Just wondering if it is necessary to disconnect the batteries from the boat electronics prior to hooking up the Battery Tender and starting a charge cycle.

 

[Murf'n'surf]

I have always separated while charging. Typically you'll have a battery switch that isolates the electronics from the battery when it's in the off position.

Not a big deal if you don't have a battery switch. Just make sure that your battery tender/charger is SMART. By that I mean that it needs to have the newer tech built into it that senses the batteries charge state and will not over charge the cells.

 

[subysti]

Same here. I just turn off the battery switches while charging.

 

[MOA_Chaser]

My Guest 16202 charger is worth every penny. I hook it up once at the beginning of the season when I put the batteries in, and simply plug it in every time I get back from an outing. It charges the batteries quickly and keeps them maintained.

 

[smthng]

I just bought a Battery Tender and I'd like to use it from time to time to top-up the boat batteries. Just wondering if it is necessary to disconnect the batteries from the boat electronics prior to hooking up the Battery Tender and starting a charge cycle.

Nope... I've been charging many vehicles with Battery Tenders and other trickle-type chargers for years without disconnecting. On some motorcycles, it's nearly impossible to even get to the battery, so disconnecting wasn't an option. We had a Jeep who's brain was always "on" in storage for a year on a tender while connected. It's battery lasted at least 6 years (then we sold it). If I had a disconnect switch, I'd use it when charging just because I could, but I wouldn't unscrew cables every time. Neither of my boats has a disconnect (yet) and they're on trickle chargers any time they aren't on the water.

 

[scokill]

I turn the battery switch to off as a habit whether charging or not just to eliminate the possibility of leaving something on and draining the battery.

 

[txav8r]

No need to disconnect the batteries. If you have a battery switch, turn it off, if not, don't worry about it. A word of caution, if you run the battery down playing music or with lights for hours, the charging system on the boat will not bring the battery back up sufficiently in a short boat ride. And...a small Battery tender won't "charge" the battery with enough amperage to exercise or desulfate the battery effectively. The small 1.25 amp battery tenders are just maintainers, not chargers, but they can charge at that very reduced rate. On average, batteries can only absorb about 10 amps per hour, so even a 20 amp charger will only charge the average lead acid battery at a rate of 10 amps. But a slow trickle charger could take a week to bring even a mildly discharged battery to full charge. So if you have any added equipment that puts a drain on your battery, you may want to consider a smart charger that can exercise the battery more effectively, otherwise the tender is fine!