On board battery chargers

Got a ton of info from this site regarding on board battery chargers. Do they charge slow or cool enough that you don’t need to pop open the caps on the battery? Seems to me you don’t if you are able to leave it plugged in as a trickle charger, but I’ve watched bubbling activity with a regular charger and wouldn’t want to blow anything up. Either way I can see the convenience of not having to haul them in and out of the boat, but if there’s one less step for me to take it could solidify my decision to purchase a unit.

Welcome to IDA The bubbling effect your seeing is called “gassing”. Its normal and needed to bring a deep cycle battery to full charge. The Minn-kota series of onboard chargers properly gas your batteries and are fully automatic. Just plug it and and forget about it. You should never remove the caps during charging. The fumes are highly flammable. Also, marine onboard chargers don’t trickle charge. They fast charge. Some quicker than others. Once the batteries are fully charged, the charger shuts off until it senses amperage drop then it will start charging again.

To expand on Dereks post…The best chargers are three stage. The first stage is a fast charge that gets the batteries to full charge 14.5 volts. They then will go into a float stage and hold the voltage at a predetermined voltage around 13.4 depending on the brand to allow for maximum absorption. The last stage will go into a hold stage and keep monitoring the batteries and apply charge as neeeded.

Some gassing and heat are normal but if they are hot (not warm) to the touch I’d get excited.

Most of us who fish a lot are using AGM batteries now that are sealed and have incredibly long life. They are sealed and are not the flooded, vented batteries most folks use. They are more expensive but are worth it in the long run. They’ll last at least three times longer and don’t have to be removed in the fall. They won’t spill acid all over your jacket or if you should forget to pull the plug and flood your battery compartment they won’t get compromised by water. Think about it.

The clamp on the posts style

Question, is a slow charge better than a fast charge on a marine battery? I have been told that slow charges will help prolong the life of the battery. Here is a pic of my charger.

As you can see in the pic the charger puts out 1.5 AMPS, I assume this would be considered a trickle charge. I have two of these chargers one on my 12 volt bow mount trolling motor & one on my starter battery. This works good for me because most of the time I do not fish 2 days in a row so the next time I go fishing the batteries are fully charged. The chargers are plugged in all the time when the boat is not is use.

Trickle charge is fine as long as the battery is charged back to 110-120%. Full charging usually takes 5-7 days. Run your trolling motor for about 10 minutes and check the battery with a meter to see if your trickle charger is doing its job.

Kevin,

Do you have a brand preference for the AGM batteries? Have you tried different brands?

I have used Trolling Thunder but I plan to rig my new Warrior with either the Cabelas or Dual Pro. I’m leaning towards the Cabelas AGM.