Onboard Charger

[RickyBobby]

I'm shopping for a new onboard charger for my bass boat. I've got a 24 volt trolling motor and my electronics run off the cranking battery. I've heard differing opinions on 10-amp per bank vs. 5-amp per bank. Anybody have an opinion on 5-amp vs. 10-amp chargers?? Those of you with 5-amp chargers how long does it take to charge your batteries after a full day on the water?? Anybody have issues with over charging with 10-amp chargers?? Anything else to consider when choosing??

Thanks in advance

[mamohr686]

The first step is you check how much space you have for mounting the charger. The size is highly variable between brands. Next, only buy a fully submersible waterproof charger. I would stick with a 3 bank charger with your set-up. With all the electronics and pumps etc running on your cranking battery, It's a good idea. I've had both 5 and 10 amp chargers before. I had a 10 amp defective dual-pro that would cook my batteries, but lots of guys have good luck with them and their customer service. Mine was out of warranty before I figured out the problem, I thought I had bad batteries and not a bad charger. I like the minnkota 10 amp chargers the best, and guest also makes a decent unit. My understanding is pumping up the last 10 percent of a battery is kind of like blowing up a baloon, it gets tougher at the end. The advantage of the 10 amp is that it will charge you batteries much faster, and keep them charged at a higher level for better battery life.

[BobT]

The time it takes to recharge using a 5A charger vs. 10A will be about double. The 5A will only deliver 5A maximum so it will take roughly twice as long. Not exactly but close. According to the research I've done the best charger will be able to deliver 10A-15A but also use electronic multi-stage charging sequence. Many chargers use three modes in the sequence and some use four. Most quality on-board chargers will utilize multi-stage charging and include a maintenance mode so you don't have to worry about unplugging it when not in use.

Here's a description of the modes or stages.

Stage 1: Bulk mode. In this mode the charger will deliver full current to the battery but due to the low impedance of the battery, the voltage will start out low and climb as the battery takes on charge. This quickly returns the battery to a specific state of charge where it will then switch to the second mode in the sequence. This is roughly 80% of full charge give or take.

Stage 2: Absorption mode. In this mode the charger output voltage is regulated to a constant value and as the battery continues to take on charge the impedance continues to increase causing a reduction in current flow until the battery is ready for the next mode. This will be roughly 95% of full charge.

Stage 3: Equalization mode. This mode is the one that some chargers don't use because it is optional. Some battery manufacturers specify this should be used for optimum performance. In this mode the charger returns to controlling current flow to a constant low amount to top off the battery.

Stage 4: Float or maintenance mode. In this mode the charger only outputs a voltage slightly above the batteries no load voltage (12v) to maintain the battery without cooking it. Batteries will gradually lose charge while on the shelf and this mode is good for holding it at full charge and ready to go when you need it.

[RickyBobby]

Thanks for the replies. Sounds like 10 amp with multi stage charging is the way to go for deep cycles. Would you hesitate to hook up a 10 amp bank to a cranking battery?? Any one aware of chargers that have 2 10-amp banks and a 5-amp bank for the cranking battery??

[marine_man]

I wouldn't be concerned about hooking up a 10 amp charger to a starting battery.

I'm not aware of any chargers that have a lower amperage bank.. but I haven't spent much time looking lately.

marine_man

[BoxMN]

We have Guest 25 amp in big boat - I think model 2625 or something like that. 10 amp / 10 amp/ 5 amp. Works great. About 5 or 6 years old.

Had a two bank Guest (2610?) that died about 9 years into its life, and Cabelas Brand 8 amp dual bank that died after boat sank... haha! And now have another Guest 8 amp dual bank, it was cheap but works good.

Never had a Dual Pro but heard good things. Guest has worked awesome for us.

[BobT]

Actually, the cranking battery would prefer to get recharged quickly using higher amperage. Just like you car's starting battery, they are recharged pretty fast. The charger will take care of it. That's what it is designed to do. My charger actually had a set of leads specifically labeled for the starting battery.

[walleyewild]

My 3 bank Advanced angler had one set labeled for the starting battery.

I would recomend getting a charger that has a fully distributed output, then if the starting battery only needs a maintenance charge the rest will go to the deep cycle.

But if you plug in the charger after every trip then there is no real need to worry about your batteries.

As long as you plug the charger in soon after you you are done with the day's fishing you will be money ahead in the long run, it'll increasethe life of the batteries just by maintaining the charge on the system.

WW