Looking to replace the battery charger on my 1985 Hoyt F32. Does anyone have any recommendations for my 2 bank, 3 battery setup? Ideally looking for something that can charge AGM batteries with both shore power and solar.
Here’s a stupid question, is our battery charger connected to the alternator in any way? I’m assuming it’s like most boats and it is NOT connected to the alternator, but the wiring diagram I have in my manual doesn’t make it clear where the alternator wires attach to. Is the alternator just connected to the starter solenoid only or something?
The alternator output should be connected to your starter solenoid, which is connected by a large cable to your battery. The battery charger shouldn’t connect to it, as it is for charging up your batteries when you’re connected to shore power. The battery charger is basically just a rectifier and transformer that converts 110v AC from the shore (or a generator) to 12v DC, along with some regulator circuitry to manage different charging stages and turn off when the battery is charged.
For solar panels, they output DC voltage, so you just need a charge controller to go between the panels and the battery. The controller will prevent overcharging and provide optimal voltage for your batteries’ chemistry.
As for a charger recommendation, I have the Sterling Power Pro Charge Ultra which has been working fine. I honestly don’t remember how I selected it, but it hasn’t died. I also have three AGM batteries in two banks.
One other thing: I recommend that you stay away from “inverter/chargers.” This is a battery charger that also functions as an inverter, which turns DC voltage from your batteries into AC voltage that you can use to power a microwave or whatever. If you need AC, get a separate inverter. The combined units save some space, but they make troubleshooting a nightmare if there’s ever an issue.
Thanks for your input! Did you add a regulator and/or isolator to your setup when switching to AGM? I am assuming you have a 3gm30. I currently have a 2018 3ym20 with the stock 60A Hitachi alternator. My alternator is not compatible with external regulators, so I would have to switch alternators if my current one is not compatible with AGM.
In my previous boats, they already had AGM so buying AGM was a direct replacement. This vessel came with flooded lead acid batteries, so I want to make sure that I’m not going to destroy 3 AGM batteries over only a few seasons.
I am thinking I should:
A - replace my batteries with 3x group 24 lead acid batteries, keep the original battery charger, and keep the factory 60A Hitachi alternator on my 3ym20
B - switch to 3x group 24 AGM batteries, replace the battery charger with a 3 battery shore power smart charger (although I will rarely if ever be connected to shore power), find a new alternator for my 3ym20 that is optimized for AGM. Balmar?
C - switch to 3x group 24 AGM batteries, replace the battery charger with a 3 battery shore power smart charger, keep my 60A Hitchai alternator, and add a solar smart charger to top off the AGMs as needed.
I keep the boat on a mooring and will pretty much never be hooked up to shore power. I assume this means I must either upgrade my alternator and/or add solar charging to avoid PSOC or damage to AGMs.
Which of the 3 options seems the best? I am halfway between keeping a modest budget and the ‘buy once cry once’ philosophy. I am open to other options as well
My setup is a bit different than what came stock from the factory. I repowered with a 3YM30AE in 2018, and it came with a Valeo 120A alternator. It is internally regulated, but I had an external regulator from my previous engine, so I needed to figure out how to make that work. Turns out Balmar made a “Smart Ready” retrofit kit made for the new Yanmar engines that allows this specific alternator to bypass the internal regulator. After sorting that out, I decided I wanted to feed my alternator output directly to my positive bus, so I ran new cables—one from the battery for the starter, and one from the alternator output to the positive bus that connects to the batteries. But you don’t have to do all that.
I think you should do the following:
Keep your alternator, keep the flooded batteries. If they’re dead, get new flooded batteries that can be charged by your alternator.
Forget about getting a battery charger. It’s nice to have at a dock, but if you’re on a mooring there’s no point. Now that my boat is on a mooring, I only use mine in the winter to charge the batteries when the boat is on the hard.
With the money you saved on the alternator and batteries, get as much high quality solar as you possibly can. Invest in a sturdy mounting setup for the panels, and a quality MPPT charge controller. Also, get a good battery monitor that tracks amperage use and state of charge. I hear the newer charge controllers can also feature this functionality, so I’d look into that.
Switching to AGM batteries is an easy move, and installing a new alternator/regulator is only slightly more complicated. You can do all that relatively painlessly in the future. A proper solar setup is a different story. You will need to figure out the wiring run, decide on a good panel location, figure out how many panels you can reasonably fit, and then decide on their wattage. This has significant implications for the aesthetics of your boat, which need to be carefully considered.
However, it is an investment that will pay immediate dividends. Apart from keeping your batteries topped up when you’re away from the boat and thus extending their life, a good solar array will prevent you from having to rely on the engine to charge your batteries while cruising. As you cruise with this new setup, you will learn what your energy demands are, and get a better sense of how close you are to your system’s capacity (this is why a good battery monitor is key).
Do this right, and you will only have to do it once.