My '99 258V had a factory-installed dual-output Guest 2815 dry-mount that failed after three or four years. I replaced it with a Guest 2620, which failed and was replaced under warranty; the second 2620 also failed and boiled two batteries. I switched to ProMariner ProSports - which both failed.

I subsequently realized that the charger in a cruiser needs to both maintain batteries and supply continuous power to 12v loads when docked and occupied. The Guest and ProMariner models I tried can't do that. I settled on an Iota DLS45 dry-mount.

If you run 12v loads when docked very much, consider that most chargers just aren't designed to do that; choose one that is intended for the service you subject it to.

> ... supply continuous power...

I'll try to rephrase.

Most chargers are designed to charge and maintain a battery. They are not designed to charge batteries and continuously illuminate cabin lighting, run freshwater pumps or power electronics. Those loads will cause most chargers to misinterpret the battery charge condition; the battery appears to be drawing more current than it actually is so it appears to be undercharged. The result can be overcharged batteries and an overworked charger.

Consider that while you are on shore power it is the charger that is powering the boat, not the engine or the batteries. If you live aboard or spend much time on board and on shore power, the charger might not be up to the task.

My 258v was supplied with a Guest dry-mount which I replaced with a lesser, waterproof, model. That was a mistake and lead to its failure and several failed batteries.

The larger boats use the Progressive Dynamics chargers and this unit seems to work very well.

http://www.progressivedyn.com/prod_deta ... d2000.html
http://www.progressivedyn.com/prod_deta ... d2100.html

It does maintain the batteries as well as have several charging modes to maximize the charging. Just wish it had a remote display since it is buried in the engine compartment and hard to see.

Maybe a bit of overkill but better than dead or cooked batteries.

I replaced the Guest charger on our 258 a couple of years ago. It fried a couple of batteries when it went too. One thing I did discover is that Guest suggests you have inline fuses between the charger and the batteries. There were none on my factory install. I think my second Guest is on the fritz and on its way out. Any idea what they want for one of those Progressive Dynamics 20 amp chargers?

Mine had inline 15A fuses between the charger and battery, they were located behind the panel that holds the battery selector switch.

I blew them both when the batteries were low and I had the charger plugged in and went to start the boat, I thought I blew the charger since it quit charging and the 'ready' light was on both sides but the batteries were not charging. I read there were internal fuses on the Guest, there wasnt any on mine, I checked the output at the charger and it was putting out 14v, had to trace the wires down to those 15A fuses.

Been fine ever since.

That's interesting. It was always my understanding that the chargers went directly to the batteries and that the "1/2, On-Off" switch" was later in the circuit. As such, I always thought that when the charger is on, both batteries are charging regardless of what position the switch is in. I always thought the switch governed only which battery the boat's systems were drawing from. I say all this with a relatively limited understanding of electrical circuitry, so somebody fill me in if I'm incorrect (which I readily admit is entirely possible).