Typical 12 Volt DC Common Ground Installation WiringFor 24 Volt installations, always make sure you have a 24 Volt Common Ground ProTech-i Series Charger, and that your batteries are configured in series as a 24 Volt battery bank or banks. Each 24 Volt bank will require a 24 Volt positive connection. Not sure you know what voltage system you have on board your boat? Contact your local certified ABYC marine electrical technician.
Hi Rick, I am happy to help out.Your assumption is correct, the Protech i 12v would basically melt your batteries and destroy your boat. No joke.The output voltage of what you are charging needs to match the specs on the charger. As the Protech i is a 12v charger, hooking up a 24 or 36v battery system to it will not work. Just a rule of thumb, if the voltages do no match, it will not work.What you need is a multi voltage charger with the amount of banks necessary to support the batteries.The best choice is a Prosport 20 + ( not the 20, but the 20+). It has 3 banks and will support your situation. Actually, this charger wasdesigned with your setup in mind as it is extremely common.Check out ebay # 151192086056. I am low on these, but I am always get more in if this sells out.Let me know if I can help more.Thank youJason
Rick - JMHO, but think twice about the AGM battery and 24 volt charger... You might want to consider just putting a pair of 31s under the console for your 24 volt setup. You can pick up a lead/acid flooded marine 31 at Batteries Plus or AutoZone for about $100 with a 2 year replacement warranty with replacements available all over the country. An AGM will cost you 2-5 times that amount and really does not perform a lot better in actual use. My experience is the flooded batteries last 3-5 years - then just replace as necessary. Get a charger that isolates the batteries (see other posts on this) and you are good to go - the charger won't have a problem with different battery types, cuz they are the same flooded type. I'm not a fan of 24 volt chargers because they treat both batteries as one 24 volt set of cells and can hide a weak battery or a bad cell that would be obvious when you see the batteries separately. Also put a volt meter on the dash with a Left-Right (on-off-on) switch so you can check each battery separately.
One more piece of advice (a lot of our experts will NOT like this one) is to use stainless wing nuts (with stainless lock washers) on the 2nd battery and keep a set of jumper cables on the boat. If the main ever fails on you (of course in the middle of nowhere), you can quickly disconnect the second battery from the 24 volt setup and jump the main/starting battery off the secondary without having to get out two different size wrenches to get the nuts off the terminals (at night, in the rain, with the wind blowing). Anyway - a bit of a derail here, but some food for thought... Also, somebody told me you can't derail your own thread!
All this charger talk is making my head hurt ProMariner chargers are the best chargers I have used, be it personal or in customer boats. They are smart chargers that direct the amperage to the lowest battery then adjust as they come up. Number of batteries = number of banks. Extend the charge leads if they are not long enough. Never mix batteries on a charger as AGM have different charge requirements than lead acid. I never liked charging batteries in a 24v configuration as 1 battery may be weak causing the charge to over charge the good battery in the system, where as bank chargers charge each battery independently.
NOTE: AGM (Absorbed Glass Mat) batteries are not GEL (Gelled Electrolyte Lead-acid) batteries and require a completely different charge profile that must be selected versus the out of the box factory setting. AGM batteries can accept the same charging profile as Flooded (Lead-acid) batteries.
Rick, in regards to batts...what I've seen last, what I've see work, and won't break the bank...Deka Marine Master Lead acid...