Quote:
Originally Posted by wadekranz
Hi I want to replace my stand alone House 12 Volt AGM 27 and would like to add a second House battery to increase the off shore power cycle for my refrigerator.
I am in Ontario, Canada. My Boat is a 2001 Doral 360Se and has dual 7.4 Mercs which have separate 12 volt starting batteries.
Questions:
1. Where in Ontario can I get a good/best Deep Cycle 12 volt AGM 27 size battery?
2. Should I connect the 2 batteries in series or parallel for max deep cycle off shore power?
3. Is it OK new second 12 volt deep cycle battery is about 2.5 to 3 feet away from current House battery?
4. I have a generator as well.
5. When connecting a power gauge to monitor the battery power, what is the proper method to connect it to the 2 House batteries?
Wade Kranz
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1. Why do you want AGMs? If you discharge them very deeply (>25% DoD, ie 75% full) they need to be recharged at a high C-rate. AGMs need to be bulk recharged at 0.2C minimum. 0.3C is a better target. 0.3C for a 200Ahr bank (2 group 27 batteries in parallel) is 60amps. Can you get 60amps from one of your alternators? If you want low
maintenance get GEL batteries. If you have good access and don't mind watering your batteries every 2-3mo then get a good Flooded Lead Acid (FLA) like Trojan which will be significantly cheaper than the other 2 types.
2. Parallel. If you wire in series you need to have 24v accessories which there are not a lot of compared to 12v.
3. Shouldn't be a problem as long as you tap the positive and negative feeds from different batteries. (see sketch) Actually it's a good idea to tap from opposite ends even if they are right next to each other.
4. If you use this to recharge and you have a big charger (75Amps) you could stay with the AGMs.
5. Follow the instructions with the gauge.