Old Outboard, Charging Optima AGM Batteries

[1985mariner20]

I have read many mixed reviews and thought I should post here to get some good opinions. I have recently been having battery/charging issues on my boat. a 88 VIP 22' CC. I have fried new rectifiers in as little as 10 trips out. After reading many reviews, it seams that having batteries of different types and size in Parallel could have been causing an issue with the old style rectifier. To resolve the issue, I bought two Optima d31 Dual purpose deep cells. Now I am reading many differing opinions on if my non regulated charging system will fry my new batteries. at $300/each, I don't want to kill these things in a month or two. I bought a CTEK 4.3 battery maintainer. It was recommended by many for the AGM batteries in storage. I usually put the maintainer on every time I park the boat in storage(after every outing) I have a 77 johnson 175 on my boat. Am I going to fry these high dollar batteries without adding a regulator in the system or will I be ok. My rectifier usually doesn't put out over 14V while cruising. The CTEK is an automatic smart charger with desulfation mode and is supposed to keep these Optimas in tip top shape. Basically, Is my set up going to be ok long term?! Thanks!

 

[coolbri70]

Re: Old Outboard, Charging Optima AGM Batteries

disconnect the batteries from the motor when charging them to save the rectifiers

 

[metriccrescentwrench]

Re: Old Outboard, Charging Optima AGM Batteries

.... it seams that having batteries of different types and size in Parallel could have been causing an issue with the old style rectifier.

That would likely cause issues with the batteries as well.

....I bought two Optima d31 Dual purpose deep cells.....

I'm curious why you need two batteries, and do you have these connected in parallel?

 

[1985mariner20]

Re: Old Outboard, Charging Optima AGM Batteries

Will the old style rectifier with no regulator work fine with the new AGM batteries? Should I look at adding a regulator or making one? I have read several threads about adding/making regulator setups for the older boats..


I run two batteries on the boat b/c occasionally the boat has a hard start issue. Running two batteries allows me to only drain one when parked fishing and using accessories. We do a lot of night fishing so there are lights, radio, chartplotter, etc running. The batteries are connected through a battery switch now to decide which I am using/charging. I have also added LED Voltage monitors to each battery box to easily monitor battery conditions.

 

[metriccrescentwrench]

Re: Old Outboard, Charging Optima AGM Batteries

The batteries are connected through a battery switch now

That's the right way to do it. I wasn't sure if you were using a battery switch or not.

Will the old style rectifier with no regulator work fine with the new AGM batteries?

Well, sure, it'll work, but a regulated charging system would be better. Over-charging any battery will shorten it's life, and with a non-regulated system that's always a possibility. A previous boat of mine had a non-regulated system, I put a digital volt-meter in the dash (bought on ebay for just a few dollars, worked great), wired it directly to the battery (through a fuse), and whenever the voltage started creeping up I'd turn on some lights to provide a load on the electrical system.

 

[1985mariner20]

Re: Old Outboard, Charging Optima AGM Batteries

That's a much easier solution until I come up with a regulator set up. I ordered an extra digital voltage monitor when I ordered the two for the battery boxes. I will install the 3rd on the dash to monitor the system from the console. Will be much better than the old analog gauge.

Now I just need to look up the voltage specs on these optimas and make sure these digital gauges are calibrated correctly!