Yes, I know there have been dozens of threads about replacing the original factory supplied AGM batteries. I’ve read quite a few of them before starting this thread.
The boat is a 2017 C-28 with the original four AGM batteries. Im pulling out the Morningstar SunSaver Duo solar controller and replacing it with a Victron Energy SmartSolar which will connected ONLY to the house batteries.
I’m leaning towards the Optima Blue Top dual purpose battery for the engine starting role.
In thinking about the thruster+windlass battery it seems to me that it should act more like a starter battery than just a deep cycle battery. Only used for short duration where lots of amps are needed. So I’m also leaning towards a second Optima Blue Top for that replacement as well. Having both the independent engine and thruster+windlass batteries having identical charging profiles would seem to also be beneficial.
Any downsides to this?
PS: I’ll be using East Penn Manufacturing deep cycle AGM batteries for the house bank which will be connected to the Victron Energy solar controller.
In thinking about the thruster+windlass battery it seems to me that it should act more like a starter battery than just a deep cycle battery. Only used for short duration where lots of amps are needed. So I’m also leaning towards a second Optima Blue Top for that replacement as well. Having both the independent engine and thruster+windlass batteries having identical charging profiles would seem to also be beneficial.
Any downsides to this?
That's what I would do. Thruster and engine batteries as starter batteries. My RT27-OB came with a deep cycle battery for the thruster. It works today. When I replace it, I'll replace it with an identical engine battery, both as starter batteries.
I have a different approach when it comes to battery replacement. Yes the house bank would be better served with Deep cycle, the engine with a cranking battery and the thruster bank with Cranking? Deep cycle? (the windlass operates off the house in a C28). When we are cruising I want AH for the house bank. 2 batteries at 105HR AGM give you 105HR at best for the evening. You have a thruster battery sitting in the bilge getting used a couple minutes a day and that is it. You have an engine battery sitting there too. Two batteries doing nothing for you when anchored out.
Scross you stated you are using Deep Cycle AGM East Penn batteries. I am assuming you are using Group 31. I am a fan of East Penn and have used the flooded version East Penn for years. The flooded are Cranking, Dual Purpose, and Deep cycle. The AGM EastPenn are Deep Cycle/Dual Purpose. Group 31 have 105 AH and 800CCA = 1000 MCA. Why install two Blue tops with less capacity when you can install the same battery in all applications and have the thruster bank installed with a parallel switch that can combine the house and the thruster bank when on the hook at night increasing your AH by 1/3 more. You also have the same batteries in all positions. The solar will charge all batteries with the same profile and the Promariner will too.
Your choice of AGM is good but I think your understanding of this particular battery is not fully understood or we are talking about a different battery.
scross":3eiw5of4 said:
PS: I’ll be using East Penn Manufacturing deep cycle AGM batteries for the house bank which will be connected to the Victron Energy solar controller
Brian,
Yes that’s the same East Penn Mfg Group 31 battery I was looking at for the two house batteries. The Optima Blue Top Marine Batteries are rated at 900 CCA and 1125 CA which is a step up from the East Penn in both CCA and MCA. The Blue Tops don’t have the high reserve minutes like the East Penn but in an engine starting role I’m ok with that.
For the VP D4-260 SOLAS application, VP recommends a minimum of 1150 CCA which I’m trying to get closer to meeting with the Blue Tops. At 900 CCA the Blue Tops are still lower than recommended but closer than the East Penn.
PS: I was also looking at the now discontinued, but on sale at WM, North Star Ultra High Performance Group 31 Thin Plate Pure Lead AGM Battery with 1150 CCA and 1370 MCA but your experience with the North Star turned me sour on them.
PSS: Also, if I were to rewire the batteries, I’d move the windlass over to the thruster battery. On the C-28 the wiring diagram shows the windlass going to the house battery. In our old boat, the R-25 Classic, the thruster and windlass were on a common dedicated battery. The windlass draws too much power off the house batteries for my liking.
North Star Ultra High Performance Group 31 Thin Plate Pure Lead AGM Battery with 1150 CCA and 1370 MCA but your experience with the North Star turned me sour on them.
I would not shy away from NorthStar Batteries. I personally think they are matched right up with EastPenn as a battery manufacture. My personal experience with what I consider the short longevity of the Northstar AGM's was more on me than the battery quality. I feel if I had East Penn, or any other AGM batteries installed my experience probably would have been the same. Lead acid batteries all have limitations to discharge capabilities. Flooded, AGM, Gel. Many AGM batteries will advertise that the discharge can exceed 50% capacity and provide a quicker charge rate without harm to the batteries. There is a catch to that. You need to have the capability to fully recharge the battery each time you deplete the charge. If you can not do that the batteries will eventually suffer and loose capacity. In my case I did not have solar and the only way I could charge the batteries after a full night anchored was to run the generator for 4 or 5 hours or pull the anchor and start cruising for a few hours to fully charge the batteries back to 100%. I did not have a battery monitor just a volt gauge. That is really not a good way to monitor battery capacity. The volt gauge shows the battery voltage when charging but not the full charged amount. The Monitor (Victron) paints a different picture. So what happened to my North Stars would have happened to any batteries. Two days on the hook and depleted the batteries to 50% capacity then charged to 70 % then discharged back to 50% or lower until we finally left an anchorage and ran the engine for a number of hours to fully charge the batteries. We cruise a lot and did this a lot. Then you take into consideration that most of our cruising charging was done by a conventional alternator with a standard regulator. The charging method was not done by Bulk, absorb and Float. It is done by all or nothing. Not the best way to charge AGM batteries that were depleted to 50%. We all worry about matching batteries in the boat so we can set our battery charger for correct setting. When we are cruising and using the alternator what happens then? Unless you have a DC to DC charger installed the batteries are charged conventional with a alternator. If you are a dock lover, don't anchored, have a large solar capacity, the AGM's will last a long time. This is my opinion !!
I have switched over to Flooded for now. 105AH, Large 900 CCA group 31 East Penn batteries Dual Purpose (4) for house, 4D dual purpose 180 AH Thruster battery bank ( I can combine my thruster battery with house bank ( 600 ah total 300 usable) and 2 group 31 start batteries for two engines. 30 amp charger with 3 outputs, two alternators ( 55 amp each) and 600 watt solar. I used Flooded because I wanted to try the system before spending the money on AGM or Lithium. The results so far are 4 days anchored. I average 8 amp draw 24 hours a day = 192AH. In the morning before the solar starts charging I am normally at 68% to 70% charge by 10 am my solar is charging at 18 to 20 amps but maintaining the 8 amp constant draw of 12Volt accessories. At noon the solar charge is 28 amps plus maintaining the 8 amps. At late afternoon the batteries are all charged the monitor is showing 100% and the batteries are on float charge + the solar is maintaining the 12 volt usage. I have 600 watts and the most that I have actually seen is 430 watts from the panels. I expected more but honestly have not needed it ( I am just learning about solar). I installed it and have used it for 3 months while cruising to Florida from Wisconsin.
This is off subject to the thread. I wanted to give an explanation of why I think my North Star AGM's did not give me the performance I expected. I was not able to charge them to 100 % after a full 50% to 60 % discharge each time. Lead acid batteries require this. Flooded or AGM. AGM are maintenance free and have many advantages over Flooded but are not capable of sitting at a discharged state without reducing the performance. You must fully charge them if you want longevity.
