Need a new house battery, what should I get?

[Ryan Blocker]

I have a 1995 hunter 430 with no generator (I do have a honda 2000 generator with shore power adapter). I am running the basics, microwave, TV/DVD, and refer. I have the standard, factory installed, Heart interface inverter. I have two 8D, 6volt, centennial deep cycle batteries (purchased in Jan 07). I have a starter battery also.
One of the batteries is not holding a charge well. I know I need to replace that battery.
I have a few questions for all of you.
1, What type of batteries should I Buy (Standard deep cycle, Gell, AGM)? I Know the Gell or AGM are the best but are the worth the money?
2, If I replace battery with another deep cycle should I replace Both?
3, The inverter shuts off at 10.5 volts, is that when it should?
4, It seem to run the inverter hard with the refer on. Is that hard on the inverter?
Thanks for your help!

 

[Terry Cox]

Hi Ryan, not sure why you have the inverter on to...

run your reefer. We have two wet 8D 12 volt marine batteries for our house bank and they supply 12 volts DC to operate the reefers on our boat. About the only time I run the inverter is for the entertainment system, microwave and a few other appliances.

Our boat came equipped with wet cell batteries and I replace them with Interstate wets when they died. I've been very happy with their performance. We do have an 8kw Genset and usually run it for two hours every other day while we're cruising. I never let the bank fall below 12 volts (50%) before recharging.

Terry

 

[Don S/V ILLusion]

battery bank sizing

I'm not positive (no pun) but I don"t think there is any such thing as an 8D 6 V battery. If one isn't holding a charge and they are in fact 6V each, this makes no sense so I'm assuming you really have two 8D 12 V batteries. Based on this premise, if one isn't holding a charge, it has already deminished the capacity of it's twin by drawing it down sufficiently such that the new repacement, if connected to the existing "good" battery, will suffer. It is easy enough to properly test the good battery to see how much capacity remains but the general rule is to connect only similar sized, similar capacity new batteries together. Essentially a matched set is what you want.

You want ONLY deep cycle batteries for your house bank. Whether you obtain the benefit AGMs offer and therefore if it's worth the cost to you (as they are more expensive than wet cells) is a function of your charging system - does your current charging system allow you to recharge AGMs as fast as they allow? If not, there is no real benefit other than in maintenance which isn't very much in a properly operating system - just checking the water level periodically usually isn't worth the extra money AGMs cost to aviod this simple task.

Inverters generally shut down at between 10.5 and 12 VDC with 10.5 being the absolute minimum - if you draw them down that far, you are killing them prematurely.

Lastly, what in the world are you doing running your refrigeration on an inverter for? It may not destroy the inverter but it will certainly draw more current from the batteries than connecting them directly. This is the most inefficient way there is.

 

[Manny]

Check the battery's warranty

If you purchased the battery in '07, it should still be under warranty. You may be able to get a replacement.
Letting them drop to 10.5 volts will definitely shorten their lifespan...

Manny

 

[Dick 119]

Ryan..We had a '95 430, and unless there has been some drastic

changes to your boat, it's equipped with 2 8ds for the house and a group 27 for a starter battery. If yours is equipped with the Grunert (sp?) cold plates like ours was, there is no need to run the inverter for the refer it's 12v. In fact if the Heart inverter is set correctly the inveter should just "idle" drawing next to nothing unless you turn on some 120v appliance.

The other comments are right about killing the batteries if you take them to 10.5 volts. It could be why one is failing so soon. You should recharge, IMHO, at about 12 to 12.1 volts.

 

[GuyT]

You should not

run your batteries down to 10.5V because this is a complete discharge!
Cycle life dramatically decreases when you deplete your batteries that low.
Some rough numbers are around 200 cycles for a complete discharge and close to 1000 for only 50 percent discharge. Yeah these numbers vary by mfgs's but you at least see the trend - depth of discharge affects battery life.

If your batteries are in a hard to reach spot and are difficult to maintain the electrolye level, you should consider the AGM. If you do not mind adding water, the flooded batteries are hard to beat dollar wise!