battery replacement

[CSY Man]

Yeah, I second that:

I installed a battery monitor last year and found all kinds of surprises.

Also replaced my batteries last year, the four golf cart DEKA batteries lasted me 5 years. Put the same ones back in. Got 'em for about $62.00 a piece with a discount.

I never go below 70%, battery life will increase will shallow cycles.

[irwinsailor]

I bought the xantrex remote panel with gauges built in and it has helped me see what is going on. Would that be called a battery monitor too?
A big problem for me is that I do not have a good grasp of amp hours. The other day I watched the inverter draw gauge and found that we were using 200 DC amps for about 15 minutes. We do that 2 or 3 times a day. Is that a lot of power?

[Jon D]

Gunnar

if you are talking about the remote panel for the charger that does not count as a amp hour meter. this is an example of one

http://www.xantrex.com/web/id/97/p/1/pt/8/product.asp



Link 10 (part#84-2016-01) and Link 20 (part#84-2020-00) use sophisticated microprocessor technology to provide complete battery status information for one and two battery banks, respectively. Simple and easy-to-use multicolor displays show volts, amps, amp hours consumed, and operating time remaining. The Link 10 and 20 allow you to select Automatic, Sleep and Scanning modes and automatically calculate and display charging efficiency. The Link 20 can monitor a house bank and starting bank or two house bank batteries at the same time. By adding an optional prescaler, Link 10 can monitor single battery banks up to 500 volts.

in your example 200 amps for 15 minutes 3 times per day [45 minutes total] is 200 amps for 45 minutes which means you are using 150 amphrs for that application alone. [200 amps x 0.75 hrs]. That would represent 50% discharge on a 300 Ahr bank. That is a fair bit of power for comparisons sake we use about that amount running the whole boat for a day, i.e. refer, autopilot, radio, lights, cooking, showers, watermaker, etc..

[Richhh]

Question? When you installed these batteries, did you 'break them in'. Every battery needs to be 'broken in' so that the acceptance charge in the future is correct. "break-in", to insusre long term service life, is usually accomplished with new batteries by a slow discharge to about 10.5v then slow recharge at 10% of the battery's amperage capacity. Several breaking-in cycles are usually recommended.
For better details go to: amplepower.com and follow the links. The site also includes links in which 'old' batteries can sometimes restored to adquate acceptance by repeating the 'break-in' process (after 'equalizing' non-gel batteries).
I run large gel batteries and found the offered methods of restoration to be of good value for cost savings.

[hellosailor]

Gunner, we're not getting the full picture here. You say you have eight 6V batteries rigged up in two banks, presumably each bank is a series/parallel bastardization with two batteries set up to make 12 volts then two more paralleled as second 12V "battery". That's going to be a problem right there, because even if the batteries are from the same manufacturing lot, no two batteries are identical and every battery in parallel will continually discharge in an active circuit. The "better" one tries to "charge" the weaker one and there is always, always, an active discharge. Then it reverses, so both/all of them get pulled down. That's unavoidable with parallel battery banks which are not being actively charged/discharged with an outside source/load.
But then you say "Charging is not a problem with my genset and 140 amp charger. I took all the batteries home and charged them individualy for about 40 hours each. " You took each battery, individually, and put it on a 140A charger for 40 hours? Or what?

Sounds like there is something basic and simple and wrong, and using a hydrometer and digital voltmeter could tell what. But, you'd also want to break up those paralelled banks in any case.

[sv_makai]

I would not recommend breaking up the battery banks unless the batteries are of different types. The larger the amp hour pool avalaible the better in reaching the maximum usable amps when drawing.

batteries are not 1 amp in and one amp out. they are gennerally 1.1amps in to 1 amp out. Also the faster you draw from the batteries the less that will be avalaible. The larger the bank the lower the percentage draw and the better chance to maximize the total amps in the bank. Under higher draw conditions smaller banks with the same total of one large bank will provide less overall amps.

If anyone has read my past posts you would understand that we are a very electically intesive boat and for the last 2 years have been on 6 - 6 volt sries paralleled battieries. I agree with the state above that it is something simple. Check the basics including a load test to see if there is a weak link in the batteries. Check the wiring to insure that it is correctly installed. It is easy to wire a battery backwards. In a 6 volt battery banks for 123 volts you have sets of 6 volts wired in seris and then wired parallel.

[Alan Wheeler]

200A for 15Mins? are you using an inverter??
That only equates to 50Ahr, but it is still a very large draw for that period of time and there are some very important issues that can affect equal discharge and charge with such high currents.
The reisitance figures with batteries are very small numbers. So added ressitances in varying cable lengths, diameters, connections anywhere, can result in very big current difference numbers. So it is essential when you have series parrelled configurations, that all interconnecting cables are as identicle as possible, ALL connections are as perfect as possible and all cables are of a size that there resistance is as low as possible. As soon as one battery gets out of kilter with the rest, it's resistance will alter such that it will fail to equalize with the rest of your banks. A battery monitor over the overall system bank, will not tell you what an individual battery is doing. You may only get to see a discrepancy in charge and draw currents and time.
Makai also touched on an important aspect. Deep cycle batteries are not good at delivering high current demands in a short time. They are better at longer term loads of less current than say a starting battery that can deliver a high current demand for a very short period. So for a deep cycle set, you need to ensure too points for sizing. Firstly that you bank has enough energy to last for the between charge period, with out deep cylcling down to low. And Secondly, that the bank high current instant supply, without overly drawing from the bank. So if you have say, 400Ahrs of bank, you may only be able to safely draw 200Ahrs as a max drain. The actuall amount depends on the battery.

[rsn48]

I don't know if you have room, but after purchasing 4 golf cart batteries, I just saw the same golf cart battery I purchased in a taller version - West Marine. My standard sized battery is something like 230 amps (6 volts - need two to make 12 volts). So with two batteries, I have approximately 115 useable amps. The tall ones I saw were 370 amps (6 volts), so two of these would be 185 useable amps. If I had four, I'd have 370 amps useable roughly. They aren't cheap.

For Catalina 27 owners with outboards, these batteries will fit in the "engine room."

[Strygaldwir]

One of the points one should consider is that we can't always do what is best for our batteries if we are cruising. I have had several instances where it I had to drop my utilization below 50%. When I am cruising and on the hook, it is VERY difficult to equalize the batteries. I usually reserve that function for when I am in a marina and have access to shore power.

The issue is, even though we have montiors and systems designed to optimze our battery utilization, the reality often gets in the way. If I am doing EXTENDED cruising away from the docks, I would/will go with a rather robust battery system. If I am in the marina and only going away for a week or two at a time, I think the robustness of the battery may be secondary to cost. But, try replacing a bank in the middle of the South Pacific, or some other remote location. (like the Bahamas! ;-)) Gives one a new appreciation for things that don't break, wear out, or need replacement!

Fair winds

Keith

[Vasco]

In the past I have been very lax regarding equalization mainly because I had no way of doing it. Last season I got a Honda EU2000i and used it to equalize the batteries. Worked very well, got the batteries up to 15v and ran the Honda for eight hours or whatever the cycle took. With the Link monitor you just punch equalize and it runs it the whole cycle. Just ventilate well and keep an eye on the batteries. The hardest part was carefully re-filling the gas tank. Going to do it once a month this winter.

[DeepFrz]

Rick, don't overdo it now. You should bring your batteries up to 100% charge once a month, but not equalize that often. Once or twice a yr. if necessary.

Deep

[Strygaldwir]

For me to equalize with my portable generator would require about 12 hours of running it. First 4 hours to top up the batteries, then 8-10 hours of running the generator for equalization.

After almost burning a car up in my youth by messing with running engines and gasoline, I am a confirmed, turn it off before you fill it kind of person. Who needs a fire on their boat. I am already distraught because I have a gasoline dinghy motor and have to carry gas for that. So, in for a penny, in for a pound. I have a portable generator. To run the generator for equalize would require me to refill the generator at least once while the engine is running. Not something I will do. I have thoughts of putting on an outboard motor fuel line on the generator and using an external tank to keep it running. That may be a viable solution. We'll see.

I guess, I could get used to listening to the generator run for 12 hours. It would only be once every 2 or 3 months or so. Who knows?

[CSY Man]

Question? When you installed these batteries, did you 'break them in'.

Hmm, I never did..never heard of it until now.

Perhaps next time..If the manufactor recommend a battery "break-in procedure"....?

[DeepFrz]

Something to keep in mind, the Amp/hr capacity of a battery rated at the 20 hr. draw will not be the same when drawing a higher current. Again, I refer you to Rolls web site, take a look at the spec sheets for any deep cycle marine battery. They show the amp/hr. capacity for different current drain. A high current will drain a battery much faster (in terms of amp. hrs.) than a slow drain. For example the 100 hr. rate will yield a much higher amp/hr. capacity than a 20 hr. rate.

hth,
Deep.

[sv_makai]

Per everything I have read if you use your house bank regularly use should be equalizing at least once a month and the more often you deep discharge the more often the equalize needs to be performed.

The longer the battieries go between equalization the greater the levels of permanet sulfation (crystallation) occurs and the greater the permanent reduction in the avaliable amps in your bank.

We spent the last 3 years cruising (not going marina to marina) and we would notice the morning voltage levels drop lower and lower after a 3-4 weeks on the hook. After an equalization we are back to normal.

Makai uses a RV power products solar controller which has an equalize function that allows us to use solar to equalize. Makes a big difference both in amps and battery longevity.