Electronics/ battery use and charging.

[Frank C]

Wonder what the diff is between Cold Crank Amps and Marine Cranking Amps

I saw that defined somewhere. IIRC, unlike for a car, they figure it's rare to use a boat in freezing conditions, so the environmental parms are less severe for MCA.

[albion]

Wonder what the diff is between Cold Crank Amps and Marine Cranking Amps

Catigale I was thinking the same as you. What is the difference?

[DLT]

CCA ia at 0Deg
MCA is at 32Deg
http://www.htmarine.com/tip2.htm

[Trav White]

I have a starting and a deep cycle in parallel with a Perko 1-both-2 switch. I don't know the condition of my batteries, but after reading Don Casey's "simplified" book, I'm sure I've been running them down. My question is: What type of meter do I use to tell me my batteries are at 50% and I need to recharge? I would like to mount a meter next to the DC panel. Do I use a volt meter? ammeter? both? in my research, I have found a Goldeneye battery gauge. Would something like that work?

Total newbie at this..

[kmclemore]

If you have two batteries and you plan to use them independently (starter / house) then IMHO the best meter is the Xantrex (aka "Heart") Link 20. I have one on my boat and it's just great. Gives you battery voltage, amps being used and capacity remaining in really simple digital readout, and if you don't understand that it gives it to you in a linear readout of coloured lights.

If you choose to get it, also get the custom 'twisted-wire' hook-up cable for the Link... although I made my own, if you're a 'newbie' you may want to avoid the hassle... there's about 8 colours of wires that need to be properly twisted in pairs (x-many turns per inch) and then assembled into a harness.... not fun, but do-able... takes about 1/2-to-1 hour depending ou your skills.

Color-coded, twisted pair cable (eases installation). Available in 25 (part#84-2014-00) or 50 foot lengths (part#84-2015-00).

LINK for more info.

I put mine in the aft wall of the V-berth, in between the dinette seat and the port setee, so that when the companionway is open I can see it from the helm and it's also visible to anyone in the cabin. (It helps that my batteries are also located under the V-berth, too.)

[Duane Dunn, Allegro]

This is what is typically called an amp hour meter which I advocate. With my single bank I use the Link 10 which is a smaller round gauge.

Once installed (which involves numerous wires in the twisted pair cable as well as at least one more heavy negative wire to hook up the shunt) it keeps track of all the power going into and out of your battery. I justed a chunk of standard Cat5 data cable for the twisted pair part and it works great. The colors aren't what are listed in the installation manual however so you have to translate.

You tell it the size in amp hours of your battery bank(s) and it will tell you how many amp hours you have used and at the current consumption rate how many hours you have left. It also tells you voltage (the least useful of all it's measurements as it is meaningless unless the batteries have sat un-used for 24 hours) and amps which is very useful in knowing the load your devices put on the battery system.

With a meter like this you can make appropriate power use decisions that will avoid ever getting into a dead battery position.

The biggest issue with these meters for some people is getting a good zero starting point. In theory you set some conditions in the meter that indicate a full charge and it self resets to zero. In practice some battery chargers are not able to meet these conditions in certain circumstances and the meter doesn't get reset leading to confusing output such as positive amp hour readings. Full should say zero. There is a key sequence you can push on the meter to zero the display if you know your batteries are fully charged. I usually do this at the start of each trip to make things simpler. It is mainly at home where the boat is plugged in and trickle charged continuously with monthly (my charger does this automatically) full charge cycles where the meter goes positive.

[kmclemore]

The biggest issue with these meters for some people is getting a good zero starting point. In theory you set some conditions in the meter that indicate a full charge and it self resets to zero. In practice some battery chargers are not able to meet these conditions in certain circumstances and the meter doesn't get reset leading to confusing output such as positive amp hour readings. Full should say zero. There is a key sequence you can push on the meter to zero the display if you know your batteries are fully charged. I usually do this at the start of each trip to make things simpler. It is mainly at home where the boat is plugged in and trickle charged continuously with monthly (my charger does this automatically) full charge cycles where the meter goes positive.

Actually, this positive reading is normal. If you are charging the battery, even if it is fully charged, it will still accept about 1 amp or so, making the readings positive. However, once you disconnect the charger and give it a bit, it should begin to read correctly. The meter, for the most part, resets itself. However, if it does not, here's the scoop:

[Duane Dunn, Allegro]

Perhaps the link 20 is different than the link 10.

From the manual:
http://www.xantrex.com/web/id/72/docserve.asp

Conditions to reset to zero
1. Discharge 10% of declared battery capacity to trigger algorithm.
2. Recharge until 100% of the kWh removed have been returned.
3. Voltage must be above the Charged Voltage Parameter.
4. The current must be below the Charge Current Parameter.
5. Conditions 3 & 4 must be met for 5 minutes.

When all 5 of these are met the right most green LED blinks indicating a full charge and the meter resets to 0 ah.

I can't say which one is failing with my charging system and meter settings, but even after the batts have been on AC for weeks and I know they are fully charged, the charger has switched from bulk phase to maint phase, yet the meter doesn't reset. Occasionally it does but not always. It's not quite as simple, at least with the link 10, as starting to use it and it will reset. That's why I check it as part of our loading procedures and if not reset, I simply run through the reset procedure with the buttons.

[50/50]

Had a discussion with a sparkie friend of mine about connecting two batteries in parallel. He says I cant do that with a single battery switch as
the good battery will discharge in to the lesser battery.

I'll have to fit a three way switch off 1 2 and both to isolate one from the other whilst not undercharge

Have any of you any thoughts on this

[James V]

That is what I have and it works fine. You just have to remeber what setting it is on. For longer passages a emergancy battery for starting would be advised.

[DLT]

Had a discussion with a sparkie friend of mine about connecting two batteries in parallel. He says I cant do that with a single battery switch as the good battery will discharge in to the lesser battery.

I'll have to fit a three way switch off 1 2 and both to isolate one from the other whilst not undercharge

Have any of you any thoughts on this

If the two batteries are identical (type, size, manufacturer, age), there "SHOULD" be little difference between them. They can be wired in parallel, as one bank, but should be kept that way.

Yes, if you parallel two batteries with different characteristics, or just different levels of charge, the better charged one will try to charge the lesser, until they equalize. The down size is that you will lose some of the energy to heat and other losses, so a significant portion of it it just gone, wasted...

For a 1-2-off-both switch, the "both" position is probably rarely used, except to charge both batteries from the same source at the same time. It really all depends on how things are wired.

[Duane Dunn, Allegro]

50/50

Two batteries connect in parallel are one single bigger battery. They are no longer separate and do not require any switch (other than a main cutoff if you so desire). They are a single bank that charges together and gets discharged together. One battery will not get more discharged than the other or more charged than the other. They are connected to any charge source or load in tandem. You do not wire separate charging circuits to each one. You just charge the bank and they each get an equal amount of juice. Likewise loads are pulled from both at the same time.

What you don't want to do is make a single bank out of two used batteries of different vintage as the weaker one from the start will handicap the stronger.

It is always best to start with a fresh pair. From then on they will each get the same treatment and be in equal shape as they age.

By the way, wiring the batteries in parallel is exactly the same as putting the 'off-1-both-2' switch in the both position.

All batteries really are a series of many small cells connected in series or parallel. The typical battery cell is 1-1.5 volts and these are internally wired in series to create the 12 volts in the first place. Wiring in series give you more voltage with the same capacity, wiring in parallel gives you more capacity with the same voltage.

My engineer brother-in-law who runs his whole house off the grid with batteries and a deisel generator tells me batteries are more efficient when wired in series. My 220 ah 6 volt GC2s wired in series are more effiecient than two Group 31 12 volts wired in parallel for an equal 220ah.

[DLT]

My engineer brother-in-law who runs his whole house off the grid with batteries and a deisel generator tells me batteries are more efficient when wired in series. My 220 ah 6 volt GC2s wired in series are more effiecient than two Group 31 12 volts wired in parallel for an equal 220ah.

Duane,

What he's saying is true, but you gotta understand the context...

Power is Volts x Amps. So, 10amps at 12volts is the same power as 1 amp at 120volts.

The difference is that anytime you have 'amps' running through a wire, you lose some power to heat. The more amps, the more power lost to heat. So, in the example above, the 12volt scenario is 10 times less efficient.

What this means is two 6v batteries, in series, are not more efficient than two matched 12v batteries in parallel... Provided that both banks provide the same ah, and with no other information, they are identical. Well, not quite, when one of the 6v batteries dies (and all batteries die) you're stuck until you get a replacement, as you risk damage trying to run 12v stuff off 6v... When one of the 12v batteries dies, you just disconnect it and continue on at half capacity...

on edit:
Thinking it through a little more, the issue may well be that its not likely that any two 12v batteries will actually be completely matched. So, the better conditioned one will always equalize with the lesser, with the accompanying line loss.

On the other hand, two 6v batteries would never try to equalize each other. In fact, they aren't even connected in a complete circuit unless there is a load. So, you wouldn't have equalization losses. But, the weaker battery will still 'control' the ah of the bank, as it won't give more than its got...

So, either way, the better conditioned battery will always be pulled down by the lesser... But, you may just save equalization losses with series 6v batteries. For me, though, I still prefer the flexibility of all 12v batteries...

[50/50]

Theory is then, that paralleled batteries will always equalise to the lesser battery unless controlled?

[Night Sailor]

Catigale, asks the diff between cca and mca.

Example: On my Optima blue tops deep cycle 24s, the rating is 55ah. The other ratings are as follows according to the temperature testing. As you can see, the colder the battery ambient temps, the lower it's efficiency.
CCA (BCI 0°F): 750 amps
MCA (BCI 32°F): 870 amps

My Expedition started right up with a size 24 Optima red top starting battery after sitting two days in -25F. temps in CO. Those ccamps can be important!