Battery Replacement with Balanced Interconnections

Solace has three battery banks. One bank is in the forward cabin and has a long run of wire. I added two batteries to that bank (#3) in  2007 because we were going cruising and needed the extra battery capacity. I had no other place to place the extra two batteries and hence the unequal array of batteries. But there was nothing I could do about that. You have to put the batteries where space dictates.
It is now time to change all the batteries (my oldest battery is 12 years old) and it doesn't pay to mix old batteries with new. In changing the batteries I intend to fix some of the (lack of) balance in the system.
One of the things I have done, is to have all three banks combined all the time. There are reasons for this; namely the bigger the bank and the smaller the discharge percentage before recharging, the more recharge cycles one will get out of the batteries.

Here is a diagram of my boats wiring diagram for the three battery banks I have. I have been long aware that the draw from the 3 banks, which are always combined together is not balanced and the charge to the batteries is also not balanced. I'll try to explain.

A common method used to connect batteries, and then feed the load, are all taken from one end, i.e. from the end battery like in the diagram to the left.
The interconnecting leads do have some resistance. It will be low, but it still exists, and at the level of charge and discharge currents we see in these combined batteries, the resistance will be significant. In fact, it will have a measurable effect.
Often the batteries are linked together with heavy cable around 35mm. 35mm copper cable has a resistance of around 0.0006 Ohms per metre so the 20cm length between each battery will have a resistance of 0.00012 Ohms. This, looks like it is nothing to worry about. But add to this the potential 0.0002 Ohms for each connection, such as cable to crimp, crimp to battery post, we find that the resistance between each battery post is around 0.0015 Ohms. Plus the batteries themselves have an internal resistance of about 0.02ohms
So armed with that data we can then look at each battery to determine the draw.What ever we draw from this battery bank (say100amps), most would think the draw is evenly divided (25amps) between the four batteries. Least that's what we may think. But that's not the case; when you take the internal resistance and add that to the cable resistance the batteries supply a different amount. Without going into the calculations it would look like this
First battery draws 39.5 amps
The next battery up draws 26.2 amps.
The next battery up draws 20.4 amps.
The top battery draws 17.8 amps.
What can we deduce from these numbers? Clearly, the first battery is working harder than the last, but because the first battery looses capacity quicker, the other three will start to take more of the load. Because of the unbalanced nature of this battery bank, the bank as a whole will age faster than if it was properly balanced. Also the charging input works to the same inbalance; the first battery will receive more charge than the last battery in the line.
So how do we change the battery set up to give a more balanced draw and charge. Look at the next picture

What has changed in this diagram is that the main feeds to the rest of the installation are now taken from diagonally opposite posts.
It is simple to achieve but the difference in the results are truly astounding for such a simple modification of moving one of the connecting leads; everything else in the installation remains identical.
The results of this modification, when compared to the original numbers are shown below. It was simply done with one single connection being moved.

The bottom battery provides 26.7 amps of this.
The next battery up provides 23.2 amps.
The next battery up provides 23.2 amps.
The top battery provides 26.7 amps.
Clearly these numbers are better than those shown in the first example. But we can improve on this too.

One final method I'll present here gives a complete balance to the bank

It is  quite simple to achieve but requires two  terminal posts, by which the short leads, all which must be of the same length and size, are connected to the terminal posts.

The difference in results between this and the prior example are much smaller than the differences between the 1st and 2nd (which are enormous) but with expensive batteries it might be worth the additional work.




And here's what I have changed to (picture below). Simply, I have changed the interconnections for the batteries on Bank 3. Unfortunately, I can't do anything about one bank (#3) being so far from the other two.

• When motoring the alternator can supply to Bank 1,2, and 3, individually or combined. Because mine are usually combined, Bank 3 will lag behind in charging compared to Bank 1 and 2 (because of the small resistance in the long run to Bank 3's batteries). Solar and wind will not charge because my set point for the alternator is set higher than the wind/solar and therefor the wind/solar see's the batteries as being charged and dumps their load.
• Alternatively, when motoring, I can have Bank 3 turned off and have the alternator charge Bank 1 and 2;  OR turn off 1 & 2 and charge #3.
• When at anchor with no motor going, wind/solar charges all three Banks.. I have the option of turning Bank 1 and 2 off to give Bank 3 a faster charge.

Now all I need now is a method to remember to switch banks on or off while on the go.

406 EPIRB with User Replaceable Battery

I wrote recently about the poor product support for EPIRB's over 10 years of age. Most of the manufacturers won't do it. You can read about that here.
Today, while in a Chandlery, I came across an EPIRB with stated "user replaceable battery". I have blogged about that one with the manufacturers details here and there is another manufacturer purporting a user replacement here.
Here's the blurb from Kannad Marine about their Safelink EPIRB (with GPS).

This ultra compact and stylish 406 MHz EPIRB comes with a built in high accuracy GPS as standard, for enhanced position location and a user replaceable battery* with a 6 year life.
Meeting the demands of both commercial mariners and recreational boaters, the new Safelink EPIRB heralds the arrival of the next generation in EPIRB technology. The Safelink EPIRB range offers two models, one features a manual deployment bracket and the other an automatic deployment housing which also includes a hydrostatic release unit.
This ultra compact and stylish 406 MHz EPIRB comes with a built in high accuracy GPS as standard, for enhanced position location and a user replaceable battery* with a 6 year life.
The Safelink EPIRB range offers two models, one features a manual deployment bracket and the other an automatic deployment housing which also includes a hydrostatic release unit. The Safelink 406 MHz EPIRB is designed to operate with the COSPAS-SARSAT international search and rescue system. The unit can be activated automatically by immersion in water, or manually by following the activation instructions printed on the unit.
The built in GPS receiver ensures that an accurate position of a casualty is relayed to the rescue services. This in turn improves the speed of recovery by updating the position of the beacon at regular intervals.

Key Features:

• FCC approved
• Internationally approved
• Ultra compact and stylish
• Transmits on 406 and 121.5 MHz
• Integral 20 channel GPS
• User replaceable battery* (leisure users only)
• High brightness LED flashing locator light
• 72 comprehensive diagnostic and self-tests during battery life
• Once activated, will transmit for a minimum of 48 hours
• 6 year battery life
• 5 year warranty
• Non hazardous battery for safe and easy transportation

[download a full spec sheet]

Battery Replacement in Older 406 EPIRB's.

What do you do with an older 406 EPIRB who's battery needs replacing? For some, it is a simple issue of getting the battery replaced; but for others (when the unit is older than 10yrs), the EPIRB is no longer serviceable and agents will no longer service them. They say that once an EPIRB is over 10 years old, the unit is obsolete. This exert was taken from a Practical Sailor article and is reproduced below.
"Upon completion of the successful testing I was informed that after the battery theoretically expires in July of 2011, they will not be able to install a new battery as ACR will not permit this, the contention being that the EPIRB has lived out it’s useful life as a piece of electronic gear and therefore can no longer be placed in service any longer. If I wish to continue having an EPIRB aboard my vessel, I will need to purchase a new unit!"
I can't understand why the electronics date. If it still tests OK and is working, why are we making these units obsolete?  It's so these rip off dealers can sell us more EPIRB"s. That's why! :-D
Replacing batteries in these units is not for you average handy man for the most part. In fact, even if you were to replace the batteries (assuming you get the right ones), you still miss out on the service center, complete test of the unit. Often to the same standard that new one's are tested to as they run the assembly line.  Having said that, it is possible to replace the batteries yourself, provided you get the correct one's. Remember, your life may one day depend on this device. Get this wrong and well........ Please, if you are not up to this, send your unit in for the service or buy a new one.
We are discovering, 1. Our EPIRB's (2 of them on "Solace"{406's}) will no longer be able to have their battery replaced due to there age. and 2. The cost of new ones has reduced significantly so that it can often be cheaper to buy a new one. So for us, we will buy new one's and leave the old one's on board as "back up" .
So, below is an description of how to change the batteries on an McMurdo E3 EPIRB. The limiting factor to start with may be your ability to source the battery kit from a McMurdo dealer. Usually, if supplied, it is done with all responsibility resting with  purchaser. Good luck!!
AND a uTube on the change of batteries on another type of 406 EPIRB with hydrostatic release.
Does anyone else have a project they can direct me to, on changing batteries on a EPIRB? What about dealers who will sell the battery kits for EPIRB's? Please send any details you have to the email in the header, or leave a comment below this post. TIA

 Changing McMurdo E3 EPIRB Battery

Recently, I have to change an expired McMurdo E3 EPIRB battery. I never changed an EPIRB battery before but after understanding its internal structure, I am confident enough to try for the first time.

The replacement kit comes with a battery unit, a gasket, a silica gel package, new battery expiry date sticker and 8 pieces of new screws.

This is how the new gasket looks like. It is used to replace the existing gasket on the top/antenna housing

The screws comes with o-ring to ensure watertight integrity to the EPIRB unit

First of all, remove all the holding down screws around the housing useng a flat face screwdriver. Total of 6 screws if not mistaken.

There are 2 screws hidden behind the lanyard. Pull the lanyard holder to reveal the screws ports (2)

After removing all the screws, gently pull up the top/antenna housing to disengage it from the lower part of the unit. The printed circuit board can be seen after the top housing been removed.
The printed circuit board is been secured with 3 screws

Use the Philips screwdriver to remove the centre screw. Extra precaution not to lose the washer below the screw














Then remove the spacers by either removing screws from the bottom of the spacers or loosen the spacers with finger. There are washers below the spacers and should be careful so not to lose the washers

Slightly lift up the circuit board gently. The battery unit can be seen at the bottom of the printed circuit board.

Try to locate this 2 connections attached to the printed circuit board. One of the connection is to the battery unit and the other one is to the unit test button. Gently disengage the connectors from the printed circuit board.

Note there is an old silica gel package (white package) at the bottom of the printed circuit board.

Remove the previous silica gel and replace it with the new one which comes with the replacement kit. Use the double sided adhesive tape to ensure the new silica gel glued to the area. The purpose of the silica gel is to keep the internal area dry from moisture

With the printed circuit board removed, the battery unit is visible underneath it

Use a narrow head pliers to loosen the bolt that is securing the battery unit. There is a washer below the nut and be careful not to lose it.

After the nut is removed, the battery will slide out easily. There is a tiny shaft in the middle that secure the battery unit.

Change the gasket for the top/antenna housing

Reassembled it in the reverse order. Once it is reassembled, push and hold the test button for 10 seconds to ensure the EPIRB unit is in working condition and able to transmit.

Lastly, put on the new battery expiry date sticker on the EPIRB unit. The battery has a lifespan of 5 years.

Also the EPIRB casing should be updated with the new battery expiry date sticker.

Practical sailor blurb
We received the letter below yesterday from Practical Sailor reader Arnold Rowe. He was kind enough to let us share it (with some minor edits of his well-expressed and understandable ire), with the hopes of raising awareness of the limited service life of 406 EPIRBs. Having had a similar experience years ago with the torpedo-sized RLB23 (which set me back more than a $1,000 in the ’90s) I can sympathize. The now obsolete RLB23 is officially consigned to Practical Sailor’s Gear Graveyard, and I expect a series of other newly obsolete EPIRBs to join it.

As we move forward with Ralph Naranjo’s report on Personal Locator Beacons (PLBs) in the April issue of Practical Sailor magazine, we’ll also look at effective service life. Battery life has become an even more critical issue these days as ACR—and I assume other makers will follow suit—add non-emergency functions to their PLBs, like the AquaLink View PLB . According to ACR Electronics , the new unit is designed with fixed limits for non-distress messaging and tests, so that using the non-distress features will not tap into the required reserve battery life for distress alerting. We look forward to testing this product and hearing readers’ take on the messaging feature, as it raises some important questions regarding the purpose of emergency signaling devices.
By the way, some safety equipment dealers are offering trade-ins on old ACR EPIRBs, which should help ease the financial pain of replacement. According to Mr. Rowe, Avalon Rafts is one of them.
Finally, I’ll emphasize here again that it is very important that owners of EPIRBs routinely drop in at the NOAA beacon registration website to make sure all their data is correct and up to date:

Dear Practical Sailor,
I own an ACR Satellite 406 EPIRB, Product No. 2758, Category II/Class 2.  This unit is manually deployable. A date stamped on the side of the unit reads Sept 15, 1997. A sticker on the same side reads Serial No 5990, Date: 9605.
On April 13, 2006, I had the battery in this EPIRB replaced at my local ACR service center at a cost of $222.38. A statement on the back of the EPIRB reads “Battery must be replaced after emergency use or by: 07/2011.”
Yesterday I happened to be in my local ACR service center and they kindly checked out my EPIRB using their computer based system.  It immediately passed all tests with flying colors.
Upon completion of the successful testing I was informed that after the battery theoretically expires in July of 2011, they will not be able to install a new battery as ACR will not permit this, the contention being that the EPIRB has lived out it’s useful life as a piece of electronic gear and therefore can no longer be placed in service any longer. If I wish to continue having an EPIRB aboard my vessel, I will need to purchase a new unit!
My EPIRB is in absolute pristine condition.  I am perfectly pleased with my existing EPIRB and wish to keep it for many years to come.  Purchasing an EPIRB was not a trivial initial investment and I find it irritating that I am forced to chuck a perfectly adequate piece of gear at the manufacture’s whim.
Arnold Rowe
Riverside, Calif.

Battery Fill System

 The company at flow-rite.com has some interesting products. This is one of four different battery fill systems they have on offer. For those with lead acid batteries and a need to fill them up with water from time to time, this could be the answer

Qwik-Fill

Previous :: Next

Qwik-Fill On-board Battery Watering System works with group size 24 through 27 and most 29 through 31, 12-volt marine deep cycle batteries.
One of the primary causes of short battery life is a failure to maintain proper water level. Whether your batteries are in plain sight or hard to reach, adding water to the proper level couldn't be easier with the Qwik-Fill On-board Battery Watering System from Flow-Rite.
After a simple, one time installation that takes only a few minutes, you can fill all your batteries simultaneously from a single remote fill point without ever having to remove a single battery cap. You no longer have to touch or even see your batteries. The level in each cell is controlled independently, adding water only to cells that are low. It will not overfill and its precise accuracy would be almost impossible to match with conventional filling methods. Finally, the battery accessory we've all been waiting for has arrived.

Remote Battery Wiring

A separate battery to run a winch or bow thruster is cheaper, safer and works better than running a heavy cable from your starting or house bank.

This installation requires some electrical skills and since errors could cause an electrical fire you should not attempt it unless you feel confident. This project has not been checked for compliance with ABYC or USCG standards and the author presents this as a guideline to be interpreted by qualified installers. No warranty or guarantee is given or implied.

THE THEORY BEHIND THIS PROJECT

Winches and bow thrusters, located in the bow, are usually a long distance from the starting or house batteries. These items draw a heavy current for a short period of time. Unless you use very heavy cable for the long run, the voltage drop by the time it gets to the device, will have reduced the available power.
What is worse, however, is that very heavy copper cable is an invitation for an on-board fire if it gets shorted so for safety you have to add a large fuse - large enough to take the stalled motor load of the winch without giving you a nuisance blow - yet small enough that a short at the far end can draw enough current through that long cable to blow the fuse.

In many installations, these requirements conflict making practical current protection impossible.

The current drawn by the stalled motor is often so close to the current drawn by a short at the remote end that any fuse or circuit breaker that can protect against the short, will give nuisance blows just when you really need it.

PROVIDING A REMOTE BATTERY IS SAFER, CHEAPER AND WORKS BETTER

Instead of installing a very expensive heavy gauge copper line up AND BACK, and the expensive fuse to protect it, install a battery in the forepeak to provide local power. Now, the heavy wire is very short with very little voltage drop, and you can keep the battery charged with an economical charging line. Depending on the size of the device to be powered you can usually get by with a low cost automotive starting battery. These are made to take heavy loads for short periods of time and remain on float charge the rest of the running time. Since the charging line is low current, it is easy to provide fuse or circuit breaker protection. By installing a 50 amp combiner in series with the charging line, the remote battery will be maintained at full charge without any diode drop yet it will not discharge back into the house or starting battery.

NOTE:- Since there is a battery at each end of the charging line you need a fuse or circuit breaker at EACH end.

INSTALLATION

Parts List:-

• Automotive battery with enough capacity to run the device for the longest job. (Multiply AVERAGE current by time in hours to get amp-hours required, then double this figure. Example, 80 amps x 30/60 hours x 2 = 80AH ) For charging compatibility it should be the same type (lead-acid or gel) as the starting battery.
• 50 amp combiner The combiner should be mounted with the remote battery.
• Two fuses or circuit breakers. I prefer the automatic reset thermal breakers that are typical in the automotive industry. 
• A good quality battery box. 
• Red and Black cables for the charging line - 10 gauge is adequate.
• Conduit to protect charging line - essential on a metal boat, desirable on others.

Select a location for the forward battery. It should be ventillated because the battery will be on charge much of the time and producing small amounts of hydrogen that could be explosive if allowed to concentrate. Larger installations might consider an automatic power vent that only runs when dangerous gasses are being produced. A gel type battery is much less of an explosive gas problem but it is still present if overcharged.
Provide a SOLID mounting for the battery and battery box. Keep in mind that the bow takes much more of a pounding than the traditional battery locations so go overboard (not literally) on strengthening the mounting. The battery (box) must be rock solid when strapped down. Due to the motion and stresses, I would not use the conventional webbing strap they supply as the buckles provided are usually poor. Good quality ratcheting strap(s) of a material that is acid proof would be better, or provide a stainless retainer with through bolts and wing nuts.
Connect the device to the battery following manufacturer's suggestions. Connect the charging line, following this schematic and the installation instructions supplied with the combiner. If you use our thermal circuit breakers, you must use crimp on ring terminals to connect the wire - the screws are too small to adequately secure 10 gauge stranded wire, even if tinned.

24V from 12V

This is a traditional problem that typically has very dangerous and expensive switching. Typically it is done with a second battery that is kept in parallel with your 12 volt starting or house battery for charging, but is switched in series with that battery to run the 24 volt item - bow thruster, winch etc. This is expensive and dangerous. You have to use two very heavy duty switches, one to switch the negative of the additional battery from the -12 to the + 12 of the starting battery, and the other to disconnect the +12 of the additional battery from the starting battery.

BUT THE TIMING IS CRITICAL. If one switch is operated before the other you will end up shorting a battery and cause an explosion.

So here is how to do it the safe way using only a single pole single throw switch.

In the circuit diagram, you will see that the auxilliary battery is connected in parallel to the 12 volt battery through a pair of headlamps, one in the positive lead and one in the negative. With the "24 VOLT" switch open, the charge on the additional battery will be the same as the 12 volt starting battery because the headlamps, which carry a couple of amps when lit, will trickle charge the additional battery to the full voltage. Under normal circumstances, the headlamps will only have a fraction of a volt across them so except under heavy charging/discharging conditions they will stay off or have a very dim glow.
There will be 12 volts going to the 24 volt load when the switch is in the 12 volt position but since the headlamps are in series with the circuit, if the bow thruster were turned on, only a couple of amps would flow and the headlamps would light. When you close the 24 volt switch, the batteries are now in series and 24 volts is available for the bow thruster. While in the 24 volt mode, a couple of amps will flow through each headlamp and they will come on full brilliance. The amount of energy wasted, however, is small compared to the battery capacity and the few amps through them does not materially diminish the high current available for the thruster.

COMPONENT SELECTION

The BATTERY capacity of the auxiliary will be a function of how long you think you will need the bow thruster in one session, and how often sessions will occur. Refer to the bow thruster current requirements to determine this figure. For example, if the bow thruster draws 50 amps (about 1.5 horsepower) and you need to be able to run it for up to 30 minutes, that comes to 50 x 0.5hr = 25 amp hours. You should double this figure to provide a safety factor and reduce cycling the battery below the 50% charge level. So a 100 amp-hour automobile battery for about $35 would be ideal. You should match the chemistry of the battery to that of the starting battery - don't mix an AGM or GELL battery with a WET lead acid. Otherwise the batteries can be of different ages, manufacturers or style. You don't need a deep cycle battery here - the usage is more like that of a starter motor battery in an automobile.
Charging time after a typical use can be calculated by dividing the amp-hours used, say 25 in a 30 minute period, by the charging current, say 4 amps = 6 hours, or 12 times the discharge time.
The HEADLAMPS should usually be the highest wattage you can find. In fact I use a high/low beam headlamp and wire the high and low terminals together so both filaments are in parallel. The high temperature will reduce life but since they are only going to be on for a few minutes a day maximum, who cares? A major advantage of using headlamps to limit the current is that the resistance is non linear. As they cool down the resistance goes down dramatically and they tend to draw a constant current for charging even though they are not brightly lit. You should consider placing the headlamps so the light is visible from the bow thruster control panel location so you don't forget to switch back to CHARGING when the bow thruster is no longer needed, otherwise the headlamps will eventually discharge the auxiliary battery.
The SWITCH should be sized for the maximum current of the bow thruster plus a safety margin. For an economical installation, a simple battery disconnect switch is ideal. If you want a remote control, then you should use a simple single pole, normally open relay instead of the switch. We have a 130 amp relay in our Parts and Kits catalog that will handle many thrusters.
The CABLES should be sized as recommended by the bow thruster manufacturer with regard to the length of the run. Note that only the cables to the switch have to be this size. The cables to the headlamps only have to carry a few amps so a 12 or 14 gauge wire would be adequate.