Battery Combiner & Monitor

When we bought Circe there was a very basic DC power system in place. General utility needs were supplied by a 'House' system comprising two Trojan T105 6volt lead-acid golf cart batteries, connected in series, delivering 12volt power with approximately 225 Amp hour capacity. One additional group 27 (DieHard) 12volt lead-acid  battery rated at 550 CCA capacity provided starting power for the main diesel engine. All three batteries were re-charged either from a small, engine driven, 70 amp Balmar alternator or from 110 VAC shore power source controlled by an on-board Heart Freedom 10 combination charger/inverter. To monitor the system, analog voltmeter and ammeters were installed. To manage the system, the three batteries were linked through a user-operated selector/isolator switch that had to be manually switched to suit battery condition and charging mode.

View of DC distribution panels showing analog instruments in the right hand panel voltmeter (top) and ammeter (bottom). Below the instruments is the control panel for the Freedom 10 inverter/charger.

Shot of the original Perko selector switch that had to be operated as necessary to select the preferred power source and control the charging and discharging of the three batteries.







This simple system is very common on production boats and has proven to be reliable and stable, but it has some limitations. The biggest shortcoming is the lack of any active monitoring and control capability. This means the operator must physically monitor power useage on all three batteries and use the selector switch to control power sources and replenishing charges as necessary. While this process isn't particularly difficult, any oversight in the monitoring or switch operation can cause complete or partial loss of power. We wanted a more active, smart system that required minimal operator input so we started looking for some professional advice.

http://www.mathiesenmarine.com

Earl Mathiesen of Mathiesen Marine was our 'go-to' resource and he proposed some options that would fit our requirements. We were originally planning to combine this upgrade with a complete electrical panel clean-up and re-wire but based on Earl's advice we decided to just do the power management upgrade first and then build the new panel and re-wire as a second step. The new power management system comprised a Blue Sea automatic charging relay monitored through a shunt by a Xantrex LINKLite unit and controlled by a combiner switch.

Here is the new Blue Sea automatic relay and combiner switch.

This shot shows the old selector switch coming out.

Here is the new combiner switch installed. It has the same footprint as the old selector switch and so was an easy swap. In normal operation the switch stays in the 'on' position, the relay switches the battery connections automatically between House and Start batteries based on power input and output from either circuit.

The shunt for the battery monitor was located on the battery box to keep the cable runs short. The blue multi-conductor cable is the hook up to the Xantrex  LinkLITE monitor.

This  is the Blue Seas combining relay we used.

Not the best shot but it shows the automatic relay in place next to the combiner switch, again to keep cable runs short.

For speed and convenience, pending the new panel being built, we put the LinkLITE monitor where the ammeter had been. The voltmeter was left in place but it is redundant in the new system. It will disappear when the new panel is built.






So far the new system is working perfectly and a quick glance at the monitor shows exactly how much power is being used and the overall condition of the batteries. An alarm will alert us to the batteries reaching 50% of capacity. When we have our wind and solar generation and LED lighting projects completed we will disconnect from shore power for a few days and see exactly how much power we are using and how much we are able to replace without running the engine. This will help us decide if we need a bigger alternator and/or house battery bank. Putting more batteries on the boat can extend periods between charges but also extends the time needed for re-charging. We are currently investigating Lithium-iron-phosphate batteries that can solve that problem without the weight and space penalty of lead-acid or AGM batteries. We will be updating this post periodically as and when we have more data and operating experience.

Battery Vent Caps

In an earlier post we showed how we cleaned up all the primary wiring to the two 6 volt L-16 batteries and put them in a secure enclosure built from starboard. That upgrade was a major improvement, but we still had some problems keeping the tops of the batteries dry.

We considered replacing the lead-acid batteries with AGM's but the Trojans were in really good shape and holding charge well. Also, we keep reading that lead-acid batteries are best suited to our situation, where the DC system is run with dock power plugged in for the majority of the time. 

Difficult to see in this shot but there is 'weeping' or 'sweating' on the caps of a couple of cells on the forward battery.

We fussed with the acid levels for several months but never found an ideal condition. If we kept the acid just barely above the lead plates it eased the problem considerably but we had to watch the levels very closely and top the cells up frequently to avoid exposing the plates. If we were more generous with the distilled water and let the level come up, even a quarter inch above the plates, the sweating started. It got worse with a heavy equalising charge and/or a bumpy ride, such as motoring into steep chop. 

Things came to a head when we found that despite our efforts to keep them dry, the moisture on top of the batteries had been enough to rot the hold-down straps and corrode the strap anchors. The acid had slowly wicked along the straps and corroded the buckles and anchors. The stitching on one webbing strap actually disintegrated.

Corroded buckle on one of the hold down straps.

Corroded anchor bracket for hold down strap.

Corroded buckle on second hold down strap.

A poor photo but it shows the stitching on the strap above that actually fell apart due to the acid!

We had to do something. While surfing the net for solutions we found several products that promised to fix our problem, which evidently is quite a common one with lead-acid batteries. After a bit of research we decided to try the Water Miser made by Flow Systems.

http://www.flowsystemsusa.com

The Water Miser vent caps are designed specifically to eliminate misting from escaping gas during charging cycles and are a direct swap with the standard 1/4 turn caps on most wet cell batteries. They are also very inexpensive.

  

We sent of for a half dozen caps figuring we couldn't get hurt too badly. Here they are, installed, about two weeks ago. We topped up all the cells to a level that previously would have guaranteed some weeping and, at the time of publishing this post, we have seen no sign of any problem.....Yippee!  

The old caps on their way to the dumpster, another item crossed off 'The List'! 

Battery Re-wire

In one of our earlier posts we noted that Circe's pre-purchase survey, conducted by Peter Minkwitz (a first class and extremely thorough Bay Area marine surveyor 510.465.2527), was 'mostly' satisfactory. Overall, Peter's findings validated our initial inspection and assessment of the boat but he did re-emphasise several issues. Some were more serious than others and the biggest problems were electrical, on the supply side of both the AC and DC circuits. We had seen wiring and security issues on the house batteries but Peter also picked up on an AC supply issue. 

There were two major concerns:

1 Although they were all nearly new, the starting and house batteries were not securely mounted in proper trays and the primary wiring was a real rats nest! Beyond that, a second battery selector had been incorrectly wired when the new Heart inverter/charger was installed, essentially creating an unecessary redundancy with the original selector.  A side issue was that with all the batteries on the port side, along with the galley, head, holding tank, water heater and outboard on the stern rail, we were seeing a distinct list to port!

2 The wiring problem on the AC side involved the main AC breaker  which wasn't doing anything at all! As soon as the shore power cord was plugged in, with the main breaker on or off, there was power to all the AC circuits! Evidently the breaker was being bypassed somehow, meaning there was no AC protection on the boat. 

While cleaning up these issues we also decided to relocate the starting battery and move it behind the engine, to put some weight back on the centre line. Also, because the battery can easily be removed, it will give us better access to the stuffing box, which was difficult with the heater fixed in the stock location. This meant relocating the water heater but it was shot so ditching it and moving the new one wasn't a problem. 

Is that a rats nest or what, scary actually! A couple of inexpensive busses would have helped a lot. The #27 starter battery (far left) will be relocated to where the water heater was, in a removable tray for improved access to the stuffing box. The house batteries will be going into an acid proof box and  the wiring cleaned up.

The hot water heater was in bad shape, rusted, leaking and not well located, right over the stuffing box. A new one will go under the Pullman next to the holding tank, making way for the relocated starting battery, which will be in an easily removable tray for the times we need to get to the stuffing box.

Much better.....clean, tidy and SAFE! The edge of the access panel in the dinette bench had to be notched to make it easier to lift the house batteries in and out but the result is a much better set-up.

Heck, we're already using up the free space we created by moving the starting battery. They say boats are like a women's purse, if there is space in it then something will fill it!

There is now all kinds of room to access the stuffing box whenever we need to. We considered putting a PSS in but after re-packing the gland with ten bucks worth of Tefpak we have an almost completely dry bilge and a much simpler set-up.







We were really happy with the changes. It was a big improvement, securing things properly, getting rid of the spaghetti, taking some weight off the port side, freeing up some additional space under the forward dinette seats and improving access to the stuffing box. It was a lot of work but we solved a lot of issues.