Wiring problem - best next move?

[Docker]

I need help regarding my 33 foot 1980 steel cruiser.

It is a 1980 boat with most of the original wiring in situ. The original engine loom is in situ and the original loom wiring from the domestic batteries to the distribution busbars at the lower helm position is in situ.

Recently there has been a complete re-wiring of the upper helm position with connections made from here to the lower (inside) helm position - at the same time, some redundant wiring has been removed from the lower helm position.

In addition, a new diesel generator was installed last year and at the same time the two domestic batteries were replaced.

Since this work has been done it has been impossible to maintain charge in the domestic batteries for more a 24 hours - either by charging them using the genny or by running the boat engine.

I'm concerned that the re-wiring of the helm and/or the genny/charging system is causing a current leak or has been done incorrectly.

Ultimately, the lower helm position and the original wiring between the domestic batteries and the main distribution busbars needs updating. But in the first instance, I am more concerned about the current problem - the boat is unusable as such.

Is there anything glaringly obvious in that summary that points to a possible cause or do I need to consider moving ahead with a re-wire of the domestic system?

Help appreciated - thanks!

 

[Don S]

Re: Wiring problem - best next move?

What's "situ"?

 

[Don S]

Re: Wiring problem - best next move?

Quite honestly, without seeing the wiring or knowing how things are hooked up your question is un-answerable.

 

[Docker]

Re: Wiring problem - best next move?

Don - "in situ" means "in place"

Appreciate that no wiring diagram makes this a difficult question to answer - the original wiring diagram for the boat is limited to the engine/instrument panel wiring loom.

My question is asking if there is any obvious reason that my problem is occurring, such as the batteries themselves not holding charge or the battery charger having difficulty with two input sources, etc.

Any suggestions would be welcome.

 

[glenn property of pam]

Re: Wiring problem - best next move?

docker we have to get a few more details so lets get back to basics first

If I understand you have 2 batteries that are running the house, Are they only running the house or are they also being used by the main motor, I would presume that these batteries are linked in parallel. I think you are saying that you have a battery charger connected to them and you also have them connected to the genny (how are they connected to the genny e.g are they connected to the alt and the starter or ????????).
Now I think you are saying that the batteries go flat after 24hours even if you try to recharge them (you are not sure if they are getting charged). Now is that in 24hours with no load the batteries are going flat? Or with normal house load the batteries are going flat even with the genny running that's meant to charge them, Is the genny charging via the battery charger or the alt or both?

 

[Docker]

Re: Wiring problem - best next move?

GPOP - that's right - the domestic battery bank is two batteries connected in parallel. These were replaced at the same time as the genny was installed one year ago. The amp hour rating of the batteries is the same as the ones that they replaced and the domestic services load has not changed. There is no battery monitor on the boat so the capacity of the domestic batteries was confirmed to be adequate using an electrical audit. They are only being used for the domestic services. Both the genny and the motor have their own cranking batteries.

I have not tested the batteries in isolation to see if they are holding their charge - or are defective from new.

The battery charger is an older type Victron Pallas (http://www.victronenergy.com/Manuals/pallas/pallas 12-25/Pa03001e.PDF). It takes a 220V (based in Ireland) input from the shore-power, genny or the motor alternator and supplies the domestic battery bank. As far as I am aware, the genny is charging only via the battery charger.

If the genny is run for an hour or so, and then switched off, the domestic services function fine off the batteries. The next day or 24 hours later, the domestic services don't run well at all - cabin lights dim, no hope of switching on fridge, etc. During the time away from the boat there is no load on the batteries.

I am not sure if the battery charging is ineffectual or if there is a current drain on the batteries. Is there anything obvious in this description that would suggest one cause over the others as being the likely reason?

 

[Grandad]

Re: Wiring problem - best next move?

There is nothing more logical than the flow of electric current. I would take a very logical and patient approach to solving what must be a drain on the system. Just to give you a baseline, confirm that the batteries do in fact hold a charge by disconnecting and isolating them for a period of time from all possible connected loads. Next, with all distribution breakers turned off (or fuses removed), connect a portable ammeter between the battery (attach meter positive lead) and the distribution system positive leads (attach meter negative lead). This assumes you are using a negative grounded system with breakers or fuses in the positive wires. Meter reading should be zero. Make sure that all loads (motors and lights, etc) are turned off and then connect the circuits one at a time by closing the breakers or installing a fuses. As long as every appliance is turned off, the reading should remain at zero.

Treat the generator and battery charger as just other loads, keeping them isolated from the system, connecting them (while not running) only sequentially when you want to confirm that there is no current leaking through them. When you connect a circuit that draws current as shown by a meter reading when nothing is turned on or operating, you've found the culprit. Note - do not turn on any significant loads while the ammeter is inline with the battery leads. Many inline multimeters have only a maximum 10 amp capacity and you'll likely take out a protective fuse in the meter if you exceed its rating. Since your leak is such that it takes 24 hours to weaken the batteries, I would expect that your leak does not exceed 10 amps. If your meter has a higher amp range, use it. - Grandad

 

[low277]

Re: Wiring problem - best next move?

+1 on what Grandad said.

 

[Georgesalmon]

Re: Wiring problem - best next move?

I wonder what the domestic load is for sure. When you mentioned "fridge" I get to thinking you have a pretty good load on your batteries. It's possible your "normal" load may cause the batteries to drain in 24 hours.

 

[glenn property of pam]

Re: Wiring problem - best next move?

amp meter is the best tool for the job but a basic digital volt meter would be a good start. With the batteries charged what is the bank voltage (both in parallel) undo the jumpers between the batteries and what voltage is each battery. You may find that you have one weak battery or one that has dropped a cell and is causing a problem with the other one that's connected in parallel.
When was the last time you checked and added water to the batteries, If they have been on charge they might have boiled off the water and that could also account for the problems you are having.

 

[Docker]

Re: Wiring problem - best next move?

Grandad - thanks - that outlines the steps in a logical way. I'll check the batteries in isolation first to make sure they are not the culprit - and thanks GPOP for describing how to ensure that even if the domestic bank is ok overall, that one of the batteries is not causing the problem. Some newer battery chargers can treat different battery banks (cranking and domestic) separately and I wonder if my charger is charging the motor cranking battery and once it senses that this battery is fully charged it is switching to float mode?

George - the new batteries are rated, in terms of amp hours, exactly the same as the older batteries that they replaced. The domestic load - calculated using the audit, has not changed since the genny and new batteries were installed - yet this problem did not occur with the older batteries. In fact, I could spend 36 hours running the fridge and some other lower demand loads off the old batteries before having to start the motor to recharge if I was not at shore-power.

Appreciate this advice - it's a great help - and hopefully I can get to the bottom of this quickly......