Electrical Problems Redux

Pat,

As stated above, take the batteries in for a load test (Napa in North Bend or Model Garage in Fall City should be able to do this). My guess is that when you direct shorted them one of the cells died on you.

Also, as Boris said, don't just wire them up in parallel. They will discharge each other quickly due to the different size of the two batteries.

Those BEP systems are nice. But I don't know how much voltage your Honda will put out when it is charging at full output. It might not actually put out enough to turn on the relay (but I would guess it does). I looked at the Blue Sea system a while back, and it is basically the same thing as the BEP. Since you already have the BEP, I would stick with it. You should be able to replace just the one switch at Fisheries Supply in Seattle.
 
I have a new BEP 716 ordered from Defender (best price and no sales tax). The Honda BF150 was outputting 14.5 volts as measured by the Navman. I'll replace it, confirm the BEP is working, and finally load test the batteries if problem persists. Stay tuned!
 
I agree that paralleling the two batteries when the engine is 'off' is not a good idea and the batteries will fight each other to try to achieve balanced voltage. However when the engine is charging and the charge voltage (14.5V in this case), is well above the voltage of either battery, both batteries are drawing current from the charger only. There is no interaction between the two batteries. They're only drawing current from the charge circuit at different rates.

As a temporarly measure, I think you are safe to: switch to parallel after starting the engine to keep both batteries charged; then switch off the parallel before turing the engine off. Any disagreement?
 
seahooked,

Unless there are regulating sensors in each line of that parallel charging arrangement, charging in parallel may not result in each battery reaching full charge if the two batteries have different "internal resistances." In the training I got in DC electricity, the "equivalent circuit element" for a lead acid battery is a "pure" EMF source and a resistor, with the value of the resistor a function of the battery's health: as it degrades, the value increases. That's why you get less voltage off a sick battery: the "internal resistor" causes an "internal" voltage drop which is proportional to the current drawn. the more current you draw, the greater the voltage drop.

What that means is that two lead acid batteries in parallel, although subject to the same charging voltage, will receive different charging currents, with the "sicker" battery receiving less charging current than the healthy battery. This sounds counterintuitive, because on discharge the weaker battery puts out a lesser voltage; you have to remember that an unhealthy battery is more resistant to receiving a charge than a healthy one, thus demanding a higher charging voltage to get the same charge a healthy one would.
 
Well, this probably should go under the heading of Wallas, but since I started it in this thread, guess I'll keep it here. Finally found a pack of 2 amp AGC fuses at NAPA (ALL the other places only had 5 amp, had never heard of 2 amp). Stuck her in and flicked the switch - same thing that happened out on the water at Andrews Bay, the light came on for a second, and then went out, and I had a brand new blown fuse (got a 5 pack, they were cheap). Can anybody hazard a guess as to why the Wallas would be blowing fuses when switched on? If the battery is wounded, would that do it? It had been on charge with all the switches off, and was showing 13.3 volts when I tried the Wallas with the new fuse...
 
Jody, I don't think that's the deal, because we used the Wallas to cook dinner on Saturday night the last time we were out. It was the following morning that it blew the fuse when I switched it on. Very baffling.
 
Ok one test that you could do would be to leave the fuse out and set your meter to amps DC and put your test leads across the fuse holder. This will give you the current on that circuit. But if the loop is shorted or drawing high amps it could finish off what has gone wrong. When I worked in manufacturing we would put a 20 amp fuse in and see were the smoke would come out. This was a quick way to find what part needed to be replaced. You will need a meter that can read 10 amps DC.
 
There are a bunch of things which could cause a fuse-blow in the Wallas, but the first, easiest and cheapest thing to check is that the two spade connectors for the main power and ground (red and black) which come from the battery, and the additional ground (black) which nestles right in with the two main connectors, are firmly seated to the circuit board underneath the unit. Remember, unless you pull the fuse at the battery, the red is hot 12 volts, even after the 2 amp fuse on the unit has blown. So, don't go shorting anything out.

I've had fuse blows which must have been the result of poor connection at these terminals, because after the fuse blew, I found one of the connectors was loose, reseated them all, replaced the fuse, and had a nice, hot dinner.

If this doesn't solve the problem, there are some other things you can do, if you're good with a multi-meter. Let us know.
 
Pat,
You probably need to take your boat to someone equipped to troubleshoot electrical problems like yours.
Without a lot more information I can't help you other than describe how I would troubleshoot it. I am thinking that you may not have the test equipment needed.

WARNING: Following a detailed test procedure like the one below could make you hair hurt and / or fall out.

Rule #1- Never assume anything; Methodical measurement is the quickest way to find where your current drain is coming from unless you luck out.

Test Equipment:
- DVM (I use Fluke) You can buy a reasonably decent, inexpensive DVM at LOWES and it would be a good investment to troubleshoot any future DC or AC electrical problems for your boat, house, car, etc. You might also want to buy a basic book on electrical circuits.
- DC clamp on current probe: this will save a lot of time because you can quickly clamp it over any wire and directly measure the current draw (AMPS) in that circuit. Unfortunately, these are too expensive for a one-off troubleshooting situation. METHOD 2: Purchase a .1 OHM, 100W power resistor at Radio Shack and measure the drop across it with your DVM to read AMPS directly. Example, if you read 1Volt, then your circuit is drawing 10 AMPS (I= V / R) ie. 1V / .1 OHMS = 10A. The resistor introduces a slight measurement error but it is insignificant in this case and you can measure up to a little over 30 Amps with this kleuge.

Strategy:
What you want to do is start at the battery and isolate which circuit is drawing the current when everything is supposed to be OFF.
1. First, test each battery to confirm full charge (IMHO that the chance that two new batteries are damaged or bad is possible but remote; some electrical fault is draining your batteries. Yes, I am breaking my 1st rule by making an assumption)

Fully charge both batteries and confirm that they are charged to 13V + with no load on them. The charger will create a surface charge that would eventually bleed down to about 12.7V.

I would start troubleshooting the Wallas since that is where you noticed a problem to begin with.
One question: Is the Wallas drawing any current when turned off (you know that is drawing > 5A when you turn it on but let's save the smoke test for later.
2. Determine which battery (should be the starter battery) is connected to the Wallas. There should be a fuse (~15 - 20AMPS) between the battery and the Wallas if it is connected as the factory requires (#12 Red wire). This may or may not be the case since you have some battery switch bank banjo work connected therein.

3. Set your DVM to a scale that will read 10VDC and clip the DVM leads across the resistor for all of your measurements. Find a convenient (relative term) location to connect the .1 ohm resistor in series with the circuit that feeds the Wallas. You could start by disconnecting the +12v RED main cables from both batteries and then clip one end of the resistor to the red battery cable and momentarily touch the battery Positive terminal with the other end of the resistor while reading the voltage (current) since this is a easy connection. Record your reading.
If there is no current, then try the identical test on the other battery.
Determine from which battery current is being drawn and how much.

4. If any significant current is being drawn (say > .1 A or so), then try to isolate the source by disconnecting loads one at a time, starting with the Wallas. If significant current is being drawn, disconnect the Wallas by removing the main fuse and determine if the current still flows.

5. If the Wallas is drawing significant current when switched OFF, then the problem could be one of several possibilities including: a low resistance between positive and ground in the wiring or connectors, a low resistance on one the Wallas circuit boards, or a component such as the pump.
6. The fact that the smaller 5A fuse is blowing indicates a low resistance in the Wallas or in the wiring /connections associated with it. I use the term " low resistance" and not "short" because a short is Zero ohms.
7. If the problem is confirmed to be associated with the Wallas, I would disconnect everything from the batteries and use the OHM scale on your DVM to determine where the low resistance is located. Set your DVM to a full scale of 10 OHMs to begin with and measure the resistance between the connector terminals where the red and black main power is connected to the motherboard. If this reads less than 1 ohm, then something has likely gone south on the Wallas. I assume that you would send it to Scan Marine and not troubleshoot it further. I am nuts and would definitely troubleshoot further.
8.If the Wallas checks out ok somehow, then we want to reconnect the battery from which current is being drained and systematically disconnect devices at switch and / or fuse panels until the current drain goes to zero.
9. Determine which device is causing the drain and disconnect it at the a convenient location to verify that the current drain is gone. Warning: Do not use your DVM on the OHMS scale with power on the circuit; disconnect all power at the batteries to be safe.

If you want to pursue this, send me an email and I will help you. If you lived a lot closer, I would come over to help diagnose further.

I hope this helps rather than confuses you.
Good luck,

Richard
:roll:
 
Back
Top