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Old 24-08-2005, 14:05   #1
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Location: Winters - Out Cruising / Summers in the NC mountains
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Battery Monitor

We have three battery banks (house - start - windlass) that are charged via a Pathmaker 250/3. I want to monitor the house bank, but do I really need to spend the extra money for a 2 battery bank there any advantage to monitoring the start or windlass battery since their charging is liked via the Pathmaker?

I appreciate your input.


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Old 24-08-2005, 15:34   #2
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Battery banks, food for thought

In my opinion you only need to monitor the house battery bank for capacity removed/returned, temperature, etc.

In the case of start-only start batteries it is sufficient to monitor the voltage (digital resolution to 50mV). One notes the start battery voltage at times when the PathMaker is not engaged. You should set up the PathMaker's "high voltage" disconnect setting to not connect when the house battery is being charged much above above float voltage (say, set the HV disconnect to 14.0 or 14.1V) merely to aviod unnecessarily gassing the start battery which should always be "full", in essence.

Revisit your philosophy in having a separate windlass battery, here's why: If you have a high-output alternator (and you should have at least a 100A capability for cruising with a deep-discharge house bank of any consequence) it is a "waste" to not be able to deliver that amount of current during the time that you use the windlass so that you achieve maximum rate of retrieval for the anchor when you need to. To do that you need to have the 14.4V or so available in an "accept" mode of charge. The higher the voltage the faster the rate of retreival with the windlass. In addiiton, there will be less likelyhood of blowing the windlass breaker for heavy loads (all things being equal).

Now to deliver sufficient current to the windlass from a high-output alternator you need big cables to the windlass. If you have sufficiently large cables to the windlass why do you need a separate battery? In fact, for boats around 50ft or less it is difficult to rationalize the weight of a separate battery over the weight of the cable to do a proper job of delivering current. In addition, the weight of the cable is distributed better over the length to the bow whereas the weight of the separate battery adds to the rocking moment of inertia of the boat (and, therefore, detracts from the amount of chain that you can carry up forward).

As a final note, if you desire to recharge a deep-discharged windlass battery properly you need to have sufficient current at a sufficiently high acceptance voltage (14.4 V or more at lower temps) which REQUIRES large cable, again, why have a separate windlass battery? Move it back to your house bank for added capacity.


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Old 24-08-2005, 17:43   #3
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windlass already there


Thanks for the thoughtful reply. "Seperate windlass"....this was the set-up when we purchased the boat. The only change I have made is to add the Pathmaker. The cable from the Pathmaker to the windlass is #8 @ a 25' run, then 2/0 from batt to windlass...8' run.

"Move it back to your house bank for added capacity."
I am adding as much as space will allow....600AH AGMs.

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Old 31-08-2005, 01:31   #4
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I use a two bank system. I use a Pathmaker to isolate the starting battery from the house bank and a monitor only on the house bank. It's great. A monitor is great because you learn quickly how much power you use. Personally, I wouldn't have a "windlass" bank. If you can keep a starting battery isolated then I don't think you need a thrid bank.

If you use flood batteries the case for the third bank gets better as flood batteries can be more of a problem when one goes south on you. It can take the others in the same bank with it. After having three equal flood banks of golf cart, I'm back to one staring and 2 - 12 volt AGM batterries and I like it better. AGM's cost more but are worth it.

Adding the single bank monitor however was the best thing I did. I sleep better knowing where the battery level is at. If it makes you more comfortable it's clearly worth it. Lots of opinions on the types of banks but the monitor is just great.

If you need a 3 stage charger and such the Link 2000 is maybe worth it, bit I found a Link10 single bank for about $100 and at that price anyone can afford that.
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
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