House Batteries

[Sandero]

For what it's worth our volvo MD 17D is 25 years old. We have engine drive refrigeration and when we are aboard we do run the engine to cool the refer and at the same time recharge the batts. The engine now has north of 4500 hours and the only performance signs of wear is a tiny amount of blueish smoke which I think is unburnt fuel because of worn rings. Compression is fine and starts on the first try with a bit of cranking in very cold weather - shoots out a lot of unburnt fuel and then the exhaust becomes less and less smokey.

This condition may be the result of running without load or simply normal wear and tear. Considering its age it's been quite reliable and had only one serious problem with a broken valve spring.

I now use a small Optima start batt which is charged via an Echo charge. The house bank is 2 - 8-D (500 AH) and they are charged by regulated 110 watt solar which keeps them topped up. This system supplies all our electrical needs.

[S/V Illusion]

Originally Posted by Teej

s/v illusion, thank you for your reply. I am so "untechnical" I will not be able to answer your questions. All I know is that I have oversized alternators (which I have been told is "good") and the charging system is controlled by a Balmar smart regulator, which I know nothing about other than I had to have the centerfielder replaced last year.

The voltage readings while under charge can get up to 14.2 volts after running the engines for an hour prior to bedtime. By morning the reading will be down to as low as 12.2 volts so I usually fire up the engine(s) to charge the house batteries first thing in the morning.

I don't know the regulator settings as you have asked.

And the charging intervals for most days at anchor will be an hour morning and night with the solar panels and wind gen assisting during the day.

Keep in mind any alternator will show a relatively high voltage at low (idle) RPM but not produce sufficient current (amps) to recharge quickly. In other words, 14.2 v at a fast idle for one hour might put pack 20-40 amps depending on the regulator settings which is probably NOT fully recharging the bank.

As others have implied, failure to fully recharge kills batteries.

I know you said your battery monitor indicates recharge rate but as you are not that familiar with the elec system, you probably are also not familiar with the need to recalibrate it to give you a precise set of readings. Consequently, I think your monitor is misleading you.

My advice is to not replace the batteries without a thorough check of the charging scheme first so you don't unnecessarily keep making the same mistake and spending a fortune needlessly on new batteries.

[foggysail]

Originally Posted by S/V Illusion

My advice is to not replace the batteries without a thorough check of the charging scheme first so you don't unnecessarily keep making the same mistake and spending a fortune needlessly on new batteries.

Good advice!

[Tashtego]

You have assumed that the problem is with your charging circuit but nobody has mentioned the simplest problem. There may be something else using up battery charge. Charge your batteries up full then disconnect them (all cables off) overnight and check the state of charge the next day. If they have held their charge then there may be a current leak in your system. If they have held their charge, reconnect them and switch everything off overnight once more. Check to see if they are still charged. If not, you have a hidden drain on your batteries.

Remember when disconnecting/connecting batteries that the ground cables come off first and go on last. I have seen a fatal accident caused by not following this rule.

[Teej]

Originally Posted by btrayfors

Very common problem, unfortunately.
BTW, I had my boat in Tortola for 11 years and had my share of battery problems, especially since I was often away for 3-4 months at a time.

My cat is on the hard in Tortola for the next month. May I ask where you had your boat serviced during its 11 year stint in the BVI's.


OK, here's my prescription.

1. Use deep-cycle golf-cart batteries. Trojan T-105s can be had there for a not unreasonable price. Ask around.

2. I assume you have six 12-volt West Marine batteries. If so, that's about 600AH total capacity. To match that, you'll need six 6-volt golf-cart batteries (225AH each), totaling 675AH capacity. They will need to be connected in series/parallel, i.e., as 3 pairs of 12-volt batteries.

My six 12v batteries fit neatly in a storage cupboard that has access both from the starboard hull hallway and also above from the settee. Will the six 6v golf cart batteries fit in the same space as the 12 volt ones?

3. How you charge them is important, but most important is to keep them as fully charged as you can. Unless you power everywhere, you can't do that with your engine(s). Solar and wind generator sources will be needed to give those batteries a full charge. Happily, both sun and wind are freely available in the BVI :-)

I do complement the daily charging with the charging capabilities of solar panels and an Air X wind generator.

4. Be sure to watch the electrolyte level...check it frequently. WaterMiser or HydroCaps are a very good thing to have as they help to reduce water loss and they make it easier to check the levels. Add ONLY DISTILLED WATER, when needed, until the level is about 3/8"-1/2" above the plates.

I will look into the caps that you mention (am not presently familiar with them).

5. Make sure all your connections are clean and tight. Do voltage measurements with a good multimeter AT THE BATTERY TERMINALS, until you are sure that whatever meter you're using now is providing accurate information.

6. You didn't say how your battery charger(s) and alternator(s) are set up. External regulator(s)? Temp sensors? Capacity of alternator(s)? Capacity of battery charger(s)? How are they wired? Do you run all batteries as a single house bank? It would be good to know.

I have a Balmar smart regulator system which, unfortunately, is all a big mystery to me in terms of its operation. I also have a Xantrex Freedom 25 inverter/charger which provides temperature controlled three stage charging. All six batteries are run as a single house bank but the starting batteries for each engine are independent.

If you take good care of the new batteries, you should get 3-5 years out of them.

I sure would be satisfied if I was able to achieve that kind of battery life.

Bill

Had submitted an earlier response but I do not see it so will do so again with thanks for your input.

[Mark Zarley]

When you see 14.2 volts your batteries are not fully charged. They are in fact just reaching their maximum charging voltage. When you see your voltage drop to 13.35 volts ( or there abouts) your regulator has decided it has charged you up. But if your batteries are starting to sulphate they are probably not fully charged. The belt and suspenders approach is to check the specific gravity of each cell , confirming fully charged cells

[Maine Sail]

Originally Posted by Teej

I do achieve a full charge when I recharge with a reading of 100% capacity if I can believe the battery meter on the electrical panel, which displays voltage, amp draw and battery capacity for both the house and starting batteries.
teej
s/v afLOAT

Teej,

With your admitted "hour in the morning and hour in the evening" charging protocol your meter is not to be believed. There is virtually no way you are recharging to 100% in just two hours per day of engine run time on a 600 Ah bank. The bad cells could be tricking your battery monitor or it needs to be re-calibrated.

The last 10-15% of charge takes hours and hours to replenish due to battery acceptance not just a couple this is why cruisers often cycle their banks between 50% & 80% state of charge. Also, due to charge inefficiencies, even when putting back 100 Ah's used it may take you 120 Ah's returned to replace the 100 Ah's you used not 100 for 100. You may be getting back to 70-80% SOC but probably not much more with just 2 hours per day of charging.

The most your banks will even accept when very low is in order of roughly 120 amps of charge current for a 600Ah wet cell bank. If you drew your bank to 50% state of charge you would need to replenish the 300 Ah's to be at 100% but this maya lot more than 300 Ah's to get back to 100%, and lots of time.

Two hours of run time would barely get you back to 80% even if you had a 150 amp or 200 amp alt. At about 80% SOC the batteries would begin accepting less and less charge current until they are accepting roughly .5-2% of the banks entire capacity when near full. So while at 50% SOC you may see 100 amps flowing at 90% you may only be seeing 12 amps and at 95% only 5 amps and at 98% only 2 amps and so on. (not exact number just an example)

You are likely chronically undercharging your bank due to an out of sync monitor giving you erroneous information, bad batteries and your minimal re-charge times of just 2 hours per day.

12.2 volts, if measured correctly, with a true resting voltage reading, is only about 60% state of charge. So perhaps your out of sync monitor is also allowing you to draw your bank deeper than 50% depth of discharge and your not even getting back into the 80% SOC range with your two hours of charging.

The best measure you can use with an out of sync monitor is to monitor the amps flowing back into the bank. If your monitor is telling you that you are at 95% and the bank is still accepting 60 amps then your are NOT at 95% SOC. In order to be anywhere near full there will be very little current flowing back into the bank. When you are seeing amps flow at less than 2% of the banks 20 hour Ah capacity then you can consider your bank near fully charged. Don't go by the "fuel guage" on your battery monitor if you suspect it is out of sync. Instead use amps flowing as a rough measure of state of charge. Lots of amps flowing means not full, little amps flowing means near full..

[Teej]

Thanks for picking up this thread again in December. I am back from our Christmas visiting and soon heading back to the boat in the BVIs to deal with the battery purchase for the house bank. After all the wonderful info and insights provided, two basic questions remain:
1. Accepting that I have to replace all six 12v deep cycle batteries, what is the recommended practical choice of replacement battery. I would like to go again with wet deep cycle batteries rather than AGM because of the significant cost difference, a cost that is greatly increased in having to buy them in BVI's.
2. Is is possible to get my meter on the panel checked/adjusted if it is not giving me true readins of volts, amps and capacity remaining as some posters have suggested?

Again, may I ask for your input (and indulgence in going back to this topic) as I have to make a decision on the battery replacement in the next few days.

Happy New Year all!
Teej