Testing suspect batteries after electical problems crossing the atlantic

[crazyhorse77]

Hey,

On our atlantic crossing our the voltage regulator on our alternator failed on day 10, so a I followed instruction on Nigel Calder book on creating a emergency regulator.This involved removing volage regulator and applying a set current to the field wire. So the alternator would create some output, after much tweaking it would output 30 amps for 10mins then drop to 20 amps for 10 mins then 10 amps for 10mins then drop to less than 5 amps after that regardless of battery charge state. The voltage would climb to above 15Volts if you didnt watch it so there was the odd time the batteries would have been getting around 15V for short periods.

This seems to have done strange things to our 3 sealed lead acid batteries for the domestics(not suprising). We arrived in port replaced the alternator. Even after replacing alternator the battery would not accept many amps (battery monitor states around 25amps over charging period before charge rate drops to 1 amp). Hmmm not good.

Next we charged with shore power for 12 hours yet not all batteries read simular voltage. The readings were taken when the battery was disconnected.

AT 0900
bat 1 : 12.75v
bat 2 : 13.34v
bat 3 : 12.72v

Now all batteries are disconnected completely from each other to allow charge to 'soak in'. The boat maintenance book told me this also

AT 1600
bat 1 : 12.61
bat 2 : 13.14 ???? IS THIS NORMAL ????
bat 3 : 12.59

Is seems strange one the batteries in 13.14 seven hours after been taken off charge.

Does any one know the damage bypassing alternators voltage regualtor would do to SLA batteries. The charge voltage was often at 14.6 to 14.8 volts.

Just to rest your mind at ease this 'bush mechanic' is not my usaul style yet the prospect of no autohelm, gps, fridge for remaining 12 days was not that exciting.

thanks in advance for your help!


Crocbones.blogspot.com

[btrayfors]

You said, "sealed lead-acid batteries". There are at least three types: the so-called "no maintenance" batteries (actually flooded batteries); the AGMs of various flavors; and gelled batteries. All are "sealed lead-acid batteries".

Which do you have?

Bill

[crazyhorse77]

Good point, they are the flooded SLA type. They are 100 Amp, deep cycle of the 'Avon' brand and about 6 monthes old
cheers

http://crocbones.blogspot.com

[witzgall]

When the voltage reached the 15v mark, gassing would occur. In a typical flooded battery, this would happen when equalizing the batteries. The trouble with flooded SLA batteries is that there is no way to add water back into the cells. This is why you don't see them often on boats -they are designed to fail over time, and there is nothing you can do about it.

Chris

[btrayfors]

+1 what Chris said.

In general sealed (flooded) lead acid batteries -- also called "maintenance free" batteries -- should not be used on a boat.

OK, let's get to your original question: was any damage done due to the unusual charging regime?

Maybe. Maybe not. Resting voltages won't tell you much, except the state-of-charge (SOC). They say nothing about the capacity of the batteries. Only a good load test will tell you that, either with a sophisticated device like the Midtronics testers which measure internal conductance and resistance (the current industry standard, but expensive) or with a timed load test with a known load and, preferably, a measuring device like the WattsUp (about $60).

A good timed test is one which starts with the SOC near 100% and puts a purely resistive load on the battery calculated to deplete the battery in 20 hours at it's rated capacity. Example: a 100AH capacity 12V battery with an 8A resistive load. You would expect such a battery in excellent health to run for about 20 hours before the voltage reaches 10.5 which is essentially dead. If you only get, say, 10 hours from this test before reaching 10.5 volts, then the battery capacity is at least 50% degraded.

Sorry, but there's no quick and easy and inexpensive way to tell the health of the batteries.

BTW, congratulations on your trans-Atlantic and on your inventiveness for maintaining the electrical system after the voltage regulator failed.

Bill

[djmarchand]

I agree with the last poster that likely no damage was done to the batteries.

But IMHO any sealed flooded cell battery is not a deep cycle battery. Replace them with 6V golf cart batteries wired in series/parallel to get the amphours and voltage you need.

[Captain Koch]

Originally Posted by crazyhorse77

Hey,

On our atlantic crossing our the voltage regulator on our alternator failed on day 10, so a I followed instruction on Nigel Calder book on creating a emergency regulator.This involved removing volage regulator and applying a set current to the field wire. So the alternator would create some output, after much tweaking it would output 30 amps for 10mins then drop to 20 amps for 10 mins then 10 amps for 10mins then drop to less than 5 amps after that regardless of battery charge state. The voltage would climb to above 15Volts if you didnt watch it so there was the odd time the batteries would have been getting around 15V for short periods.

This seems to have done strange things to our 3 sealed lead acid batteries for the domestics(not suprising). We arrived in port replaced the alternator. Even after replacing alternator the battery would not accept many amps (battery monitor states around 25amps over charging period before charge rate drops to 1 amp). Hmmm not good.

Next we charged with shore power for 12 hours yet not all batteries read simular voltage. The readings were taken when the battery was disconnected.

AT 0900
bat 1 : 12.75v
bat 2 : 13.34v
bat 3 : 12.72v

Now all batteries are disconnected completely from each other to allow charge to 'soak in'. The boat maintenance book told me this also

AT 1600
bat 1 : 12.61
bat 2 : 13.14 ???? IS THIS NORMAL ????
bat 3 : 12.59

Is seems strange one the batteries in 13.14 seven hours after been taken off charge.

Does any one know the damage bypassing alternators voltage regualtor would do to SLA batteries. The charge voltage was often at 14.6 to 14.8 volts.

Just to rest your mind at ease this 'bush mechanic' is not my usaul style yet the prospect of no autohelm, gps, fridge for remaining 12 days was not that exciting.

thanks in advance for your help!


Crocbones.blogspot.com

Hi. I think your battery 1 and 3 are weak. All my good batteries go up to 12.8V to 13.3ish volts on a full trickle charge. Here is a story for you. I was on the Chesapeake and ran into Gail winds and my start batteries were 2 deep cycle batteries. They fell over and got acid on me and ate my clothes off of me. I went home later after getting to a marina and took the gel cell batteries out of my wheel chair. I trickle charged them with a standard deep cycle charger and they read exactly the same at 13.4 if I remember right. They are on my sailboat now and can be up side down and still perform. These are expensive at about $225 each but lookey here! They were about 3 years old or more when I got them and they sat under my travel trailer 3 whole years outside winter and summers never used and still work great now. Golf cart batts are great. Trojans are excellent about $159 each for the hi amp hour ones. I know because I have a cart and the Trojans last 5 years easy with good maintenance every month. Add acid not water and keep them clean. Cosco brand about 3 years. Gel cells are better. Buy and use them or not using them works too. They will be there when you need them and don't require adding acid. Less weight also and no fancy wiring + to + -to -. My opinion. One more thing I found if I ran stereo or lights my charging voltage went down from hi 14v ish to about 12.9-13.5v ish