trickle charge or not
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Batteries
Jack and Robin~ Check the water levels if they are a flooded battery and add distilled water if needed. Charge both batteries because they both need a charge.
Jack and Robin~ Check the water levels if they are a flooded battery and add distilled water if needed. Charge both batteries because they both need a charge.
How..
How warm was the storage area? Were they totally disconnected as in Negative cable removed from the post? Those voltages are quite low and perhaps they were not 100% charged going into storage. You may have some sulfation damage to one or both. As an example mine sat un-trickle charged from late October until two days ago when I re-connected my solar panel. The voltage was reading 12.5 after five months and they were stored in an un-heated space. Warmer temps discharge batteries quicker than cold but if storing in cold they MUST be fully charged before putting them away for the winter or they could freeze.. Add distilled water if necessary then charge them..
How warm was the storage area? Were they totally disconnected as in Negative cable removed from the post? Those voltages are quite low and perhaps they were not 100% charged going into storage. You may have some sulfation damage to one or both. As an example mine sat un-trickle charged from late October until two days ago when I re-connected my solar panel. The voltage was reading 12.5 after five months and they were stored in an un-heated space. Warmer temps discharge batteries quicker than cold but if storing in cold they MUST be fully charged before putting them away for the winter or they could freeze.. Add distilled water if necessary then charge them..
From my point of view,
your batteries are theoretically dead. See chart below: 100% = 1.265 = 12.7v *75% = 1.225 = 12.4v 50% = 1.190 = 12.2v 25% = 1.155 = 12.0v Discharged = 1.120 = 11.9v *Sulfation of Batteries starts when specific gravity falls below 1.225 or voltage measures less than 12.4 (12v Battery) or 6.2 (6 volt battery). Sulfation hardens the battery plates reducing and eventually destroying the ability of the battery to generate Volts and Amps. I would not be very optimistic about being able to save these batteries. I think you'll have to figure out why that happened in order to prevent it from reoccurring. A trickle charger will not help your batteries much at the point of discharge they seem to be in. What may help is to try to reduce "suflation" (see link). While it is certainly worthwhile to try to recharge dead batteries, the question will be how long can they hold a charge ... and will they fail just when you really need them. Try charging with a 30 amp charger, let them sit for at least 48 hrs without any load on them, and then have them load tested.
your batteries are theoretically dead. See chart below: 100% = 1.265 = 12.7v *75% = 1.225 = 12.4v 50% = 1.190 = 12.2v 25% = 1.155 = 12.0v Discharged = 1.120 = 11.9v *Sulfation of Batteries starts when specific gravity falls below 1.225 or voltage measures less than 12.4 (12v Battery) or 6.2 (6 volt battery). Sulfation hardens the battery plates reducing and eventually destroying the ability of the battery to generate Volts and Amps. I would not be very optimistic about being able to save these batteries. I think you'll have to figure out why that happened in order to prevent it from reoccurring. A trickle charger will not help your batteries much at the point of discharge they seem to be in. What may help is to try to reduce "suflation" (see link). While it is certainly worthwhile to try to recharge dead batteries, the question will be how long can they hold a charge ... and will they fail just when you really need them. Try charging with a 30 amp charger, let them sit for at least 48 hrs without any load on them, and then have them load tested.
Try it
I have had dead batteries take a charge and be fine. I have also had dead batteries that would never again hold a charge. I haven't noticed much of a difference between a trickle charger and a larger charger except the amount of time required to charge a battery. Of course it will take a week for a 2 amp charger to charge two dead 100 amp/hr batteries. When I kept my batteries in the basement I put them on a wooden board not directly on concrete. Theoretically it shouldn't make any difference but seemed to help...no data to support that statement. But the bottom line is that hooking them up to a charer costs very little compared to buying new batteries. Little risk for a big reward.
I have had dead batteries take a charge and be fine. I have also had dead batteries that would never again hold a charge. I haven't noticed much of a difference between a trickle charger and a larger charger except the amount of time required to charge a battery. Of course it will take a week for a 2 amp charger to charge two dead 100 amp/hr batteries. When I kept my batteries in the basement I put them on a wooden board not directly on concrete. Theoretically it shouldn't make any difference but seemed to help...no data to support that statement. But the bottom line is that hooking them up to a charer costs very little compared to buying new batteries. Little risk for a big reward.
It's all about specific gravity
Follow Warren's advice regarding the sp gravity. The only dependable test is to check each cell with a hydrometer to see how badly sulfated the plates have become. It may be possible to revitalize the battery by charging but then again the only way to tell how much damage was done and therefore how much life remains is to check sp gravity. Simply recharging them may result in raising the voltage (temporarily) but unless you know the actual condition of the plates, your success may be short-lived.
Follow Warren's advice regarding the sp gravity. The only dependable test is to check each cell with a hydrometer to see how badly sulfated the plates have become. It may be possible to revitalize the battery by charging but then again the only way to tell how much damage was done and therefore how much life remains is to check sp gravity. Simply recharging them may result in raising the voltage (temporarily) but unless you know the actual condition of the plates, your success may be short-lived.
Interesting! I have AGM batteries and they never seem to reach the
standards of fully charged by voltage measurement. The most they ever show after sitting for a couple of days is 12.25V. but after sitting in the boat from november to late march they had lost only .3 volts and started the engine with no indication of a strain and very little drop in voltage with a cranking load on them. Do AGM and gel batteries have different charge and discharge curves form wet cell batteries?
standards of fully charged by voltage measurement. The most they ever show after sitting for a couple of days is 12.25V. but after sitting in the boat from november to late march they had lost only .3 volts and started the engine with no indication of a strain and very little drop in voltage with a cranking load on them. Do AGM and gel batteries have different charge and discharge curves form wet cell batteries?
Yes, and they like a different charge voltage too.
No, I don't have the correct rate on my finger-tips (tap,tap,tap) But the battery manufacturer does.
No, I don't have the correct rate on my finger-tips (tap,tap,tap) But the battery manufacturer does.
You can trickle charge for a while to
try and bring them up a bit. A full charge on a high capacity charger (100 amps or so) can boil them out. a full charge with a smaller charger (10 amps) might be OK. Take off the battery caps, Fill them to over the plates, and to just above the bottom of the fill cylinder (that's about 3/4" below the top with distilled water, and give it a try. they might recover. Ross, I'm not an expert but here is what I've picket up in my reading. AGM's And Gel Cel's do have different curves. AGM's & Gel's charge faster, can be discharged deeper without failure and will hold their voltages longer. They are different from each other however. AGM's can be charged with the same voltage as wet cell (14.4V) where that much voltage will damage a Gel Cel. Neither should see an equalization charge of 15.5, and all three types should see a float charge around 13.5v. The Gel Cel is supposed to be good for more discharges than the AGM. I personnaly like the AGM's and have them in my boat too. Happy sailing Joe S
try and bring them up a bit. A full charge on a high capacity charger (100 amps or so) can boil them out. a full charge with a smaller charger (10 amps) might be OK. Take off the battery caps, Fill them to over the plates, and to just above the bottom of the fill cylinder (that's about 3/4" below the top with distilled water, and give it a try. they might recover. Ross, I'm not an expert but here is what I've picket up in my reading. AGM's And Gel Cel's do have different curves. AGM's & Gel's charge faster, can be discharged deeper without failure and will hold their voltages longer. They are different from each other however. AGM's can be charged with the same voltage as wet cell (14.4V) where that much voltage will damage a Gel Cel. Neither should see an equalization charge of 15.5, and all three types should see a float charge around 13.5v. The Gel Cel is supposed to be good for more discharges than the AGM. I personnaly like the AGM's and have them in my boat too. Happy sailing Joe S
answers to questions...
thanx everyone... still a newbe, i am incredibly grateful for all the info... here are some of the specifics... both were completely disconnected from the cables and were stored on the boat... pretty standard winter here in the north east... not sure how long she sat unplugged after we delivered her to the marina...but i believe only the bilge would have been drawing power... water levels are right where they should be... retested and now the numbers are jumping from 10.8 up to 12.25... off to radio shack to buy a new voltmeter... will retest and repost... thanx... J&R
thanx everyone... still a newbe, i am incredibly grateful for all the info... here are some of the specifics... both were completely disconnected from the cables and were stored on the boat... pretty standard winter here in the north east... not sure how long she sat unplugged after we delivered her to the marina...but i believe only the bilge would have been drawing power... water levels are right where they should be... retested and now the numbers are jumping from 10.8 up to 12.25... off to radio shack to buy a new voltmeter... will retest and repost... thanx... J&R
Joe S. I typically get five years or better and charge only with the engine
alternator. The batteries are buried in the lazerette and only will see the light of day when they get replaced. Overcast here. About 60 degrees and I am at home and the boat is still on the hard. But it is a good day. Thanks for the response. Ross
alternator. The batteries are buried in the lazerette and only will see the light of day when they get replaced. Overcast here. About 60 degrees and I am at home and the boat is still on the hard. But it is a good day. Thanks for the response. Ross
trickle charge or not...new volt meter...
thank you to all...again... as we all know it is hard to see old 'faithful' tools that have lived out their life, but... the new meter gives me 12.2 and 12.6...which makes me feel a lot better... and it will fit in my shirt pocket, providing i am wearing a shirt... so sorry to send everyone on a bit of a wild goose chase with bad numbers, but the answers i received will be very helpful going forward... so back to the original idea... since one battery is down to 50% is a trickle charge the best choice? or do i reinstall and let the alternator charge them after she is back in the water? is there an optimum maintenance schedule for a deep cycle wet cell battery? Warren, thank you for the numbers and the link, makes things much easier to understand... thanx again J&R
thank you to all...again... as we all know it is hard to see old 'faithful' tools that have lived out their life, but... the new meter gives me 12.2 and 12.6...which makes me feel a lot better... and it will fit in my shirt pocket, providing i am wearing a shirt... so sorry to send everyone on a bit of a wild goose chase with bad numbers, but the answers i received will be very helpful going forward... so back to the original idea... since one battery is down to 50% is a trickle charge the best choice? or do i reinstall and let the alternator charge them after she is back in the water? is there an optimum maintenance schedule for a deep cycle wet cell battery? Warren, thank you for the numbers and the link, makes things much easier to understand... thanx again J&R
lots of ideals little data
I've read lots of ideals but little data. Some swear taht a little solar trickle charger does great. Some swear that you have to have 20 amps . My experience is that it doesn't matter a whole lot. Keep them charged and full of water..use distilled water only. Right now I have a fully automatic charger. bulk trickle and float stages. But I also did like ross and let my alternator do almost all of my charging. My bilge pump stuck and killed one of my batteries but it seems to be holding a charge just fine right now. My protocol right now is to use the charger when I am at the boat assuming that the alternator does most of the charging and that the mulistage charger is topping off.
I've read lots of ideals but little data. Some swear taht a little solar trickle charger does great. Some swear that you have to have 20 amps . My experience is that it doesn't matter a whole lot. Keep them charged and full of water..use distilled water only. Right now I have a fully automatic charger. bulk trickle and float stages. But I also did like ross and let my alternator do almost all of my charging. My bilge pump stuck and killed one of my batteries but it seems to be holding a charge just fine right now. My protocol right now is to use the charger when I am at the boat assuming that the alternator does most of the charging and that the mulistage charger is topping off.
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