Still eatng batteries?

[smileypete]

Doubt there's an easy cheap off the shelf way, unless a bench supply can be borrowed.

 

One not so easy way but cheap would be to charge one or more batts, then use a current limiting DC converter to eq one or more isolated batts after you have fully charged them:

 

http://www.ebay.co.uk/itm/P4PM-Boost-Converter-Step-up-Module-Power-Supply-600W-DC-DC-10V-60V-to-12V-80V-/400737138976

 

Don't forget fuse protection at either end in the positive near the batts.

 

ETA: Another way could be to get hold of an old style unregulated mains car charger.

 

cheers, Pete.

~smpt~

Edited September 12, 2014 by smileypete

[Naughty Cal]

 

I only wish I did know why. The engine, the alternator, and the wiring, are all new. They always get fully charged every day and never get excessively discharged. The only thing that is in common with 2 sets of 4 previous batteries that have performed in exactly the same way is the manufacturer (Varta) and that detail will certainly be eliminated when I next buy batteries

We are finding with our current set of Varta batteries that they like to be used. They appreciate a deeper discharge every now and then. They seem to perform better after a deeper discharge and then a full recharge.

 

After several partial discharges they appear to not perform very well but then recover again with a deeper discharge.

 

We find it isn't always easy to give them a deeper discharge mind as we tend to cruise every day.

[Detling]

"We are finding with our current set of Varta batteries that they like to be used. They appreciate a deeper discharge every now and then. They seem to perform better after a deeper discharge and then a full recharge. "

 

Today I had a chat with my neighbour who works in the UPS and standby generator industry. He said that they have stopped using wet cell batteries as they can't get any 'old types' any more. All the current supply have characteristics similar to those described above, they seem to lose capacity easily, but in fact they haven't if you use them fairly hard they recover capacity over a few days. What seems to be the cause of the issue is the continuous trickle charge and lack of real work, His UPS batteries basically sit on a charger, like our boats on a shoreline or with solar, and when required to work are asked for about 300 amps (each battery) for about 10 minutes while the diesel generator kicks in and takes the load. This may only happen once a year on the annual test, and wet batteries no longer cut the mustard, they just haven't been worked enough. They now use only AGM as this still works in his situation (incidentally he charges at 100A per battery up to 13.4 volts ouch! ) the discharge is fierce and lasts for several minutes I suppose a bit like using a microwave or kettle via the inverter. They used to use lead acid wet until recently as they were cheap as chips and worked for about 5 years, the AGM's seem to be good for longer so far 6 years and counting.

 

The UPS set he was installing last week was 60KVA with a 24Volt battery bank of 20 batteries, on load takes about 250A per battery until the diesel cuts in. it has a 1000A charger for heavens sake, makes my boat set up look puny. 60KVA is deemed enough for about 12 domestic houses but the hospital has 5 of them!.

[GUMPY]

It has always been the case that batteries left on float for long periods need equalisation every so often.

When I had open wet cells this used to be once a month (ifI remembered) should be once every 3 months as a minimum, only problem is 90% of chargers don't have this setting.

Now using sealed batteries so can't safely equalise without reducing life.

Equalisation charge is often over 15.4volts at low current <2amps

[Keeping Up]

Well I worried that my batteries may have been dead before I got around to building myself a charger so I called into Maplins and bought myself a current-limited voltage-limited power supply yesterday. 0-20 volts at 0-5 amps so this week I'll connect it up and see what it can do.

Edited September 14, 2014 by Keeping Up

[Keeping Up]

I had a VERY interesting reply from Varta today. They have actually taken the time to read and understand my question this time, and have given me a comprehensive response.

 

Basically they have said that for this type of application their batteries will only perform properly if the alternator can provide a daily charge to between 14.8 and 15.2 volts to prevent sulphation, plus they will need a frequent higher charge to prevent stratification.

 

At the moment this seems somewhat impractical, and is close to being an admission that their batteries are not suitable for this purpose. Meanwhile I will just have to settle for a regular equalisation charge to 15.5 or so, and keep my fingers crossed. Today 6 hours at 15.6 has shown a small but definite improvement, though so far the current is continuing to decrease and at the moment is down to about 1A per battery. The texts I've read say that the sulphation isn't being permanently reversed until the current has stopped decreasing and is showing a big increase again so I reckon I've a long way to go yet.

[smileypete]

Good of them to give a comprehensive answer and 'come clean' so to speak.

 

From what they say, it sounds like the Varta Hobby are similar to calciums, despite being not sealed. From what I've read, calciums may need 14.8V+ to recharge properly from deeper discharge levels, like some other types.

 

Trouble is some suppliers insist that 14.4V is enough for calciums, also many users don't understand and monitor charging properly. So that makes me reluctant to advise higher than supplier recommended charge voltages, since the users can't fully take responsibility for doing so.

 

If you have a direct contact at Varta, it might be interesting to ask if the Varta Promotive Black (their bog standard commercial batts) would be more suitable or suffer from the same problems, (as commercial batts can get hammered where the vehicles have tail lifts.)

 

For off grid eq charging, a solar panel directly connected on a sunny day might be enough. There are also some 12V timers around which could be handy for timed eq, just switch the solar panel from controller to direct connection with a double pole changeover relay.

 

cheers, Pete.

~smpt~

Edited September 20, 2014 by smileypete

[by'eck]

As I understood it the calcium was introduced into the plate construction to reduce gassing at any particular voltage, allowing higher charge voltages to be usefully employed. The most noticeable characteristic is the well defined cut off of current draw when fully charged. Little more than an amp on a 550 Ah bank even as 15 volts is approached.

[John V]

By'eck, By'eck thanks for that about calciums, I have 280 Ah of calciums, When I first joined the forum I asked if I should change my charging system as my batteries were getting elderly.......Gibbo told me to just keep doing whatever I was doing as it was working.......As always with Gibbo it was good advice. However the batteries are now noticeably failing and replacements and upgrades needed. There is lots of information about how to charge etc but that is one of the few scraps of information I have come across as to WHY..Ta! (incidentally the batteries are now 12 years old!!!)

 

 

 

edit fer spelnigs

Edited September 21, 2014 by John V

[Kae]

Having read this thread, and more importantly Allan's e-mails with Varta, I wonder if it would be best to charge my Numax CXV31MF sealed batteries at 14.8v rather than the 14.4 that they currently are charged at?

This is for liveaboard use.

 

I believe (although get a clear answer isn't straight forward) that these are calcium based batteries, as it says in Numax's documentation that they are "Calcium technology".

[Alanji]

Just been reading this thread. I replaced my batteries in July with 4 Numax CXV35MF 120aH. They seem to be discharging too quickly and I wonder what voltage I should be charging at?

Not on boat at present so cannot check what the current charging voltage is.

[PaulD]

Having read this thread, and more importantly Allan's e-mails with Varta, I wonder if it would be best to charge my Numax CXV31MF sealed batteries at 14.8v rather than the 14.4 that they currently are charged at?

This is for liveaboard use.

 

I believe (although get a clear answer isn't straight forward) that these are calcium based batteries, as it says in Numax's documentation that they are "Calcium technology".

I fitted same batteries and spoke to Tanya and Manbat. Both advised that absorption voltage should be set at 14.2 to 14.4. I questioned the advice because of the calcium technology but the Manbat technical department were insistant.

 

After reading many many articles and threads I also conclude it should be at least 14.8 for calcium batteries. As a weekend / holiday boater it would not amount to many hours in a year on absorption so I would not expect any significant loss of electrolyte. Might be different for liveaboards.

 

General opinion seems to be that they are just starter batteries overfilled with electrolyte and not really suited to frequent deep discharge.

[smileypete]

Having read this thread, and more importantly Allan's e-mails with Varta, I wonder if it would be best to charge my Numax CXV31MF sealed batteries at 14.8v rather than the 14.4 that they currently are charged at?

This is for liveaboard use.

 

I believe (although get a clear answer isn't straight forward) that these are calcium based batteries, as it says in Numax's documentation that they are "Calcium technology".

 

Up to you if full responsibility can be taken for doing so.

 

As always monitoring the charging current is definitely worthwhile, often with failing batts the charge current tails off at abnormally high levels.

 

Also, for unattended charging eg shoreline probably best stick to the recommended charge voltage and a low power charge source.

 

cheers, Pete.

~smpt~

Edited September 22, 2014 by smileypete

[Kae]

Thanks all. I'll do a little experiment and see if there is any additional current draw at the higher voltage to see if fully charged is fully charged.

[Keeping Up]

I've been giving mine a day at 15.6 followed by two days/three nights at 13.8 by using my power supply for a day then my normal charger for a couple more, and repeating that cycle. The current at 15.6 has steadily fallen and is now at 3A for the bank of four, with gentle gassing, this seems to set them up to respond well to the period at 13.8 which is when the best improvement in SG seems to occur. The SG has now risen to 1250 in many cells but there is still one in each battery down at 1230. None of the cells has shown a rise in temperature yet.

 

Many texts say that the current at 15.6 should start to increase when the sulphate has gone. I've not seen anything to confirm that yet.

 

Meanwhile I asked Varta if they could explain why their advice directly contradicts the charging information on their website, that categorically states 14.4 for flooded batteries and 14.8 for AGM. They have referred that question to their second line tech support who are apparently all away at a conference in Frankfurt at the moment, I'll let you know when I hear from them.

[Naughty Cal]

I've been giving mine a day at 15.6 followed by two days/three nights at 13.8 by using my power supply for a day then my normal charger for a couple more, and repeating that cycle. The current at 15.6 has steadily fallen and is now at 3A for the bank of four, with gentle gassing, this seems to set them up to respond well to the period at 13.8 which is when the best improvement in SG seems to occur. The SG has now risen to 1250 in many cells but there is still one in each battery down at 1230. None of the cells has shown a rise in temperature yet.

 

Many texts say that the current at 15.6 should start to increase when the sulphate has gone. I've not seen anything to confirm that yet.

 

Meanwhile I asked Varta if they could explain why their advice directly contradicts the charging information on their website, that categorically states 14.4 for flooded batteries and 14.8 for AGM. They have referred that question to their second line tech support who are apparently all away at a conference in Frankfurt at the moment, I'll let you know when I hear from them.

Will check our charger at the weekend as Im fairly sure its set at 14.4V and we have the AGM versions of the Vartas.

 

Could this explain why we seem to get better performance from them after they have been a bit lower when we are out cruising and charged via the alternator rather than charger?

[fudd]

There is no unexplained leakage. Everything is clean and dry. The current drains are all known and accounted for, being basically 2.2 amps constant plus the fridge

 

 

When the batteries were new I set it at 440, it tracked accurately enough for a couple of days. Now it tracks accurately when set to 280. By this time next week it'll probably need resetting to 220

I recently put 4new 125 ah batteries on Hunter. I reset the Mastervolt monitor as per the instructions. We were on a landline and I left them connected to the Victron charger. Everything seemed fine. We went on holiday and after 5 hours cruising they showed fully charged. Watched a DVD, went to bed. Left the inverter on. Only had laptop and a couple of phones and ipad on charge. In the morning the monitor showed between 20-40% left. It just got worse over the next couple of days even after switching everything off at night and no telly. Couldn't figure it out till I re-read the monitor manual. It said the batteries must be fully charged when the monitor is set up. I had assumed they were charged when I installed them. We cruised for about 5 hours. The monitor showed 80-100% charged. I then reset the monitor. Things were much better. The next day after another 5 hours the monitor showed them to be fully charged. I reset the monitor again and it now shows between 80-100% in the morning even after a couple of hours telly fridge freezer and all the other stuff left on. Could this be anything to cause your problem? I checked the batteries and they were fine. I just think they weren't fully charged when I installed them.

[Keeping Up]

NC (and others) here is a link to Varta's page showing charging voltages.

 

Fudd thank but this isn't a monitoring issue, I'm not relying on anything except the voltmeter, ammeter, and hydrometer which all give me absolute readings, I regard all derived readings such as SoC as just interesting suggestions.

[Keeping Up]

Varta have now complicated the issue again. Their second-line technical people say that the original reply was wrong and that the person who sent it must have mis-read the title on their graph. They now say that whereas AGM batteries need 14.8v, these flooded cells should definitely be charged at 14.4.

 

They have said that they do not usually find sulphation to be an issue, but that stratification is a known problem. Their recommended cure is to pick them up and shake them about once a week. I replied that this isn't practicable, and they said that the other solution is to charge them at 15.6v for a while. Is it coincidence that this is the same cure, at the same voltage, as is generally applied to get rid of sulphation.

 

They also expressed surprised that the Hobby range of batteries was still being sold at the beginning of this summer - in their words they have "not been in circulation for some time" - but I note that suppliers such as Tayna and Alpha are still advertising them on their website.

 

Looking at the range of batteries on Varta's website I wonder if any of them is suitable for this application. I will be asking them what their specific recommendation would be.

 

Meanwhile mine seem to be getting better. All cells are now at 1250 or better.

[dmr]

I expect both de-sulphation and de-stratification are based on the concept of "charge as hard as we dare" which is why they both happen at 15.5 volt. It's ok to go even higher than this but the risks of nasty accidents will increase.

If its ok to equalise at 15.5 then this implies an open flooded battery and accepting a little water loss, so i would think charging at 14.8 should be fine and much better than 14.4.

Battery use and lifestyle are factors in all of this. If we want absolutely maximum battery life and have shore power then 14.4 is probably best, but for an off grid boat that is burning diesel to charge the batteries then 14.8 would make much more sense.

 

..............Dave

[Keeping Up]

I have had another very interesting reply from Varta, including a copy of a Word Document called 'Charge Recommendation - Flooded Batteries'.

 

One paragraph which stands out for me is the one that says:

 

"The maximum charging voltage should be 14.1 – 14.4 V. In automotive applications this voltage will be enough as the vibration during the use will prevent from acid stratification. In boat or ship use a higher charging voltage (up to 16 V) is needed to prevent acid stratification. This overcharge ‘with’ 16 V should only be used for short time period. A permanent charge with 16 V will cause increased water loss."

 

They have made a couple of other suggestions which I will investigate in 2-3 weeks time after I have got back from my American trip. Meanwhile they will be on float charge.

 

It is good to see that the manufacturers are continuing to take an interest in this problem.

[bizzard]

I have had another very interesting reply from Varta, including a copy of a Word Document called 'Charge Recommendation - Flooded Batteries'.

 

One paragraph which stands out for me is the one that says:

 

"The maximum charging voltage should be 14.1 – 14.4 V. In automotive applications this voltage will be enough as the vibration during the use will prevent from acid stratification. In boat or ship use a higher charging voltage (up to 16 V) is needed to prevent acid stratification. This overcharge ‘with’ 16 V should only be used for short time period. A permanent charge with 16 V will cause increased water loss."

 

They have made a couple of other suggestions which I will investigate in 2-3 weeks time after I have got back from my American trip. Meanwhile they will be on float charge.

 

It is good to see that the manufacturers are continuing to take an interest in this problem.

So you need (a battery shiverer) You could mount the battery box on a tray of ball bearings and mount a cars windscreen wiper motor with its crank arm attached to the battery box. Wire up the motor with a switch and every so often switch it on to give the batteries a good shuffle and shiver about. The same motion as the ''Cake Walk'' amusement at a funfair that shuffles and shivers people about. Minus the blasts of air of course that blew up from the floor and blew ladies skirts and dresses up around their heads.

[dmr]

I have had another very interesting reply from Varta, including a copy of a Word Document called 'Charge Recommendation - Flooded Batteries'.

 

One paragraph which stands out for me is the one that says:

 

"The maximum charging voltage should be 14.1 – 14.4 V. In automotive applications this voltage will be enough as the vibration during the use will prevent from acid stratification. In boat or ship use a higher charging voltage (up to 16 V) is needed to prevent acid stratification. This overcharge ‘with’ 16 V should only be used for short time period. A permanent charge with 16 V will cause increased water loss."

 

They have made a couple of other suggestions which I will investigate in 2-3 weeks time after I have got back from my American trip. Meanwhile they will be on float charge.

 

It is good to see that the manufacturers are continuing to take an interest in this problem.

 

When they say "automotive" do they mean deep cycle batteries like in a mobile home or do they mean starter batteries??. 14.4 is fine for a starter but 14.8 is much better for mobile deep cycle applications where charge time is limited. To (miss)quote the infamous Gibbo:, You can charge at 13v if you want, it will just take a very very long time.

 

Increased water loss is much better than sulphation.

 

..................Dave

[system 4-50]

Would a once a week high current discharge for 10 seconds prevent stratification? A question from a complete ignoramus. What sort of current would be required?

[nicknorman]

Would a once a week high current discharge for 10 seconds prevent stratification? A question from a complete ignoramus. What sort of current would be required?

I don't think so. Stratification is (allegedly) dealt with by an overcharge that causes gassing - it is the bubbles rising to the top that mixes the electrolyte. With a high current discharge (on batteries in good condition) you don't really get gassing.