Finally Replacing My Batteries.

Submitted: Thursday, Jun 24, 2004 at 21:12
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On my trip away over the June weekend I noticed my battery voltage coming down lower than ever before and much earlier in the evening. This was raising alarm bells because I was running the tv and sat decoder on 240v from a power pole not on 12v .... so the only draw from the batts was the fridge and the lights. Early signs of not holding charge. The batteries are 3 x AC delco 80 amp flooded aged 2 yrs and 7 months. I will test them this weekend. It will involve equalising them with the Trucharge 40 charger until the specific gravity reads equal in all cells for three consecutive hourly readings. They will then rest for 24 hrs and have my battery tester connected. It uses a 75amp load and an analogue meter to see battery condition. The writing is on wall I suspect and I dont want battery probs at Copeton. The batteries I have chosen are 3 x Powercel AGM 108 amp hr (at 20hr rate). This will significantly improve my draw down capacity before shortening battery life. The flooded I have now give me 240 amp avail but as they should not go below 50% discharge give me 120 amp available. The AGM's having a 40% depth of discharge without significantly shortening their life give me ... 3 x 108amp by 60% = 194 amp. This gives me a 62 % increase in draw down amps or to look at it another way, over the total amps for the fridge for 24 hrs .... not bad !!! The AGM's will charge significantly faster and take all amps available from the solar because they are much less inhibited by flooded battery internal resistance. No more checking of electrolyte !! Hooray !! Drawback ....the 108 amp hrs wont fit in the existing battery box ... I can use 98 amp AGM's (at 20 hr rate) that will fit but I like the extra 30 amp. They are only 30 longer so will fit under the settee but not in the box. I intend making the whole area under the settee where the box resides the battery box. This will involve lining the area with 4mm plywood and then fibreglassing the walls and floor of the area. A gelcoat will be rolled on to give a finish like the ensuite. The battery tie down will 50mm x 25mm RHS aluminium across top of batteries and tied to sealed anchor points in floor. Lid will be 10mm clear perspex sheet with a gasket. Existing vent line will be plumbed back to new box. This will also give me chance to clean up all wiring in battery box by fitting bus bars. The only wires going into batt box will be +ive and -ive cables and the temperature probe from the battery charger. The true voltage wires from the Prostar and Victron charger with be on bus bars less than a foot away. I'm also using a 60 amp manual reset circuit breaker between the battery and bus bar as my inverter is very small. I estimate the weight increase with new timber/glass work and extra battery weight to be about 18 kg. I would expect these batteries to last 4-5 yrs. Cost for the batteries is on special at the moment at $289 inc. I really wanted Concorde Lifelines but the Prostar preset float of 13.7 is too high for the Concordes. Long periods of float that high will really hurt them they only specify 13.35 as a max. I was going to upgrade to an adjustable solar controller but the cost of the controller and difference in cost of the Concordes came to over $1100 and for my use of my BT was not justified ($1950 total) Thats over half a Webasto !!! [smile] Regards Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
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Reply By: Wadefarers - Thursday, Jun 24, 2004 at 21:14

Thursday, Jun 24, 2004 at 21:14
Anthony I knew you were looking at new batteries and glad that you have taken the plunge on the Powercels. As you know, my AC Delco's died around the Easter weekend and after a lot of deliberation I replaced them with the Concorde AGM Sun Xtender 100's. I was looking at the Powercels after talking to Griff at the Sydney Show but couldn't get any reply from their agents until a month after installing the Concordes. After talking to you about the float problem, I went ahead with the Concordes. Also, after conversing with the Concorde people here, I am trying different methods with the batteries. One method was to turn the batteries and the solar off, which seems ok and the other is to let the batteries cycle with the fridge running. So far every thing seems to be going ok but haven't decided which is the best way. I guess only time will tell. With a lot of differing methods being used, Copeton should be a useful forum for discussion on the merits or otherwise of what owners are using. Power to the (BT) people (!!!) Regards Jeff
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:15

Thursday, Jun 24, 2004 at 21:15
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:16

Thursday, Jun 24, 2004 at 21:16
Jeff, As I use my BT i.e. the 3-4 trips for a week or so per year and the long weekends, my preference would be to turn the fridge off and disconnect load and solar to minimise float from the Prostar to the Concordes.. The AGM's as you know have a very low self-discharge rate in the order of months before needing a top up. I'm a little worried that because the fridge is so efficient especially when not opening the door much ...and that you have so much battery capacity now ...that the solar might still keep them in float when not drawing its 5 amp or so ? The Coolmatic HDC-190 is quoted as 25% duty cycle at 20 deg C. So with the fridge on and not opened for a week or two it might achieve this 25 % duty and with 300amp available and only drawing 5 amp for 15 min per hour it might float for the other 35- 45 min ? Obviously this (float time per day) is dependant where you have it parked and therefore the light available to the panels and for how long. See how it goes in real world ...check the Prostar for float voltage time with the fridge on ..?? Now there's an excuse to have a beer or two in the BT for an hour or so. If you get a rev for drinking in the BT by yourself just say "Anthony has me doing tests on the battery !". [wink] Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
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Reply By: Wadefarers - Thursday, Jun 24, 2004 at 21:17

Thursday, Jun 24, 2004 at 21:17
Anthony Any excuse has got to be a good one When I had them turned off (load and solar) as I did originally, it did not take long (about an hour) to have the shrine blinking with shedding. With the fridge cycling I was just running a little test but I agree with your assessment and will go back to the "off" method. Think I will still tell Helen that I am out "testing" as per Anthony's instructions. Anyway, what better "doghouse" could a bloke get!!!!!!! Regards Jeff
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Reply By: Noosa Fox - Thursday, Jun 24, 2004 at 21:18

Thursday, Jun 24, 2004 at 21:18
Like Anthony I think I will have to replace the van batteries soon. I have noticed lately that they can be fully charged at night and with only the fridge using power, be down to 12.3 volts in the morning. If we have the car connected via the Anderson Plug and 8mm Dia wires, then they still have a lot more power in the morning with the extra vehicle batteries in parallel. They quickly charge up fully using generator and 50 amp charger, so I think it might be a case of them loosing their efficiency after 2.5 years. It is good to have someone like Anthony on the site to do all the hard miles working out what are the best batteries to replace them with. I will have a talk to you when we return home as to where to buy them from. Brian
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:19

Thursday, Jun 24, 2004 at 21:19
Brian and Anthony, I'm no electronics whiz, but I too was experiencing batteries dying (to flashing red on pro-star) during the night on our last trip. Despite good winter sun supply, 13.2v at the trailer plug when travelling, plus a couple of hours 240v from the Honda 2.0is, it was still happening. I tested the output from the 35amp charger and it was reading 12.3.....the same as the batteries. I slept on that and next morning woke up to myself!! To measure the output from the charger you have to disconnect the battery leads! Otherwise you get a reading which could be fed back from the batteries. Nontheless it was zero from the charger. I rang BTi and Peter directed me to Omegalec, who manufacture the chargers. They (Kerry I think) asked me to send it back to them, which I did. Now, Kerry told me that there were about 20 chargers that went to BTi in 2002 (Mine was delivered 27.6.02), that had an internal bracket which could break from vibrations of rough roads. This is what had happened to mine and they repaired it free of charge ( I paid $12.95 postage to them. He subsequently told me that there must be 19 others out there, to which this will happen. So, check your charger (with 12v leads disconnected) before you rush out and buy new batteries. If you have a problem contact :- Omegalec, (02) 9755 3766 or (02) 4229 6077 - They are at 304 Keira Street, Wollongong, NSW 2500. During this episode, I also had a Mobitronic 240~12v converter fitted to the fridge, so that whenever I'm connected to 240 (incl. generator) the fridge is not using any battery juice. - Nice to see the green light still on in the morning! Cheers...... and keep on having fun on your trip, Brian & Margaret!........................Rob
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:20

Thursday, Jun 24, 2004 at 21:20
G'day Rob, Good info in your post ! The BT chargers have had their share of bugs that hopefully have been ironed out. I know of one BT on their third replacement charger. My battery problem is one of capacity, with them being only 80amp flooded x 3 I have only 120amp available before going below 50% discharge thus markedly shortening their life. Charged and discharged within their design limits flooded batts should last 5 yrs plus. I have two flooded batteries in my shed that I use to supply 24v to a specific smart charger for ni-cads. These batteries started life as our camping batteries for lighting in tent days before the BT. I tested these batts with a 75 amp load tester and they are now pretty well not holding charge and showing weak on the tester. They are date stamped (by me) when purchased 1996 .... not bad ...8 yrs life. My original BT charger (35amp) has been in the cupboard as a spare since mine arrived home in late 2001. Initially I used a Trucharge 40 but now have a Victron 30. The Victron has provision to alter the absorption and float voltages to suit the type of charging regime of the battery brand/type used. Side note ... No need to disconnect the charger leads to see if it is working as both its voltages (boost and float) are way above a full battery (12.8+V). Just place a voltmeter across the charger output terminals and turn charger on and off ... the voltage should rise to anywhere around 13.8- 14.4 if the charger is working. To take the solar away from the equation switch of the solar input or test it at night. Regards Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:21

Thursday, Jun 24, 2004 at 21:21
The new batteries I've purchased I had originally listed as Powercel. These batteries are now re-labelled as Absorbed Power. Another battery manufacturer already had the Powercel name although searches, by the Aust agent at the time revealed that name was ok ! They are the same type and brand as BTi is now using as part of their battery options. The ones I'm actually using are the next size up from the standard BT battery I believe. Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:22

Thursday, Jun 24, 2004 at 21:22
Brain fade !!!! Dont even need a voltmeter to check charger voltage, just look at the battery volts readout on the Prostar and switch charger on and off !!! Duh ! [smile] Same applies ..turn solar input off or do at night. Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
AnswerID: 562531

Reply By: Noosa Fox - Thursday, Jun 24, 2004 at 21:23

Thursday, Jun 24, 2004 at 21:23
When I connect my generator up and run the fridge via adapter and our new 50AMP Bti charger the batteries get up to 14.1 volts and it stays there until the charger is turned off. A short time after charger is turned off the voltage drops to between 13.2 and 13.6 volts, but if we go to bed at 9pm on 13.6 volts and with only fridge running it will have dropped to 12.3 to 12.4 by morning. With my fridge when the compressor starts it draws a lot of power and for a short time this causes the voltage to drop to about 10.5 amps at which point the sensor in the fridge says that the voltage is too low so it turns off the compressor to protect the battery. I then have to turn inverter on and run on 240volt via adaptor or wait for sun to put some extra charge in batteries. Brian
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:24

Thursday, Jun 24, 2004 at 21:24
If you think of a battery as a 13volt item instead of a 12v item, battery voltage/capacity becomes a bit clearer. The following is not absolutely exact for every type of battery but for all intents and purposes it is not a bad guide for the "non-battery savvy" user. Battery level verses voltage .... 12.70+ volts -100% capacity of the rated capacity of the battery in amps. 12.45 volts - 75% capacity 12.24 volts - 50% capacity 12.06 volts - 25% capacity 11.89 volts - effectively discharged. After a battery has just been charged you have to let it settle to avoid plate surface voltage giving you a false reading or apply a light load to read true voltage but the above is a reasonable guide. The worst thing we can do to our batteries (especially AGM types) is leave them in a discharged state. Some AGM's left at 11 volts or less for even a day can be very hard to be "recovered/recharged (if at all) with extreme sulphation the culprit. Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
AnswerID: 562533

Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:25

Thursday, Jun 24, 2004 at 21:25
Chargers, This is all good stuff!! When my Omegalec charger failed, I bought a Matson Intellegent Charger...20 amp with a charge capacity from 40A/h ~ 500A/h & max charge voltage of 14.7V. It's power consumtion is 0.03A. It charges in three stages... It detects the "at rest" state of the batteries before charging commences. If the battery is damaged or in deep discharge (under 2V) it will not work. Constant Current Charge (Bulk Stage) : Current remains steady at 20A and when the battery is charged to 80% (voltage rises to 14.7V), the charger goes to the next stage... Constant Voltage Stage (Float Stage) The charger supplies constant voltage (14.7V) to the batteries and will remain doing this for a max. 6 hours. The current will reduce gradually until the battery is fully charged. When the charging current is under 0.35A or 6 hours have passed the charger switches off automatically. It will switch itself on again when the battery voltage has fallen to 12.4V. It will then repeat these three stages. Seems to be a better unit than the Omegalec, and I'm wondering if I should use it in lieu and keep the Omegalec as the spare. Cheers...............Rob
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Reply By: Deleted User - Thursday, Jun 24, 2004 at 21:26

Thursday, Jun 24, 2004 at 21:26
Rob, The three stages of charging in a three stage charger (some are now five stage with my Victron a four stage) are .. 1. Bulk mode. Constant current is supplied until a specified voltage is reached usually in a range of 14.1-14.8 v at 25 deg C. (My charger does this when 1.3 volts below the set float is reached and uses my preset volts of 14.4v at 25 deg C as the max voltage I'm willing to put into my AGM's) 2. Absorption mode. Constant voltage is applied in a range usually 14.25 -14.8 with the current dropping away and absorption mode complete after a time frame usually controlled by time and/or a temperature probe. 3. Float mode. A voltage is applied to keep the battery fully charged and protect it against self-discharge usually in the range of 13.0-13.8 volts at 25 deg C. My charger uses a 4th stage called battery safe mode and it basically raises voltage gradually until the set absorption voltage is reached. It is part of the calculated absorption time and is temp monitored by a probe on the battery (in all modes). If your supplied charger voltages are correct (and I cant find a spec on their website) I have some a small concern about the highish max bulk voltage depending on the type of battery. It might get a bit hot? But more importantly the float seems way out ??? As an example applying a float voltage above 13.35 to a Concorde Lifeline (for long periods) will severely shorten their life. According to Concordes Technical Manager who e-mailed me ...You will turn a 5 yr battery into a 3 yr battery. Likewise my new Absorbed Power AGM's must be floated around 13.6 -13.8 with over 13.8 doing the same damage to them as the Concordes floated above 13.35 (for long periods) What type and brand of batteries do you have ? The battery manufacturer will specify voltages for all modes of charging and a charger should be sourced to suit these specs. Battery life will shorten markedly if you're outside the stated charge specs with warranty possibly flying out the door as well ? As an example I'm dropping the float voltage in the Victron by 0.25 volts for the new AGM's as against what I had it set for with the unsealed flooded. For most people this is a bit much but I like get the most of what I've paid for and use it. The Prostar set on "sealed" will be fine with 14.35 boost and 13.7 float. I'm certainly no battery expert but have a good understanding of 12v stuff. In the case of most, $1000 every 2-3 yrs for some new AGM's is an acceptable cost of vanning and why not .... but in the case of say "Cracker" with 8 AGM's it better be right. In his case it is .... Anthony Explore this Great Land ...Do it Easy ... Tow a Bushtracker
AnswerID: 562535

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