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Old 07-15-2016, 07:04 PM   #1
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Default Any simple way to insure full charge on AGM?

I just finished doing a few upgrades to our 08 Roadtrek RS Adventurous Sprinter.

Replaced the Dometic 3 way fridge with a NovaKool R4500 compressor fridge and replaced the two underhood wet cell golf cart house batteries with two Lifelines. No solar at the moment but may add it in the future.

Looked at installing a Trimetric but in the end decided to try a Zamp BatteryCheck Bluetooth shunt based monitor that is self contained under the hood with no need to wire it to a remote display, iPhone is the display. Somewhat of a black box device compared to a Trimetric with not much info on the details of how is works. Does display the current % battery capacity based on a configured amp hour battery capacity, battery voltage, and +/- amps of charge/discharge current. No details on how it decides when the battery is fully charged other than some verbage about it learns it over time. You can set alarms on battery capacity and battery voltage. Has the option of connecting something to an internal relay for the alarm but I am not using that. As long as your mobile device is within Bluetooth range you will get the alarm on your device. Designed and made by a company in Australia that does a lot of other RV electrical stuff, seems well done but not sure of the accuracy as yet.

Considered replacing the Tripp-Lite 750 watt inverter/charger under the driver's seat but have not found any option with a similar form factor that would fit under the seat. Long term may have to go with something better mounted elsewhere.

Based on all the info I have seen here it seems likely that the Tripp-Lite will not reliably bring the Lifelines to full charge. So my question is, is there any battery charger that I could plug into shore power periodically that would reliably bring the Lifelines to full charge? It seems from the discussions here that there are few, if any battery chargers that do a good job. Is it possible to use a fixed voltage charger of some type to simply complete the absorption phase while monitoring the charge current to manually stop at 1.1 amps (0.5% C for the 220 amp battery bank).
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Old 07-15-2016, 07:27 PM   #2
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BatteryMINDer 12V Maintainer for Sealed AGM Lead-Acid Batteries
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Old 07-15-2016, 07:32 PM   #3
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I just finished doing a few upgrades to our 08 Roadtrek RS Adventurous Sprinter.

Replaced the Dometic 3 way fridge with a NovaKool R4500 compressor fridge and replaced the two underhood wet cell golf cart house batteries with two Lifelines. No solar at the moment but may add it in the future.

Looked at installing a Trimetric but in the end decided to try a Zamp BatteryCheck Bluetooth shunt based monitor that is self contained under the hood with no need to wire it to a remote display, iPhone is the display. Somewhat of a black box device compared to a Trimetric with not much info on the details of how is works. Does display the current % battery capacity based on a configured amp hour battery capacity, battery voltage, and +/- amps of charge/discharge current. No details on how it decides when the battery is fully charged other than some verbage about it learns it over time. You can set alarms on battery capacity and battery voltage. Has the option of connecting something to an internal relay for the alarm but I am not using that. As long as your mobile device is within Bluetooth range you will get the alarm on your device. Designed and made by a company in Australia that does a lot of other RV electrical stuff, seems well done but not sure of the accuracy as yet.

Considered replacing the Tripp-Lite 750 watt inverter/charger under the driver's seat but have not found any option with a similar form factor that would fit under the seat. Long term may have to go with something better mounted elsewhere.

Based on all the info I have seen here it seems likely that the Tripp-Lite will not reliably bring the Lifelines to full charge. So my question is, is there any battery charger that I could plug into shore power periodically that would reliably bring the Lifelines to full charge? It seems from the discussions here that there are few, if any battery chargers that do a good job. Is it possible to use a fixed voltage charger of some type to simply complete the absorption phase while monitoring the charge current to manually stop at 1.1 amps (0.5% C for the 220 amp battery bank).
Lots of discussion here on that topic, so you should be able to search for details.

Bottom line, IMO, is that there are basically two choices in chargers that will get the batteries full based on amps. The first choice is a Magnum of MS2000 range or better with an ARC remote and BMK monitor kit. It will do it all for you without intervention, just plug in. The Magnum is what we use. The other option, that I have used and Crank is building now, is a Blue Sea charger with an add on circuit to remove the load from the battery charging bank and put it on its own circuit. The add on is two inexpensive parts (relay and time delay) and easy to build.

The next step would be to use a Progressive Dynamics charger, with a pendant, along with a monitor to manually watch the amps or fully charged indicator to either shutoff or repeat the absorption stage. This is what Marko is doing.

I don't readily know of any other option except using a Victron monitor and building a circuit off it's internal relay output to shut off the charger. You would not get the benefit of float powering the loads in that case.
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Old 07-15-2016, 08:25 PM   #4
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In the long term I may replace the Tripp-Lite with something better but in the interim I am just looking for something to connect to shore power when we happen to have it available while traveling to top off the Lifelines to keep them in good shape. Normally we drive enough to get them close to full and when boondocking in place it is only for a couple days so the generator does the charging through the Tripp-Lite but I typically won't run it long enough to get through absorption phase.

Would the Battery Minder linked above do a decent job of topping off the Lifelines if they are already into absorption phase at the start? I can monitor the charge current and voltage and see how it does but wondered if anyone knows how it will do??
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Old 07-15-2016, 08:43 PM   #5
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In the long term I may replace the Tripp-Lite with something better but in the interim I am just looking for something to connect to shore power when we happen to have it available while traveling to top off the Lifelines to keep them in good shape. Normally we drive enough to get them close to full and when boondocking in place it is only for a couple days so the generator does the charging through the Tripp-Lite but I typically won't run it long enough to get through absorption phase.

Would the Battery Minder linked above do a decent job of topping off the Lifelines if they are already into absorption phase at the start? I can monitor the charge current and voltage and see how it does but wondered if anyone knows how it will do??
I seriously doubt a Battery minder would have any significant affect on getting full as the output is so low, even if you could keep it in absorption the whole time. I just ran a 50% recharge on Lifelines like you have, and it required 10 hours to get to .5% like Lifeline recommends. That also makes the idea of driving to get totally full impractical. The test showed that the current would start dropping at about 70-75% full and absorption started at about 80% full and needed over 6 hours there. The Tripplite won't do that and the one we had couldn't be put into absorption again once it time out if the battery voltage had any surface charge on it.

You only choice for an add on, I think would be a fixed voltage charger of at least 20 amps for your 220ah of battery, and if you really want to get totally full, you need to have temp correction so you don't inadventently overcharge due to high voltage issues. You would need to watch the amps to the batteries, which can be tough if you are doing the overnight shore power routine.

A small Cteck charger will be pretty safe for not overcharging, and can be restarted back into absorption, so it might be OK, but they tend to be pretty small (ours is 8 amps). For the cost, you might be better just to go to a PD in addition to the Tripplite, but big enough to replace the charging part later when you would need to add an inverter. Ctek is not a cheap charger, though, for their size.

All of this has been what we have talked about often, with the problem always being there are no easy and inexpensive ways to take good care of the batteries by good charging. The cheapest would probably be a PD and a monitor, then Blue Sea and a monitor and add on circuit, and the the Magnum. The PD would be a manual system, the other two would be automatic, in the charging process to get full.
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Old 07-15-2016, 09:00 PM   #6
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Looked at installing a Trimetric but in the end decided to try a Zamp BatteryCheck Bluetooth shunt based monitor
Be careful. The shunt in that Zamp device appears to be only rated for 80 amps. With your inverter running, that doesn't give you a lot of head room.
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Old 07-15-2016, 09:08 PM   #7
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Never use the inverter for anything but watching video so just a TV and BluRay player and a laptop charger at most so no danger of getting anywhere near 750 watts. Could plug the laptop into its 12 volt power adapter instead but the 120 volt outlet is handy...

Tripp-Lite has a 45 amp charger...
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Old 07-15-2016, 09:25 PM   #8
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Would the high end Ctek 25 amp 8 stage charger for $209 do the job? I realize the price is high but it would seem to be a good charger to have on hand...
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Old 07-15-2016, 09:50 PM   #9
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Would the high end Ctek 25 amp 8 stage charger for $209 do the job? I realize the price is high but it would seem to be a good charger to have on hand...
I think it would, as it looks to have the same setup as our older 8 amp version. To use it to get your batteries full, you would likely have to run multiple charge cycles. On ours, you can either just reconnect it to the shore power or you can step it thought the options with the button to get back to where you started, and it will run another cycle. You would have watch the amps and volts at the batteries on the monitor to know when it has finished to the right volts and amps, and then shut it off. IIRC, ours has a fairly short absorption time, so it would require a bit of monitoring.

I have used ours for the small stuff for a long time (lawn tractor, etc), and it did recover an old Optima in our hotrod that was in pretty poor shape and very old, so no real complaints. The clamps are crap, however, rotted out very quickly. I don't use it as much anymore as I have the Blue Sea that was in the van as a bench charger now. It is totally setable for whatever battery I am charging, so it is the best charger I have ever had on the bench.

Of course for the same money you could have a 60 amp PD charger and Charge Wizard, which would be faster and easier to use. Then if you do ditch the Tripplite, all you would need would be small inverter.

If you can figure out a way to get the Tripplite to go back into absorption to finish the charging after a cycle, you could do the same thing with it. I couldn't get ours to do that, as it would always go right to float if the batteries were over about 85% full.
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Old 07-15-2016, 09:55 PM   #10
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The Blue Sea charger does look like the cat's pajamas but for that price I guess that is what you should expect...
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Old 07-15-2016, 10:29 PM   #11
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I like the idea of the PD charger and a small inverter and I might be able to get them both under the drivers seat replacing the Tripp-Lite. Probably do that when we get back from our long trip around the country, leaving this week and back later in the fall. Not enough time to tackle that now so I will go with the Ctek for the trip...

Thanks for the suggestion...
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Old 07-15-2016, 10:42 PM   #12
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I am a little confused by the PD converter chargers. Do they have any configured for AGM charge profiles that would be close to what Lifeline recommends?
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Old 07-15-2016, 11:28 PM   #13
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I am a little confused by the PD converter chargers. Do they have any configured for AGM charge profiles that would be close to what Lifeline recommends?
AFAIK, they aren't settable, but the voltages they use line up well with the Lifeline specifications. The charger itself is fixed voltage, and the mulitstage part comes from adding the Charge Wizard. The biggest benefit is the ability to force it in and out of the stages with the Charge Wizard, so you can control what it is doing manually.

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Old 07-15-2016, 11:36 PM   #14
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I get it, you force it back into boost mode at 14.4 volts until you get to 0.5% C charge current and then put it into storage mode. It then jumps up to 14.4 for 15 min every 21 hours for an equalization charge which I guess is fine for the Lifeline or do you stop it from doing the equalization somehow??

Is that it??
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Old 07-15-2016, 11:49 PM   #15
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I get it, you force it back into boost mode at 14.4 volts until you get to 0.5% C charge current and then put it into storage mode. It then jumps up to 14.4 for 15 min every 21 hours for an equalization charge which I guess is fine for the Lifeline or do you stop it from doing the equalization somehow??

Is that it??
That is it, although you may want to go to float instead of storage right off of full charge. We have found the batteries will continue to fill very slowly for a couple of days of floating. Nice safe way to finish all the way. I don't see any problem with the 15 minute boost. Marko has been using it for quite a while successfully, and his batteries seem be checking nicely full at all times from what we have seen.
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Old 07-16-2016, 12:22 AM   #16
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Thanks, that sounds like the way to go. Small enough to go under the seat and maybe enough room to still add a small pure sine wave inverter with no need to change any wiring.
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Old 07-19-2016, 09:23 PM   #17
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Would the Battery Minder linked above do a decent job of topping off the Lifelines if they are already into absorption phase at the start? I can monitor the charge current and voltage and see how it does but wondered if anyone knows how it will do??
The Battery Minder should work just fine in that scenario. The owner's manual is downloadable from the web site and has a chart that details the voltages and current in the various phases. If you're unsure try dropping them a note with the size of your battery bank and see if they would be able to tell you how long it should take. As long as the charger supplies the correct voltage the absorption phase will take that same amount of time as a "bigger" charger.
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Old 07-19-2016, 09:51 PM   #18
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The Battery Minder should work just fine in that scenario. The owner's manual is downloadable from the web site and has a chart that details the voltages and current in the various phases. If you're unsure try dropping them a note with the size of your battery bank and see if they would be able to tell you how long it should take. As long as the charger supplies the correct voltage the absorption phase will take that same amount of time as a "bigger" charger.
That is about $100 for a 2 amp, fixed timer based charger. The absorption is limited to 4 hours and the bulk to 20 hours. If Greg had a charger that got him to 80% full, he would need another 50AH or so of more charge from it (44 to replace the 20% left and then another 6+ to give the 10% overcharge it takes to get full). At 80% full the Lifelines will be accepting quite a bit of amps if it is available, probably close to 40 amps, so if at that point you are at two amps, you will have a long ways to go, way more than you would get at the occasional overnight recovery charge. If there were any load running in the van, you might have no power available for the batteries, and he is going to have a compressor frig.

IMO, there are many way better options for Greg. Nothing wrong with a Battery Minder, but they need to be doing what they are intended and capable of doing, which is maintaining a full battery that is not being loaded. If you believe the Lifeline literature, they want 20% of capacity for the charger, which is 44 amps, for discharges over 50%.
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Old 07-20-2016, 02:30 AM   #19
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In the long term I plan to replace the Tripp-Lite inverter that has a 45 amp charger with a charger with the capability to get a full charge, probably a PD converter charger along with a small inverter. For the next 4 months of travel I plan to supplement charging while driving and Tripp-Lite charging with the generator/shore power by using a Ctec 20 amp 8 step charger to top off the batteries regularly when I have shore power. It might take some experimenting with this to refine the process but I think it is the best short term solution until I get a chance to make bigger changes to my setup. And the Ctek will be good to have around later when I need a good charger.

Thanks to all for the suggestions on options...
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Old 07-20-2016, 02:22 PM   #20
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In the long term I plan to replace the Tripp-Lite inverter that has a 45 amp charger with a charger with the capability to get a full charge, probably a PD converter charger along with a small inverter. For the next 4 months of travel I plan to supplement charging while driving and Tripp-Lite charging with the generator/shore power by using a Ctec 20 amp 8 step charger to top off the batteries regularly when I have shore power. It might take some experimenting with this to refine the process but I think it is the best short term solution until I get a chance to make bigger changes to my setup. And the Ctek will be good to have around later when I need a good charger.

Thanks to all for the suggestions on options...
Sounds like a good plan. It will also give you a chance to watch the time it takes to taper the amps to the desired .5% (it will likely even be able to go lower than that with new Lifelines, but the times increases exponentially). It will be interesting to see how far your current charger gets the batteries full from a 50% or more discharge cycle, as well as what amps the batteries are drawing at that point. We don't have a lot of data on stuff like that. Ours was only for wet cells with the Tripplite we had. I would guess they will be still taking over the 20 amps that the Ctek can do, but you will certainly find that out.

If you happen to catch the bulk to absorption transition (I think you would have to see the voltage stabilize on the Trimetric and amps starting to decrease to know), and then how long the absorption time to float is, that would be interesting. I think our Ctek is in the 1-2 hour absorption time range, but I have never caught it precisely. (ours is smaller output and older), which is fairly short. Of course, your new frig coming on and off might jump the Ctek in and out of absorption, too, sometimes, although with 20 amps available it isn't really likely. We have seen our frig and other loads do that with our solar when the sun is low.
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