What sort of batteries? With AGMs I kept mine connected to the solar permanently. All lead acid live longer if kept fully charged. If you have a decent solar controller, they won't get over charged.
With lithium, I disconnect the solar after a trip and let them drop back in SOC to around 50%. I have a few minor parasitic loads, but have never seen them lower than that yet. Keep an eye on the SOC and voltage. Cheers, Peter
-- Edited by Peter_n_Margaret on Saturday 12th of October 2024 02:40:43 PM
I'm with @Peter n Margaret, GEL/AGM's leave them on the solar, topped up during the day and rested at night, mine were happy that way for many years with just a couple of gas sensors drawing power, now with the lithiums I just shut off the load and solar input and they sit happily at about 13.2v between trips .............. even in the old ute the calcium deep cycle under tray was happy with constant solar feed for years....
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Checking out the places I drove past a thousand times................
What sort of batteries? With AGMs I kept mine connected to the solar permanently. All lead acid live longer if kept fully charged. If you have a decent solar controller, they won't get over charged.
With lithium, I disconnect the solar after a trip and let them drop back in SOC to around 50%. I have a few minor parasitic loads, but have never seen them lower than that yet. Keep an eye on the SOC and voltage. Cheers, Peter
-- Edited by Peter_n_Margaret on Saturday 12th of October 2024 02:40:43 PM
Peter,
It is a Enerdrive Lithium. the van that it is in does a 4-month trip each year and then lies "farrow" for the rest.
I wonder at the capabilities of the batt. management system and the Enerdrive controllers attached.
What happens and how reliably do the somewhat competing systems manage when inevitably the
battery is fully charged. Who wins?
Come to think of it, I think that it would be worthwhile to install a 50-amp isolation switch - and that
could be the panic handle in the event of overheating or melt-down. Actually, I'm surprised that one isn't
Multiple battery input devices, like 240V chargers, solar controllers and DC-DC chargers will generally all play happily together and each will do what it is set to do. Our new build OKA will have 5 @ 430W solar panels, each with a seperate controller plus the ability to charge the Li house battery direct from the alternator. It will have an isolator capable of switching off all power from the battery. Our current vehicle also has this. Never used it in anger. Cheers, Peter
EDIT: I think (from memory) a battery isolator is required under the new AS3001 standard.
-- Edited by Peter_n_Margaret on Saturday 12th of October 2024 06:13:57 PM
AGM batteries are best if fully charged ..... leave on charge. Lithium are better with well under 100% charge, and they have a very small self-discharge rate. They are best stored at around 50% state of charge.
I read a suggestion to turn off solar or other chargers a day before you finish a trip. The theory is that by the time you park the van, the battery is in an ideal storage state. Then turn everything off to avoid a slow trickle discharge as this can bypass the battery BMS and take it below the recoverable voltage.
With the battery stored this way, note the voltage and check on it in a week to ensure it is not being discharged, then every couple of months. Give it a partial charge if the voltage shows it is getting low.
-- Edited by Are We Lost on Saturday 12th of October 2024 06:22:15 PM
They can be and are but when they are full I suspect that the charger will "keep the pressure on."
I don't know whether this is good or bad - but it certainly prevents one keeping the battery in a
"restful" state of say, 50% charged.
I'm not a fan of having something on to burn up what's charging in - thats just another factor in
wearung the battery out - and i want all 200 amps available when I hit the road and not a battery
that is worn down somewhat.
Getting back to my query, I wonder what others have done and how their batteries have lasted
under different management techniques.
Just like the batteries in cars - they wear out - but I have no knowledge as to how sensitive our
van batteries are to degradation with charging.
I have a 38ah gel that I use in my camper, it is 2 years old, stays at 12.8 volts religiously, and is charged weekly by a 10watt solar panel and 10amp regulator, charging at 14.4 volts. My cabin batteries are also gel, it is a 24 volt system 2 x 100ah on solar panel charge of 500 watts with a 20amp regulator, the batteries are also 2 years old, they stay on charge always, because my previous 2volt gel batteries x 12 (535ah), were running on same system but 1000watts of solar panels and constant charge, they lasted 22 years, and are now over in the open barn sitting on 24 volts, being chrged one day a week by a 6kva diesel genny. They are slowly dying but I wont remove them until they get below 22 volts, as they will still run everything over there even in that condition.
-- Edited by Bicyclecamper on Saturday 12th of October 2024 08:02:46 PM
With LiFePo4 it is recommended for long tern storage that they should be left at around 80% charged. The self discharge rate is very slow so even after a few months they will still have significant charge.
Personally I dont bother with the 80% for my LiFePO4 and leave mine connected all the time. I build my own though and even with 2,000 or 3,000 cycles they will probably still outlast me. I opened one of my boxes up last week and the cells were all fine without any signs of swelling, even though I do not install any compression of the cells as recommended by manufacturers.
In the end it is a case of what you feel happy with but the sky isnt going to fall down.
Even with my lithium shut down between trips, when Im getting ready to go again I fire everything about 2 days before and the battery is back to 100% before the fridge has even started to show cold, fridge may be on 240 but battery charging on my rig is 100% solar .. If I want to tend to something while battery shut down its only a switch flick and all systems are go .............
Though once I left the load on and forgot to shut down the TV and Vast STB, Solar was off and much later the beeping from van soon showed me battery had really dropped down to cut off, luckily my Epever Controller brought it all back to life ............. a good test run of the whole system actually as I wrote the lithium parameters for the solar controller as it didn't have a Lithium parameter and I didn't trust flashing the updated programme in case I bricked the whole thing .................... Dumb Truckie winged it again .
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Checking out the places I drove past a thousand times................
With LiFePo4 it is recommended for long tern storage that they should be left at around 80% charged. The self discharge rate is very slow so even after a few months they will still have significant charge.
Personally I dont bother with the 80% for my LiFePO4 and leave mine connected all the time. I build my own though and even with 2,000 or 3,000 cycles they will probably still outlast me. I opened one of my boxes up last week and the cells were all fine without any signs of swelling, even though I do not install any compression of the cells as recommended by manufacturers.
In the end it is a case of what you feel happy with but the sky isnt going to fall down.
Tim
This is one of the most hotly debated issues in online caravan discussions. Most people say that you shoudn't leave your lithiums on charge. Which is odd, as the manual for my van is adamant that you should, and when I have had the opportunity to check this with senior factory reps, they also said to leave them on charge.
Enerdrive have a video on their Youtube channel which says that it's fine to leave them on charge, IF you have a charger with a lithium profile, like an Enerdrive one. The video also says that the alternative - charging and then disconnecting all loads and monitoring - is also ok. Earlier this year I had the opportunity to ask an Enerdrive rep what he recommended. He acknowledged the video, but conceded that the topic was actually hotly debate inside Enerdrive. His own view was that for short to medium storage (3-6 months) leaving them on charge is ok, but for long term storage he would disconnect. The issue with that is that you still need to monitor the SoC periodically. If that's not practical then I'd be inclined to leave them on charge. If you can do that for the short to medium term, then why not longer term?
Enerdrive have a video on their Youtube channel which says that it's fine to leave them on charge, IF you have a charger with a lithium profile, like an Enerdrive one. The video also says that the alternative - charging and then disconnecting all loads and monitoring - is also ok. Earlier this year I had the opportunity to ask an Enerdrive rep what he recommended. He acknowledged the video, but conceded that the topic was actually hotly debate inside Enerdrive. His own view was that for short to medium storage (3-6 months) leaving them on charge is ok, but for long term storage he would disconnect. The issue with that is that you still need to monitor the SoC periodically. If that's not practical then I'd be inclined to leave them on charge. If you can do that for the short to medium term, then why not longer term?
I had a look at that Enerdrive video. The advice to check the state of charge every few weeks for a totally disconnected battery seems unnecessary.
"The topic was actually hotly debate inside Enerdrive". I can understand that. Most battery manufacturers say best life is achieved by not keeping lithiums fully charged. My phone has a feature that detects if I have a regular charging pattern, and will only charge to 80%, but completes the charge just before I routinely disconnect it from the charger.
Back to RV batteries, my Voltx says to store at 80%.
They also suggest if stored for a long time to cycle the battery every 6 months.
Discharge without reaching the overdischarge level.
Fully charge it.
Discharge to 80% then store again.
I checked the Renogy advice for their batteries.
Charge the battery to 30%-50%.
Disconnect the battery from the system
Charge the battery at least once every 3 months to prevent it from overdischarge.
Fully charge the battery when it is taken out of storage;
Based on the multitude of suggestions not to keep lithiums on charge, and the specific advice from battery manufacturers, I will only keep mine fully charged when planned for actual use.
The latest set of EVE cells I have coming from China are supposed to have a 4000 cycle life span. The end of lifespan is considered to be when they only have 80% capacity and a cycle is considered to be a full discharge from 100% to 0%. Even if I discharged those cells every day down to 10.5V being a full 100% discharge they would last me 10.95 years and yet still supposedly have 80% capacity. Of course the reality is I would not be doing a 100% discharge every day but at even 50% that would still be nearly 22 years.
Even if my keeping the cells fully charged whilst in storage reduced the lifespan by 20% then they will still last a very long time and will probably outlive my caravanning days.
The Enerdrive batteries have a lifespan of 2500 @ 80% which are the equivalent of 2000 cycles @ 100%. Again if keeping them fully charged whilst in storage reduced their life by 20% they are still going to last a very long time.
I have to laugh at the Renogy instruction to charge the batteries up every 3 months to prevent over discharge. Cells are shipped from China at about 80% charged. They generally take about 3 months to get here and are still around 70-75% charged. Of course you do need to be mindful of parasitic currents when in storage.
At the end of the day it is not about theory but all about what happens in the field. Hope that puts things in perspective and I hope to let you know in 10 years how it is all going .
Tim
-- Edited by TimTim on Thursday 17th of October 2024 07:10:31 PM
I have been asking around and doing a bit of reading on the subject,
but a definitive answer so far has not been forthcoming.
There's plenty of recommendations that they are best kept at 20 - 80%
state of charge, but with solar connected they inevitably hit 100% in
no time.
Even at 100% there must be pressure on the battery to accept more,
one would think?
The other thing, is safety - is it wise to have the batteries virtually
on solar charge indefinitely - does this increase the likelihood of
a "meltdown".
B
My apologies as I missed a few points in your post.
You are obviously concerned about LiFePO4 being overcharged. What you need to remember is that you have two levels of protection against overcharging. Firstly the BMS inside the battery provides overcharge protection and secondly, the solar controller provides overcharge protection. Therefore you would require both systems to fail at the same time for overcharging to happen.
LiFePO4 do not have meltdowns when on constant charging.
The latest set of EVE cells I have coming from China are supposed to have a 4000 cycle life span. The end of lifespan is considered to be when they only have 80% capacity and a cycle is considered to be a full discharge from 100% to 0%. Even if I discharged those cells every day down to 10.5V being a full 100% discharge they would last me 10.95 years and yet still supposedly have 80% capacity. Of course the reality is I would not be doing a 100% discharge every day but at even 50% that would still be nearly 22 years.
Even if my keeping the cells fully charged whilst in storage reduced the lifespan by 20% then they will still last a very long time and will probably outlive my caravanning days.
The Enerdrive batteries have a lifespan of 2500 @ 80% which are the equivalent of 2000 cycles @ 100%. Again if keeping them fully charged whilst in storage reduced their life by 20% they are still going to last a very long time.
I have to laugh at the Renogy instruction to charge the batteries up every 3 months to prevent over discharge. Cells are shipped from China at about 80% charged. They generally take about 3 months to get here and are still around 70-75% charged. Of course you do need to be mindful of parasitic currents when in storage.
At the end of the day it is not about theory but all about what happens in the field. Hope that puts things in perspective and I hope to let you know in 10 years how it is all going .
Tim
Thanks Tim, I agree with your premise on storage charging.
I think there is over thinking on this issue.
I continue to solar charge the batteries when van is between trips and have done this for several years.
There are some accessories that trickle draw battery power constantly.
My LiFePO4 charge parameters float at 90% SOC and I do a full discharge once yearly as a test.
No deterioration to date. The batteries, I feel, will outlive my camping journeys and so far, I predict, there are many years left in the life of the batteries.
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Cheers, Richard (Dick0)
"Home is where the Den is parked, Designer Orchid Special towed by Jeep Grand Cherokee Limited"
"4x250W solar panels, Epever 80A charger and 3x135Ah Voltax Prismatic LiFePO4 Batteries".
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