Need Advice on Maintaining/Charging New Lithium Battery for my Car Trailer Using 20w Solar Panel

[zac]

I have ordered a replacement battery for my car trailer / motormover and i have chosen a 105ah Fogstar lithium battery rather than the usual lead acid variants which i seem to go through every 2-3 years. I am hoping the lithium will last longer and will be lighter which will help the trailer. The issue i have is that I want to use a 20w Solarpanel that i purchased quite sometime ago but never used to top up the battery when not in use and when on sites, this is the one i am referring too Here . I believe that the controller is not suitable for lithium so i will need to replace it with one that is, anyone have any recommendations on a cheap controller that will work on solar and for lithium?

 

[Reallyretired]

I wouldn't have thought such a small panel would even need a controller, it's really just a maintainer (if you're lucky)
I had one I used to stick on my car ,(landrover) notorious for parasitic battery drain and just connected it straight to the battery.

 

[Kannon Fodda]

20W panel, in ideal sunlight would be about 1.6A at 12V (in practice to charge lithium it probably needs to be outputting at closer to 14V, but controllers would adjust that). But this is the max charge rate. Even on a sunny summers day you would only achieve that for 3-4 hours, if the panel is neatly angled at the sun. Spring, Autumn you won't get that much.

So at these figures you will be doing very well to get even 10Ah back into your 105Ah Battery in the course of a day.

Lithium batteries tend to hold their charges quite well, unlike lead acid which due to the chemistry gradually lose. So unless you have some other drain on the battery, the lithium doesn't need to be topped up from time to time, where lead acid did need that maintenance charge. But reality is the 20W solar panels are designed to be maintaining batteries, not recharging them

How much will your trailer mover take from the battery per use, and how often does it get used? Will it have any hope of restoring the charge from the small 20W between your uses?

 

[zac]

20W panel, in ideal sunlight would be about 1.6A at 12V (in practice to charge lithium it probably needs to be outputting at closer to 14V, but controllers would adjust that). But this is the max charge rate. Even on a sunny summers day you would only achieve that for 3-4 hours, if the panel is neatly angled at the sun. Spring, Autumn you won't get that much.

So at these figures you will be doing very well to get even 10Ah back into your 105Ah Battery in the course of a day.

Lithium batteries tend to hold their charges quite well, unlike lead acid which due to the chemistry gradually lose. So unless you have some other drain on the battery, the lithium doesn't need to be topped up from time to time, where lead acid did need that maintenance charge. But reality is the 20W solar panels are designed to be maintaining batteries, not recharging them

How much will your trailer mover take from the battery per use, and how often does it get used? Will it have any hope of restoring the charge from the small 20W between your uses?

i don't mean to charge them from flat but more that it will top them up after using them to operate the motormover which save then having to plug it back in to charge via mains, the trailer will usually be on a site for a min 3-4 days and most of time longer. Its just something to save me having to plug it back in to charge whilst on a site.

If it's not feasible then i will just leave it as usually i am dealing with Lead acid batteries so lithium is new to me on the trailer side (i have them in the motorhome).

 

[Tombola]

i don't mean to charge them from flat but more that it will top them up after using them to operate the motormover which save then having to plug it back in to charge via mains, the trailer will usually be on a site for a min 3-4 days and most of time longer. Its just something to save me having to plug it back in to charge whilst on a site.

If it's not feasible then i will just leave it as usually i am dealing with Lead acid batteries so lithium is new to me on the trailer side (i have them in the motorhome).

Yes on that basis it will be fine lithium lose hardly anything when stood.

But It's more just a question of adding too much charge voltage with you not having a controller.
Unlikely as you only have a 20w panel but I'd check it with a voltmeter as the panel has no way of knowing when to stop adding charge and lithium's are easily damaged by too much

^{_{Subscribers  do not see these advertisements}}

 

[zac]

Yes on that basis it will be fine lithium lose hardly anything when stood.

But It's more just a question of adding too much charge voltage with you not having a controller.
Unlikely as you only have a 20w panel but I'd check it with a voltmeter as the panel has no way of knowing when to stop adding charge and lithium's are easily damaged by too much

with that in mind then i think i am going to need a cheapish controller as i don't want to ruin a new battery.

 

[Tombola]

Yeah a cheap one like below will suffice but What usage does the motor mover draw zac remember that it's a 100ah battery.. so if 5 mins of moving takes out 5 ah then there is a lot of usage in the battery. May be worth just sticking it back on charge when back home.

Amazon product ASIN B08YN6FHHT

 

[zac]

Yeah a cheap one like below will suffice but What usage does the motor mover draw zac

Amazon product ASIN B08YN6FHHT

I did see that but in the comments it says not compatible with lithium

 

[Tombola]

I didnt see that, it does say 3 stage... but for a 20w panel anyway it may just cut off a bit early thats all isnt it ?

edited post just checked, Im getting mixed up with LA mains chargers

 

[jongood]

I did see that but in the comments it says not compatible with lithium

Have you checked that you haven't got a starter battery feed on your existing solar regulator? If so you could hijack one of the plugs on your trailer socket.

^{_{Subscribers  do not see these advertisements}}

 

[zac]

Have you checked that you haven't got a starter battery feed on your existing solar regulator? If so you could hijack one of the plugs on your trailer socket.

Not sure i follow as the controller i have with the 20w panel is def not compatible with the lithium

 

[jongood]

Not sure i follow as the controller i have with the 20w panel is def not compatible with the lithium

The solar regs on your motorhome, some have an outlet for a maintenance charge to a starter battery

 

[jongood]

I wouldn't have thought such a small panel would even need a controller, it's really just a maintainer (if you're lucky)
I had one I used to stick on my car ,(landrover) notorious for parasitic battery drain and just connected it straight to the battery.

Having thought about it - if you have no regulator then how do you stop over voltages at the battery? Because most panels run at greater than 14v.

 

[zac]

The solar regs on your motorhome, some have an outlet for a maintenance charge to a starter battery

Ah i see. I am not looking to charge it from the motorhome solar controller. Need something to keep it maintained when onsite and when the trailer is parked up in storage (outside).

 

[Lenny HB]

Ah i see. I am not looking to charge it from the motorhome solar controller. Need something to keep it maintained when onsite and when the trailer is parked up in storage (outside).

You don't need to do that with Lithium, providing it is 50 to 60% charged turn everything off connected to the battery or disconnect it and it will be OK for months.
You shouldn't store lithium fully charged best left between 50 to 80% when in storage.

^{_{Subscribers  do not see these advertisements}}

 

[zac]

You don't need to do that with Lithium, providing it is 50 to 60% charged turn everything off connected to the battery or disconnect it and it will be OK for months.
You shouldn't store lithium fully charged best left between 50 to 80% when in storage.

ah ok i didn't know that, so if i charge it before storing my trailer it will be ok if i don't use it for 6 months or maybe longer? just want to ensure that i don't mess this one up like i have with all the previous lead acid ones.