Solar powered trickle charger

This might seem a silly question but here goes does the solar powered trickle charger have to be connected to the battery and plugged into the cigarette lighter switch?
As the battery is in the boot I just wondered if it had to be connected to the cigarette lighter I would need a ■■■■ of a long cable
Thanks for any help

Ummm, I think its been established that the cigarette lighter/power socket can’t be used as there is no power to it with ignition off, so no connection through to the battery.

Hi Tony, I think the cig, lighter becomes dead after 30 mins so cant be used for top up charging. Also my experience with solar chargers is that they will just about maintain a decent battery but will not help a failing battery or add charge to a part discharged one.

Thanks for the response I need the solar charger as the car is located in Spain (very sunny) but used infrequently and usually when I go to use it the battery is flat, it recharges as its a fairly new battery (two years old) but I thought a solar charger would keep the battery topped up and save me having to take it out of the car and recharge every time
Do you think a solar charger would be appropriate for my circumstances?

Is the car kept outdoors or in a garage?
If in a garage that has power, a smart charger would make sense.
If outdoors, would you keep the solar charger on the dash??

The car is kept outside and the solar charger panel would have to be on the boot lid as the battery is located inside the boot

I’ve experimented with assorted solar energy collectors (electric and water) for various applications over several decades including charging the car battery. Most recently I tried a Noco BLSolar2 on my Mazda3, it worked via OBD2 but had nowhere near enough output to replace almost 1 Ampere-hour a day of dark current and battery self-discharge.

My conclusion is that to extract worthwhile electrical power here in UK you need to have something massive, several square metres, which is far bigger than the majority of toys being sold to go inside a car.

The time our little cars need them most is during winter when the car is least used. However this is also when solar is least effective, with weak low-down sun and short days. And then there is the conversion efficiency of the panel itself depending on type, varying from abysmal to poor.

The figures quoted for the majority of commercial solar chargers are for basking in bright midday sun right overhead cooking down from a clear tropical sky. In UK at 50degrees North in winter we might be lucky to catch even a tenth of that irradiance peaking briefly at noon in a short day, even if the panel is perfectly aimed with no glass in the way.

If you count the Ampere-Hours in a day (how much recharge the battery might need), and compare a normal grey UK winter with that blue-sky tropical location, the total amount of solar insolation (ie joules to produce a smidgeon of charge) from the same panel perched inside the car on the dash-board in the UK is likely to be less than a hundredth of what is possible lying on the beach in the tropics!

One possible idea is to have a secondary battery or power bank that can be easily moved from house to car and connected to a suitable 12V to 12V Smart charger for a week or so at a time as a maintainer. But I’ve yet to find one that is properly Smart and more than just a simple jump starter, not that I’ve been looking all that hard.

A better idea is simply to have something like perhaps this jump starter (but I’ve not tried this one). Then use it occasionally to make sure the car can start without caning a nearly dead battery, and take the car for a proper run to make sure everything is exercised, all moving parts and not just the battery.

Ah, in contrast to my previous post with that location you might stand a chance!

Look in the ships chandlers for the bigger chargers intended for use on boats, they have the durability to survive weather, heat, rain and salt, some even have over-voltage cut-off control systems.

1 Like

I used a solar powered trickle charger on my motor home which was stored in the UK. Worked a treat in Summer and Winter. Get one with a good controller to turn off when fully charged. Used for 3 years and never had any problems.
I would feed a cable from the Positive terminal from the battery and a good earth connection from the chassis, (not the negative on the battery).So you can connect/disconnect easily. :+1::slightly_smiling_face:


I decided a while back that solar chargers were a bit of a waste-of-space marketing hype … at least in terms of keeping MX5’s topped up over winter.

My Panasonic Agm is in the state now that I can charge it up one day, and it won’t have enough oomph in it the next day to start. I do though have one of those power bank jump starter things ( similar to that mentioned above ), and that’s always started the car instantly. I’ve currently put a new, cheapo, 053 type battery in , and disconnected the +ve terminal ( with the 053, or048, batteries, there’s virtually no room to get at the -ve terminal ).

I did that for financial reasons. However, when things return to something approximating to normal, post Covid, my intention is to cough up the £100 ish for a new Panasonic, fit that, and add my Richbrook battery isolator on to the -ve terminal. Which means that over winters, I don’t have to worry about draining the battery due to immobiliser drainage etc…, and just have to run a voltmeter over it once in a while. [ I don’t have a garage, so permanently connected Ctek’s etc are not an option ].

1 Like


So the Panasonic AGM is about a hundred quid.

Good investment in that case, as legend appears to have it that they last and last.
The Yuasa AGM was about £400.00 fitted for my 3 series stop start diesel.
Fitted because the charging system has to be coded for a new battery.
Thankfully I didn’t pay the bill, the lease company did shortly before I bought the car off them… :wink:

As my car conked out on me yesterday and would not start I guess the battery has given up and just will not hold a charge anymore so am not sure what to do
If I buy the Panasonic battery or the Westco will the same happen as the car is only used occasionally hence the batteries keep going flat even though I do disconnect it when not in use for long periods, but this is now the third battery in less than ten years, so not sure what to do
All I want is to keep the battery topped up when the car is not being used for long periods.
Living in Spain we get 320 days of sunshine hence looking at the solar trickle charger but I still now need to buy a new battery
Any suggestions please

I may be missing something and which model you have as I can’t see it in the original post.(I assume an ND?).
Very popular battery (For the NC) which I purchased this year as a direct replacement.
Go on the YUASA web site and it will point you in the right direction for which one you need.
“Many” other brands available too.
Honestly, if you are living in Spain with 320 days of sun, the solar charger will work for you as my above post.
If you route a cable from the battery you can place the solar panel where ever you want to put it. No idea where you park the car etc, but if near a building/wall mount it on there with quick release waterproof cable and job done.
You can make your own kit up very easily.

Hi Its a 1997 Mk1 1.8 MX5
Just got it started first pull on a jump start so still not sure if the battery will not hold a charge and is u/s or I noticed the positive battery terminal was loose so maybe that was the issue, but the battery is now back on a trickle charge to fully charge it again.
Need a voltage tester to find out if its holding its charge or not first before buying a new one
But thanks for the link much appreciated

All the voltage tells you is when the remaining usable capacity of the battery is fully charged.

The simplest test to see how well it can “hold charge” is to measure how much charge can be safely put into it after it would not start the engine.

  • If the Smart charger (with a maximum current usually something between 3A and 5A) thinks it has fully charged the battery in only half an hour (say), that means the battery only has a very small capacity, maybe only one or two starts, and the dark current will drain it in just a few days.

  • If the Smart charger takes all night but eventually gets there happy, then there is a nice big pot to fill, and the battery is probably a good one.

Battery capacity is measured in Ampere-hours.

  • A 3Amp simple charger will take slightly more than 10 hours to fully charge a good 30Ah battery (always some losses). After that it will just carry on dumping energy into it, heating it possibly even to boil the battery, and this is bad news.

  • A Smart one will back off during the final phases to keep the temperature down to nearly the same as the surroundings so add another hour or two here.

Thanks for that my battery is on a slow trickle charge and has been on charge nearly 24 hours and only now is it showing the green charge light but it goes off frequently although the green light is starting to stay on for longer and longer but once in the car it seems not to charge up when on a run, I have noticed that the positive terminal was loose so I am wondering if that is the reason the battery is not charging whilst in the car

Just an update
The battery has now been on charge for four days and is not really showing much sign of charging up so it looks like a new battery will be needed but as I use the car so infrequently I really don’t want to purchase the OEM Panasonic or the Westco does anybody else have any recommendations for a cheaper battery that I can then leave in the car on a solar trickle charger, remembering I do live in sunny Spain so sunlight is not an issue
I was looking at the Bosch S5 063 battery

The Yuasa as above.

I went on the Yuasa website and the recommendation batteries are not much cheaper than the Panasonic
YBX1063 @ 86.03 euros or YBX3063 @ 95.60 euros or YBX5063 @ 99.43 but the nearest dealer to purchase one is over 355 kilometres away and they want to charge nearly 50 euros delivery charge I can get the Bosch S5 063 for 80 euros including delivery

Ahhh, easy for us over here. I suppose only you know what you can get cost effectively where you live. As long as it’s the correct fitment etc. Good luck :+1::slightly_smiling_face: