Portable battery pack for battery tender

Just joined the forum - thanks for the wealth of information here - it's been so helpful and I wanted to contribute some data which may be useful for those who do not have access to a power point for their trickle charger.

I bought my 2018 Ferrari 488 Spider last week, but it's not currently possible to get power near its garage to run the trickle charger. Research here and elsewhere did not come up with a remote / battery-powered solution that would work, so I decided to get a Li ion portable power pack/inverter to see how it would work.

The power pack I tested is the Jackery 500, capacity 16.8 Ah / 240 Wh. It will run my Ferrari battery tender connected to its 230v AC inverter outlet for between 20-25 hours. That should scale linearly for higher capacity power packs (e.g. 2 days for a Jackery 1000; longer for larger-capacity units from other suppliers).

So, on the one hand, definitely no substitute for a mains-powered trickle charger! And no solution for extended periods where the car is not driven (e.g. if I am away). But it does give a temporary solution to keeping the battery topped off when the Ferrari is not driven for a few days.

Hope that may be useful info to someone!

Cheers,
David

 

Yes, good point - and I wanted to try using a timer to switch on the charger for an hour or two per day to try to maintain the battery for up to two weeks if I'm away. Sadly, the Jackery 500 has a 'feature' which auto shuts down after a few hours (exactly how many seems to vary) when the draw is less than 10 watts...

 

Yes, I looked at solar, but the garage is in a conservation area so panels need planning permission. However, I am only renting the garage, so that complicates things.

I could connect the power pack's 12V DC directly to the battery, but I've not tried it. It would be very inconvenient compared to the magnetic tender connection though, so it would have to give substantially better life from the power pack. I drive the car 3-4 times per week and disconnecting from the battery and replacing the cover each time would quickly get boring.

It's longer periods, like when I'm away, that I'm worried about. I don't think there's any alternative for me than disconnecting the battery.

 

Short answer is, unfortunately, no. I disconnected the battery if I was going to be away for more than a few days; this was fine, apart from the car losing its settings each time.

I actually did manage to get power to my garage in the end (courtesy of a friendly neighbour and a very long cable), so I now have my 488 tendered all the time. It's been particularly useful now it's winter, and I'm driving the car much less often.

I'm not sure I completely understand your question. I think my Ferrari battery is 60Ah capacity, while the Jackery is 16.8Ah. I don't know what the efficiency loss is in the tender itself, but I assume that using the Jackery 500 extends the time for the car to run the battery flat by about 25%. In reality I used to charge the Jackery every 2-3 days and the car always started, but it was tedious.