TheSamba.com :: View topic - How to charge a battery jumper pack while driving?

Thu Mar 18, 2021 6:31 pm

I have an older battery jumper pack. It has a light and a non functioning air pump.

The brand?
I don't know, the labels are long gone.

About two years ago I put new SLA diehard batteries in the pack.

It charges with a 110v shore power cord
or you can see in the phito a small charger port fir a charger pack that steps 110v shore power down to ?not sure how many? DC volts.

It has a cigar lighter socket on the side.

It works great!
But.....

Rather than installing a house battery setup to run my truckfridge, this will be my house battery.

How would I charge this while traveling?

The lighter socket will power the fridge.
Though I could plug the fridge into the Van while underway.
Would I use the lighter socket as an input or the DC charge port plug as an input?

Or...... is this a really dumb idea?

Dave

Thu Mar 18, 2021 7:14 pm

I can’t imagine the internal battery in that jump pack is very big at all. Maybe 10-20ah max? I doubt you would be able to run your fridge on that for very long.

Thu Mar 18, 2021 7:22 pm

charge it up fully, unplug from wall, then plug your fridge in and see how long it runs. the disappointment may save you trying to figure this out.

otherwise, just charge it with a 120v cigarette plug inverter. the thing will use a VERY slow trickle charger and draw probably less than 20 watts of 120v power or 2amps from the cig plug.

Thu Mar 18, 2021 8:04 pm

That is not going to run a fridge for long at all. It is designed to give a jump boost a few times. Like mentioned give it a try to see how long it lasts.

Thu Mar 18, 2021 8:40 pm

I travel with my boost pack for decades. it's my 'jumper cables'
I keep it charged with a cig lighter cable.

and yeah that boost pack will only let you down running a fridge and leave you with warm beer.

Thu Mar 18, 2021 10:14 pm

djkeev wrote:

About two years ago I put new SLA diehard batteries in the pack.

...is this a really dumb idea?

Dave

What ah rating did those batteries have?

How many ah does your fridge consume?

How long do you want to run the fridge without running the alternator not running?

Say you have 24ah of SLA batteries in that pack. Say the fridge consumes 2ah. In 6 hours it will consume about 12 ah of the battery's storage and the batteries will be harmed if you consume more than half their capacity. In other words, that battery pack won't run the fridge overnight.

If you consider running the fridge for less than, say, 8 hours w/out running the van's motor a really dumb idea you may answer your question.

Thu Mar 18, 2021 11:36 pm

I have one of these similar.
I don`t have a proper charger for it. I replaced the internal battery which is tiny, to charge it I just put the clamps on another battery and use and external home outlet battery charger that charges both this way, or you can clamp it to your engine battery while you drive. There`s no diode on mine, so this works, worth a try on yours.

Fri Mar 19, 2021 3:31 am

Thanks, I mostly use it fir shop testing things.

I've had it on charge all day and night.
I'll test it on my fridge and see what it gives.

Just trying to cut a corner is all, utilize what I have in hand if possible.

I'm not talking days of boon docking.
I'm talking hours over night.

Dave

Fri Mar 19, 2021 8:17 am

it's still not going to do overnight.

not that 'economy' jump pack, has a 14ah battery if lucky.
probably less since it had a compressor in the case also taking up real estate.

Fri Mar 19, 2021 9:52 am

When I first got my CPAP I tried running it off a very similar sized battery pack, thinking it might
be the ticket for backwoods camping...pulling barely 2 amps, it lasted about 2 hours.

Just sayin... <shrug>

- Dave

Fri Mar 19, 2021 10:01 am

OP Dave,
You want something like the Bluetti in this thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=751355

On a cheap Chinese 12v refrigerator (50 qt size) with an LG compressor, the fully charged Bluetti ran the unit for 43 hours without any input to replenish the drain of the fridge.

I'm currently at the 36 hour mark on testing my 50 qt, 12v ARB fridge with the Danfoss compressor and the Bluetti displays 60% of battery left. I estimate that to be closer to the 40% range right now but the display hasn't lowered yet. I'll probably get 45-50 hours out of this on the ARB.

There is a link in my thread to enter and win one of several models Bluetti is giving away but there are only 4 days left to enter...

Fri Mar 19, 2021 11:37 am

splash out on a 50Ah LiFePo battery and call it done.

Fri Mar 19, 2021 11:41 am

I recently bought a Schumacher SL1396 jump starter pack and have been sufficiently impressed with the performance. I've used it to jump various late model BMW sixes, a Prius and my TDI Vanagon. It charges surprisingly quick from a USB port. It's probably my favorite purchase of 2020.

Fri Mar 19, 2021 11:56 am

Question of how to charge...

Well, you know that it is meant to assist a start, hooking it up to the start batt, right? Hook it up like that, and run the engine, and veee-OHHHH-laaaaa! its charging. Done this too many times to count. My old jump pack had broken 120V input, now my kids jump pack is that way.

Other part of how to use it, well, that is different.

Fri Mar 19, 2021 12:03 pm

dhaavers wrote: When I first got my CPAP I tried running it off a very similar sized battery pack, thinking it might
be the ticket for backwoods camping...pulling barely 2 amps, it lasted about 2 hours.

Just sayin... <shrug>

- Dave

we camp at Winnipeg with a friend that MUST have a CPAP at night. so arising to the occassion it was the perfect excuse to install 100watts of solar and a 100AH AGM. she bought a 12v cord dealy for her CPAP and i made a 30' long cigarette lighter extension cord to run to her tent. kept her going for all 5 days!