Jump Starter Recommendations

[littlex5]

Looking to buy a battery jump starter. They range from 500 to 1200 Amp peak. Most are 18000mAh. What would you recommend for a 4.4 E53? Bigger the better?

[80stech]

The cables will not carry 500 amps and you will never use that so that spec is meaningless. AFAIK the specs for those booster packs are usually BS anyway. Probably you will get what you pay for.

[andrewwynn]

I use the bolt power model. The $60-70 model is the one I recommend for most people it will start an 8-cyl car no problem. I have the $90 version it has a display that shows battery charge as % vs the cheaper one only has 4 LEDs.

The more expensive one has a fancy automatic cable clamp set that is the most likely failure point.

There is one brand that is higher rated but it's 50% more expensive.

Prices have come down a bit : Bolt Power D28-Ultimate 500 Peak Amps 12V Car Jump Starter for Cars & Trucks (up to 5 Liter V4, V6, V8 Engines) and 13600mAh Portable Battery Pack Phone Charger
https://www.amazon.com/dp/B073VZ9H7Q..._OeJZBb6EE287W

Bolt Power D29 900 Peak Amps 12-Volt Car Battery Jump Starter for Cars, SUV, Heavy Duty Trucks, Motorcycle (up to 6.5 Liter V4, V6, V8 Engines) & 18000mAh Power Bank Portable Pack Charger
https://www.amazon.com/dp/B01N3SEJIJ..._6fJZBbWNSD7NQ

I've started 6L diesel truck with my 900A model.

You need about 200-300A to start the X5 but most will come from the battery the little starter will pump some joules into the battery raising it's charge state then when you start current comes from both the battery and the jumper.

[jsoto]

JNC 660 is popular. I've got their JNCXFE

[lo_jack]

How often do you have to check the charge state on those? Is there much internal discharge? More in colder climates? I've always been curious but never really looked at them.

[jsoto]

All batteries like to be at a full SOC. The batteries in a traditional jump pack are SLA. I just connect the battery maintainer on it every 2-3 months just to make sure it's a SOC. SLA has a low discharge rate

[andrewwynn]

The new jump start batteries use lithium polymer cells. Lithium batteries actually last longer when half charged but of course that's not practical because you need it charged to use it. I usually charge mine about monthly even if I've used it 2-3 times and the chage level is 80%

[StephenVA]

I have this one after purchasing a "does everything model" that had a battery failure. The Chinese replacement battery was $150 from Canada and since it was a one hit wonder application, I chose to replace the whole unit with a more tied and true unit.
Here is what I have:
https://www.tooltopia.com/solar-jnc770r.aspx

[jsoto]

Call me old skewel. I would not want the lith. charge packs sitting in any of my vehicles unattended.

And for a charge pack, if one is not using it as a one time let me grab the charge pack but leave it in the car for indefinite periods, SLA can be keep at full and the lithiums @ storage like to be around 70'ish percent.

IMO the old school tried and true ones are more reliable AND when the battery goes poop, just open up the shell and shoehorn a new SLA in it. Or if you want to go crazy, buy the biggest Autozone Duralast AGM that will fit

[andrewwynn]

Since lithium batteries like to be not full I tend to leave mine after I've used it and only charge when it gets below 75 or so. I've jumped as many as five cars before charging and it's rarely been below 60%
The pack I use is 1/4 the size of the one in the previous post and the tiny size means I can use one finger to carry and I bring it with on trips with friends/family no problem it'll fit in a door pocket out of the case or in a tiny part of the trunk in the case.