I’ve had this Stanley Booster Jump Starter Pack (J5C09) for several years. I was never really impressed with it when compared to a “Booster Pac” brand jump starter that I’d used at my Dad’s shop for years. It would only seem to have enough power to crank an engine if the originally battery was only mildly depleted. If the battery in the car was completely drained, it didn’t have enough juice to get it going. The “Booster Pac” on the other hand seemed much more powerful and could generally start a car even missing its battery. I lived with the subpar performance of the Stanley unit until it finally seemed to be petering out even more.
I looked long and hard at the endless lithium ion jump pack options all over the internet, but decided against them because at best it seemed they are good for one or two jumps before needing recharged. I had a JNC660 in my Amazon Wishlist for two years even; sadly, through several anniversaries, Christmases, and birthdays, my wife had not bestowed me with a new jump pack of her own accord. I could have purchased the jump starter I had picked out, but what fun would that be.
On my particular jump starter, it charges via a 2 prong plug that conveniently plugs into an extension cord. It has the wall wart transformer built into the unit instead of on the part of the charger that plugs into the wall. That’s all fine and dandy, except I wanted to attempt to use my BatteryMinder desulfator to see if I could recover some of the battery’s performance. I attempted to hook up the jump starter connections with the alligator clips on the charger, but something in the internal circuitry of Stanley won’t allow it to charge that way.
I started researching replacement batteries for jump packs, and found that a lot of the lead acid jump starter packs seemed to have the same 7.2 by 3 by 6.57 inch replacement batteries. The largest advertised amp hour capacity I could find in this size is 22AH. The battery I ordered is from Absolute Battery and is supposed to be a replacement for jump starters. I was stoked when my battery showed up, but quickly disappointed when I looked closer at the battery, it was only an 18ah. I felt like I had been the victim of a bait and switch. Luckily though, Absolute Battery made it right and sent me the correct battery, along with a return label for the wrong one.
While I had the 18ah battery though, I went ahead and weighed it for curiosity sake to compare it to the 22ah to see if the extra 4ah was just labelling gimmicks or if there was really a measurable difference. The 18ah battery weighed in on my highly accurate* digital bathroom scale at 11.4lbs. The 22ah weighed in at 13.2 lbs. This result made me feel warm and fuzzy that I might actually be accomplishing something by replacing the battery in my jump pack.
Now for the fun part, swapping the battery into the jump pack. There were about 16 tiny Philips screws holding the two halves of the case together, and they all came out relatively easily, with no stripping. I could not take the case completely apart due to the air compressor attached to one side of the case, but I was able to stretch the wires far enough to get in and work. I found something interesting that I did not think was possible on a sealed battery. The negative terminal of the battery had a large amount of corrosion on it. My best understanding is that there must be a break in the seal of the battery around the negative terminal somewhere for this to occur. I also believe this corrosion was a major contributor to the reduction in performance I’d noticed from Stanley. Due to the design of the battery, with indents around the terminals, it was quite difficult to get pliers on the corroded up hardware, and eventually I came to the brilliant idea to drill the screw out, and it took about thirty seconds. I wish I would have thought to do that sooner, as I wasted at least an hour trying different pliers, wrenches, vice grips, etc. to get that screw out without damaging the connections or the battery.
Once the old battery was free the project got easy again, just pop the new battery in, tighten down the terminals and, and put Stanley back together again. Before I installed the replacement battery, I did a quick test with my battery load tester. The 22ah battery showed 800ca on the tester when I hit the load switch. With the old battery out, I was able to charge it with the desulfator. The old battery was labelled 19ah capacity, and it weighed an identical 11.4lbs to the wrong 18ah battery I had received. I left it on the charger for a week and tested the battery right away after taking it off. The old 19ah battery showed 600ca on the load tester.
This upgrade should make Stanley the jump starter perform better than new, and at a third of the cost of a new jump pack using a similar battery. My plan for the old battery is to replace the busted batteries on my demo derby Power Wheels Jeep, so this one purchase ought to knock out two birds with one stone. I hope you learned something from this project post, I sure did.
UPDATE: I have gotten to use the jump starter quite a few times since replacing the battery, and am happy to report that it will jump start a 4.6 ford with no other battery connected, as well as with a completely dead battery. The old Stanley battery would not even come close to turning this engine over. Its amazing what a difference 1.8lbs of lead and 3 amp hours of rating makes.