Did I kill my jump pack, or my battery, or both?

Max Mini

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I have a '91 E350 7.3L IDI short school bus. I replaced the batteries about a year ago with two deep cycle starting batteries, and haven't had any problems until now. But now... I didn't start the bus for about six weeks, and unknown to me the extension cord I was running to my trickle charger wasn't working. I had a reading of 11.9 on the main battery, put it on the trickle for a while, and had no problem starting it. I drove it around for about 15 minutes, and all seemed well. Started again a couple days later with no issues, though it only read 11.9. But this time I only really moved it a few yards to get it out of some pictures my realtor was snapping.

Due to circumstances beyond my control I had to run my diesel heater quite a bit over the course of two days and I had moved the bus just far enough that I can't reach the 110V maintainer. The heater is currently wired into the starting battery, which I keep saying i'm going to change. I connected to a solar maintainer, one I've used with success in the past, and the charge mostly stayed at 11.9 while I was running the heater, popping back up to 12.3 when the heater was off. Today was the second day of running the diesel heater and I tried to keep my eye on it but all of a sudden it dipped to 10.5v. I turned off the heater and it immediately went back up to 11.7. I put the solar maintainer back on but lost sun shortly after that so I took out my trusty jump pack, rated for up to at 8.0 diesel. it has served me really well in the past. I It showed 13.9v going in to the battery, but it didn't work, and after 3 unsuccessful attempts it was down to 35% so I stopped trying. I'm charging it now but it's going very slowly.

Both batteries under the hood read 11.9v. When I first tried to start it sounded entirely dead (even though it read 11.7) and though it sounded more lively after being on the jump pack, it still isn't close to starting. Everything on the dash lights up bright, and gradually dims as the crank gets slower.

I'm wondering have Ijust not given these batteries enough driving around time to really bring them up? Or... never thought about the fact that the jump pack has a lithium ion battery in it, and I left it in the bus all winter, unused. I brought it in the house and charged it up about a week ago (it was at about 80% and I can't remember if that's because I had used it or if it lost that 20%), and it seemed to charge more slowly than usual, but it did eventually reach 100%. When I hooked it up the vehicle it dropped more rapidly I think than it has in the past. I kept trying till 30% and now it's inside getting charged, but it's really crawling.

Do I have dead batteries, or a dead charger, or both/neither? I don't have another vehicle to jump from.
 

IDIBRONCO

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My guess would be that your jump pack is getting weak. Your biggest issues with your batteries is that you're only looking at the voltage, but not taking the amperage into consideration. Our engines need a lot of amps to get started. Even more in the winter time. You can still have fairly high voltage (11.7/11.9) and not have nearly enough amps to start your engine which is what you're probably experiencing here. Take the time to let your batteries fully charge even though it will take a long time. I'll bet that your bus will start up fairly quickly with fully charged batteries.
 

JPM4

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I'd recommend charging the batteries with a good 6 to 10 amp charger overnight if possible. Trickle chargers and solar chargers can passivate lead acid batteries. A good high amp charger can sometimes burn the passivation/plating off. IDIBronco is correct. Voltage may look good, but capacity could be very low. Lead acids typically should settle around 12.1, higher if they are being used routinely. You may want to clean all the cables while your at it.
 

Cubey

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HFT sells a nice smart charger with a battery restore feature and three amperage settings.
 

Max Mini

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My guess would be that your jump pack is getting weak. Your biggest issues with your batteries is that you're only looking at the voltage, but not taking the amperage into consideration. Our engines need a lot of amps to get started.
Thank you, I sort of knew this but conveniently forgot about it. The problem is I don't really have a way to charge them overnight at the moment. Working on that, though - I have a couple of feelers out to borrow someone's.
I'd recommend charging the batteries with a good 6 to 10 amp charger overnight if possible. Trickle chargers and solar chargers can passivate lead acid batteries.
I'm not sure I know what this means - my charger could be making my battery LOSE charge?
HFT sells a nice smart charger with a battery restore feature and three amperage settings.
Can you point me to it? I'm not sure which one you're talking about.
Thank you, all of you - you are awesome
 

Cubey

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Can you point me to it? I'm not sure which one you're talking about.
Thank you, all of you - you are awesome
Ouch, like so many things, the price has gone up a lot, but it's still not terrible. It's still $30 cheaper than the 10A one linked above by chillman88.

The HFT one has generously long battery cables too, which I like. You can manually select the amperage, or have it be fully automatic by just hitting start, and you can start/stop it at will, unless you're doing the battery recondition... then you just have to unplug it, if you want to stop it.

 
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ISPKI

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Something to keep in mind with those smart chargers. If the battery is low enough, they will return an error and refuse to charge it. Alternatively, the older non "Smart" chargers tend not to have maintainer logic and can overcharge batteries if you dont keep an eye on them. Theres an older Schumacher charger that has a mechanical method of preventing overcharge and it can juice up dead batteries, but they are hard to find. I have found it best to have an old mechanical charger like this silver beauty unit (this isnt mine but I have the same unit) and one of those smart trickle chargers for maintaining charge. Like others have mentioned, most of those hand held jump packs just dont have the amperage capacity to start up our trucks without the batteries helping out.

Other thing to keep in mind, if it is below freezing where you are and your batteries lose enough of their charge, they will start forming ice internally which will cause them to lose amperage capacity but not voltage. The only reliable method for verifying the health of your batteries is to have them load tested. Voltage testing is really only helpful to check if your alternator is charging, thats about it.

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JPM4

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BLUF you really need charge the batteries with a good charger, see if that helps. If not, get them to an autoparts store to have them load tested.

After resting for at least 2 hours (no charging/discharging), 12.7 is considered 100% State of Charge. 12.06 is 50% SOC. If you are at 11.9, your batteries are very low and depending on temperatures, are very weak or you could have a bad cell. When maintaining batteries, you want to keep them at 12.06 to 12.7 for best life expectancy. Anything lower, it starts degrading the battery. Load testing will tell you if you need to replace them.

Also, you always should replace both batteries at the same time.
 

chillman88

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I chose that particular charger because I've heard hit and miss issues with the harbor freight chargers, and I was tired of messing around with spotty chargers. They may work fine, but I didn't want to chance it and have to drive an hour to exchange it....

Also, to add to @ISPKI comment, this charger has an option to "force" a charge for batteries that are too low for a typical smart charger to detect.

I'm certainly not saying not to get the harbor freight version, just stating why I made the choice I did.
 

Cubey

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I chose that particular charger because I've heard hit and miss issues with the harbor freight chargers, and I was tired of messing around with spotty chargers. They may work fine, but I didn't want to chance it and have to drive an hour to exchange it....

Also, to add to @ISPKI comment, this charger has an option to "force" a charge for batteries that are too low for a typical smart charger to detect.

I'm certainly not saying not to get the harbor freight version, just stating why I made the choice I did.

Yeah, I get that. I got mine for something like $40 several years ago during some holiday sale (Black Friday, probably) and it has done it's job fine for me, the several times I have used it. Mostly on old weak batteries. Never had the restore work, at least not very well, but that all depends on the battery you're using it on ... so maybe it works fine under the right conditions.

My tiny old Yamaha generator has a built in 10A dumb charger, if I want something that forces a charge regardless of the battery voltage.
 
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Selahdoor

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Sounds more like you are having a problem with your charger reaching to the batteries. You talk about having moved things, and now you can't get them charged up.

If that is the problem... Take the batteries out of the truck and bring them to the charger.

Sometimes the answer is simpler than we think.

If that's not the case, then, in my best Rosanne Rosannadanna voice... "Never mind". LOL
 
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