Battery explosion
Rennlist Member
Joined: May 2001
Posts: 2,640
Likes: 117
From: Cypress (Houston), TX
We had a 928 battery explode here in Houston near me a few years ago in a beautiful low miles '91. The car hasn't run right since, so we're thinking the computer might be damaged, but haven't swapped it out with one of mine yet.
Thread Starter
Racer
Joined: Apr 2021
Posts: 309
Likes: 71
From: Tucson, AZ
Oh, god. I am just thankful then that nothing happened with mine. She seems to idle fine.
I tested the old charger. I measured above 14V with a multimeter straight at the connection. I tried one of mine (a new one) and that only puts out 1.6V. Maybe it really was just the charger.
Anyway, people, look at your chargers and your battery voltage!
I tested the old charger. I measured above 14V with a multimeter straight at the connection. I tried one of mine (a new one) and that only puts out 1.6V. Maybe it really was just the charger.
Anyway, people, look at your chargers and your battery voltage!
Pro
Joined: Jul 2018
Posts: 548
Likes: 39
From: SW Oklahoma, USA
FYI, the cen-tech trickle chargers are Harbor Freight's old, cheap line (~$10 for the little "float" charger), and this is not the first time I've heard of them cooking a battery.
I hadn't heard of one exploding, but I had heard of them boiling cells dry.
I can give good reviews for the Battery Tender brand float chargers.
I just sold a motorcycle after not riding for the last 2.5 years, and the battery was a few years older yet. The tender had been plugged in the whole time, and the bike fired up with no issues starting.
I hadn't heard of one exploding, but I had heard of them boiling cells dry.
I can give good reviews for the Battery Tender brand float chargers.
I just sold a motorcycle after not riding for the last 2.5 years, and the battery was a few years older yet. The tender had been plugged in the whole time, and the bike fired up with no issues starting.
Instructor
Joined: Apr 2014
Posts: 196
Likes: 21
From: Colorado
My experience is that if you need a trickle charger you have a drain somewhere in the system. Find it and fix it. I have owned many “collector” cars such as my 928 , and belonged to the associated forums. Many owners seem to use trickle chargers on their cars that get driven infrequently. I have never had the need as long as I start and run the car at least once a month. Trickle or battery tenders seem like a band-aid to me. Long way for me to throw in my opinion that you should not add a new charger to the mix. See if you need one first, and if so, try to track down the drain and repair.
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Joined: Oct 2007
Posts: 28,601
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From: Clemson, SC
Get a C-Tek or Battery Tender brand charger. They're 4-8x the cost of the one you posted, and now you know why. I have a C-Tek on one 997 but everything else I maintenance charge is on Battery Tender brand chargers - 2 dirt bikes, 2 batteries in a wake boat, 2 928s, another 997, a 914, a Cayenne Turbo, and a backup generator with electric start.
Never had an issue with any of them, and my AGM batteries last a ridiculously long time (6-12 years). All of them are connected directly to the battery with the quick connect plugs, with the exception of the Cayenne that's connected to the under hood jump posts.
Never had an issue with any of them, and my AGM batteries last a ridiculously long time (6-12 years). All of them are connected directly to the battery with the quick connect plugs, with the exception of the Cayenne that's connected to the under hood jump posts.
Administrator
Joined: Aug 2001
Posts: 27,523
Likes: 3,079
From: Up Nort
My experience is that if you need a trickle charger you have a drain somewhere in the system. Find it and fix it. I have owned many “collector” cars such as my 928 , and belonged to the associated forums. Many owners seem to use trickle chargers on their cars that get driven infrequently. I have never had the need as long as I start and run the car at least once a month. Trickle or battery tenders seem like a band-aid to me. Long way for me to throw in my opinion that you should not add a new charger to the mix. See if you need one first, and if so, try to track down the drain and repair.
Either way it's really good practice to keep batteries in tip-top shape and that's done with a maintainer. Even my daily drivers go on a maintainer if they are going to sit over a long weekend. I typically get 10-12+ years out of a battery.
The more modern the car, the more a maintainer is needed between drives. Some cars with all systems working as intended, can drain a battery in as little as two weeks.
RL Community Team
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Rennlist Member
Joined: Oct 2007
Posts: 28,601
Likes: 8,393
From: Clemson, SC
That can vary quite a bit depending on the car. One month is probably good for a 928, but much longer there is enough drain from the electronics on board (computers, alarm etc..) to bring a battery close to a critical level. The early cars the analog clock will drain a battery in a couple of months (winter storage).
Either way it's really good practice to keep batteries in tip-top shape and that's done with a maintainer. Even my daily drivers go on a maintainer if they are going to sit over a long weekend. I typically get 10-12+ years out of a battery.
The more modern the car, the more a maintainer is needed between drives. Some cars with all systems working as intended, can drain a battery in as little as two weeks.
Either way it's really good practice to keep batteries in tip-top shape and that's done with a maintainer. Even my daily drivers go on a maintainer if they are going to sit over a long weekend. I typically get 10-12+ years out of a battery.
The more modern the car, the more a maintainer is needed between drives. Some cars with all systems working as intended, can drain a battery in as little as two weeks.
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Rennlist Member
Joined: Jul 2006
Posts: 5,424
Likes: 630
From: Bloomfield, MI
I concur that the battery tender was over charging the battery.
I've switched my collection to this one, note the 25watt also works well.
I buy the ones w/ the display so I can see exactly how many amps it's supplying and they also are a great battery testing tool.
The old "dumb" battery tenders, many are floaters as mentioned above give too many amps when the battery doesn't need it, had one damage a battery in my '85 (blue 928) resulting in me having to use baking soda to neutralize some acid and respray part of the battery box lid (it was an old "Battery Tender" brand, like someone said the HF ones are total junk and have fried more than one ATV battey's before I got wise.
I now buy the AGM batteries as less chance of acid damage (no out gassing too) and use these smart tenders, via the jump post under the hood.
https://www.batterysaver.com/store/p78/2365-lcd.html
I've switched my collection to this one, note the 25watt also works well.
I buy the ones w/ the display so I can see exactly how many amps it's supplying and they also are a great battery testing tool.
The old "dumb" battery tenders, many are floaters as mentioned above give too many amps when the battery doesn't need it, had one damage a battery in my '85 (blue 928) resulting in me having to use baking soda to neutralize some acid and respray part of the battery box lid (it was an old "Battery Tender" brand, like someone said the HF ones are total junk and have fried more than one ATV battey's before I got wise.
I now buy the AGM batteries as less chance of acid damage (no out gassing too) and use these smart tenders, via the jump post under the hood.
https://www.batterysaver.com/store/p78/2365-lcd.html
Thread Starter
Racer
Joined: Apr 2021
Posts: 309
Likes: 71
From: Tucson, AZ
Alright, I have one more likely big thing to add here: This was an Interstate vented-style battery that was not vented! At this point, I think what happened, was that gasses accumulated outside the battery, there was a spark during cranking, which resulted in the battery igniting also on the inside. If you install one of these vented style batteries, make sure to vent them, otherwise, you are making a little bomb in there.
Rennlist Member
Joined: May 2004
Posts: 1,164
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From: Tampa, FL, USA
Where does the vent tube exit?
1. a slit-like hole which is too small for the tube,
2. one of the two holes under the battery which I don't know how I could use without potentially pinching the vent tube, and
3. the rubber grommet where the battery wires exit the compartment - this is what I end up using but inevitably manage to rip the rubber boot part when doing so.
Where do folks vent their battery vent tubes?
Last edited by hernanca; Aug 30, 2021 at 01:30 PM. Reason: Claire Hitty
Thread Starter
Racer
Joined: Apr 2021
Posts: 309
Likes: 71
From: Tucson, AZ
It doesn't help that on both my 86.5's I was never sure exactly where to vent the battery vent tube. I could only see three options and none seemed "correct":
1. a slit-like hole which is too small for the tube,
2. one of the two holes under the battery which I don't know how I could use without potentially pinching the vent tube, and
3. the rubber grommet where the battery wires exit the compartment - this is what I end up using but inevitably manage to rip the rubber boot part when doing so.
Where do folks vent their battery vent tubes?
1. a slit-like hole which is too small for the tube,
2. one of the two holes under the battery which I don't know how I could use without potentially pinching the vent tube, and
3. the rubber grommet where the battery wires exit the compartment - this is what I end up using but inevitably manage to rip the rubber boot part when doing so.
Where do folks vent their battery vent tubes?
Rennlist Member
Joined: Jul 2006
Posts: 5,424
Likes: 630
From: Bloomfield, MI
It doesn't help that on both my 86.5's I was never sure exactly where to vent the battery vent tube. I could only see three options and none seemed "correct":
1. a slit-like hole which is too small for the tube,
2. one of the two holes under the battery which I don't know how I could use without potentially pinching the vent tube, and
3. the rubber grommet where the battery wires exit the compartment - this is what I end up using but inevitably manage to rip the rubber boot part when doing so.
Where do folks vent their battery vent tubes?
1. a slit-like hole which is too small for the tube,
2. one of the two holes under the battery which I don't know how I could use without potentially pinching the vent tube, and
3. the rubber grommet where the battery wires exit the compartment - this is what I end up using but inevitably manage to rip the rubber boot part when doing so.
Where do folks vent their battery vent tubes?
That is why I switched over to the AGM, however I've been running the standard "Wet" batteries for over 20 years in my 928's w/o venting issues or explosions, only acid damage from over charging from the Floater type "maintainers".
As stated the "dumb," floater type are just an on/off and do not provide a metered current supply, if they state 1.2 amps per say, that is what you get each time they turn on 1.2 amps whether needed or not, boiling off the water, and over heating the battery.
Last edited by davek9; Aug 30, 2021 at 01:42 PM.