Author Topic: How to stop a car charger from blowing a fuse.  (Read 907 times)

Offline Dumb and Dumber

  • Trade Count: (+3)
  • AVForums Super Veteran
  • ****
  • Posts: 1,301
Re: How to stop a car charger from blowing a fuse.
« Reply #15 on: July 20, 2021, 12:52:19 PM »
If the battery is that flat, it is best to charge it outside of the car. (The electrolyte is most likely going to boil)
Also, if you have a charger that has no regulation (as evident by it blowing a fuse) I would also not connect it to the car. Being unregulated, it likely outputs much more than 14V and could go high enough to damage your car electronics. It is also possible that that is the reason why it is blowing fuses - car electronics protection devices kicking in with overtvolt event.

I have no idea if my charger is regulated. Its a Motoquip MQ7551. 6amp.
Hopefully it is my cars protection that kicked in to try and save itself :thumbs:
Battery was tested by the experts. Got a 100% health rating, so will see how it goes.

Offline chrisc

  • Trade Count: (+166)
  • AVForums Grandmaster
  • *****
  • Posts: 13,273
  • Condition your mains to condition your ears
Re: How to stop a car charger from blowing a fuse.
« Reply #16 on: July 21, 2021, 03:19:07 PM »
A specific gravity electrolite test is usually a good indication of battery condition

But the alternator's charging rate should also be checked.  Now and then the diodes fail and deliver a high AC voltage to the battery
Music is the shorthand of emotion

Offline marantz123

  • Forum Moderator
  • Trade Count: (+4)
  • *****
  • Posts: 881
  • I learnt more from The Internet when it was slower
Re: How to stop a car charger from blowing a fuse.
« Reply #17 on: July 21, 2021, 05:45:19 PM »
For a very flat battery, a 12v charging voltage may be too high especially if theres a partial short anywhere in the cells. I had a so called smart charger (MVP brand) that ruined every battery it attempted to charge. I would suggest attempting to restore the cells gently with a lower voltage. Connect your 47 Ohm resistor (since you have that 10W one) in series with an expendable 5 Volt cellphone charger. Connect this to the battery. It will charge at 5V with a limited current of 106mA through the resistor. Measure the voltage occasionally across the battery during charging to get some idea of the voltage across the battery. Leave it on this for a few days. It then has a better chance of handling a higher charging voltage and current. All this with the battery disconnected from the vehicle or any other external load.

That should get the first three cells conditioned if possible. Theres still three more cells in series. If you have a wallwart DC type charger that has switchable voltage selector, use that after this and switch up to 9 Volts with the resistor in circuit. Monitor it. Leave this for a few hours, then switch up to 12V on the DC adaptor. After a few hours, disconnect and measure the battery, monitoring if it holds its voltage. It then may be conditioned enough to handle a higher charging current.
« Last Edit: July 21, 2021, 06:18:42 PM by marantz123 »

Offline Dumb and Dumber

  • Trade Count: (+3)
  • AVForums Super Veteran
  • ****
  • Posts: 1,301
Re: How to stop a car charger from blowing a fuse.
« Reply #18 on: July 21, 2021, 09:08:06 PM »
I was at work, but got a mechanic to look at my car. He could not jump start my car either, not even with the big battery he brought along. After checking everything, he removed my cars battery and had it tested, apparently no issues with it. He came back, fitted the battery and there the car starts. What was wrong? Not even he knows. I just hope it was a once off fault :sd:

Offline chrisc

  • Trade Count: (+166)
  • AVForums Grandmaster
  • *****
  • Posts: 13,273
  • Condition your mains to condition your ears
Re: How to stop a car charger from blowing a fuse.
« Reply #19 on: July 21, 2021, 09:22:15 PM »
12 volt connections need to be really clean, especially when a large current draw is needed by a starter motor. 27 amps is typical

The battery posts must be shiny, the inside of the clamps can be cleaned with 100 grit water paper.  Make them really tight

With 230 volts there is so much pressure that a dirty plug isn’t so important
Music is the shorthand of emotion

Offline Dumb and Dumber

  • Trade Count: (+3)
  • AVForums Super Veteran
  • ****
  • Posts: 1,301
Re: How to stop a car charger from blowing a fuse.
« Reply #20 on: July 22, 2021, 05:29:29 AM »
12 volt connections need to be really clean, especially when a large current draw is needed by a starter motor. 27 amps is typical

The battery posts must be shiny, the inside of the clamps can be cleaned with 100 grit water paper.  Make them really tight

With 230 volts there is so much pressure that a dirty plug isn’t so important

Only 27 amps? I always thought its much more. If its only 27 amps why are the jump starter cables staring at basically 200A? I did see up to 800A cables in Makro when I went to look for a better charger.

Offline DACMan1

  • Trade Count: (+1)
  • AVForums Veteran
  • ***
  • Posts: 585
Re: How to stop a car charger from blowing a fuse.
« Reply #21 on: July 22, 2021, 08:36:39 AM »
Only 27 amps? I always thought its much more. If its only 27 amps why are the jump starter cables staring at basically 200A? I did see up to 800A cables in Makro when I went to look for a better charger.

No, 27A is probably an order of magnitude off. But it will depend on the car and the engine. If it is a diesel 27A would not even be enough for glow plugs.

Offline Dumb and Dumber

  • Trade Count: (+3)
  • AVForums Super Veteran
  • ****
  • Posts: 1,301
Re: How to stop a car charger from blowing a fuse.
« Reply #22 on: July 23, 2021, 07:55:34 AM »
I am looking at buying a Motoquip 30A charger. At this rate I should be able to start the car in 2 hours. I have not yet bought a new battery as the shop said battery is fine. But with my experience, the battery will behave badly again in a few days time, hopefully not. I do want a fast charge next time I cannot start the car.
However, it is printed on the box its for 100Amp to 600Amp batteries. My battery is only something like 70 Amps. Are a cars alternator not charging a battery at a much faster rate than 30 Amps? Then the 30A charger should work just fine?

Last question about this charger. It also got a 150A Jump starting function. How does it work? I feel 150A might be too low to jump start my car, and the wires looks way to thin to be rated at 150 amps?

Offline chrisc

  • Trade Count: (+166)
  • AVForums Grandmaster
  • *****
  • Posts: 13,273
  • Condition your mains to condition your ears
Re: How to stop a car charger from blowing a fuse.
« Reply #23 on: July 23, 2021, 08:10:34 AM »
Sorry, a typo.  I meant to say 270 amps.  I looked up the spec of my Honda (petrol engine) and it states

No load - 60 amps
Warm start  - 190 amps
Cold start below freeezing conditions - 270 amps
Music is the shorthand of emotion

Online FranZAR

  • Forum Moderator
  • Trade Count: (+26)
  • *****
  • Posts: 3,335
Re: How to stop a car charger from blowing a fuse.
« Reply #24 on: July 23, 2021, 08:15:05 AM »
I am looking at buying a Motoquip 30A charger. At this rate I should be able to start the car in 2 hours. I have not yet bought a new battery as the shop said battery is fine. But with my experience, the battery will behave badly again in a few days time, hopefully not. I do want a fast charge next time I cannot start the car.
However, it is printed on the box its for 100Amp to 600Amp batteries. My battery is only something like 70 Amps. Are a cars alternator not charging a battery at a much faster rate than 30 Amps? Then the 30A charger should work just fine?

Last question about this charger. It also got a 150A Jump starting function. How does it work? I feel 150A might be too low to jump start my car, and the wires looks way to thin to be rated at 150 amps?

Maybe 100Ah - 600Ah, not Amp.
Exclamé 150|Whisper|Croak SL1200|SP10|Moth Audio MK808|Sumiko Pearwood|AuraLic|Cardas|Sonor Claro

Offline Dumb and Dumber

  • Trade Count: (+3)
  • AVForums Super Veteran
  • ****
  • Posts: 1,301
Re: How to stop a car charger from blowing a fuse.
« Reply #25 on: July 23, 2021, 08:22:32 AM »
Maybe 100Ah - 600Ah, not Amp.

You are correct.
My battery is 73Ah.

Offline Family_Dog

  • Administrator
  • Trade Count: (+44)
  • *****
  • Posts: 11,244
  • Real Amplifiers Glow in the Dark.
    • Repcom 2-way Radios
Re: How to stop a car charger from blowing a fuse.
« Reply #26 on: July 23, 2021, 11:29:56 AM »
You should not charge a battery at more than about 10% of its rated capacity, so don't waste your money.

I'm not promoting myself here but we sell the Benton range of chargers, the BX-2M is all you need. It is a "Smart" charger and charges at 7A max.


More details here:
https://www.4x4community.co.za/forum/showthread.php/19733-Benton-BX-1(M)-BX-2-BX-4-BX-5-Multi-Stage-Automatic-Battery-Chargers?p=4205783#post4205783


-F_D
« Last Edit: July 23, 2021, 11:40:48 AM by Family_Dog »



-Eric

That Guy in South Africa...
*************************************
http://groups.yahoo.com/group/vintage_tube/
*************************************

Offline Dumb and Dumber

  • Trade Count: (+3)
  • AVForums Super Veteran
  • ****
  • Posts: 1,301
Re: How to stop a car charger from blowing a fuse.
« Reply #27 on: July 23, 2021, 04:27:49 PM »
Nothing wrong with promoting yourself :thumbs: