what max voltage can a 12V system deal with

[JBE]

I decided to trial the battery reconditioner they sell at Jaycar. It is a chemical additive which claims to enhance the performance of older batteries. After adding 15ml of the stuff to every cell as per instruction, I noticed that the battery gets charged up to 20V and drops down to approx 15.5V during operation (i.e. driving the car). This behavior has been consistant for the last couple of days. I double checked my multimeter and it is ok. I did not expect the voltage to jump by 80%.
Now, I am a bit worried that I might trash electrical componets and appliances in my car (GPS, radio, UHF, HF,…).
Can anyone tell me if I’m at risk of causing expensive damage to my gear or if I’m just overly worried.
BTW, I’m driving a GQ TD42 Patrol.

Cheers
Joachim

[84ZOOKSTA]

I personally would not like to see any more that 16volts in a 12 volt system, I know that CB's and Broadcast radios dont like to much voltage.

What charger are you using that allows it to reach 20 Volts???

When charging you do not want to exceed about 15Volts MAX, 14.4volts is Normal.

Cheers
Simon.

[JBE]

The battery gets charged by the alternator. I was quite suprised to see the voltage rising that much.

[RAY185]

I personally would not like to see any more that 16volts in a 12 volt system, I know that CB's and Broadcast radios dont like to much voltage.

What charger are you using that allows it to reach 20 Volts???

When charging you do not want to exceed about 15Volts MAX, 14.4volts is Normal.

Cheers
Simon.

I don't think he's talking about charging it with a battery charger. From what I understand he has bought some sort of substance from Jaycar to pour into the cells.

Simon, I've never heard of this stuff. Any chance of a link to it on the Jaycar website? 20V is definately too much for your appliances and for your battery itself I would have thought. If you've followed the instructions to a T I'd be ringing Jaycar for an explanation personally.

[RAY185]

Is this the stuff?



Lead Acid Battery Conditioner

Removes or reduces sulphation which kills batteries. We have been looking at this product for about 5 years now. Frankly, we were skeptical. A product in a bottle that brings dead batteries back to life? Well, fact is, it does work. As many of you know, when wet-cell lead acid batteries are allowed to sit around they will sulphate up in as short a time as 6 months. The silphate builds up on the plates and separators. This product basically dissolves the sulphation. The product is so good that the manufacturer will extend the warranty on a new battery by a year if used when the battery is new.
- One bottle will do up to a N7OZ size battery (4WD, boat, truck, etc.)

[JBE]

Yep, that's it. I followed the instructions (15ml per cell) and can't work out why I have these voltage readings. I use a digital multimeter which shows correct readings on my other cars battery (untreated).

I really can't work out what's going on.

[DamTriton]

Yep, that's it. I followed the instructions (15ml per cell) and can't work out why I have these voltage readings. I use a digital multimeter which shows correct readings on my other cars battery (untreated).

I really can't work out what's going on.

Do you have another working non-treated battery that you could put into the vehicle? Put it in and measure all the voltages again...

It's time to work out whether you have an alternator that is frying batteries.

[F'n_Rover]

I doubt the additive would cause higher voltage ?
the cell voltage is defined by the different metals inside - the electrolyte would determine the available power, not voltage.

[JBE]

Fair point. What are other possible causes? The only thing, I can think off is the alternator or the voltage regulator thingi. What puzzles me is that I did not see this problem util the moment, I put the chemical into the battery. The charge of the batteries (dual battery system) was allways between 12.5 and 14.5V. I'm just lost trying to explain this.

[DamTriton]

Fair point. What are other possible causes? The only thing, I can think off is the alternator or the voltage regulator thingi. What puzzles me is that I did not see this problem util the moment, I put the chemical into the battery. The charge of the batteries (dual battery system) was allways between 12.5 and 14.5V. I'm just lost trying to explain this.

Is it a three terminal alternator (Batt+, sense, and lamp)? One possibility could be the sense lead has a bit of corrosion on it since you have had the battery terminals off. If the alternator is not sensing the voltage correctly then the alternator will simply ramp up the voltage to as much as it can. CHECK ALL LEADS ON THE BATTERY TERMINALS, EARTHS, AND ALTERNATOR FOR CORROSION (good clean with a wire brush).

If it is a 2 terminal alternator (Batt+, and lamp) then there could be a problem with the regulator.

It does not sound like a battery issue, more a "disturbed wiring" issue. I doubt whether the conditioner was at fault.

[JBE]

I checked the wiring and it seems to be fine. My car is a Patrol GQ TD42. I could not find a label on the alternator to work out the exact type.

I'm now also leaning towards cabling or regulator. I think antother candidate would be my dual battery solenoid. My understanding is that the solenoid tricks the regulator thinking that the main battery isn't fully charged and redirect charge to the secondary battery. I'll disable the solenoid and have a look if this changes anything.

Thanks for all the input so far.

[Shadow]

the altenator should never supply more than about 14.7 volts. Sounds like a regulator problem to me and it will kill your batteries

[Goatse.AJ]

Yep, definitely sounds like a regulator problem to me, or a faulty multimeter??

Anything over about 16.5v will usually start popping things like radios, etc.

[JBE]

As embarassing as it is, it turned out to be a faulty multimeter. I was convinced that it was ok as I used it on another car last week without any issues. Having spent a couple of hours with reading manuals and checking cabling, I decided to re check the meter and it showed the same behaviour on the other car.
The moral of the story is, dont assume and always double check measuring equipment before jumping top conclusions.

Thanks for everyones' input.
Joachim

[claud]

yes ive used this inox stuff too and it did work fine for a while on my two batteries that i added it to . a really old lawn mower ride on one which it brought back from the dead for a few weeks only. and my cheap no name 9 plater .which was i yr old. it lasted another 6mnths. for 10bucks thats great if ur out on a trip for emergencies and every dollar counts.