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Old 05-17-2004, 04:22 AM   #16
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Originally posted by V12
Beside this your math regarding battery voltage isnīt completely correct. A battery at end of charge will have usually more than 9V. If itīs a little older the voltage will be higher. Also battery voltage will be higher with higher charge current. This will result in up to 10,5V battery voltage. Also you donīt have to care too much about any voltage reading at the chargers display. This isnīt very true so you will have to use an external voltmeter for correct results.
I know, it's for the cause of simplicity, just to get the point through.

Yep, different chargers have different voltage requirements. It's always a good idea to check the specs, when combining equipment from different suppliers.

About talking a risk; It's obvious, that the modification of a PC PS involve some kind of a risk (which is also mentioned in the link I supplied). But I cant see how you risk the charger - I've heard of PC PS going down, that is, they either deliver the voltage or dont deliver a voltage. Like all other PS. So that wont risk the chargers life. But I've never heard or seen a PS, that delivers a TOO HIGH voltage by accident - which would damage the charger. Nor have I heard of other chances of damaging the charger. So can you please enligthning me about in which manner a PC PS user risk the chargers life?

Thanks.
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Old 05-17-2004, 04:28 AM   #17
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Originally posted by V12
Regarding output voltage regulation every PS have one at least inside for factory setting. Usually Iīm adjusting this for the output voltage I prefer.
Good tip, thanks.
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Old 05-17-2004, 04:31 AM   #18
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Originally posted by V12
Also you donīt have to care too much about any voltage reading at the chargers display. This isnīt very true so you will have to use an external voltmeter for correct results.
I've noticed this too. Can the reason be the voltage drop over the cables/connectors or is they simply not precise enough? Or a combination?

My CDC have voltage sensing leads, but I haven't cross checked the voltage reading yet with a voltmeter.
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Old 05-17-2004, 09:33 AM   #19
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Quote:
Originally posted by Cole Trickle
I know, it's for the cause of simplicity, just to get the point through.

Yep, different chargers have different voltage requirements. It's always a good idea to check the specs, when combining equipment from different suppliers.

About talking a risk; It's obvious, that the modification of a PC PS involve some kind of a risk (which is also mentioned in the link I supplied). But I cant see how you risk the charger - I've heard of PC PS going down, that is, they either deliver the voltage or dont deliver a voltage. Like all other PS. So that wont risk the chargers life. But I've never heard or seen a PS, that delivers a TOO HIGH voltage by accident - which would damage the charger. Nor have I heard of other chances of damaging the charger. So can you please enligthning me about in which manner a PC PS user risk the chargers life?

Thanks.
one thing is something may go wrong and may deliver a too high voltage by accident. I canīt say for sure if this can happen or not in regular use but I wouldnīt say this canīt happen. Most PS have an overvoltage shutdown but I think this is happening at a voltage too high for some chargers. Talk of 18-19V.
Most of the PC PS are so cheap constructions regarding design and especially electronic parts used. I know of a very good PC magazine making extensive tests with all kind of hardware and PS also. I have seen damaged PS in about each of their tests and they donīt do any crazy tests. Just everything a PS have to pass to be working OK according to all national and international rules.

What I know from personal experience:
Some years ago at the European Champs 1/10 Onroad in the UK there were some problems with the main voltage. It was somewhat higher than in other countries and due to a high load shutting on and off all the time there were bad voltage spikes which caused a lot of switching PS being damaged. Most of them (about 30) were the Victor PS. This isnīt a bad PS and way better than most PC PS but not as good as industrial PS. What happened- not only PS but also some chargers also were damaged.
What I want to say there are some extrem situations where a switching PS could go bad and damaging the nowadys expensive chargers also and you can be shure this could happen at about every bigger race if you are not using a PS made for this conditions. Working at home is an easy task for a PS as you have constant conditions at the main voltage usually.
But at the race there are lot of chargers shutting on and off all the time causing fast changing conditions for the main voltage. This is even bader as not every driver have his own power outlet but some drivers are using one line. So in the end you will have a big and fast changing voltage range where the PS have to work.
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Old 05-17-2004, 09:56 AM   #20
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Quote:
Originally posted by Cole Trickle
I've noticed this too. Can the reason be the voltage drop over the cables/connectors or is they simply not precise enough? Or a combination?

My CDC have voltage sensing leads, but I haven't cross checked the voltage reading yet with a voltmeter.
One reason is the voltage reading at the charger isnīt calibrated as this is too expensive. But this is true for most external voltmeters also for same reason.

Next reason is as you wrote already. If a charger have voltage sensing leads the voltage reading should be more true. This doesnīt mean the reading is true completely but the difference will be always the same even if the charging current changes.
If there are no voltage sensing leads the difference between voltage reading and true voltage value will be changing with the charging current. Higher charging current will affect more voltage drop across the charging leads and this will affect a more false reading. This is even worse with longer and thinner leads.

There arenīt very much chargers using voltage sensing leads for some reasons. I know of the CE chargers using them.
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Old 05-17-2004, 10:59 PM   #21
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Originally posted by V12
There arenīt very much chargers using voltage sensing leads for some reasons. I know of the CE chargers using them.
Eagle /Integy CDC v6 got them too.
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Old 05-18-2004, 01:00 AM   #22
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Quote:
Originally posted by V12
one thing is something may go wrong and may deliver a too high voltage by accident. I canīt say for sure if this can happen or not in regular use but I wouldnīt say this canīt happen. Most PS have an overvoltage shutdown but I think this is happening at a voltage too high for some chargers. Talk of 18-19V.
Most of the PC PS are so cheap constructions regarding design and especially electronic parts used. I know of a very good PC magazine making extensive tests with all kind of hardware and PS also. I have seen damaged PS in about each of their tests and they donīt do any crazy tests. Just everything a PS have to pass to be working OK according to all national and international rules.

What I know from personal experience:
Some years ago at the European Champs 1/10 Onroad in the UK there were some problems with the main voltage. It was somewhat higher than in other countries and due to a high load shutting on and off all the time there were bad voltage spikes which caused a lot of switching PS being damaged. Most of them (about 30) were the Victor PS. This isnīt a bad PS and way better than most PC PS but not as good as industrial PS. What happened- not only PS but also some chargers also were damaged.
What I want to say there are some extrem situations where a switching PS could go bad and damaging the nowadys expensive chargers also and you can be shure this could happen at about every bigger race if you are not using a PS made for this conditions. Working at home is an easy task for a PS as you have constant conditions at the main voltage usually.
But at the race there are lot of chargers shutting on and off all the time causing fast changing conditions for the main voltage. This is even bader as not every driver have his own power outlet but some drivers are using one line. So in the end you will have a big and fast changing voltage range where the PS have to work.
I'll be the first to admit that PC PS is low quality - the hardware is cheap and the 12 volt section is non-regulated.

On the other hand, if one buy a PS with a good reputation of a quality brand (like the Victor, which I dont know personally) and the charger blows up anyway, then how can the end user be sure and safe?

At large race events I've seen Robbe chargers with built in PS, which didnt work, when the main supply lowered due to the huge load. But the PC PS's worked fine in these circumstances.

Hmmm. A kind of buttom line: With a PC PS, you take a risk during building and there's safety precautions to take care of too, due to the dangerous main supply. And there's no kind of warrenty - with a PS like the Victor, you at least can try contact the dealer and maybe get a new charger for free. With a PC PS, there's absolutely no warranty. So they are only intended for people who: 1) know what they do and, 2) are willing to take a certain risk.
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