Using your charger in vehicle

All I can think of is that they're afraid of load dump; if you design devices for automotive applications you gotta pay attention to that or plan on having _lots_ of product returns.

It's always worked for me, except for LiPo's, as the club where I use them doesn't allow them to be charged at the field. Actually, I wouldn't have any qualms about charging them at the field where I can properly monitor them, but I'm not yet confident enough in the LiPo charger technology to be comfortable with charging them in my vehicle while my attention is necessarily on driving.

Abel

A number of chargers list maximum input voltage of 13.9V. At least 4 chargers, of three different brands, have been brought in for service over past 4 years where failure was clearly excessive input voltage. At least one occurred when plugged onto a 12V heavy duty marine battery at same time a

230 VAC wall CVC (supposed 13.8v)charger was also connected. The others were plugged into car cigarette lighter sockets. X 2 in motor vehicles whilst being driven to field and X 1 in a car stationary at field with motor running "so as not to have a flat battery when heading home". Motor vehicles were known to be X 2 ex Japan and German X 1. Fewer chargers are now seen with a lighter plug attached or included in packet. Relative instruction sheets usually advise engine must not be running when charger is in use. Consumers should take heed of instructions for each unit - these tend to differ between the cheapest and most expensive unit in range, hence brand names are not relevant. regards Alan T. Alan's Hobby, Model & RC Web Links

Tim, Exactly what do you mean by "load dump" I've not run into that term associated with automotive devices. But then I don't have all that much experience in that specific area.

Red S.

You've already eliminated the problem by not having it plugged in while starting the car (or turning it off for that matter). During startup, the alternator/regularor circuit can cause momentary spikes and RF frequency noise on the hi current circuits (read--cigarette lighter outlets) which won't cause damage to most equipment but RC chargers are designed to run from a battery supply and are susceptable to these spikes.

Geezer

Do you recall what these three different brands were or the any details of how the overvoltages might have occured? Connected to car battery while the car was running? The only one that I have had any experience with is one that the owner tried to run from an unkown AC transformer which turned out to be 24 volts AC output.

OK, lets review what charger documentation I have:

Astro Flight 109 "This charger is designed to operate from a 12 volt regulated power supply, or from a 12 volt automobile battery. Never use an automobile battery charger as a power source for it could damage your charger."

Miniron mobile Accu-Computer Charger (Sommer) "External DC 12-20 volt supply"

Kokam LiPo-402 & 502 "The charger can be powered by a 12 v lead acid battery or any source that can provide 10-15 volts DC."

Orbit Microlader V6.2 "Power supply - 11-14 volt car battery, min 55 Ah or power adapter 13.8 volt/20A. Low/High switch-off voltage 15V."

Triton "Input voltage 12-15 volts DC"

SuperNova 250S "Input - 12 - 15 volts DC"

Robbe Power Peak Infinity 2 "Operating voltage 12 V car battery or well stabilised 12 v or 13.8 v Mains power supply. Do not power the charger from a car battery charger."

Litco Alpha 4 "Field operation from 12 volt DC wet or gel cel, or 10 cell Ni-Cd battery."

Multiplex LN 5014 "Input voltage 11-15 V DC."

None of these mention consequences of connection while the car is running. It is possible that I may have missed it during quick scan of instruction manuals so if anyone finds something to the contrary please let me know.

Then we have several million cell phone auto adapters for charging while the vehicle is running.

AP

There are millions of LiPo powered cell phones being charged while the vehicle is running.

Are you serious? A club that doesn't allow LiPos to be charged at the field? Must be in Kalifornia, right? :-) How did this ever get passed by the membership? Or is it an anti-electric thing and this is just a means to an end.

Red S.

Yes, and there are no controls on the charger for the user to possibly set in error, and their battery packs have charge protection modules built into them. Ours don't.

It's a lot better than the policy that preceded it. Lipos were not allowed to be at the field, period. It did not get passed by the membership (nothing is), but was dictated by "the board."

I expect we will see more products offered in the hobby market that will incorporate charge protection. However I don't suppose that will change your "the board" . Ignorance can be fixed, stupidity is incurable. Who elects these clowns anyway? If there is a good answer lets change the thread subject for it and keep this one on topic.

Red S.

FYI, I've had my Alpha-4 plugged into my car's power port and charging while I stopped for gas and/or coffee en route to the field. No apparent interruption to the charging cycle.

Load dump.

The starter motor is an inductive device. You cannot stop current instantaneously in an inductor.

When you stop cranking, the current reverses direction from the starter motor into the vehicle wiring harness, known as "load dump" or "inductive kick".

This reversed current can induce large voltage spikes into the vehicle wiring harness.

Typical tests for automotive devices can involve voltage spikes of 90volts or more usually lasting mico seconds

RCS

So you are only supposed to use a DC charger in your car with the vehicle running or stopped?

Wouldn't the capacitance of the car's battery being connected act as a filter against spikes?

RS

Load dump can also occur when loads get switched out of circuit, not just on starting.

3for3 wrote:

| It doesn't -- load dump is real, and must be dealt with in any | automotive (or aviation) application.

More accurately, the battery does filter (though I'm not sure filter is the right word) the spikes, but not completely.

If you take a running car and disconnect the battery, the odds of you frying the entire electrical system are quite good, since there will be nothing to stop any spikes anymore.

Personally, I run my chargers in the car with the engine running or not, and have for years, and so far have had zero problems ...

| Red Scholefield wrote: | > Wouldn't the capacitance of the car's battery being connected act as a | > filter against spikes?

IIRC much of the concern about load dump is loose connections, either to the battery or elsewhere. There's no reason you couldn't build a battery charger that could survive the transients, but you'd have to add circuitry, and cost, etc. -- it's much easier for a manufacturer to just impose a blanket veto on operating on a running car.

What it probably boils down to is this:

Having a feature on the outside of the box "you can charge when your car is running!" doesn't outweigh the extra $10 or $20 bucks they'd have to charge for the thing. Just telling you "no" in the instructions means that by the time you find out you've already bought it and opened it. Leaving off the cigarette lighter plug means that if you _are_ using it in a running car then you've modified it, you bad boy, you can't return it and it'll be difficult to sue their pants off.

Has anyone actually seen any charger manuals that state not to use it when the vehicle is running? As I recall I only found one.

Red S.

I saw that and was kinda ignoring it for the purposes of spouting off about load dump.

While doing so I was wondering if the longevity of Doug's charger is due to luck on Doug's part or planning on his charger manufacturer's part?

And can I put a cigarette plug on my Triton and charge things in my car? The only reason I haven't is 'cause opening the hood reminds me to keep the batteries away from all that flammable upholstery while charging.