Charging GPS units

Keeping batteries under constant charge shortens their lifetime, unless you have, like an auto battery charger, one that will stop the charge automatically when the batteries are fully charged. That is not a USB connection.

You are better charging the unit fully & then storing it until next use.

Fred

Plus - whenever I use my 765T, I plug it into my auto and it starts to get a charge then - or - if I am planning a trip, I plug it into my PC by USB and it gets charged.

Either way works for me.

Thanks to both jgermann and FZbar. One of my friends keeps his iphone hooked up to his computer whenever he is home (to keep it sync'd and charged). I'll let him know that it is not a good idea. As always, the POI-Factory comes through with informed advice.

That is true. But it is not easy. You do not want to go out of battery suddenly in a long trip.

Lithium battery charge termination is a simple peak voltage detection (usually 4.2vDC). Almost any device with an internal lithium battery that charges via a USB connection has the charge control circuit in the device itself, so the external charger does not keep charging the battery indefinitely. Some chargers designed to charge lithium-polymer batteries (the type in any of these devices) do have charge control circuits in them but they typically have a red/green LED on them to indicate charge status, e.g.: http://i.ebayimg.com/t/AC-Travel-Power-Charger-MAGELLAN-GPS-Roadmate-1400-1412-/24/!BwyJtO!BWk~$(KGrHqV,!hsEv1+0GM+NBMKks9HUMw~~_35.JPG

Learn more about how to maximize the calendar and charge-cycle lifespan of lithium batteries here: http://batteryuniversity.com/learn/article/how_to_prolong_li...

While charge level is important, temperature is even more important. You can significantly prolong the lifespan (and reduce the self-discharge rate) of a lithium battery by keeping it in the refrigerator. The worst possible condition to store a lithium battery is fully charged in a warm (or hot) place (e.g.: left in a car, even in the summer). The best possible condition to store a lithium battery is half-charged in a refrigerator (but not the freezer).

And yes, strange as it may seem, you could keep your entire PND in a refrigerator too, as long as you protect it from condensation. You should put some of those little moisture absorbing packets in the bag with it.

I have a Garmin AC charger that I acquired with my 200W. I use that to charge up my battery, when I need to do so. Other than that, I let the car do the charging.

Lithium batteries have an absolute lifetime, normally quoted as 3-5 years though I have working batteries that are older, as well as a charge cycle lifetime. If you're using yours infrequently it will probably die of old age before it dies of overcharging.

I often see the life expectancy disclaimer of 500 discharge-charge cycles for Lithium batteries. That would equate to something more like 2-3 years, which more closely aligns with my own experience with a variety of electronics with Lithium batteries.

Don (And The Group),

I have a number of rechargeable devices around my home. They include flashlights, radios, smartphones, tablets, GPS units and other devices. I have noticed with my flashlights that have lithium ion battery packs that the shelf life is quite good. So good, in fact, that if I don't use the flashlight at all or very little during the month that it is topped off right away when it goes on the charger, So, I just make it a habit to "top off" the battery pack about once a month.

Age is a Battery's worst enemy.

One could argue that heat was a lithium batteries worst enemy. Yes, they deteriorate with age, but without a catastrophic failure, they age with grace. Just look to the Mars Exploration Rovers - Oppies battery is sting going strong after 10 years on Mars.

Yes, and there's not really any argument about it.

See table 3, here: http://batteryuniversity.com/learn/article/how_to_prolong_li...

And here I thought routine round trip discharge -> recharge cycles were good for lithium batteries.

...and my GO 930's old battery is almost completely dead. It will only hold a charge for about five minutes. That is not a problem for me since I only use it in my car and then it is plugged in.

My 660 is the same way but works good in car.

I just got rid of a 7 year old cell phone that had the original battery in it, but every night I would top off the charge which I believe may help the longevity of that type of battery.

That guideline applies much more to NICADs which are subject to memory issues. The chemistry in lithium ion batteries is different, and the needs are different, so there's no benefit to depleting them to discharge and then fully recharging them several times in a row.

sorry inadvertent double post

I learned not to keep my units plugged into the power adaptor all the time. It seems to lengthen the battery life. I constantly had my 760 plugged in wherever I went, but still was able to keep the battery properly working until last year. I now try to only use the power adaptor when the unit gets really low. I don't know if there is any truth to this or not, but I think I remember someone commenting that it wasn't good to let you GPS start up on the connector every time you start the car as it could overload the power. Any truth to this?

I just let my gps start up when my car starts, and no prombles so far for over a year now

Age is the worst enemy of everything!!!!

Sometimes I wish I chould get fancy chargers like the MAHA or LaCrosse for batteries other than the AA and AAA variants. My experience with NiMH batteries is much better after using good chargers; I have to think that using a similar charger for lithium batteries would have a benefit as well.

I read somewhere else (related to smart phones): While the lthium battery couldn't care less about it, the charger itself benefit from full recharge of an almost empty battery. It "re-learns" what full really it and will allow deeper charges in the future instead of cutting off charging prematurely.

Ah, okay. Interesting. Could be. (Might depend on the charger as well--maybe some chargers benefit from this and others do not.)

This occasional deep cycle applies to devices with smart charger/battery meters. It allows the circuitry to determine the current capacity of the battery, and more accurately display charge state.