Rapid BAttery Charger - Kayak Fishing Adventures on Big Water’s Edge

jbm · 09-16-2010, 01:52 PM

How many Amp-Hours is your battery? And how fast do you need it charged? 12V or 6V?

bigbarrels · 09-16-2010, 02:06 PM

Quote:

Originally Posted by jbm

How many Amp-Hours is your battery? And how fast do you need it charged? 12V or 6V?

12 volts and 10.5 amp/hr........looking to charge as fast as possible if plugged into a generator

jbm · 09-16-2010, 02:21 PM

Any 10 amp car charger should work fine. It should charge in under an hour unless it's fully depleted. Just watch the temperature of the battery while it's charging. It shouldn't get more than warm to the touch. If it starts to get real warm, disconnect it.

GregAndrew · 09-16-2010, 02:25 PM

If I remember correctly, when the voltage is held constant, then amps = watts/volts. So a 5 watt solar charger is only going to give you 5/12 amps per hour of charge. So 12 hours charging time will produce 5 amps. Might need something in the 12 -15 watt range to keep that size battery charged (with the spare battery charging all day).

jbm · 09-16-2010, 02:39 PM

Quote:

Originally Posted by GregAndrew

If I remember correctly, when the voltage is held constant, then amps = watts/volts. So a 5 watt solar charger is only going to give you 5/12 amps per hour of charge. So 12 hours charging time will produce 5 amps. Might need something in the 12 -15 watt range to keep that size battery charged (with the spare battery charging all day).

You remember correctly. And that 5W rating is generous. You'll probably only get about 0.3 amps out of it on a sunny day.

You can do the jumper cable thing, but have the vehicle running. And again, monitor that battery, watch for heat or gassing.

-scallywag- · 09-16-2010, 02:15 PM

jumper cables from the truck battery, while the truck is running will get it up to 13-14V.

even without the truck running, it will dump enough juice in the battery after a few minutes to use for a day.

This should save some space, time and weight....wish I could tag along, ojos and scorps (and a million others) are going off right now

.

bigbarrels · 09-16-2010, 02:22 PM

Quote:

Originally Posted by -scallywag-

jumper cables from the truck battery, while the truck is running will get it up to 13-14V.

even without the truck running, it will dump enough juice in the battery after a few minutes to use for a day.

This should save some space, time and weight....wish I could tag along, ojos and scorps (and a million others) are going off right now

.

Now we are talking

nice and simple......how long would you want to keep it connected to the truck battery if the truck is running without blowing something up? Guess I could go run a test.....There may be a third space open (have a friend getting back to me) trip is from oct 4th -14th

-scallywag- · 09-16-2010, 02:49 PM

you can leave it connected as long as you like....with the truck off, both batteries will equilize (power transfer will stop when the dead battery reaches the same voltage as the truck battery) with the truck running, the trucks voltage regulator will keep both batteries from overcharging....easy breezy.

Also if you bring a few extra 12V batteries (never a bad idea in mex) and a inverter (12V dc to 120V ac), you can connect the spare batteries in parallel (pos. to pos, neg. to neg.) and charge the whole bank with jumpers (this may take an hr+ to fully chare) then at night you dont have to run the generator (or even bring it depending on who power hungry your camp will be). We have even pre-wired, secured the batts and enclosed it all in a simple wooden enclosure so eveything stays put and doesnt take up much room in the back of the truck cause you can stack on it....and if you use some cheap, used batteries, it also makes a very nice gift to some hombre suerte when you're ready to leave.

bigbarrels · 09-16-2010, 03:14 PM

thanks for the advice............great info and much appreciated.......going with the jumper cables

Useful Idiot · 09-16-2010, 03:18 PM

Be aware, you may lessen the overall life of your battery, the faster you charge it. My understanding is that you'll get more charges if you charge slow (1 or 2 amp charger) over the life of the battery. Charging fast like that reduces the number of re-charges the battery will take. At least that's what I've been told.

-scallywag- · 09-16-2010, 04:40 PM

just because you have a 10A charger dosn't mean your charging at 10A. the amount of current going into the battery is inversely related to it's resting voltage (the higher the resting voltage, the lower the amperage the battery will draw)

So a battery on a 10A charger with a resting voltage of 11.5V may only draw 3A,
-while the same battery on the same charger with a resting voltage of 12.5V may only draw 0.5A,
-while that same battery at 9V would probably pull the full 10A, which on a small battery like the ones we use would create alot of heat and potentally cause a problem or lower it's usefull life.

Most 12V systems have voltage shutoffs that keep you from completely discharging a battery, therefor making them safe to recharge. As long as there is 10-11V on the battery when you hook it up you'll be fine.

09-16-2010, 03:18 PM	#10
Useful Idiot Senior Member Join Date: Apr 2005 Posts: 286	Be aware, you may lessen the overall life of your battery, the faster you charge it. My understanding is that you'll get more charges if you charge slow (1 or 2 amp charger) over the life of the battery. Charging fast like that reduces the number of re-charges the battery will take. At least that's what I've been told. __________________

09-16-2010, 01:52 PM	#1
jbm Member Join Date: Jun 2010 Location: Escondido<->Carlsbad Posts: 81	How many Amp-Hours is your battery? And how fast do you need it charged? 12V or 6V?

09-16-2010, 02:21 PM	#3
jbm Member Join Date: Jun 2010 Location: Escondido<->Carlsbad Posts: 81	Any 10 amp car charger should work fine. It should charge in under an hour unless it's fully depleted. Just watch the temperature of the battery while it's charging. It shouldn't get more than warm to the touch. If it starts to get real warm, disconnect it.

09-16-2010, 02:25 PM	#4
GregAndrew Senior Member Join Date: Mar 2009 Posts: 2,384	If I remember correctly, when the voltage is held constant, then amps = watts/volts. So a 5 watt solar charger is only going to give you 5/12 amps per hour of charge. So 12 hours charging time will produce 5 amps. Might need something in the 12 -15 watt range to keep that size battery charged (with the spare battery charging all day).

09-16-2010, 02:15 PM	#6
-scallywag- Banned Join Date: Mar 2009 Location: on the road... Posts: 598	jumper cables from the truck battery, while the truck is running will get it up to 13-14V. even without the truck running, it will dump enough juice in the battery after a few minutes to use for a day. This should save some space, time and weight....wish I could tag along, ojos and scorps (and a million others) are going off right now .

09-16-2010, 02:49 PM	#8
-scallywag- Banned Join Date: Mar 2009 Location: on the road... Posts: 598	you can leave it connected as long as you like....with the truck off, both batteries will equilize (power transfer will stop when the dead battery reaches the same voltage as the truck battery) with the truck running, the trucks voltage regulator will keep both batteries from overcharging....easy breezy. Also if you bring a few extra 12V batteries (never a bad idea in mex) and a inverter (12V dc to 120V ac), you can connect the spare batteries in parallel (pos. to pos, neg. to neg.) and charge the whole bank with jumpers (this may take an hr+ to fully chare) then at night you dont have to run the generator (or even bring it depending on who power hungry your camp will be). We have even pre-wired, secured the batts and enclosed it all in a simple wooden enclosure so eveything stays put and doesnt take up much room in the back of the truck cause you can stack on it....and if you use some cheap, used batteries, it also makes a very nice gift to some hombre suerte when you're ready to leave.

09-16-2010, 03:14 PM	#9
bigbarrels Senior Member Join Date: Aug 2008 Location: Vista Posts: 1,111	thanks for the advice............great info and much appreciated.......going with the jumper cables

09-16-2010, 04:40 PM	#11
-scallywag- Banned Join Date: Mar 2009 Location: on the road... Posts: 598	just because you have a 10A charger dosn't mean your charging at 10A. the amount of current going into the battery is inversely related to it's resting voltage (the higher the resting voltage, the lower the amperage the battery will draw) So a battery on a 10A charger with a resting voltage of 11.5V may only draw 3A, -while the same battery on the same charger with a resting voltage of 12.5V may only draw 0.5A, -while that same battery at 9V would probably pull the full 10A, which on a small battery like the ones we use would create alot of heat and potentally cause a problem or lower it's usefull life. Most 12V systems have voltage shutoffs that keep you from completely discharging a battery, therefor making them safe to recharge. As long as there is 10-11V on the battery when you hook it up you'll be fine.