charger for battery

[russelln114]

Hey guys. Through alot of advice from you guys i got the lowrance mark5x pro fishfinder from cabalas. I also purchased a battery and charger for it. The battery is a 12v 8Ah sealed battery. The charger they sent with it is a basic plug in no lights. After reading the charger directions i really don't like the charger. After using the battery you have to put it on charge for 15to 18 hrs. It also says not to over charge the battery but you don't have any way of telling the state of charge. I do have a 12v charger that i can control the amps 2 being the lowest. This charger also switches to float when the battery is fully charged. Can i use this charger?

 

[Lyle29464]

Re: charger for battery

The papers that came with your battery should tell you what is required. My guess is 2 amps is too much for a small sealed battery.

 

[russelln114]

Re: charger for battery

No papers came with the battery. I wonder if a battery tender would work

 

[russelln114]

Re: charger for battery

Ok i found out that the charger that came with the battery has an output of 500mA or .5amps. The battery tender i'm looking at is the junior which has an output of .75 amps or 750mA. Would this charger be ok?

 

[vfrkent]

Re: charger for battery

750mA or .75 amps would be fine with that battery, that current out put would only be seen initially with a fully discharged battery as it charges up the current tappers off, rule of thumb is charge rate of 10% of the amp rating of the battery.

Regards,
Kent

 

[Silvertip]

Re: charger for battery

Why do you suppose they sent a 500 ma charger with the battery? Why do you feel the 750 ma charger would be any better? And what makes you think that charging the battery at a higher rate is better? You have a gel battery and the battery manufacturer knows which charge rate is best. Why mess with success. Use the locator, when done, plug in the charger and overnight charging with the supplied charging will be fine. A 500 ma charger is not going to "toast" any battery. That battery would likely run the locator for a full day with no problem so an overnight or next day charge will be fine.

 

[russelln114]

Re: charger for battery

Why do you suppose they sent a 500 ma charger with the battery? Why do you feel the 750 ma charger would be any better? And what makes you think that charging the battery at a higher rate is better? You have a gel battery and the battery manufacturer knows which charge rate is best. Why mess with success. Use the locator, when done, plug in the charger and overnight charging with the supplied charging will be fine. A 500 ma charger is not going to "toast" any battery. That battery would likely run the locator for a full day with no problem so an overnight or next day charge will be fine.

Silvertip. I wanted to use the other charger so i can take the guesswork out not that i think charging the battery at a higher rate is better. The directions for charging the battery are contradictive.They say it is a bulk charger and to charge the battery for 15to 18 hours but don't overcharge it.If you don't know the batterys state how the heck can you safely charge it?Lets say i use it for three hours With that type of charger I won't know how long to charge the battery because i don't know the batterys state of charge at that point and who wants to run their battery til it's dead before you charge it. Therefore can i use the charger?

 

[Silvertip]

Re: charger for battery

That is a gel battery! Does the charger you intend to use have a charge profile for that battery? Every battery has a specific "charge rate" and although 750 ma may still be within the maximum for that battery, does it have the correct charge profile. Charging a battery is not rocket science. You know what the current draw is for the locator. If you don't, look in the specs section of the user manual. If you use the locator for three hours, and the unit draws one amp, you sucked 3 amps from the battery. The charger puts back 1/2 amp each hour. It then takes six hours to recharge. That's about an overnight charge and a couple extra hours won't hurt anything at that charge rate. A simple wall timer can be used to turn the thing on and off at any times you wish.

 

[vfrkent]

Re: charger for battery

Let me see if I can bring some clarity to the issue, I am a EMC engineer and am involved with power supply designs on a daily basis, mfg's don't necessarily provide the best charger for the product, they look at the price point they want to hit and try to decide where they can cut cost with the least hit on the function of the product.

That said, the bulk charger is the least expensive way for a mfg to go, the charger will take the longest time to charge the battery with out over heating it when its pumping out its peak current, with a bulk charger it is a non linear current output, what that means is when the battery is discharged it will pump out up to its max current as the battery takes on its charge the current drops off because the internal resistance goes up.

With a 8Ah battery and a 500mA charger it would take much longer then the 16 hour you would think to charge the battery because of the tapering off of the current.

With most of the new smart chargers they go about charging a bit different, on a discharged battery they will go to full current and charge for a period of time, then they stop sit and wait a minute for the charge to stabilize and measure the voltage at the batty evaluate were the battery is in the charge process and then continue on until the battery is charged, the difference between this process and the bulk charger is the smart charger can go over typical peak voltage for the battery when its in the later charge process to actually charge faster then a bulk charger would, higher voltage with the same resistance equals higher amp output, as the battery gets closer to being peaked out the current output is pulled back by the processor in the charger until the batty is fully charged, at that point the charger just sits and monitors the voltage until it sees its dropped below as specified level and then it goes into the last stage charging process again until its peaked out and just continues to repeat.

this process is actually better for the battery and less damaging in the process of charging and potential over heat situation.

The battery tender is a very well designed charger and actually would be a better choice then the bulk charger supplied , sorry for the winded story.

Regards,
Kent

 

[russelln114]

Re: charger for battery

That is a gel battery! Does the charger you intend to use have a charge profile for that battery? Every battery has a specific "charge rate" and although 750 ma may still be within the maximum for that battery, does it have the correct charge profile. Charging a battery is not rocket science. You know what the current draw is for the locator. If you don't, look in the specs section of the user manual. If you use the locator for three hours, and the unit draws one amp, you sucked 3 amps from the battery. The charger puts back 1/2 amp each hour. It then takes six hours to recharge. That's about an overnight charge and a couple extra hours won't hurt anything at that charge rate. A simple wall timer can be used to turn the thing on and off at any times you wish.

The paper with the battery says that it is a sealed lead-acid battery. I don't see anywhere where it says its a gel. I just wanted a charger that i could set it and forget it. I will have this battery in storage for 4 months. With my deep cycles i'm very faithful in keeping up with the charge while in storage. With this battery i won't know how long to charge it when in storage. Is it different in that it won't loose its charge while in storage?

 

[vfrkent]

Re: charger for battery

Rest assured the battery tender will keep it charged with out over charging it while it sits, I have used them on my motorcycles for 25 years, on my Honda VFR my battery lasted 13 years before I had to replace it, unheard of on bike battery's.

Regards,
Kent

 

[russelln114]

Re: charger for battery

Rest assured the battery tender will keep it charged with out over charging it while it sits, I have used them on my motorcycles for 25 years, on my Honda VFR my battery lasted 13 years before I had to replace it, unheard of on bike battery's.

Regards,
Kent

Then in conclusion you would say that the battery tender junior @ .75 amp would be fine for me. Thats the lowest controled output i can find

 

[vfrkent]

Re: charger for battery

Yes!

Regards,
Kent