Battery Tender Question ???

[Kevin Palmer]

I have put my Sea Doo's up for the winter.



I pulled the batteries and purchased a battery tender (not a charger).

This tender has a float mode when thebattery is fully charged, when the battery drops to 11.1 volts it trickle charges at 2 amps to 12.4 volts or 12 volts if it cant reach 12.4 after 2 hours at 12 volts.



Here is my question.



Can I use this SINGLE tender to maintain two batteries?

I would assume so as it outputs at two amps and then floats down to 11.1 volts as compared to putting a load on the battery to get it down to the 11.1 volts.

Further, I would assume this would need to be in PARALLEL not series. Here is a picture of what I plan on doing.

Any thoughts????



[Broken External Image]:

 

[Robert Caffyn]

Ya know, I'm not sure. Since the tenter only puts out 2amps or so to recharge, it "floats" on microamps. If one battery is really low or on the verge of needing replacement, I don't believe it would work. I paid $24 for a Magnacharger brand(Advanced Auto), and if I needed more than one, I'd buy another, just to be safe or to have it work the way it was intended. Bob

 

[Kevin Palmer]

How about this....



This picture shows the same premise, but it each battery would stand more alone than in the first picture.



Yes, both batteries would get the 2 amp charge once either needed a boost, but this would eliminate the float issue from one battery to another????



[Broken External Image]:

 

[Wes Davis]

As a boater your first picture is correct. However both batteries should be exact duplicates type/brand/model/age etc.. Also keep in mind it will take a significant longer time to charge and then float both batteries. Its not just double time, its exponential time.

 

[MikeSondra Grossen]

I have a pdf file that I will put in my library that may help!

 

[Kevin Palmer]

svt1848



Page 6 is EXACTLY what I am after.



This way the voltage MUST pass through both batteries and the cells as opposed bypassing one if one of the batteries does have an issue.



Thanks much...

 

[MikeSondra Grossen]

Glad I could be of assistance! :haveabeer:

 

[Bob McDonald]

LOL Kevin,



Those two rough drawings may look different, but circuit wise, they are identical.

 

[Kevin Palmer]

Uncle_Bob...



I don't think so.



I say this as, in picture one, if battery 2 is weak or poor, it would pull from battery 1. Once the level drops enough OVER-ALL, then the tender would kick in.



In picture two, the batteries are not tied to each other directly, only through the tender itself.



The end result may be the same as if one battery is poor or weak that the other battery would get the charge aspect, but the poor battery would not affect the other battery directly.



I think anyways ????

 

[Bob McDonald]

Kevin,



I understand what you are saying, but I think, given the length of wire between the tender and the batteries is probability relatively short, there would be no measurable difference in the sensing/charging between either of the two diagrams. In both drawings, the two (-) posts are commonly connected to the (-) terminal of the tender, and the same is true for the (+) posts.



If we put enough wire in the circuit to detect any difference, it may only be in the micro-amp range. And the difference may only be because of the difference in the resistance of the two different wire lengths.



At least, that is my thoughts and I do admit to NOT being an electrical engineer.

 

[Kevin Palmer]

UB...



I follow you and agree they are similarly tied together...

But I like the second picture better anyways... LOL



Just kidding.

I will hook them up as page 6 of svt1848 library shows. In looking at the picture, it is easy to see it is the right way...