Adding a 12volt battery

[Hemicj]

I had read a post on this forum about adding a 12 volt battery to a 36volt cart for lights and a radio but for the life of me I cant find the link, it had pictures. Does anyone have the link??

[rib33024]

I think this is what your talking about, But i would see what people have to say before you hook this up, because there might be a problem with keeping the 36v pack charged right


http://www.buggiesgonewild.com/elect...battery-3.html






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[Hemicj]

Thats the post. Thanks

I cant see any reason why that would not work, if a switch is used.

[rib33024]

with it hooked up this way, i don't think it will keep the battery pack fully charged, i saw another post where Andy said something about it not charging right, so i would wait and see what others have to say about this, Before you try this

Originally Posted by Hemicj

Thats the post. Thanks

I cant see any reason why that would not work, if a switch is used.

BGW...or... anyone on this forum, ... BGW itself, is/are NOT responsible for your actions in the result of using, or, misusing this information that may cause possible damage to yourself, your property, or someone else!

[kernal]

It seems to me when Andy posted about this set up he was having a problem with his kids running the 12v down using the sound system and then when he jumped on the cart to drive it home form the beach or whatever he didn't have any power left for lights and/or music. By wiring it this way he could close the switch and have 12v power from 2 of the main pack batteries so he had lights and music for himself on the trip home. This way the main 12v power source is from the 12v with the backup from the main pack thus keeping the main pack balanced. The charger doesn't see the 12v so charging the main pack is normal and the 12v still has to be charged separately. I could be wrong about this. Maybe Andy will see this and set us straight.

[rib33024]

Originally Posted by kernal

It seems to me when Andy posted about this set up he was having a problem with his kids running the 12v down using the sound system and then when he jumped on the cart to drive it home form the beach or whatever he didn't have any power left for lights and/or music. By wiring it this way he could close the switch and have 12v power from 2 of the main pack batteries so he had lights and music for himself on the trip home. This way the main 12v power source is from the 12v with the backup from the main pack thus keeping the main pack balanced. The charger doesn't see the 12v so charging the main pack is normal and the 12v still has to be charged separately. I could be wrong about this. Maybe Andy will see this and set us straight.

Here's another post about this, i would like to hear from Andy on this





Rib look at the drawing Andy did. It is a 12 volt battery tied in just like you would if you were running lights off the main pack. In this case all that does is charge all 6 of the pack batteries and the AUX 12 volt battery. If you dont add the switch he has shown then you could theoretically pull amps off the 12volt battery in to the main pack.
I wouldnt advise that but If you can charge all 7 batteries off the same charger than why not? Your still powering all you items off a battery that isnt the main drive pack of 6 or 8 batteries. This could also be used in a 48 volt setup as long as you used 6 volt batts for the main pack.








BGW...or... anyone on this forum, ... BGW itself, is/are NOT responsible for your actions in the result of using, or, misusing this information that may cause possible damage to yourself, your property, or someone else!

[kab69440]

Originally Posted by rib33024

Here's another post about this, i would like to hear from Andy on this



[COLOR="Red"]but If you can charge all 7 batteries off the same charger than why not?[COLOR]

Because those two batteries tapped for the add-on 12v now have the 12v's additional storage capacity. The charger doesn't know the 12v is there, it only knows the pack as a whole is drawing more amps, so it feeds more amps. The problem with this is that the two tapped batteries are now requiring more power. The fact that none of the other batteries in the pack has a matching additional capacity and are stuck in the same circuit means that they are being subjected to more current than they can handle and the electrolyte will probably boil. If enough amps are being drawn, you may ruin (or, most certainly shorten the useful lifespan of) the four batteries not used for the 12v tap.

I hope this post can be deciphered, I don't really have a proper "textbook style" way to convey the phenomenon. Maybe yurtle or johnnieb can give a better explanation.

[yurtle]

If I were to do this, I would wire/switch it to completely bypass the dead battery. A dead battery is a drain, and if all you need to do is light your headlights, why try and charge a dead battery???

Remember the current the dead battery draws when charging from dead? That drain is added to your headlight drain.

[JohnnieB]

Kab nailed it pretty good.

Because the battery pack is now being charged in series/parallel, total charging current flows through each battery except the two that are paralleled by the 12V battery.

Net result, four 6V batteries are getting higher than normal current flow through them, while two have normal or less than normal and I have no idea what is happening to the 12V battery. (It is going to have a much smaller AH rating than the 6V batteries, so it might very well get cooked.)

Like Yurtle, If I wanted an emergency back-up for a 12V auxiliary battery, I'd use a DPDT switch and completely disconnect the dead 12V battery while tapping two 6V batteries to power lights or whatever until I could get it home and recharge the 12V battery, using a separate 12V charger.

[Hemicj]

I am trying to reason this out. If a lawn mower 12v battery was wired into the last two 6volts why would that overcharge and boil those last two 6v batteries. The charger charges until the intire pack is up. A battery will only hold so much of a charge and the charge will move on to the next in line. So if that was the case wouldnt the first and second battries in your pack always get overcharged. Just asking..