Zamp vs Battery Tender

sabel

We have the Zamp 80 watt solar panel. Takes a long time to bring things up to a full charge even with sunny days. Has anyone tried plugging a Battery Tender into the Zamp plug-in? Rather than drag out the big 30 amp power cord I'd like to use a Battery Tender pluged directly to the battery via the Zamp plug-in. Any problems encountered in doing this?
Thanks

Michigan_Mike

The battery tender is basically a trickle charger and when you park your trailer at home or wherever you store it this is a good way to keep your battery healthy, as it will maintain/float the battery charge when the trailer is sitting idle.  The battery tender does the same thing as your electric converter on your trailer, but obviously it takes a little longer for the tender to charge things up as it's a smaller unit and will take a few days to get the battery up to a full charge if it's been severely depleted.  

If you do use the battery tender remember to check the Zamp solar port connections and flip them as the polarity is reversed on the Zamp solar connector on your battery box and your battery tender will not charge the battery up.  You'd be better off to use the clamps that come with the battery tender and eliminate having to mess with the Zamp solar connections.

I use a permanently mounted 50 watt Renogy solar panel (with solar charge controller) on the side of my garage to keep the trailer battery charged up.  I also installed a battery switch so that I could eliminate (unhook the battery from the trailer) any parasitic drain (e.g. LED circuits, TV, etc. draining battery when sitting idle) when my trailer is sitting in my garage.  This works great and my battery is fully charged, maintained and ready to go when I roll out the trailer for my trips.  

jkjenn

I use a Goal Zero Maintainer 10, which is a solar panel/battery tender. I have been quite pleased with it.http://www.amazon.com/GOAL-ZERO-32202-Maintainer-Batteries/dp/B00JGR3QPO

sabel

Good to know the Zamp terminals are reversed.
thanks

Lisa33

Do we know why the Zamp polarity is reversed?  Since the Renogy panels and the Battery Tender are both the opposite of the Zamp quick connect, Zamp seems to be the odd man out.  If you aren't using Zamp panels, it is a simple thing to switch the wires to opposite terminals.  

Michigan_Mike

Lisa33 said:

Do we know why the Zamp polarity is reversed?  Since the Renogy panels and the Battery Tender are both the opposite of the Zamp quick connect, Zamp seems to be the odd man out.  If you aren't using Zamp panels, it is a simple thing to switch the wires to opposite terminals.  

Good question Lisa and one we should have answered long ago.  I took the time today to call Zamp Solar and speak to their technician, Jesse who spent some time and gave me a valid reason for the way Zamp designs their solar panels.  The reason Zamp wires up the panels the way they do is to protect the panel itself.  If the "male" plug end coming from the panel were bare, this could cause a short circuit condition in their solar panels if the "exposed" positive end made contact with a grounded surface.  So in effect the "female" (negative) end of their solar panel plugs are exposed and bare and this eliminates the potential for a short-circuit situation should someone touch the bare end to a grounded surface.  

To cure the "reverse polarity" situation you certainly can flip the wires on the Zamp Solar connector, but the real problem originates with the Battery Tender plug ends that are reversed from Zamp's design.   First of all Jesse explained to me that the Zamp Solar port was "specifically designed" for Zamp's solar panels and was never intended to be used in conjunction with a Battery Tender.  So therein lies the real problem (the Battery Tender units) and rather than have the "bare end" connector issue Zamp chose to shield the positive side of their panel.  

A more permanent and quicker resolution to the above issue might be to cut the supply side line leads of the battery tender (the charge wires coming from the Battery Tender unit to the trailer battery), flip them around and splice them back together (if you are knowledgeable in splicing, electricity, etc.) so it matches Zamp's design.  By splicing out the Battery Tender wires it becomes a permanent fix as long as you remember this should you use the "clamp type" (alligator clip style if you will) connectors supplied with the Battery Tender.  If you don't, you could end up placing the wrong leads on the battery and creating a short circuit that way!  

Zamp does sell products for the specific issue above and Jesse will email me some information later today that I will post up here on the forum.   Their explanation makes perfect sense and the light switch suddenly went on once I heard their reasoning.  

Thanks for asking!  

jkjenn

Here is a stupid question: if the Zamp port has reversed polarity, would a regular SAE cable still work and if so, how would it impact performance?

Michigan_Mike

There's never a stupid question here Jenn!   I don't see any issues with that Jenn if the polarity is correct and cable size is similar.  Your performance should be the same if you're not running a mile of cable from the panel to the battery.  

Michigan_Mike

This is the plug end that can be purchased from Little Guy if anyone is interested.   I'm not certain of a price, but could find out if anyone is interested.  

dundons

Hi Mike and Jen,
I just ordered a 12 ft extension cable from Deltran. You guys think I could just do the splicing and reversing on the extension cable and the charge the batteries by way of the Zamp port?

seajeeper

As Lisa33 said, I switched the cables leading to the port from the battery, thus reversing the polarity at the Zamp port.  If you do this you can plug your Battery Tender directly into the port.  I also made my solar controller (not a Zamp) with the same connector as the Battery Tender so either one connects to the port with the correct polarity.  I also removed the Zamp labels from the tub and frame (to avoid confusion) and marked the polarity at the port.

Michigan_Mike

dundons said:

Hi Mike and Jen,
I just ordered a 12 ft extension cable from Deltran. You guys think I could just do the splicing and reversing on the extension cable and the charge the batteries by way of the Zamp port?

Yes, and as SeaJeeper noted as long as the polarity is correct when you splice out the cable there will be no issues.  Just trace the positive/negative wiring back on the Zamp solar port on your trailer tub and splice the cable out accordingly.  

ScottG

I'll add (and forgive me if I'm stating the obvious) that you should label your modified extension cable carefully and reserve it only for use when connecting your charger to the T@B's Zamp port. If you use it with other Battery Tender accessories, you run the risk of really reversing the polarity. Zap zap!

Z_G

I don't have quick access to verify the battery charging wire setup .... but wouldn't it be simpler to trace wire from inside of tub and swap the polarity as it connects to the battery... unless the charge wire coming from the wfco or vehicle is connected to the same battery leads... if you are mixing the polarity of devices as it connects to the zamp port then it makes sense to adjust to a comon polarity for the zamp before it attaches to the tub... i am not fond of cable splices exposed to camping weather conditions

ScottG

Z_G said:

I don't have quick access to verify the battery charging wire setup .... but wouldn't it be simpler to trace wire from inside of tub and swap the polarity as it connects to the battery... unless the charge wire coming from the wfco or vehicle is connected to the same battery leads... if you are mixing the polarity of devices as it connects to the zamp port then it makes sense to adjust to a comon polarity for the zamp before it attaches to the tub... i am not fond of cable splices exposed to camping weather conditions

This would certainly work from an electrical standpoint, though it might involve having to change out the ring terminals at the battery. If I recall correctly, mine are different sizes to match their respective battery posts.

However, if you try to use Zamp equipment you'll be back to the same problem. For reasons Michigan_Mike explained in his post above, reversing the leads from a Zamp panal would not be advisable.

On mine (2015) the Zamp port is connected via dedicated leads directly from the battery. The WFCO and vehicle are connected (via the junction box under the trailer) with a separate set of leads.

Z_G

I just drill out the lead so it fits both terminals... if u are not using mixed polarity swapping from both zamp and not zamp based equipment then it would be safer and simpler to swap leads... just consider the next owner of that tab wouldn't expect that configuration and on selling would be advised to revert to factory polarity.  As I said if you are not dealing with different polarities for the devices attached to that port then you are best off to not damage to cable supplying power and allowing for moisture to ground out through a wet splice

Ratkity

Z_G said:

I just drill out the lead so it fits both terminals... if u are not using mixed polarity swapping from both zamp and not zamp based equipment then it would be safer and simpler to swap leads... just consider the next owner of that tab wouldn't expect that configuration and on selling would be advised to revert to factory polarity.  As I said if you are not dealing with different polarities for the devices attached to that port then you are best off to not damage to cable supplying power and allowing for moisture to ground out through a wet splice

A dremel tool to ream out the terminals will prevent slippage of a regular drill bit into your middle left finger while wrapping the lead around the said finger simultaneously... It really hurts! jus' saying......

9Jethro

Just a bit of information. I called Zamp technical department and asked about the reverse polarity. Their answer was ' It's an Internet myth'.  I didn't reverse any wires on my solar system and it works fine. 

pthomas745

I think this thread needs to get back on course. (Or, Maybe I'm missing the point.)  I don't know what Zamp meant by their "internet myth" comment (although I agree it has launched a brazillion internet threads.) 

Read over this thread from a couple of years ago and read about how the connector works.  I don't know how the Battery Tenders might be wired, but for those of you connecting a non-Zamp solar panel and using an SAE cable from your Solar Controller to the Zamp connector, you need to have your wiring correct. 

http://littleguy.vanillaforums.com/discussion/4885/zamp-solar-panel-connections-explained

Sharon_is_SAM

Yep, if you want to use a battery charger via the Zamp outlet, you need an adapter, too.  

dundons

SAM said:

Yep, if you want to use a battery charger via the Zamp outlet, you need an adapter, too.  

@SAM, Got a model or name for such an adapter? Sounds better than the splice n' dice method for weather resistance.

Sharon_is_SAM

Yes, as soon as I can look it up.

Sharon_is_SAM

Amazon
Optimate cable 0-27 adapter.

dundons

@Michigan_Mike, Will this thing do the trick of reversing polarity? 
http://a.co/dvy8njx

Sharon_is_SAM

If that is the Optimate Cable 0-27 - yes that will work.  It has a regular SAE on one end to plug in a battery charger cable and the other end has the SAE with the male positive that fits into the Tab Zamp outlet with the female positive.  

db_cooper

http://www.solardealz.com/Sidewall-Port-Adapter-for-Plug-N-Play-Maintainers-p/zs-bdc-adpt.htm

I use this adapter to hook our battery tender to the zamp port 

Sharon_is_SAM

Db cooper, that adapter is limited to 80 watts.  I wonder if there are limitations for a battery charger?

Michigan_Mike

dundons said:

@Michigan_Mike, Will this thing do the trick of reversing polarity? 
http://a.co/dvy8njx

Good find!  

db_cooper

SAM said:

Db cooper, that adapter is limited to 80 watts.  I wonder if there are limitations for a battery charger?

It appears to be the same gauge wire as the battery tender,. So I'm not concerned. Works great so far.  I think that spec is related to using other solar panels with extensions.

DebM11

Updated link for the adapter, battery tender to external Zamp socket. Free shipping as of this post.
http://tincansolar.com/product/zs-bdc-adpt/ 

MyTabEllie

Crazy question if you can plug a battery tender into the zamp can you plug a battery such as a jackary into it for back up when it is not sunny?  Just thought of this while reading these.