400 battery not charging while towing with frig on DC

Tundra57

(Title edited for search purposes. - Sharon)

I just did 1800 miles down to Florida. I usually keep food in the fridge cool running on gas while traveling. This time used 12v option. After 800 miles stopped at camp site. Found tab batteries low. Plugged into site power. Charged in morning. Checked trailer connections to tv seemed ok. Did 1000 more miles. After 500 miles checked tab batteries, found Half depleted. Switched to gas. Any idea if it is normal for the TV not to charge the tab batteries? I have seen a post about adding better charging but not sure if that's because there actually isn't any.

Tundra57

I should mention that I have a Toyota Tundra 2010. Which pin is used in the 7 pin?

Sharon_is_SAM

The vast majority of TaB 320 owners find that they can not tow with the frig on 12 v as it consumes 11 - 13 amps/hr resulting in a depleted TaB battery.  It’s not that your TV isn’t charging, the frig consumption is more than the ability of your TV to recharge the TaB battery.  Some members use a DC to DC charger to be able to run the frig on 12 v while towing.  Do a search.  This has been discussed here.  

Cbusguy

The biggy with the dc to dc charger is to make sure your wiring is heavy enough to support it.   Even though I have the DC to DC charger we still travel with the fridge on propane.

Tampakayaker

Try it again but make sure your TV headlights are on.  On some brand/model cars this will cause the alternator to put out more voltage and amperage. 

ChanW

Not to dash your hopes, but we've found that our 2011 Toyota (Tacoma without factory tow package) is not affected by the 'headlights on', so I'd guess yours isn't either...

Tundra57

Headlights were on as it was dark for most of the trip.

Tundra57

So since my alternator is good for over 80amps and wiring to the trailer plug is no smaller than the power wiring in the truck, why can the TV battery not be able to add 12amps to it's normal load? Unless there is a changeover charger built in which charges the tv battery first and the tv battery is not reaching full charge so not switching to the trailer plug I don't get it. What am I missing???

ChanW

Two things can effect the charge getting to your Tab.

The wire length running from the engine compartment all the way back to your Tab vs the short length connecting between the alternator and the TV battery.

If that wire running from the front of your TV to the 7pin connector is not 'heavy duty' enough, you can end up with quite a bit of voltage drop. It needs to be number 10 guage or even as large as number 8, to reduce voltage drop to reasonable level. Ideally you would want the charge voltage to be equivalent at each battery.

The other problem seems to be the computer-controlled charging system in new vehicles. In many vehicles that charge output is at a high amperage for only a short period of time after starting, and is then kicked back to a low power charge rate fairly quickly. This helps with fuel efficiency ratings. The 80A rating on your alternator doesn't mean it can actually put that rate out for extended periods of time.

I think a 'tow package' might have an alternator that's programmed differently so it can put out a higher power for the trailer battery demands.

Just my understanding from a layman's guess-point!

dragonsdofly

@Tundra57, have you tried any other means of supplementing your electrical system output, thus increasing the input to the battery?  Our former tv is a 2005 gmc Envoy xl. Like the chevy trailblazer, every vehicle had a full tow  pkg with 150 amp alternator and 10 guage charging line built in. While traveling the dessert southwest in 2016, we found even that vehicle was inadequate to keep the t@b battery charged while towing and running the fridge on 12v. We began looking for solutions and found something @Dalehelman devised. He made a set-up to attach his portable solar panel to his tv roof rack to charge the trailer battery as they traveled. We thought it was a brilliant and a near zero cost solution. My DH cut a piece of plywood to support our 80 watt solar suitcase and cut holes in the wood so it could be clamped to the luggage rack of our Envoy. Although not a large input, it was enough of a supplement to keep the t@b battery charged as we towed with the fridge on 12v. Now that we have the Chevy Silverado 2500 with a massive 220 amp alternator, which kicks into its full output and stays there in tow/haul mode, we kept the portable suitcase on the plywood, strapped it onto the top of the cargo in the truck bed, plugged it into the trailer, and kept our t@b battery literally at 100% charge all the time we traveled the Pacific Northwest (more than a month) this summer.  If you already have a portable solar panel, something to mount it to and hose clamps or even bungies, you could make something that would greatly improve the charging function into your trailer battery. We thank the master of modification, high professor of t@b university improvement and implementation department for his undeniable talent! @Dalehelman, we salute you.

Tundra57

Interesting all. I will definitely look into the tow package I have and the charging ability at the trailer socket. I know the trailer side is not that hefty as I have been in that junction box to add my led trailer reversing lights.

GatorEgg

Tundra57, I’ve been fighting this since buying my new Tacoma in July.  My last Tacoma, 2004, performed flawlessly.  I wired it myself.  Always charged whether trip was long or short.  I have the same problem as you with my new truck.  My 2019 is wired using the factory system.  I have tested my system fully.  I’m a retired Navy electronics tech so I know how to use meters.  Been down the headlight on, excite the alternator route, etc.  The voltages are correct but the amps are not enough to keep up with the refrigerator.  I have contacted two local dealer service departments.  There’re answer is they don’t know.  I contacted Toyota Corporate, they told me it wasn’t a thing they handle, and referred back to the dealer.  And this type problem is not isolated to Toyota’s.  I read about same problem on multiple late model vehicles.  So.... our options are:
1.   run a direct, heavier gage wire from truck battery with a fuse and relay using the factory plug charge line as the “on” for the relay and tap into the back of the truck 7way plug.
2.  Don’t run or expect our refrigerators to work as advertised connected to our vehicles.
3. Return to older tow vehicles which are less “tron” and sensor laden.
I’ll be performing #1, when I get around to it.

RollingBnB

what I did was install a 200w inverter under the sink and move the fridge plug to it when we travel. That allows the fridge to run on 120v ac and the thermostat is functional. 12v charge line from tv can keep up with the draw. Ac is the best of the three ways.

Tundra57

So if I am understanding you @GatorEgg my best bet would be to run some hefty wires to a separate connector like the one I have for my winch. Then fit a DC input battery charger to the trailer. That way the 12v from the TV will be boosted by the charger so amps can flow. The tv processor can't stop ohms law! I imagine when it sees the charge current to the tv battery tail off it reduces the alternator output voltage which in turn means the battery in the trailer won't receive current. Also bypasses the volt drop from the lighter 10 or 12 gauge wire in the trailer plug. The only reason I got the fridge 12v option was to use it when driving. I will not be beaten ... Yet.🤪

ChanW

I agree with @dragonsdofly (thanks to @Dalehelman and @BrianZ). I found that having the panels on the TV roof rack has quite a few advantages, although our inspiration for it was to charge faster/better while on the road.

Pro's:

• Main advantage: potential to fast charge while driving for 8 hours during the best sun.
• Less theft-prone at the campsite
• Ability to locate the panels a distance from the Tab
• Good storage location for travel

Cons:

• Required to be dismounted if wanting to charge while away from camp with the TV
• Takes up space on the rack that can be used for the kayak or sailboards

Note to @GatorEgg and @Tundra57, as I said, we have a fairly beefy #10 cable running from the TV battery to the 7pin in our '11 Tacoma, and it has not corrected the problem of lack of amperage reaching the Tab battery. It starts out at a high-power output after starting, and drops off to a typical low power maintenance charge after 30-90 seconds. Since we installed the Victron Battery Monitor I've been able to watch the details of the charging curve while driving.

Tundra57

Yeah I understand the logic. The TV system lowers the voltage of the alternator since the current tailed off so it thinks the battery is charged, so there is not enough voltage difference at the trailer plug to charge the trailer battery. By installing a separate charger, as long as there is at least 11.5 v at the plug it will boost the voltage level and charge the trailer battery only, when charged it will act as a battery tender.

I shied off from solar panels (already have 190w) as, except in summer, I spend a lot of time driving in the dark and they wouldn't help. When I got to Florida my half charged batteries charged in the storage lot by lunchtime.

Tundra57

I ordered a charger from Amazon. I'll post how successful it is. I plan to make a temp install for my trip home to see how it fares. The other plus with the separate charger is that even with the TV connected it does not allow current to flow back to the TV battery from the trailer.

GatorEgg

I get the solar ideas.  But, when we pick a campsite we try to find the shadiest spot.  And I really don't want to turn my truck into a erector set or Beverly Hillbilly's looking thing.  And as ChanW said, my rack is for my kayaks and bikes.  Don't get me wrong, I like solar.  I had 500 watts of it on our sailboat.  It kept us totally self sufficient throughout Central American and the Carib. for 5 years. 

I feel the goal is, how to teach or trick these new vehicles to charge the trailer batteries.  And I haven't given up on the vehicle manufacturer engineers yet.   Still working that angle.

Tundra57

So did some tests without the additional charger. Tundra running, 13.85V no load at the socket. Tester trailer at tv plug pins, no TV connected. 0V with disconnect switch in off, 13.5V with it on. Full sun- trailer has boondock option 190W solar panels and battery fully charged. This difference could not drive much current into the trailer. As the trailer battery voltage fell then some more current would flow, but probably not much.

One of the fuses in the TV says " towing converter" maybe it already has something in there to help. Cleaned up the pins and sockets and closed up the sockets on the trailer plug. I'm thinking of checking this out on my return journey to see if it helps. I did have the DC switch on for my last trip so that wasn't it. Hopefully the emergency brake is not powered from the same 12 terminal. I don't usually leave the disconnect on while traveling.

Sharon_is_SAM

Actually, in the event of a break-away,  the break-away brakes are powered by the TaB battery, so you need to tow with the battery switch turned on.  

TabberJohn

RollingBnB said:

what I did was install a 200w inverter under the sink and move the fridge plug to it when we travel. That allows the fridge to run on 120v ac and the thermostat is functional. 12v charge line from tv can keep up with the draw. Ac is the best of the three ways.

Does your solution work with any 12V cigarette lighter plug AC inverter?

RollingBnB

fridge draws 150w ac so as long as you use that or bigger should be ok. I use a 200w with a 400w spike capability

rfuss928

The inverter will draw about 15 amps @ 12vdc for the 150 watt refrigerator.  That is a very heavy load for a "cigarette lighter" socket and plug connection.

treefrog

I thought the battery would be charged half as fast as the fridge draws power? I think that's what we were told when we bought the trailer??? 

We just turn the fridge on and off every other time we stop when we are driving. Checking the freezer temp with an indoor outdoor corded thermometer. Seems to keep battery charged and freezer doesn't get above 20 degrees.

Tundra57

Problem with solar is that late in the year a lot of my towing time is in the dark. Also @Sharon_is_SAM you would think that there would be a big warning sign somewhere that when towing the battery switch should be on. Seems not difficult to have a fused line straight from the battery to feed the emergency brake. Ah well best to know.

@TabberJohn the charger I got is 20A it can take an input from 8v to 16v and act as a full three stage battery charger. It also has an input to activate it. My plan is to run a separate feed, fused from the battery to a separate connector, someone did this already in a previous post. There will then be a separate hefty extra plug to the charger. Charger will be mounted in the gas box and the output will replace the trailer plug charging feed to terminal 2 in the trailer junction box. The feed from the original charge connection (pin 4 I think) will then only go to the activate pin on the charger.

This way when the TV is switched off or plug removed, the charger will be disabled.

If anyone wants the part numbers of the charger and connectors just mention in this post. Otherwise I'll wait until I've mounted and tested everything before posting.

Tundra57

I ran for 6 hours in the dark disconnect switch on and fridge on 12v, medium setting. When I checked the trailer battery at a stop it was only reading half at the indication panel by the door. Did not check actual battery voltage. So put on gas next 4 hours. Stopped at campsite, shore power charged battery overnight. Tried again next day. 6 hours daylight 6 hours dark. Again around 1/2 battery when I got to destination in the dark. Put on storage lot and by lunch the next day the battery was up to full charge (Florida Sunshine🤪). It may have been earlier but that's when I went. The disconnect was off as was the fridge.

Sharon_is_SAM

@Tundra57, your comment about the indicator panel by the door made me realize you had a 400.  Please add a signature line so members can give you more specific info.  (I edited the thread title.) Also, regarding the warning to run with the battery switch on, I agree.  I wish they had a sticker somewhere near the switch or on the frame as a reminder.  

Now, about that indicator panel...the battery level indicator is a poor substitute for a true battery monitor using a shunt.  You have a KIB or KIB style monitor.  It is known that it over estimates the remaining capacity by a good margin.  A cheap, plug-in voltage monitor is probably better than the indicator in approximating State of Charge.  

Your last post was with using your new charger system?

Cbusguy

Now you understand why the big three offered a heavy duty alternator for most vehicles in their line up for years.      In researching my replacement truck,  one of them offers an upgraded alternator as part of the tow  package.   Don't remember which one.

So 80 amps isn't going to go very far with the added trailer.    keep in mind that when you connect your TV to the trailer,   in addition too trying to run the fridge it is probably trying to charge the battery and power all of the various dc loads in the trailer,  might only add an amp or two but it still counts.

I am pretty sure towing after dark maxs out your alternator especially if running the blower motor for heat or ac.

I didn't bother to check but power bastards offers upgraded alternators for a large variety of vehicles,  they aren't cheap but worth a look and will more than likely solve your under powered alternator problem.

Sharon_is_SAM

@Tundra, I think an 80 amp alternator is anemic.  I agree with Cbusguy.

jgram2

This discussion has me wondering if we could leave our fridge on DC while towing with our 2006 4Runner which has a 130 Amp alternator as far as I can tell? Will try that next time out.

Sharon_is_SAM

@jgram2, I think reducing voltage drop by having a beefier charge wire may be an equally important part of the equation.  Good experiment.  Some members are able to pull it off.