Permanent damage to tow vehicle battery?

[jymbee]

Throughout out latest trip we've had issues with your BlueOx Patriot brake. Very long story involving multiple issues and an ungodly amount of $$$ spent in repair shops. Until this last stop we finally got everything working. But now...

The procedure to get the transmission in a "towable" state requires a series of shifting through gears then the key left in Aux mode. One of the main issues was that the tow vehicle's battery which normally is charged while driving, was not being charged resulting in a a dead battery within a couple hours. As we have a fairly long drive home at this point, I'm not optimistic that we'll be able to solve the problem until we get back home and take it to the shop that did the initial installation.

As we've had fairly short stops between sites so far, we opted to just disconnect and drive both vehicles. That won't be an option for the last 20 or so hours to get home.

Previously when we realized the battery was dead, we were able to jump start the car. So the question is, if the tow vehicle is connected and we drive well beyond the point that the car battery is dead, are we risking permanent damage to the battery? Also, seems there's also not much reason to even set up the brake system given it won't do anything if the car battery is dead.

I'm not excited about the possibility of driving without the Patriot Brake system working, but as we'll be on main highways and I'm a very cautions driver in any event, doesn't seem like a huge risk.

 

[Skookum]

Discharging any lead-acid battery to zero repeatedly isn't good, just like a deep cycle RV battery. It can drastically shorten the useful life.

 

[Utclmjmpr]

Look into an additional wire from the towing vehicle to the towed to keep the towed battery charged.. a simple fix.>>>Dan

 

[_Rusty_]

I also carry an external charger for use on the road. After set-up for the night, I put the car on charge.

 

[Laura & Charles]

You said, “the tow vehicle's battery which normally is charged while driving”. Are you saying it’s normally charged when driving it towed? Or normally charged while driving IT? (Which of course it is)

And either way, any RV shop (or trailer shop will be cheaper) will be able to install (or reinstate) the towed vehicle charge power (from the coach) and shouldn’t take long. I see no good reason to wait until you get home to address this. Repeatedly draining the toad’s battery will kill it.

 

[8Muddypaws]

We use the same braking system. It draws very little from the battery. I run it from one of these and disconnect the cars battery. You can see what we tow in my signature. Some cars don't like being disconnected from the battery. We had a Honda CRV that completely spazzed out after disconnect.

https://www.amazon.com/Clore-Automotive-Jump-N-Carry-JNC660-Starter/dp/B000JFJLP6/

 

[Ray-IN]

Look into an additional wire from the towing vehicle to the towed to keep the towed battery charged.. a simple fix.>>>Dan

Yup, use pin #7 in the Bargman plugs,(AWG12) or go with a totally separate charge line from MH to towed battery temporarily.
jymbee;
OTOH, if your towed vehicle is light, you might get by without the aux. braking system. Slower with extra spacing is called for. We'd be surprised at how many are towing behind their MH without aux. braking.

 

[8Muddypaws]

Some information about your towed vehicle would he helpful. Vital actually.

I tow with my Patriot set at high sensitivity and high force. Way more that Blue Ox recommended. Still, after driving 4-7 hours my jumper battery (an old one at that) is never down more than 50%.

Seat heaters left on? Air circulation fans? An LCD display left on?

 

[jymbee]

You said, “the tow vehicle's battery which normally is charged while driving”. Are you saying it’s normally charged when driving it towed?

Normally charged while being towed behind our coach.

This is our 6th year towing the Honda Odyssey for about 6k miles each trip with only one such issue last year which was resolved at a repair shop en route.

And either way, any RV shop (or trailer shop will be cheaper) will be able to install (or reinstate) the towed vehicle charge power (from the coach) and shouldn’t take long.

Were it only that simple... As I said, it's been a very long and VERY expensive trip this time trying to resolve numerous issues, many of which I related here previously and which apparently resulted from a burned out tow cable connection to the car:

I'm not willing to spend yet more to have another shop "fix" it given I suspect there might well be something else going on and what needs to be done is a complete examination of everything in the system and I can leave it at home with the authorized BlueOx dealer that did the original install.

So I guess my question about potential harm to the battery has been answered and I may just have to accept the fact that even if I end up needing a new battery, that might well be a lot less expensive then trying to get yet another shop involved.

Appreciate the input from all.

 

[jackiemac]

Can you disconnect that battery so it doesn't lose charge?

 

[Mark_K5LXP]

Can you disconnect that battery so it doesn't lose charge?

Bingo. If you anticipate running it while dead anyway there's no difference to the car if you were to enable tow mode and then lift a battery cable.

Mark B.
Albuquerque, NM

 

[Onyrlef]

I'd just forget the brakes, I'm betting with your heavy coach and the ~ 4,500 lb weight of your Honda, you won't notice a difference.

 

[uchu]

I'd just forget the brakes, I'm betting with your heavy coach and the ~ 4,500 lb weight of your Honda, you won't notice a difference.

Auxiliary brakes are required by law in most states, provinces and territories in the US/Canada. Most certainly for towing a 4,500lb vehicle.

Don't forget the most important law at play: Newton's first one. Without aux brakes, a hard enough emergency stop can make the toad go very hard against the MH, likely damaging or destroying the towing bar, and the back of the MH.

 

[Onyrlef]

Auxiliary brakes are required by law in most states, provinces and territories in the US/Canada. Most certainly for towing a 4,500lb vehicle.

Don't forget the most important law at play: Newton's first one. Without aux brakes, a hard enough emergency stop can make the toad go very hard against the MH, likely damaging or destroying the towing bar, and the back of the MH.

That may be, but if the battery is dead he won’t have brakes regardless. I’d disconnect the battery, hit the road and take my chances with Newton’s 1st law of motion.

 

[jymbee]

Can you disconnect that battery so it doesn't lose charge?

Strangely, I actually arrived at just that strategy only after considering other, more involved possibilities. Sometimes, I'm a little slow...

 

[John From Detroit]

What I fed Google
towed charge system for motorhomes

Just one of the links I found

https://www.etrailer.com/Accessories-and-Parts/Brake-Buddy/BB54FR.html?feed=npn&gad_source=1&gclid=Cj0KCQjwwYSwBhDcARIsAOyL0fgYYphMSczeVT3OOqhl7VIyol_jc1p4_XNdVYDKWN4wDdPGn4pxAQMaAn5TEALw_wcB

 

[jymbee]

I'd just forget the brakes, I'm betting with your heavy coach and the ~ 4,500 lb weight of your Honda, you won't notice a difference.

While I understand the regs in some states that require an aux brake, it's never been clear to me just how effective they actually are. I brake the coach, see the light on the remote controller come but I can't see it "feels" any different than the times I've driven when the brake wasn't working.

I'm well aware that although I might not experience any difference any difference, the aux brake might well be most effective were I ever need to brake hard unexpectedly.

To say my driving technique when towing is conservative would be an understatement. Always looking far ahead for issues, start slowing down gently well before any stops and in general chugging along at no more than 60 MPH even on highways with a 75 MPH limit.

But of course there's always that one time...

 

[jymbee]

That may be, but if the battery is dead he won’t have brakes regardless. I’d disconnect the battery, hit the road and take my chances with Newton’s 1st law of motion.

I will be doing just that-- disconnecting and wrapping the negative terminal on the battery while driving with extreme caution until back home.

 

[A Traveler]

Just connect the “AUXILIARY +” wire to the positive terminal on the towed vehicle battery! That will fix this. Easy.

 

[Onyrlef]

I will be doing just that-- disconnecting and wrapping the negative terminal on the battery while driving with extreme caution until back home.

The biggest issue when towing a trailer w/o brakes is the tendency for it to push the tow vehicle during braking. You shouldn’t have any problems with that.