Dual Battery Charging Question

[Stateboy]

I had posted this in another forum when I thought I was posting it here. I wondered why I hadn't received much input until finally I got an answer. It was @TxDoc (thanks doc!). He gave me what I think I was looking for. I just wondered if others have had my experience when charging dual battery setups. Here's my post I originally meant to post here...

I have yet to get around and purchase one or more battery tenders for my dual battery setup. I have been taking my battery charger to individually charge up the batteries if I don't run my P1K5 often enough in the Northern Michigan winter.

My question is why does it appear as though both batteries seem to take the charge when I'm only charging one battery? For example... My battery charger will tell me that the batteries are around 80% charged on both batteries when I connect to them individually. Then, I place the charger on the accessory battery and charge it until full (I don't disconnect the batteries from the Pioneer at this time out of laziness). When I place the charger on the primary battery, it's no longer at an 80% charge but nearly fully charged.

I bought my 2019 used so I did none of the wiring. I would have thought that the item that appears to be the isolator was the item needed to keep the batteries separate. Is this normal?

 

[Admin]

 

[bumperm]

If you have a True isolator, and probably other brands are similar too, when you charge one battery, as soon as that battery reaches 13.3 volts or so, the isolator starts passing charge current to the second battery, whether that be main or aux. Kinda neat, huh?

True suggests charging the aux battery, as this is the one that is used for most accessory loads and can get depleted that way, while the main, after starting the engine, enjoys first dibsies on charging current from electrical system.

 

[Scoop]

The isolator keeps the batteries separate when voltage drops to 12.9v or below. Conversely, when voltage gets to 13.4v (whether when the vehicle is running or you are charging the batteries), the isolator connects the two batteries (in parallel) and begins charging them simultaneously.

 

[Stateboy]

Thanks guys. It went along the lines of what @TxDoc had said in his answer to me in the other forum (I joined it earlier this year but there is no activity to speak of). The answers I got from @bumperm and @Scoop added to it. I do have the True isolator.

I just went out to the pole barn to disconnect the charger (from the main battery - it showed 100% charged) and the isolator was glowing blue, which @TxDoc had said indicated a full charge or where current will pass either way through the isolator. I'm just trying to understand these things.

So, is it safe to say that if I buy a battery tender, I only need one and hook it to the main battery then? That's going with the idea that the isolator will share the trickle charge with the auxillary battery and keep both charged with one tender, correct?

 

[Scoop]

Ideally, hook the Tender to the AUX battery. With all the accessories connected to it, it's most likely to be the one more in need of charging. But realistically, it likely won't matter unless you run the AUX super low while the machine isn't running, then you don't start/run it much before putting it on the charger.

 

[bumperm]

I found it convenient to install a "charging" jack so I don't have to remove the hood. It's also convenient, as the same jack, fused appropriately, can be used for accessories like an air compressor etc. This is a Powerlet jack and plug, also sometimes called a BMW, Bosch, or John Deere plug. They are relatively small, very reliable, and when unplugged with the cover closed, are weatherproof.

 

[Stateboy]

Ideally, hook the Tender to the AUX battery. With all the accessories connected to it, it's most likely to be the one more in need of charging. But realistically, it likely won't matter unless you run the AUX super low while the machine isn't running, then you don't start/run it much before putting it on the charger.

That may be the better idea since my auxiliary rocker switches are always glowing. I haven't looked into it yet but I may install a kill switch of some sort to the auxiliary battery or rockers themselves.

 

[Stateboy]

I found it convenient to install a "charging" jack so I don't have to remove the hood. It's also convenient, as the same jack, fused appropriately, can be used for accessories like an air compressor etc. This is a Powerlet jack and plug, also sometimes called a BMW, Bosch, or John Deere plug. They are relatively small, very reliable, and when unplugged with the cover closed, are weatherproof.

View attachment 308859

I've seen something like that on motorcycles to save you from having to take the side cover off to access the battery. I wasn't sure of the name so thanks for the input.

 

[bumperm]

That may be the better idea since my auxiliary rocker switches are always glowing. I haven't looked into it yet but I may install a kill switch of some sort to the auxiliary battery or rockers themselves.

An easy convenient way to solve the always glowing switch illumination, is to use a "Key on" switched ground to the negative terminal on the rocker switches. Depending on how they are wired, (sometimes in a row with a "daisy-chained" ground going from one to the next) this may only involve changing one wire.

 

[Mark in Northern Iowa]

As bumperm suggested, a switched negative relay might be an easy solution for your glowing switches.
Here is a hot switched negative relay diagram, but it is also showing how I plan on installing my isolator. The isolator that I will be using, uses a standard negative ground. The isolator stays on after the keys is off, until a certain battery voltage is reached.
But, I have read about different ones that sometimes stick on, and after a long enough time, can drain both batteries.
When I turn off the key, I want it off as well.
.
Is it overkill? yeah.
Will it stop the isolator from sticking? Probably not haha
But what the heck, I get to play with some more wiring.
.
Now, the downside to my way of doing it, is that I will have to have 2 battery tenders. The charging, will not cross through the isolator to the other battery.
.

.
edit
Well......haha....crap...hahahaha......damn.
Looking at it again, If I shut off the isolator with a switch.
I might as well just use a continuous duty solenoid.
I laughed, because in actuality, that is what I just mimicked.
.
Electrical, what fun
.
Have a good day

 

[Hondasxs]

edit
Well......haha....crap...hahahaha......damn.
Looking at it again, If I shut off the isolator with a switch.
I might as well just use a continuous duty solenoid.
I laughed, because in actuality, that is what I just mimicked.

Yep. You just broke the automatic part of it so might as well install one of these --> Amazon.com
Well, you will need a second one for the fuse box.

 

[Stateboy]

Thanks all. You guys solved it and I'm good to go. Now, I'm going to wait to see which one of the family members will get me a gift certificate for Christmas. Then I'll buy a battery tender to keep the Honda in top shape for my winter rides. If no gift certificate, I guess I'll enjoy the chocolate and ugly ties and go buy one myself. I'm going to take a look at that solenoid or two that @Hondasxs mentioned too.

 

[bumperm]

Thanks all. You guys solved it and I'm good to go. Now, I'm going to wait to see which one of the family members will get me a gift certificate for Christmas. Then I'll buy a battery tender to keep the Honda in top shape for my winter rides. If no gift certificate, I guess I'll enjoy the chocolate and ugly ties and go buy one myself. I'm going to take a look at that solenoid or two that @Hondasxs mentioned too.

Get the proper isolator, unless you plan to always have two batteries, same age, same model, etc. as that is the recommendation for parallel or series battery banks. The isolator allows you to skip that minutia and put in two different make, size, aged, batteries. The True isolator is a reasonable deal - - probably why it's so popular here.

 

[petek5090]

I had posted this in another forum when I thought I was posting it here. I wondered why I hadn't received much input until finally I got an answer. It was @TxDoc (thanks doc!). He gave me what I think I was looking for. I just wondered if others have had my experience when charging dual battery setups. Here's my post I originally meant to post here...

I have yet to get around and purchase one or more battery tenders for my dual battery setup. I have been taking my battery charger to individually charge up the batteries if I don't run my P1K5 often enough in the Northern Michigan winter.

My question is why does it appear as though both batteries seem to take the charge when I'm only charging one battery? For example... My battery charger will tell me that the batteries are around 80% charged on both batteries when I connect to them individually. Then, I place the charger on the accessory battery and charge it until full (I don't disconnect the batteries from the Pioneer at this time out of laziness). When I place the charger on the primary battery, it's no longer at an 80% charge but nearly fully charged.

I bought my 2019 used so I did none of the wiring. I would have thought that the item that appears to be the isolator was the item needed to keep the batteries separate. Is this normal?

I have the TRUE-AM isolator, when the ignition is shut off the isolator opens to equalize the current in both batteries. This is identified by a flashing blue light on the isolator, once the flashing stops it signals that both batteries are of equal voltage.

 

[Scoop]

I have the TRUE-AM isolator, when the ignition is shut off the isolator opens to equalize the current in both batteries. This is identified by a flashing blue light on the isolator, once the flashing stops it signals that both batteries are of equal voltage.

The isolator doesn't connect or disconnect because the ignition is on or off, nor does it open/close "to equalize the current in both batteries". If the latter was occurring, a bad battery would bring down both.

When the engine is running and the charging source raises the voltage of the start battery to 13.4 volts* (cut in threshold), the True Smart Battery Isolator (SBI) engages and connects the two batteries to charge simultaneously. The SBI’s internal LED will glow blue.

When all voltage sources drop below 12.9 volts* (cut out threshold) the Smart Battery Isolator will disengage and the blue LED will go out.

When the SBI LED is out the batteries are separated thus preventing the power of your start battery from being drained by use of the accessories powered from the second battery.

When the vehicle is restarted and the start battery has recharged to 13.4 volts* the Smart Battery Isolator engages, the LED will illuminate and the second battery is connected to receive charging.

There is a 10 second delay before engaging or disengaging.

 

[petek5090]

I stand by my comment. All that info and the original question still wasn't answered. "My question is why does it appear as though both batteries seem to take the charge when I'm only charging one battery? You stated previously on Dec. 14- "The isolator keeps the batteries separate when voltage drops to 12.9v or below. Conversely, when voltage gets to 13.4v (whether when the vehicle is running or you are charging the batteries), the isolator connects the two batteries (in parallel) and begins charging them simultaneously." and clearly used the term "connects" which implies it was disconnected so you really haven't made a point other than to confirm the accuracy of my comment.

 

[Hondasxs]

I stand by my comment. All that info

You say flashing... and it works only when ign is off???

It shouldn't be flashing. Should be solid.

And it works when batteries reach 13.5+- volts. Irrelevant to ignition position. And cuts off (opens) around 12.7+- volts.

This is why you can charge one battery (either one) and it will close (turn on. Blue light ON) and start to charge the second.

Note:
You didn't connect the spade connector on the side did you? This would cause your key-off experience.



Sent from my SM-G996U using Tapatalk

 

[bumperm]

I stand by my comment. All that info and the original question still wasn't answered. "My question is why does it appear as though both batteries seem to take the charge when I'm only charging one battery?

Scoop is correct. The True isolator works in either "direction" to pass charging current to the other battery when the battery under charge (either the main battery when the engine is running or the aux battery when it is being charged by shore power) voltage exceeds about 13.3 volts. When that occurs, the True blue light will come on steady to show that it is passing current from the battery being charged to the other battery.

When either battery is being discharged, my understanding is that the True isolator will only allow the other battery to "assist" until its voltage drops to 12.9 or there'bouts.

 

[hopeicanaffordthis]

Hey,

i also have the true- am and a battery tender wired up to my main battery. it just started getting cold out so i thought i'd test the battery tender out. I had it on for about three hours and came back to my isolator being hard lit blue. is this correct?

 

[Hondasxs]

Hey,

i also have the true- am and a battery tender wired up to my main battery. it just started getting cold out so i thought i'd test the battery tender out. I had it on for about three hours and came back to my isolator being hard lit blue. is this correct?

Yes, Correct.
Here, it charged the first battery to 13.5+-, thus triggering the isolator, thus charging the second battery.