Solenoid isolator won't disconnect chassis and aux battery, causing depletion.
- Thread starter Basement Yeti
- Start date
Basement Yeti
Explorer
Awesome. Ordering now. Time to get that abomination outta there and get my 130.00 bucks back.
Edit: Is that the solenoid you have, or do you recommend some other brand?
Edit: Is that the solenoid you have, or do you recommend some other brand?
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This is what I thought he had at first (before I clicked the link). I'll throw one thought in the ring for consideration that you can take or leave it: If I were using something like this I would be inclined to put a switch between the ignition hot supply and the solenoid thus you can still manually break the connection if you want. Why would I do that? Well if you're aux battery is really low when you roll the key I wouldn't want the aux battery and the starter both pulling current from the starter battery, esp. if the truck was having trouble starting. I've not ran the numbers to know if my off hand concerns are warranted so I may just be worried about nothing but I like the option of manual control over things like this.
Basement Yeti
Explorer
I took the abomination out. Both batteries were nearly dead. I disconnected the isolator and went for a long drive, and dropped the blue top off at O'Reilly where they charged it, then swung back around.
The Yellow top charges fast, in only 45 minutes it was at 13.6v. The blue top is fully charged too.
I just ordered that Morningstar SSD-25 solar controller. I'm headed up to Norco tomorrow to get my panels/cables/mounts and see if they will let me install them in their parking lot.
The Yellow top charges fast, in only 45 minutes it was at 13.6v. The blue top is fully charged too.
I just ordered that Morningstar SSD-25 solar controller. I'm headed up to Norco tomorrow to get my panels/cables/mounts and see if they will let me install them in their parking lot.
dwh
Tail-End Charlie
Yea. That problem always sounds reasonable - so it gets brought up frequently, but it's actually a non-issue. The numbers are here:
http://www.smartgauge.co.uk/nosurge2.html
Bottom line...
When the aux battery is really low, its resistance is very high, so there is no large flow of current from the main to the aux.
The biggest surge from one to the other happens when the aux is actually "not so low" - i.e., down to around 40% capacity. In that situation, its resistance is much less than if it were really low, so there is a bigger surge.
But it's still not much.
HOWEVER!
Optimas have very low internal resistance (so they say - I've never measured it), so with them there might be a bit higher flow from one to the other - possibly even enough to warrant the disconnect switch (or the time delay before connecting that some smart split-charge relay black boxes use).
Personally, I doubt that their internal resistance is all that much lower, so its probably still a non-issue even with Optimas.
I've run my aux down to all different levels and never had any issue starting the 460 in my truck using a simple split-charge relay - except when I leave he headlights on all night like a dork. :Wow1:
dwh
Tail-End Charlie
That's called a "surface charge". It means that the voltage is up, but the chemistry is not fully activated (stirred up) so the voltage will drop faster than if it was *actually* fully charged.
This is why a 3-stage charger (like the SSD) will "bulk" the battery up to a higher voltage - usually 14.4v, though some go to 14.6v or 14.7v - and then drop down to usually 14.2v and hold it there.
When it drops to 14.2v and holds there for a while, that's called the "absorb" stage. It does that in order to let the chemistry in the battery fully absorb all it can. It'll stay in absorb until the flow into the battery drops to less than 1 amp.*
Only THEN is the battery TRULY "fully charged". It just can't absorb any more.
And then it drops to float and holds at usually 13.6v or 13.2v depending on who made the charger.
* For most chargers - the Iota IQ/4 module will run a timer and not stay in absorb longer than 8 hours no matter what. After 7 days at float, another timer trips and it start sover and does a quick run-through of the bulk and absorb stages before dropping to float again.
Progressive Dynamics' units also have a timer - after 48 hours (IIRC) at float the timer will trip and they'll kick up to a higher voltage for 15 minutes.
Some chargers will drop out of absorb when the flow is less than 2 amps.
Also a quick note on installing the SSD:
Run dedicated +/- wire to the batteries. DON'T just run the negative to the frame of the truck.
The reason is, that a PWM controller can switch the power on/off to the battery hundreds of times per second - and that rapid switching can cause noise that shows up as radio interference.
Running the negative to the frame would work fine, but it could end up creating some noise in radios or amplifiers.
Also, keep the +/- wires together - actually, twisted together is best but not really needed for 12v stuff - the further they are separated from each other, the higher the chance of EM noise.
Basement Yeti
Explorer
You are a wealth of knowledge my friend, thanks.
I like that you can set the priority for each battery on the Morningstar SSD-25.
I found that SSD-25 for 85 bucks online!
I like that you can set the priority for each battery on the Morningstar SSD-25.
I found that SSD-25 for 85 bucks online!
I wasn't so concerned about a surge between the two (in terms of wiring damage) as opposed to just robbing potential amps available to the starter at the same time. Esp if it was cold or such. Again could be completely unfounded up a couple dollar rocker switch makes me happy.
(plus since I'm using a DC-DC charger I usually keep it turned off when running around town so it doesn't start the bulk charge phase for short spurts repeatedly and instead wait till I'm going to be actually running the vehicle for a while to turn it on).
Basement Yeti
Explorer
dwh, I yanked the ground out of the busted solenoid so my alternator only charges my chassis battery. My blue top battery house battery hasn't really been taken care of in the past week or so, sitting at 10-12v. It is a blue top deep cycle/cranking battery. Can this do much damage to it?
dwh
Tail-End Charlie
10.5v is considered a "dead battery".
Couple of days - not a big deal.
But that battery has been getting the treatment for a while now. No telling how much has been shaved off its total life.
Only way to know for sure, would be to do a draw down test: First charge it properly, then put a known load on it - like a 20w light bulb and time how many hours it takes to get down to 10.5v.
With that data, you can calculate the actual amp*hours capacity, and compare that to the amp*hours rating of a new battery and know the difference.
Couple of days - not a big deal.
But that battery has been getting the treatment for a while now. No telling how much has been shaved off its total life.
Only way to know for sure, would be to do a draw down test: First charge it properly, then put a known load on it - like a 20w light bulb and time how many hours it takes to get down to 10.5v.
With that data, you can calculate the actual amp*hours capacity, and compare that to the amp*hours rating of a new battery and know the difference.