The mystery of the slowly dying batteries

mtbjonny · 12-06-2015, 02:18 AM

Hi All,

I’m an electrical noob here with a nasty issue, so apologies in advance if I say something stupid. I have done some research here. Some very helpful insights. But I still can’t seem to solve the specific issue I’m having. Specifically - I’ve had to replace my house battery every year (nearly like clockwork) for the past 3 years. And if I'm not hooked up on shore power, my starting batteries die within 2 - 3 days. My current theory is I’ve got a parasitic draw, so I’ve started to hunt for it.

To frame up the situation:
2005 E-350 V10 gas that was converted to a SMB in 2011. Van has 2 van batteries, one under the hood and one under the rear doors - it took me a while to figure this out.
It has most of the options available at that time, including an inverter/charger (Tripp-lite MRV2012UL), a separator (Blue Sea 7620), solar up top (1 cell), stereo Amp & switch to play the stereo from the house battery (was a UB-4D 200A AGM), alarm, switch to link both van & house batteries, etc.

When the van is not used, it’s docked at my house & plugged in (I know there’s debate about if this is ‘good’, would love to get advice on best way to maintain).

When we have to replace the house battery, both the house battery and the van battery system will start to exhibit signs of being heavily drained while out camping (or not hooked up to shore power). Typically during a camping trip it starts to work like this:
Friday day - the battery will show 13+ V (solar is working)
Friday evening, the house battery will creep to a low voltage (less than 12.2V) with what I would consider normal usage (fridge set to 1 - low, some LED lights, running the water pump to do dishes).
Saturday day/evening - this cycle repeats (13V+ during day to less than 12.2 at night.
Sunday afternoon, the van won’t turn over. Pressing the switch to link batteries works (thankfully).
Soon things get from bad to unuseable. Then I get a new house battery and that (usually) solves it. But why would a bad house battery affect the van battery (which is getting drained!?).

Troubleshooting that I’ve done:
Local shop has confirmed that both van batteries are good (load tested).

First: I disconnected shore power & removed the 2nd van battery from this equation (disconnected both terminals), to isolate the issue (I hope). House battery is still hooked up & @ ~12.8V.

Next: Using just the van battery under the hood, I check for a parasitic draw on the positive terminal. I got some wildly fluctuating numbers that were negative (like the battery was being charged). I covered up the solar panel & got a stable ~0.16 amps draw.
- I isolated the van circuit (removed the lead from the Blue Sea isolator to the van battery) and was able to determine that the van is drawing only ~0.04 amps. That’s acceptable (as I understand it).
Draw between the lead from the Blue Sea isolator and the van battery was ~ 0.12 amp draw.
- I pulled the circuit breakers for the 2 sensors (CO2 & propane) & the draw goes down to ~ 0.08amps.

That the house is drawing ANY current from the van battery indicates the isolator is in the ‘on’ position. Using the voltmeter confirmed this. According to Blue Sea’s site - it should be open until the voltage falls below 12.75V. I’ll check tomorrow that if it falls below 12.75V, they’re isolated.

So - maybe no parasitic load killing the van batteries? If not, I’m at a loss. So far, everything seems like it’s working, so why do my van batteries drain when they’re not hooked into shore power? Why does my house battery need to be replaced every year?

Any advice on what to check for or next steps would be HUGELY appreciated.

Thanks,

Jon

Scalf77 · 12-06-2015, 06:23 AM

Is the switch to link both battery bank a Blue Sea Switch 2146 that should let you disable the Blue Sea 7620 when you are home parked and when you are camping. Also specifically if you are plugging in at home all the time , I would disable the solar charger. Make sure you leave the radio switch in Van mode

If it is just a SPST switch to 12 volt then you can change it to a SPDT On-Off-On switch, and add ground to one side. When switched to ground it will disable, when switched to 12 it will force connection and the middle position will be open and put the Blue Sea into auto mode. Their switch will add LED's

Once you are sure you can disconnect the two systems, it will be much easier to find out what the problem is. When is the last time you replaced the house side. Was anything hooked up to second starter?

-greg

mtbjonny · 12-06-2015, 09:23 AM

Switch is not a blue sea 2146, so I assume it's a SPST (It's a simple button that when depressed, you can hear the Blue Sea 'click', bringing the 2 battery banks together).

I'll look into adding the Blue Sea 2146 (will need to get one) - sounds like that would help me troubleshoot the issue.

I replaced the house side nearly a year ago & once again, it's starting to die. I'm not sure what the second starter battery is hooked up to... Let me check that - good idea.

Thanks greg!

**daveb** · 12-06-2015, 10:45 AM

Quote:

Originally Posted by mtbjonny

Hi All,

Friday day - the battery will show 13+ V (solar is working)
Friday evening, the house battery will creep to a low voltage (less than 12.2V) with what I would consider normal usage (fridge set to 1 - low, some LED lights, running the water pump to do dishes).
Saturday day/evening - this cycle repeats (13V+ during day to less than 12.2 at night.
Sunday afternoon, the van won’t turn over. Pressing the switch to link batteries works (thankfully).

Jon

This is what is bothering me. Your normal load pulls down the 4D battery to 12.2 in a day? Then the van battery also goes down? Also what do you mean by second starting battery? First off the separator should prevent one or the other from being drained unless you have a draw from each system. What happens when you take the separator out of the equation? I'd be looking to see (with the separator removed) if the vehicle battery drops to the point it won't start the vehicle after a 24 hour period. Then I'd check to see if the house battery is down. The deal is if something is killing one or the other batteries, to test, you should do it with two new batteries. With batteries banked together one can pull the other down. Once damaged the other begins to fail and within time it's possible that the older battery starts to loose its storage capability. It would explain the time limit. The separator will stay closed even if a battery is bad...all it see's is a low state of charge on the banked system and closes once it see's a positive charge voltage. It's important to note the charge rate (in amperage) going to each battery during the charging session.

It's common for SMB to install a push button "jump start" switch. I'm curious what the charging amperage is and if it ever tapers off. My batteries (without solar assisting) will taper down to only a few amps after being fully charged. Being able to monitor this is a big benefit IMO.

I'd think that your situation seems like a bad starting battery but the separator should be protecting the house (unless something is wrong with the separator) and it's strange that all the batteries pass a load test. Who and how is the load test being done?

For what it's worth, I had battery issues on a yearly basis until I switched to all AGM starting batteries. Not saying that is your problem but I found standard wet cell starting batteries as problematic. My guess is the climate where I live and the constant solar charging day after day was the cause. Again it doesn't point toward your problem as I never had issues with my house batteries but I don't have Universal brand batteries either.

mtbjonny · 12-06-2015, 01:02 PM

Yup. I know my batteries are dying when I can't go an evening camping without the system voltage going to/below 12.2V under light usage. And yup - the van batteries end up dead as well the next morning.

For clarification: The second starting battery is the second van battery. This is located under the rear doors & appears to be connected to the alternator directly (doesn't appear to be connected to the van battery in the engine compartment).

You bring up a good point about removing the separator from the equation - which is what I tried to do in troubleshooting for a parasitic load (I removed the lead between the separator & the van battery). Let me know if you think I did something wrong in my troubleshooting. That said - I'm going to continue to monitor for parasitic loads that are sucking the life of these batteries. I know the 2 detectors (CO2 & propane) draw ~ 0.02A each, but I'm not sure what the other loads are that are contributing to the 0.08A draw. Thoughts anyone?!

I'm starting to think that this issue is not a parasitic load issue, but a combination of 1) Batteries of different quality/in different parts of their lifecycle and 2) How I am keeping the system docked when not in use (on shore power, solar also charging).

So at this point, while I continue to hunt parasitic loads on the house, I'd love advice on
a) House & van batteries
b) How to best maintain the system when not in use. Connect to shore power? Solar? Both (which is currently what is happening).

Thanks Dave & Greg for your insights so far... Really appreciate it!

mtbjonny · 12-06-2015, 03:46 PM

Done some more troubleshooting. Got a question for the folks here:

- I pulled the house battery out & removed the ground. At this point there was no power to anything. Everything's disconnected. The house has no connections to power. Both van batteries are disconnected and the separator is now disconnected (no connection between house & van).

When I powered up the house again (connected ground back to the house battery), I checked & noticed that the separator was isolating the van & house batteries (ie., the line running from the separator to the van battery had no voltage). this made sense to me as the house would have been at ~12.8V and the van was basically at ground (battery still disconnected). So the separator was separating the2 sides.

Just to see if it would work, I engaged the 'emergency' switch that combines batteries. You could hear a click & a check of the voltage of the line running from the separator was now at ~12.8V and has stayed open - which is weird because the van battery is still disconnected, so it should have no voltage.

My question is: How is the separator detecting voltage on the van side (or for that matter, the house side)? Shouldn't the separator isolate the house & van batteries when the van battery is essentially disconnected? At what point would the 2 disengage?

dhally · 12-06-2015, 04:00 PM

Is the second starting battery located on the side of the frame, under the side door step?

dhally · 12-06-2015, 04:05 PM

Quote:

Originally Posted by mtbjonny

Done some more troubleshooting. Got a question for the folks here:

- I pulled the house battery out & removed the ground. At this point there was no power to anything. Everything's disconnected. The house has no connections to power. Both van batteries are disconnected and the separator is now disconnected (no connection between house & van).

When I powered up the house again (connected ground back to the house battery), I checked & noticed that the separator was isolating the van & house batteries (ie., the line running from the separator to the van battery had no voltage). this made sense to me as the house would have been at ~12.8V and the van was basically at ground (battery still disconnected). So the separator was separating the2 sides.

Just to see if it would work, I engaged the 'emergency' switch that combines batteries. You could hear a click & a check of the voltage of the line running from the separator was now at ~12.8V and has stayed open - which is weird because the van battery is still disconnected, so it should have no voltage.

My question is: How is the separator detecting voltage on the van side (or for that matter, the house side)? Shouldn't the separator isolate the house & van batteries when the van battery is essentially disconnected? At what point would the 2 disengage?

When the emergency switch is pushed, the separator connects both batteries together, no matter the voltage. When the emergency switch is released (it is spring loaded?) The voltage on the van side should go back to zero if the van battery is disconnected. Are you saying the voltage stayed at 12.8 even after you released the emergency switch?

**daveb** · 12-06-2015, 04:41 PM

My guess is SMB wires the momentary switch to the house side as it's there to jump a dead starting battery. If that function is operating off the starting battery only and the battery was dead it wouldn't jump but I've never actually looked at it. I don't have that setup. There are several ways to configure separators depending on the make & model. Mine is set to open for 15 seconds after it see's a signal from the ignition. I have the 7622 with remote control switch.

boywonder · 12-06-2015, 05:55 PM

Quote:

Originally Posted by daveb

I'd think that your situation seems like a bad starting battery but the separator should be protecting the house (unless something is wrong with the separator) and it's strange that all the batteries pass a load test. Who and how is the load test being done?

Sounds like a bad starting battery to me too.....it's dying and you are using the house batteries to start......when the separator is connected, the van battery is pulling down the house batteries.