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14-05-2018, 04:57
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#1
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Registered User
Join Date: Feb 2008
Posts: 191
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Inverter / Battery wired Incorrectly?
I purchased my boat last fall, and was at a dock all winter so didn't use the inverter. Now that I've started using it I found that one of my batteries is dying, and that this battery isn't receiving charge from alternator or solar, even though it is part of house bank. (In theory at least. Also, physically it is not located with the other house battery) The other battery in the 'bank' is indeed receiving charge, as is the engine battery. Further, the inverter isn't getting power from the other battery in the 'house' bank, only the one that is dying / not getting charge.
I suspect there's something wrong with the way it is wired, but I'm electrically challenged, here is a simplified version of the wiring. Leaving out the engine battery.
The bad battery - the one that isn't receiving charge - is the one on the bottom. The negative from the Inverter is wired directly to that battery, and I'm wondering if that might be part of the problem.
Any thoughts greatly appreciated!
__________________
A good traveler has no fixed plans
and is not intent upon arriving -Lao Tse
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14-05-2018, 07:01
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#2
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Registered User
Join Date: Oct 2009
Location: Bermuda
Boat: Privilege 435
Posts: 586
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Re: Inverter / Battery wired Incorrectly?
Your setup appears to be fine. It doesn't really matter where the negative goes as long as they are all connected (unless there's a short somewhere). Is your house switch '2' an on/off or a 1/2/both/off? If it's an on/off then your two battery banks are constantly connected together. Therefore, if one bank is receiving a charge, the one one will be as well. Also, from your set-up, if the switch is an off/on then your inverter is being powered from both batteries. The problem might be if the switch is a 1/2/both/off, and you have managed to separate the two batteries.
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14-05-2018, 08:45
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#3
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Registered User
Join Date: Feb 2008
Posts: 191
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Re: Inverter / Battery wired Incorrectly?
Thanks,
If the setup is ok, I wonder why I'm not getting any charge to that battery when the other one is receiving charge. Also, the inverter only discharges that battery, not the other one.
The switches are on/off. There's actually two on/off switches for positive (and the one for ground) One switch for house (in my diagram) and one for engine. I ran the alternator last night with both switches on and was seeing 14.5 at the 1st house bank battery,12.5 at the one connected to the inverter, and 13.8 I think for the engine battery.
__________________
A good traveler has no fixed plans
and is not intent upon arriving -Lao Tse
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14-05-2018, 09:55
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#4
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Registered User
Join Date: Feb 2013
Posts: 89
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Re: Inverter / Battery wired Incorrectly?
It should work as wired. If it does not, I guess that one or more of the connections is loose or corroded. I would check them all and tighten them carefully. Good luck
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14-05-2018, 11:36
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#5
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Registered User
Join Date: Oct 2009
Location: Bermuda
Boat: Privilege 435
Posts: 586
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Re: Inverter / Battery wired Incorrectly?
I agree that you seem to have a problem with the hardware; not your setup. How long is the run to the second house battery? How big is the cable? If the cable is undersized or there is a restriction (coroded connections, kinks etc) this would cause a voltage drop at the battery.
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14-05-2018, 12:03
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#6
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Registered User
Join Date: Feb 2008
Posts: 191
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Re: Inverter / Battery wired Incorrectly?
Thanks again.
Just did some tests which seem to confirm what you were suggesting.
- between the terminals on the battery 12.4v
- from positive terminal on battery to negative switch 13.2v
- from negative terminal on battery to negative switch 170mv
So does look like a problem on the negative wire. It's a short 3 foot run and the battery side is fine. Must be loose or corroded on the switch end - I imagine they don't usually fail internally?
__________________
A good traveler has no fixed plans
and is not intent upon arriving -Lao Tse
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15-05-2018, 06:13
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#7
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Registered User
Join Date: Feb 2008
Posts: 191
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Re: Inverter / Battery wired Incorrectly?
In retrospect it seems obvious, but indeed the problem was with corrosion on the terminal for the negative return from that battery.
Thanks for confirming the wiring was OK.
Cleaned up the terminals this morning and everything is working great now.
__________________
A good traveler has no fixed plans
and is not intent upon arriving -Lao Tse
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15-05-2018, 08:25
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#8
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Registered User
Join Date: Sep 2013
Location: Alert Bay, Vancouver Island
Boat: 35ft classic ketch/yawl.
Posts: 1,980
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Re: Inverter / Battery wired Incorrectly?
While in theory this setup is fine I suspect it is prone to problems and will continue to be so. The problem is because the batteries are wired in parallel but using 'standard' cable. The conventional way of doing this would be to have the batteries physically next to each other and connected with heavy copper bars. As they hare monted in different places this cannot be done so you have longer cable runs. Your problem was caused by quite significant corrosion which actually prevented charging. But even a minor difference in the resistance of the cabling to the 2 batteries could cause under charging to one battery. Even though it now seems to work you need to check the voltage at the battery terminals and preferably also the current. Even a drop of 0.1v to the more remote battery will significantly reduce the rate at which it charges but your charger may just see the other battery and think the whole bank is fully charged. Ideally what you want is a charge splitting system so each battery is charged separately. If not make sure the more remote on really is fully charged (ie has a charge rate of less than 3% of its a/h capacity when a voltage of 14.8v is applied.) Given that you say you are not to good on electrics you may want to get someone who knows about charging systems to sort it out otherwise you may find that one battery keeps dieing.
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15-05-2018, 08:51
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#9
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֍֎֍֎֍֎֍֎֍֎
Join Date: Apr 2006
Posts: 15,136
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Re: Inverter / Battery wired Incorrectly?
sarge-
Consider treating those terminals and fittings to discourage corrosion. If eveything is tinned copper, that's great. If not, baking soda and vinegar to clean, dry thoroughly, and once or twice a year smear some silicone grease (brake grease, light bulb grease, dielectric grease, any silicon grease) on them. That will protect them from stray moisture and acid vapors. And gives you the chance to just make sure nothing has worked itself loose.
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16-05-2018, 06:22
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#10
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cruiser
Join Date: Jan 2012
Location: Lake Ontario
Boat: Ontario 38 / Douglas 32 Mk II
Posts: 3,250
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Re: Inverter / Battery wired Incorrectly?
Quote:
Originally Posted by sgtPluck
I purchased my boat last fall, and was at a dock all winter so didn't use the inverter. Now that I've started using it I found that one of my batteries is dying, and that this battery isn't receiving charge from alternator or solar, even though it is part of house bank. (In theory at least. Also, physically it is not located with the other house battery) The other battery in the 'bank' is indeed receiving charge, as is the engine battery. Further, the inverter isn't getting power from the other battery in the 'house' bank, only the one that is dying / not getting charge.
I suspect there's something wrong with the way it is wired, but I'm electrically challenged, here is a simplified version of the wiring. Leaving out the engine battery.
The bad battery - the one that isn't receiving charge - is the one on the bottom. The negative from the Inverter is wired directly to that battery, and I'm wondering if that might be part of the problem.
Any thoughts greatly appreciated!
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Glad you found the poor connection.
FYI, (and maybe present but just not shown in your diagram) there should be a fuse (near the battery) and a switch in the connection from the battery to the inverter.
If not present, this may be a DPO (darned previous owner) mod.
If you are not familiar with marine electrical standards, consider hiring a marine electrical technician to look it over (and while at it, give the entire boat a quick inspection).
Improper battery wiring can be very dangerous, and DIY inverter installs are notorious for wiring and installation faults.
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