How do I add a third battery (second house battery) to the stock two battery DVSR system?

[Ronnie]

I’m hoping some of this site’s electrical gurus can help me out here.

For context, I have a 2010 242 LS with the stock DVSR switching system (currently attached to two batteries, a start and a separate house battery). An aftermarket two bank onboard charger/maintainer Is also installed along with bus bars to the house switch module of the OEM system and to create a common ground for the entire system. The negative sensor lead from the dvsr module is attached to the common ground bus bar.

My goal is to run two of the same model house batteries in parallel to double amps but keep the voltage the same (12v).

Do I simply run, from the new/third battery, a new positive (+) cable to the house switch module’s bus bar and a new negative (-) cable to the common ground bus bar?

Will this effectively double my house battery capacity/usage time?

Should I use the two bank onboard charger on both house batteries or to charge the start battery and one house battery?

If I use the two bank onboard charger on the the start and one house battery would I not be charging the second house battery as well, just at half the voltage since both house batteries are wired in parallel?

 

[Tjw961]

I can't answer the charger part being a 2 batt charger as I have 3 connection battery charger, but what I did doing the same thing with the batteries (1 for start, 2 for house) by running both house batteries to a + bus bar before they connect to on/off switch. Neg to negative bus bar for all batteries and neg connections. My 3 connection battery charger has each lead going to each of the 3 batteries. With a 2 connection battery charger I would look into if possible to connect to the + bus bar in config I mention above. Charge rate for two batteries at once i would think being shared would be affected in than approach though. Or you could still direct attach the two to your house batteries and then add a second single connection battery charger to get to three on starter battery. Others here im sure have more ideas.

 

[FSH 210 Sport]

I’m hoping some of this site’s electrical gurus can help me out here.

For context, I have a 2010 242 LS with the stock DVSR switching system (currently attached to two batteries, a start and a separate house battery). An aftermarket two bank onboard charger/maintainer Is also installed along with bus bars to the house switch module of the OEM system and to create a common ground for the entire system. The negative sensor lead from the dvsr module is attached to the common ground bus bar.

My goal is to run two of the same model house batteries in parallel to double amps but keep the voltage the same (12v).

Do I simply run, from the new/third battery, a new positive (+) cable to the house switch module’s bus bar and a new negative (-) cable to the common ground bus bar?

Will this effectively double my house battery capacity/usage time?

Should I use the two bank onboard charger on both house batteries or to charge the start battery and one house battery?

If I use the two bank onboard charger on the the start and one house battery would I not be charging the second house battery as well, just at half the voltage since both house batteries are wired in parallel?

Just put the two house batteries in parallel. This will double your house battery amp hours.

The voltage will still be 12 volt on your paralleled house batteries when charging, but the time it takes to charge your house batteries will be take longer since the House batteries are sharing the single charge lead from your charger. Once your start battery is charged up to 13.2 volts the DVSR will close and parallel all three batteries, and your two bank charger will now be charging all three batteries. The best option is to have a three bank charger, one for each battery.

As far as wiring goes you can either connect your second house battery to the house bus at the DVSR switch, or you could just parallel the two house batteries together With their own leads.

 

[Ronnie]

Thanks @Tjw961 and @FSH 210 Sport. I’m leaning towards paralleling the two house batteries together with their own leads (I.e., positive to positive and negative to negative) since this won’t require me to rework any of the wiring at the switches or the bus bars. I think I will have the two bank charger only charge the house batteries and I will put a separate changer on the start battery. I already have all the materials and don’t anticipate that this upgrade / modification will take long.

I experienced a few low aux voltage alarms in the past when I have used the boat for two days in a row without putting the batteries on a charger overnight and my last time out on the boat, the first time this season I got a “voltage” alarm that out the port engine into safe mode (wouldn’t allow it to spin up past 3k rpms) until I shut down and restarted the engines initially, the second time it happened (a few minutes later) I also combined the power of the two batteries. I made it back to the ramp without seeing the alarm again. I’m not sure if this was an overchaeged Start battery alarm since thegauges read that both batteries were between 13.6 and 14.3 volts and when I had all the batteries Check at the interstate battery shop they came back with a clean bill of health. The rep said the interstate start battery was putting out 1,200 CCA even though it’s rated at 800 CCA, he went on to state that I may end up getting another 5 years out of this 5 year old battery.

it’s worth noting that I forgot to switch the dvsr negative lead on (complete the circuit) when I was on the water. I will probably just leave it in the on position going forward or remove the switch entirely.

please let me know if you think I’m about to Jack something up. I’d rather continue to deal with these voltage alarms than end up replacing the entire or part of the OEM charging system, especially now at the start of the season and with seemingly everything being in short supply.

Thanks again, I really appreciate it.

 

[FredB32]

Any updates on how this worked out? From the reading I'm doing, unless you disable the DVSR any multi-bank charging unit is going to essentially charge ALL the batteries vs. each on individually, since the DVSR will pick up the voltage and switch it. I'm taking all the threads I've read as that's what the DVSR is literally for, so it makes perfect sense, but there are ways around it.

Wondering if any of you with multiple batteries have actually monitored to see what's happening?

 

[212s]

Wondering if any of you with multiple batteries have actually monitored to see what's happening?

If all the batteries are in good condition, the DVSR will connect them all together like you said and charge them as "one" without any issues as the electron flow will balance itself naturally across the batteries, regardless of their state of charge. The problem is sometimes you have an old or weak battery in the mix and it will then suffer plate damage as the others charge up just fine. As long as they're all good batteries, you don't necessarily need a 2 or 3 bank charger. And if you have 3 batteries total, two of them in parallel for the house side, then a 3 bank charger is a waste as the two house batteries are never isolated unless you install a heavy duty switch or disconnect the battery cables manually during every charge.

Of more concern is the size of the charger in amp capacity. If you regularly run the pair of house batteries down low without a chance to charge on the water, then you need a 2 bank with enough current to charge them fully before the next day or the batteries will begin to sulfate. A 10 amp per bank or better is recommended for this scenario.

For my mild setup (500w stereo), I just have a single bank charger and the DVSR connects the start and house together to keep them both topped up.

 

[FredB32]

For my mild setup (500w stereo), I just have a single bank charger and the DVSR connects the start and house together to keep them both topped up.

Got my battery charger hooked up last night, and am simply using it as a single bank for right now with the DVSR. The longer-term plan is to add a third battery and charge each battery individually. I'll have to see how it goes with the current setup, as the batteries have build dates of 4/17 and after a bit of cruising, settle in around 11.1-11.5v floating, which makes me think I'll need to pull them and try a "fix", or more likely just replace them with new ones after the season. That will give me a chance to re-wire the DVSR as well and utilize the 3-bank charger. Overall it probably doesn't need 3 batteries right now with the factory Wet Sounds system, but we'll likely upgrade that somewhere in the not distant future as well. It's nice for a factory system, but not overly impressive on the whole (I come from a pretty lengthy car audio background!).

At this point, I'm not even certain that pulling the batteries and running the "fix" cycle on them with the NOCO would even be worthwhile, when for a small investment I can start fresh with new batteries and just take better care of them than the previous owner did.

Do you have a link to your build or anything? I'm new to forum and still figuring out navigation here, but I'll look myself too!

 

[FSH 210 Sport]

Got my battery charger hooked up last night, and am simply using it as a single bank for right now with the DVSR. The longer-term plan is to add a third battery and charge each battery individually. I'll have to see how it goes with the current setup, as the batteries have build dates of 4/17 and after a bit of cruising, settle in around 11.1-11.5v floating, which makes me think I'll need to pull them and try a "fix", or more likely just replace them with new ones after the season. That will give me a chance to re-wire the DVSR as well and utilize the 3-bank charger. Overall it probably doesn't need 3 batteries right now with the factory Wet Sounds system, but we'll likely upgrade that somewhere in the not distant future as well. It's nice for a factory system, but not overly impressive on the whole (I come from a pretty lengthy car audio background!).

At this point, I'm not even certain that pulling the batteries and running the "fix" cycle on them with the NOCO would even be worthwhile, when for a small investment I can start fresh with new batteries and just take better care of them than the previous owner did.

Do you have a link to your build or anything? I'm new to forum and still figuring out navigation here, but I'll look myself too!

You could just disconnect each batteries ground and run an equalizing charge on each battery and that may breathe some life back into them.

 

[212s]

settle in around 11.1-11.5v floating,

At this point, I'm not even certain that pulling the batteries and running the "fix" cycle on them with the NOCO would even be worthwhile, when for a small investment I can start fresh with new batteries and just take better care of them than the previous owner did.

That's what I'd do because 11.5v while floating is almost a dead battery. If you can start your engines ok, then I'd think the house is the weak battery and it's pulling down the start battery. Good batteries will read 12.6-12.7v when fully charged and resting.

I still have the original 3 year old Yamaha batteries in my boat, just basic "marine starting" batteries, as we don't usually crank the tunes too much when floating and they go on the charger after the weekend and during storage to keep them in good shape.
[/quote]Do you have a link to your build or anything? I'm new to forum and still figuring out navigation here, but I'll look myself too!
[/QUOTE]
No build post as it's pretty simple really. A search for "second battery" or "third battery" or similar should get you lots of hits.

 

[hastings246]

I am thinking of adding a third battery to parellel on the house but I have a 3 bank charger. i would assume I would need a switch between the 2 house batteries to isolate them when I put the bank charger on? I was looking at the BEP three battery distro but that seems really complicated. Thanks for any quick advice. Adding a upgrade stereo and not sure I have enough juice with just the house stock battery.

 

[Judge]

I am thinking of adding a third battery to parellel on the house but I have a 3 bank charger. i would assume I would need a switch between the 2 house batteries to isolate them when I put the bank charger on? I was looking at the BEP three battery distro but that seems really complicated. Thanks for any quick advice. Adding a upgrade stereo and not sure I have enough juice with just the house stock battery.

You can add another house battery in parallel full-time but it depends on a few factors like the size of your charger and the maximum output of the stator. The users manual doesn't list the specs on the stator but if you have a 20A - 50A charger, it can charge both batteries in parallel if you are going to be running them down quite a bit.

In motorhome applications this is very common. You often will see 2 or 4 house batteries in parallel. Motorhomes typically have a 40A or 60A onboard charger to charge the batteries on shore power and the engine alternator usually has enough output to handle charging several batteries. While the engine is running a BIM (similar to the DVSR) will determine when to connect the house batteries so the alternator can charge them.

You don't want to add a new battery in parallel to a battery that is already two years old. If you have 85Ah battery installed, you want to install another 105Ah battery..... that would give you 85Ah of power.

Just remember that you really only have about 1/2 the rated batter capacity to use for an AGM or wet battery. You don't want to discharge lead acid battery more than 50% of its capacity before charging them back up. If you keep discharging them past 50%, you will drastically shorten their lifespan.

 

[hastings246]

Hello, thanks for the response. Today I have a noco 5a per bank charger which I got on a deal so I was going to try that unless it can't handle. I just have the stock 800cca batteries and they are new so I thought I would just add a third keep the wiring and maybe add a switch between the parallels so I can isolate them for the bank charger. Seemed like the easiest for now.

 

[Judge]

Hello, thanks for the response. Today I have a noco 5a per bank charger which I got on a deal so I was going to try that unless it can't handle. I just have the stock 800cca batteries and they are new so I thought I would just add a third keep the wiring and maybe add a switch between the parallels so I can isolate them for the bank charger. Seemed like the easiest for now.

The 5A will probably work ok. If they get seriously discharged it could take a while to get them charged back up.

 

[FSH 210 Sport]

I am thinking of adding a third battery to parellel on the house but I have a 3 bank charger. i would assume I would need a switch between the 2 house batteries to isolate them when I put the bank charger on? I was looking at the BEP three battery distro but that seems really complicated. Thanks for any quick advice. Adding a upgrade stereo and not sure I have enough juice with just the house stock battery.

If you want the oem start and house batteries to charge independently youll need to either put a switch on the ground of the DVSR, or cut the red wire on the back of the DVSR and run it to an ignition hot or up to one of your spare rocker switches to keep the DVSR from paralleling the start and house batteries while they are charging off of the on board charger. Charging independently is a good idea on flooded lead acid batteries as you will be able to run an equalizing on each battery which is very import to get the most performance out of the flooded lead acid batteries. Most modern multi bank chargers have a manually activated equalizing charge profile that should be done monthly during the season and heavy usage. Not only does an equalizing charge clean the plates, it also causes the electrolyte to get stirred and eliminate stratification. One of the most important things to do is to get your batteries on a charger as soon as you get home after a day on the water to prevent sulphication of the plates.

As @Judge points out, lead acid batteries can only be discharged 50% without damaging them. Your 5A NOCO charger will take roughly 18 hours to re charge a 100 Ah lead acid battery that has been discharged 50Ah or 50%. The further a lead acid battery is discharged the longer the absorption phase will be. In my opinion you need a minimum of a 10a per bank charger.

Since you don’t know how much your house battery is going to be drained, perhaps installing a Victron smart shunt ($125) with bluetooth would be the first step. These devices are very easy to install and will measure the Ah’s used, instantaneous amps, KWh’s used and voltage, and will show state of charge in percentage. You simply download the app and read everything off of your phone or tablet. Otherwise you just don’t know what’s really going on.

Once you have the consumption numbers figured out you will be able to make a better decision on what you really need in terms battery capacity.

If you think you’d like to go with a LiFePO4 house battery check out my battery upgrade thread, the link is in my signature. That was quite a journey but well worth it ! You could probably just put in one 100Ah LiFePO4 house battery and be set.

 

[Judge]

If you want the oem start and house batteries to charge independently youll need to either put a switch on the ground of the DVSR, or cut the red wire on the back of the DVSR and run it to an ignition hot or up to one of your spare rocker switches to keep the DVSR from paralleling the start and house batteries while they are charging off of the on board charger. Charging independently is a good idea on flooded lead acid batteries as you will be able to run an equalizing on each battery which is very import to get the most performance out of the flooded lead acid batteries. Most modern multi bank chargers have a manually activated equalizing charge profile that should be done monthly during the season and heavy usage. Not only does an equalizing charge clean the plates, it also causes the electrolyte to get stirred and eliminate stratification. One of the most important things to do is to get your batteries on a charger as soon as you get home after a day on the water to prevent sulphication of the plates.

As @Judge points out, lead acid batteries can only be discharged 50% without damaging them. Your 5A NOCO charger will take roughly 18 hours to re charge a 100 Ah lead acid battery that has been discharged 50Ah or 50%. The further a lead acid battery is discharged the longer the absorption phase will be. In my opinion you need a minimum of a 10a per bank charger.

Since you don’t know how much your house battery is going to be drained, perhaps installing a Victron smart shunt ($125) with bluetooth would be the first step. These devices are very easy to install and will measure the Ah’s used, instantaneous amps, KWh’s used and voltage, and will show state of charge in percentage. You simply download the app and read everything off of your phone or tablet. Otherwise you just don’t know what’s really going on.

Once you have the consumption numbers figured out you will be able to make a better decision on what you really need in terms battery capacity.

If you think you’d like to go with a LiFePO4 house battery check out my battery upgrade thread, the link is in my signature. That was quite a journey but well worth it ! You could probably just put in one 100Ah LiFePO4 house battery and be set.

I actually just installed a battery disconnect switch directly off each battery's positive post for this very reason as I put the boat in storage. I wish Yamaha would have wired the bypass option but since they didn't, I'll turn off each battery disconnect when I plug in my onboard charger. No need for the DVSR to be doing anything in storage.

 

[FSH 210 Sport]

Battle Born has a ton of info on their website….

Here’s the link to the battery monitoring page.

Battery Monitors Archives

Your comprehensive guide to a lithium battery set up and how to monitor battery activity.

battlebornbatteries.com

Anyone who is adding batteries, stereo’s etc would be well served by installing a good battery monitor first to determine what the real load / consumption is, then sizing a battery bank accordingly, as I said above, the Bluetooth shunt is super simple to instal. Just looking at the OEM Connext volt meter takes a little bit of guess work out of the equation, but is far from you knowing what is really going on.

 

[Judge]

Battle Born has a ton of info on their website….

Here’s the link to the battery monitoring page.

Battery Monitors Archives

Your comprehensive guide to a lithium battery set up and how to monitor battery activity.

battlebornbatteries.com

Anyone who is adding batteries, stereo’s etc would be well served by installing a good battery monitor first to determine what the real load / consumption is, then sizing a battery bank accordingly, as I said above, the Bluetooth shunt is super simple to instal. Just looking at the OEM Connext volt meter takes a little bit of guess work out of the equation, but is far from you knowing what is really going on.

Good point!

I installed a Victron 500 Smart Shunt before doing a Lithium conversion in the motorhome. They are well worth the money if you spend a lot of time running on the batteries and / or have things that can chew up a lot of power.

 

[FSH 210 Sport]

Good point!

I installed a Victron 500 Smart Shunt before doing a Lithium conversion in the motorhome. They are well worth the money if you spend a lot of time running on the batteries and / or have things that can chew up a lot of power.

I will probably do the same at some point for my travel trailer…I just installed the Victron IP67 25 A battery chargers for my boat yesterday, these chargers should cut my charge time down from 12-14 hours to 4. I didn’t take a pic after I finished last night.. The CSR I was talking to who helped me set up the Victron IP67 25A battery chargers to exactly what BB likes (the chargers come with a Li-Ion charge algorithm but is customizable and is easy to do) had told me to check out their blog page, man, there is a lot of info there. Accessories Archives

 

[Judge]

That’s great!

Victron makes very good products. I think you’ll be very happy with your setup and cutting your charge time that much.

If you ever consider Lithium for your travel l trailer, check out BigBattery.com

They make high quality batteries and they have the best Ah per dollar on the market. Their batteries also have a built-in On / Off switch, voltage readout and quick disconnect cables.

 

[FSH 210 Sport]

That’s great!

Victron makes very good products. I think you’ll be very happy with your setup and cutting your charge time that much.

If you ever consider Lithium for your travel l trailer, check out BigBattery.com

They make high quality batteries and they have the best Ah per dollar on the market. Their batteries also have a built-in On / Off switch, voltage readout and quick disconnect cables.

They sound good but I need ones with heaters for when it gets really cold..