K4309 353 Posted August 12 Share Posted August 12 I have what I'm hoping is a simple question on VSR's, that I think I understand, but just want to make sure my understanding is correct. We have a basic battery system on our boat, single start batt and modest house bank. We have a standard switch bank that includes an isolating switch for each battery, a parallel switch for emergencies and a VSR so that the start battery gets charged first off the alternator. When the engine is off and the battery isolators have the batteries isolated and there is a charge source on the house batteries (solar normally, or right now a mains powered charger as we are in the shed doing work), the VSR will open, charging both batteries. Is it normal for the VSR to open and connect both batteries when the isolator switches are isolated? Below is the link to the BEP manual and wiring diagram. Whilst wiring diagrams normally make my brain explode, this one looks fairly simple, and there is a direct pathway between the two batteries via the VSR. It doesn't have any isolator switches on it. So as far as I can tell, it looks normal for the VSR to 'join' the batteries, provided the voltage is high enough. Am I missing anything? The main thing I've got to get my head around is the concept of charging both batteries off solar, not just the house batteries. I have some small parasitic loads on the house batteries (the battery monitor mainly) so have a small solar panel for floating. I like to monitor the battery resting voltages and what not and keep on getting foxed because the VSR is open and I'm dealing with two different batteries, not one. 710-140A_INSTR_BEP.pdf (bepmarine.com) Quote Link to post Share on other sites
aardvarkash10 1,065 Posted August 13 Share Posted August 13 interested on thoughts on this as well. As I am mid-rewiring on SO, should I: have the start battery as the primary ie all charging sources attach there, or; have the alternator only to the start and secondary charging (solar, shore) to the house, or; all charging sources to the house? Assume a VSR between the batteries. FWIW, I would intuatively choose option 2, but I'm not wedded to that. Supplimentary question should the charging sources be connected to the switched or unswitched side of the relevant isolator? FWIW, I would intuatively choose switched side for the alternator and unswitched side for solar. Final question If the VSR is between the batteries, should I connect the VSR to the switched or unswitched side of the isolators? FWIW, I would choose switched side. I'm aware that my logic is not clear - hoping for some clarity from the hive. Quote Link to post Share on other sites
CarpeDiem 510 Posted August 13 Share Posted August 13 2 hours ago, K4309 said: the VSR will open, charging both batteries. Is it normal for the VSR to open and connect both batteries when the isolator switches are isolated? You might need to clarify what you mean when you say the "vsr is open"? In an electrical sense open usually mean "open circuit" aka disconnected - eg there is an open air gap between the two wires. Your usage seems to imply that the circuit is "closed" eg, the wires are connected together... So for clarity in the rest of what I will spiel: CLOSED/CLOSE = the circuit is connected - if the VSR is closed then the batteries are connected in parallel OPENED/OPEN = the circuit is disconnected - the the VSR is OPEN then the batteries are disconnected from each other 2 hours ago, K4309 said: We have a basic battery system on our boat, single start batt and modest house bank. We have a standard switch bank that includes an isolating switch for each battery, a parallel switch for emergencies and a VSR so that the start battery gets charged first off the alternator. The VSR will close (depending on it's setup/features): 1. When the start circuit voltage reaches threshold (eg the engine is runnning or you have a battery charger connected) 2. When the house circuit voltage reaches threshold (eg you have a battery charger connected to the house battery) the VSR does absolutely not enstre that the start battery gets charged first off the alternator. circuit is purposefully emphasized - because it's not the voltage of the battery, it's the voltage of the circuit. 2 hours ago, K4309 said: The main thing I've got to get my head around is the concept of charging both batteries off solar, not just the house batteries. I have some small parasitic loads on the house batteries (the battery monitor mainly) so have a small solar panel for floating. I like to monitor the battery resting voltages and what not and keep on getting foxed because the VSR is open and I'm dealing with two different batteries, not one. If the VSR is closed you are dealing with one circuit. In a perfect world the voltage would be exactly the same across the entire circuit, any differences you see are due to voltage drop due to resistance of the components/wires etc. You can't monitor the voltage of either battery independant of the circuit voltage. Regarding this feature: When the house circuit voltage reaches threshold (eg you have a battery charger connected to the house battery) You can modify the installation to prevent this, by paying attention to the ignition control and storage mode sections of the manual and the red loop on the VSR. Ultimately it depends on what you want to achieve. But charging two different batteries off a single charger is a recipe for dead batteries and I can't recommend it. Quote Link to post Share on other sites
CarpeDiem 510 Posted August 13 Share Posted August 13 1 hour ago, aardvarkash10 said: interested on thoughts on this as well. As I am mid-rewiring on SO, should I: have the start battery as the primary ie all charging sources attach there, or; have the alternator only to the start and secondary charging (solar, shore) to the house, or; all charging sources to the house? Assume a VSR between the batteries. FWIW, I would intuatively choose option 2, but I'm not wedded to that. Supplimentary question should the charging sources be connected to the switched or unswitched side of the relevant isolator? FWIW, I would intuatively choose switched side for the alternator and unswitched side for solar. Final question If the VSR is between the batteries, should I connect the VSR to the switched or unswitched side of the isolators? FWIW, I would choose switched side. I'm aware that my logic is not clear - hoping for some clarity from the hive. Use a DC/DC charger to charge the start battery from the house battery. Keep the start battery floating at 13.1v. Use a solar and/or shore charger on the house battery. The DC/DC will take care of the start battery. Get rid of the VSR. Keep the parallel switch, or get rid of that too and carry jumper leads. Connect your alternator to the house battery and set up an appropriate charging profile for your house batteries using a programable alternator regulator. Depending on your engine you might need to wire the management unit into seeing the voltage from the house battery to prevent low voltage alarms instead of the start battery if the DC/DC isn't grunty enough to bring the circuit voltage high enough and fast enough after an engine start. Put engine service disconnect switch located in the engine bay on the circuit from the alternator to the house battery, you should fuse this. Connect the charging sources directly to the battery. Use the isolator switch to disconnect the house loads, not the charging sources. It's a good idea to maintain an emergency/maintenance disconnect switch, install this on the negative cable of the house battery and another on the negative cable of the start battery. Ideally a DPST swicth clearly marked "switch off in the event of smoke" - this is absolutely for emergencies, or complete isolation for maintenance - if you swicth this off the engine running you will likely smoke your alternator. NB: above assumes a non LFP install 2 Quote Link to post Share on other sites
grant 44 Posted August 14 Share Posted August 14 On 13/08/2024 at 1:17 PM, CarpeDiem said: You might need to clarify what you mean when you say the "vsr is open"? In an electrical sense open usually mean "open circuit" aka disconnected - eg there is an open air gap between the two wires. Your usage seems to imply that the circuit is "closed" eg, the wires are connected together... So for clarity in the rest of what I will spiel: CLOSED/CLOSE = the circuit is connected - if the VSR is closed then the batteries are connected in parallel OPENED/OPEN = the circuit is disconnected - the the VSR is OPEN then the batteries are disconnected from each other The VSR will close (depending on it's setup/features): 1. When the start circuit voltage reaches threshold (eg the engine is runnning or you have a battery charger connected) 2. When the house circuit voltage reaches threshold (eg you have a battery charger connected to the house battery) the VSR does absolutely not enstre that the start battery gets charged first off the alternator. circuit is purposefully emphasized - because it's not the voltage of the battery, it's the voltage of the circuit. If the VSR is closed you are dealing with one circuit. In a perfect world the voltage would be exactly the same across the entire circuit, any differences you see are due to voltage drop due to resistance of the components/wires etc. You can't monitor the voltage of either battery independant of the circuit voltage. Regarding this feature: When the house circuit voltage reaches threshold (eg you have a battery charger connected to the house battery) You can modify the installation to prevent this, by paying attention to the ignition control and storage mode sections of the manual and the red loop on the VSR. Ultimately it depends on what you want to achieve. But charging two different batteries off a single charger is a recipe for dead batteries and I can't recommend it. unrelated question, does a VSR need to have a voltage on both sides to work? thinking of a non-bating application where i want to switch something on only over a specified voltage. so battery on one side and a load on the other Quote Link to post Share on other sites
CarpeDiem 510 Posted August 14 Share Posted August 14 1 hour ago, grant said: unrelated question, does a VSR need to have a voltage on both sides to work? thinking of a non-bating application where i want to switch something on only over a specified voltage. so battery on one side and a load on the other It would depend on the product, if the VSR is deisgned to connect to batteries you'd have to test it to see - it needs to get it's logic power from one side or the other... Depending on what you want to do, the voltage might not always come up to trigger value immediately, if it's a charging source, eg a very drained house battery could result in the alternator outputting less than 13.4v for several hours. Addtionally when the load comes on it could drop the voltage output causing the vsr to disconnect. Better to use an ignition on source, or maybe the alternator charge lamp if you really need to be sure the engine is running... 1 1 Quote Link to post Share on other sites
mattm 106 Posted August 14 Share Posted August 14 2 hours ago, grant said: unrelated question, does a VSR need to have a voltage on both sides to work? thinking of a non-bating application where i want to switch something on only over a specified voltage. so battery on one side and a load on the other Yeah, that will work. I’ve seen it done with the BEP VSR’s. One side powers the VSR, that side must be to your supply voltage, or the VSR wont work. 1 Quote Link to post Share on other sites
mattm 106 Posted August 14 Share Posted August 14 On 13/08/2024 at 1:38 PM, CarpeDiem said: Use a DC/DC charger to charge the start battery from the house battery. Keep the start battery floating at 13.1v. Use a solar and/or shore charger on the house battery. The DC/DC will take care of the start battery. Get rid of the VSR. Keep the parallel switch, or get rid of that too and carry jumper leads. Connect your alternator to the house battery and set up an appropriate charging profile for your house batteries using a programable alternator regulator. Depending on your engine you might need to wire the management unit into seeing the voltage from the house battery to prevent low voltage alarms instead of the start battery if the DC/DC isn't grunty enough to bring the circuit voltage high enough and fast enough after an engine start. Put engine service disconnect switch located in the engine bay on the circuit from the alternator to the house battery, you should fuse this. Connect the charging sources directly to the battery. Use the isolator switch to disconnect the house loads, not the charging sources. It's a good idea to maintain an emergency/maintenance disconnect switch, install this on the negative cable of the house battery and another on the negative cable of the start battery. Ideally a DPST swicth clearly marked "switch off in the event of smoke" - this is absolutely for emergencies, or complete isolation for maintenance - if you swicth this off the engine running you will likely smoke your alternator. NB: above assumes a non LFP install Get rid of the vsr and parallel switch? jumper leads??? 🥴 some of the things you suggest might be considered ‘best practice’ by some, but I think on simple boats are unneccesary, over complicated and more expensive for little gain. My basic yacht go to is vsr, start, house and parallel (plus winch etc) switches (better yet BEP’s new(ish) 772-DBC), and ideally a smart alt. reg if within the budget. I routinely get 10 years out of the good brand of AGM’s I prefer to use, that’s with combined charging via the vsr. All programmable charging set for the house bank. Shore power charger. Solar is great if there’s room, requirement and budget. VSR connected live to batteries along with shore charge and solar. Alternator switched, fused at battery end only, to which bank depending on specifics. Simple. 1 1 Quote Link to post Share on other sites
CarpeDiem 510 Posted August 14 Share Posted August 14 7 minutes ago, mattm said: things you suggest might be considered ‘best practice’ by some, but I think on simple boats are unneccesary, over complicated and more expensive for little gain. Couldn't agree more - it's a opinion everyone has one 3 Quote Link to post Share on other sites
aardvarkash10 1,065 Posted August 14 Share Posted August 14 cool range of "opinions". Thanks CD for the detailed description. On SO we have lead/acid (one wet, one AGM) so I'm not going to spring for a B2B system, and the VSR is staying (hey, it has been using a heavy relay triggered off the alternator warning light... VSR is high tech by my standards). No shore power. Thanks Matt for the contra-opinion. Your "simple yacht" statement aligns. Both have helped me clarify the needs and so the plan. Quote Link to post Share on other sites
Guest 109 Posted August 14 Share Posted August 14 I have an ACR free to good home. Quote Link to post Share on other sites
Guest 109 Posted August 14 Share Posted August 14 I rewired my boat with custom (scavenged Porsche alternator) and ext regulator direct to house with ACR to start and 4x6v LA’s. Three switch setup . After 8yrs I got tired of FLA’s and got enamoured with LFP. 18mnths into LFP now and I consider mine simple when I look at the kit on some installs. Just bit the bullet and went LFP on a car. Next project maybe trying to find the Saic parameter ids for individual cell monitoring with a can sniffer. All ready done for the ZS model cell max delta, but not for mg4. Dismayed by not having access to bms on MG4 as opposed by my humble LFP boat install. Leaf aficionados, have a great utility in Leafspy. Quote Link to post Share on other sites
ballystick 79 Posted August 14 Share Posted August 14 2 hours ago, Guest said: I rewired my boat with custom (scavenged Porsche alternator) and ext regulator direct to house with ACR to start and 4x6v LA’s. Three switch setup . After 8yrs I got tired of FLA’s and got enamoured with LFP. 18mnths into LFP now and I consider mine simple when I look at the kit on some installs. Just bit the bullet and went LFP on a car. Next project maybe trying to find the Saic parameter ids for individual cell monitoring with a can sniffer. All ready done for the ZS model cell max delta, but not for mg4. Dismayed by not having access to bms on MG4 as opposed by my humble LFP boat install. Leaf aficionados, have a great utility in Leafspy. Why not buy a cheap Launch scantool or similar with Bluetooth dongle through Ali-express to get battery data 1 Quote Link to post Share on other sites
ballystick 79 Posted August 14 Share Posted August 14 2 hours ago, Guest said: I rewired my boat with custom (scavenged Porsche alternator) and ext regulator direct to house with ACR to start and 4x6v LA’s. Three switch setup . After 8yrs I got tired of FLA’s and got enamoured with LFP. 18mnths into LFP now and I consider mine simple when I look at the kit on some installs. Just bit the bullet and went LFP on a car. Next project maybe trying to find the Saic parameter ids for individual cell monitoring with a can sniffer. All ready done for the ZS model cell max delta, but not for mg4. Dismayed by not having access to bms on MG4 as opposed by my humble LFP boat install. Leaf aficionados, have a great utility in Leafspy. Apparently https://play.google.com/store/apps/details?id=com.ovz.carscanner&hl=en_GB&gl=US this has access to battery data - Version 1.98.6 has added support for the MG4. I've had a brief try of the free version, and the All Sensor list does display values for quite a lot of the EV variables, some of them jump to silly values occasionally. Things like SoC, SoH, battery cell min/max/difference values, battery voltage, instant consumption etc. 1 Quote Link to post Share on other sites
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