Best charge controller for multiple sources and multiple batteries

[chal]

I am looking at upgrading my battery system.

My current arrangement is:

- leisure battery, 110 AH, basic sealed wet lead-acid, for house
- ordinary car battery, 70 AH, for engine start
- engine alternator connected to engine battery
- single solar panel connected to house battery
- yandina charge combiner

I'm on a swinging mooring so no mains.

The house battery is getting a bit tired so I am thinking of replacing it, and maybe upgrading the whole charging system so I have more input. I'm thinking of adding another solar panel fairly soon, and then a wind turbine later when I can afford it. I'm also thinking of doubling the number of house batteries.

The ideal (I think!) would be a controller that could handle all those inputs, and manage the charging so that the engine battery gets charged first, then it charges the house batteries. The latter will be identical since I'll be buying them at the same time.

Any suggestions?

 

[FullCircle]

A Digital Voltage SAensitive Relay (DVSR) I have had one of these on my boat (the previous model actually) for 5 seasons. They do work, and it is relatively economical.


http://www.force4.co.uk/9173/BEP-Voltage-Sensitive-Relay--DVSR-.html


Best used with an alternator charge controller for best alternator output.


http://www.force4.co.uk/1005/Sterling-Pro-Reg-B-Advanced-Alternator-Regulator.html

But that is not in any way mandatory.

Continue to feed the solar through the DVSR, and it will charge both batteries

 

[halcyon]

I

The ideal (I think!) would be a controller that could handle all those inputs, and manage the charging so that the engine battery gets charged first, then it charges the house batteries. The latter will be identical since I'll be buying them at the same time.

Any suggestions?

What is the problem with you current combiner ?

The solar panels, wind gen will be connected to service battery via suitable regulators, the charge combiner will link in the engine battery when suitable voltage is available, and service battery when engine is on charge.


Or are you trying to do something different ?

Brian

 

[chal]

not particularly something different...

Calder (as I recall) recommends a charging system that does something along the lines of first charge the crank battery, then charge the house battery, because they are different types of battery and will charge most effectively in different ways. There also seem to be ways of dealing with the combined inputs of the solar panels and the possible wind turbine so that max charging benefit is derived in any given situation.

Sometimes I think that Calder is very good but recommends things that are so expensive and/or complicated that it's better to put up with something a bit more basic. So, maybe I'd be better to stick with what I've got and just add the extra battery.

If I do that, can I simply connect all the charge sources except the alternator to the house batteries, assuming that each device has a charge regulator? The solar panel I have now has an integrated regulator, and I have a spare regulator I could use with another panel, so that would be the arrangement. I'm not likely to be able to afford the wind turbine for a while yet so could ignore that for the time being.

I also find the yandina a bit unpredictable: sometimes it shows on when I would expect it to be off, and other times off when I would expect it to be on, so I'm never quite sure what it's doing. I can't get the override (to switch it off) to work either. It looks like the DVSR suggested by FullCircle might be better if I'm right in assuming that it only parallels when the engine battery is fully charged

 

[ghostlymoron]

not particularly something different...

Calder (as I recall) recommends a charging system that does something along the lines of first charge the crank battery, then charge the house battery, because they are different types of battery and will charge most effectively in different ways. There also seem to be ways of dealing with the combined inputs of the solar panels and the possible wind turbine so that max charging benefit is derived in any given situation.

Sometimes I think that Calder is very good but recommends things that are so expensive and/or complicated that it's better to put up with something a bit more basic. So, maybe I'd be better to stick with what I've got and just add the extra battery.

If I do that, can I simply connect all the charge sources except the alternator to the house batteries, assuming that each device has a charge regulator? The solar panel I have now has an integrated regulator, and I have a spare regulator I could use with another panel, so that would be the arrangement. I'm not likely to be able to afford the wind turbine for a while yet so could ignore that for the time being.

I also find the yandina a bit unpredictable: sometimes it shows on when I would expect it to be off, and other times off when I would expect it to be on, so I'm never quite sure what it's doing. I can't get the override (to switch it off) to work either. It looks like the DVSR suggested by FullCircle might be better if I'm right in assuming that it only parallels when the engine battery is fully charged

What's a yandina?
The digital VSR suggested earlier is dual sensing which means that you can connect your alternative power sources (wind or solar) to the house batteries and it will then sense when that battery is fully charged and allow volts to overflow back to the start battery as well as overflowing the other way from the alternator. I had the earlier single sense (and non-digital) version and it worked very well - no risk of flat batteries which is every boaters nightmare.

 

[chal]

What's a yandina?

it's a "battery combiner" - it's relay operated and supposed to parallel batteries if either is receiving a charge. That is a bit more primitive than diverting charge once the battery is fully charged, assuming that's what the DVSR does.

I suppose that's really the point of my original question: if the engine is running so the alternator is producing current, and the sun is shining so the solar panel is too, then something as simple as my battery combiner is just going to connect everything to everything irrespective of their relative states of charge, and there is probably a better way of doing things than this.

 

[BabaYaga]

diverting charge once the battery is fully charged, assuming that's what the DVSR does.

In my humble opinion it does not make much sense to fully charge one battery bank and only then start charging the other one.

I also doubt that a voltage sensitive relay will achieve this (although they are often claimed to do so).

In a typical charging situation the starting battery will not be much discharged, so the voltage will rise quickly and the relay close, perhaps within seconds.

If your engine is not particularly difficult to start (so that the starter battery often gets heavily discharged) perhaps it is better to take the alternator output to the house batteries first and then, via a relay, feed the start battery. You do not necessarily need to use a VSR, an ordinary relay controlled by alternator D+ (charge light) will do. An emergency paralleling switch is useful as a "safety net" with this set up.

Doubling the house capacity is probably a very good idea. Before buying some advanced alternator regulator or controller, find out at what voltage your alternator's internal regulator is charging at (with batteries fully charged). If approximately 14,4 V, the benefit will be marginal.

 

[halcyon]

it's a "battery combiner" - it's relay operated and supposed to parallel batteries if either is receiving a charge. That is a bit more primitive than diverting charge once the battery is fully charged, assuming that's what the DVSR does.

I suppose that's really the point of my original question: if the engine is running so the alternator is producing current, and the sun is shining so the solar panel is too, then something as simple as my battery combiner is just going to connect everything to everything irrespective of their relative states of charge, and there is probably a better way of doing things than this.

It's the same animal, just a posher sounding name.

The theory of a VSR is that

You charge the first battery to the trip point of the relay, the relay closes combining the battery bank.

Battery 2 is at a lower voltage and resistance, so current flows to this battery and the voltage you see falls, so it is now below the level required to charge battery 1, so the charge current flows to battery 2.

As you charge battery 2, the voltage rises with the charge level till it reaches the level that battery 1 starts tacking a charge, and the batteries now carry charging as one large battery.

It's a little more complicated, but that's how a VSR distributes the charge, the control function has no effect on distribution though.

So you should be able to use your current unit, so sorry, you may not have to spend any money.

Brian

 

[chal]

So you should be able to use your current unit, so sorry, you may not have to spend any money.
Brian

Great! And thanks for the info.