How can I check batteries are fully charged?

[Rob99fla]

Hi. Firstly, we are CC's with no hookup. I have a Victron 12/3000/120 inverter charger, Victron BMV602s battery monitor, 110amp alternator, Honda 1kw generator, Victron 30amp solar controller with 3x 100w solar panels. I have fitted 4x new Yuasa 115amp hr batteries. These are set as first set had faults within a few weeks (from Halfords are the batteries). When I charge the batteries from alternator, the BMV shows about 70amp initially and over a few hours reduces down to about 5-6 amp tail current. Charge voltage is about 14.3 volts. The BMV shows 100%. I always leave the engine running longer to see the tail current low as possible. I sometimes use the Honda generator to top up the batteries making sure they reach float status. Although the BMV shows say 70amps used since 100% charge and SOC still says about 90% charge, the battery voltage is down to below 12 volts. We have a 240v fridge freezer (new) running off the inverter plus some TV, led lights and phone charging, the actual current since last recharge (from the BMV) is correct I assume? Could it just be duff batteries again? Any ideas?

[nicknorman]

<bites tongue to stop myself commenting on the mis-use of units>

 

 

It does sound as though you know what you are doing regarding the charging, if the tail current is down to around 5 or 6A then that is considered pretty well charged for your 460AH batteries. Although 14.3v is a bit low IMO. What voltage is the solar controller set to (probably not that relevant at this time of year) and what voltage is the Combi charger set to?

 

Anyway, from the sound of it the batteries' capacity is way down.

 

You don't say exactly which model of battery you got, I can't immediately find a 115AH Yuasa battery on the Halfords website. Personally I have never got on well with leisure batteries so my somewhat biased advice is to get some semi-traction batteries such as Trojans.

 

Edited to add, are you sure the BMV monitor is wired to pick up all current flowing in and out of the leisure batteries? If it wasn't, then I suppose the charge tail current could be higher than you think (batteries not actually well charged) and only a proportion of the discharge current actually being detected.

 

So the golden rule is that the only connections on the leisure battery negative posts are the interconnects with the other leisure battery negatives, but NOT the engine battery -ve. And the shunt. No other wires coming from the leisure battery negatives to anything else. Nope, not even that one!

 

We say this often on here and the posters say "oh no, there are no other wires on the battery negatives" but then when we press them, it transpires that "Oh yes there is a wire to the Combi, does that count?" (Of course it does!) Or "Oh yes, now I look properly there is a wire to the engine battery negative, surely that's OK?" (No it isn't!).

 

So have a good look!

Edited December 28, 2016 by nicknorman

[Martin Megson]

Hi Nick,

 

I'm concerned that my setup is not correct as I have a link between the engine and leisure negative terminals. Should I remove this ?

[nicknorman]

Hi Nick,

 

I'm concerned that my setup is not correct as I have a link between the engine and leisure negative terminals. Should I remove this ?

My post above is only relevant if you have a shunt-based battery monitor such as a BMV, NASA, Mastervolt BTM etc. For these, the above applies. The engine battery -ve should be on the other side of the shunt - so they are connected together, but via the shunt. If you don't have a shunt based meter then the engine battery -ve can normally be connected direct to the domestic battery -ve.

[Rob99fla]

Hi Nicknorman. Thanks for the helpful reply. I'm sure the only connection to the -ve side is the main cable to the shunt and a small wire to the -ve terminal on the battery. I'm sure this wire to the shunt connection. It was done when I bought the boat. I wired in the solar controller myself with the connection to -ve terminal to other side of the shunt as everything else is. I can see this is working ok as on a sunny day I see amps going into the batteries displayed on the BMV. Turning off the inverter switch, I see even more amps going in. So, I'm sure that part is fine. The alternator shows about 14.4 or 14.5 volts to the leisure batteries. I probably was being a but vague about that. I'm sure the batteries charge ok as when I use the generator to use the Victron charger, the charge voltage is about the same as is the starter battery on the other alternator (My BMV does both batteries)

 

The Halfords own 115ah are Yuasa. I've checked this. I have bought an accurate battery hydrometer as I intend to check every cell of the batteries. Two of the batteries don't show the little green indicator as they should do. I understand this is a simple hydrometer. So, I suspect bad batteries again. What I want to do is get my money back and fit 4x Trojan T-105 6v batteries as I've read these are good.

 

I still suslect the batteries as I'm sure they were fine voltage wise for the first few weeks.

 

Thanks again

[ditchcrawler]

Hi. Firstly, we are CC's with no hookup. I have a Victron 12/3000/120 inverter charger, Victron BMV602s battery monitor, 110amp alternator, Honda 1kw generator, Victron 30amp solar controller with 3x 100w solar panels. I have fitted 4x new Yuasa 115amp hr batteries. These are set as first set had faults within a few weeks (from Halfords are the batteries). When I charge the batteries from alternator, the BMV shows about 70amp initially and over a few hours reduces down to about 5-6 amp tail current. Charge voltage is about 14.3 volts. The BMV shows 100%. I always leave the engine running longer to see the tail current low as possible. I sometimes use the Honda generator to top up the batteries making sure they reach float status. Although the BMV shows say 70amps used since 100% charge and SOC still says about 90% charge, the battery voltage is down to below 12 volts. We have a 240v fridge freezer (new) running off the inverter plus some TV, led lights and phone charging, the actual current since last recharge (from the BMV) is correct I assume? Could it just be duff batteries again? Any ideas?

When you measured the voltage at 12 volts did you have any load on the batteries at all. From what I have read I would discount the SOC reading. If your batteries were fully charged and you have only used 70 Ah then your SOC should be about 80% which should give a no load voltage of about 12.5 volts

[WotEver]

With regard to the SoC reading on the BMV have a read of this article: http://thunderboat.boards.net/thread/867/battery-state-charge-meters-tell

[Rob99fla]

When you measured the voltage at 12 volts did you have any load on the batteries at all. From what I have read I would discount the SOC reading. If your batteries were fully charged and you have only used 70 Ah then your SOC should be about 80% which should give a no load voltage of about 12.5 volts

[Rob99fla]

Yes, I do test with no load. The voltage rises a little with everything off but still very low. Thanks

[Martin Megson]

My post above is only relevant if you have a shunt-based battery monitor such as a BMV, NASA, Mastervolt BTM etc. For these, the above applies. The engine battery -ve should be on the other side of the shunt - so they are connected together, but via the shunt. If you don't have a shunt based meter then the engine battery -ve can normally be connected direct to the domestic battery -ve.

 

Thanks Nick, I have a BVM fitted. However a false alarm as when I looked this morning the engine -ve is connected to the correctly side of the shunt. I now remember buying the longer cable to reach.

[Rob99fla]

With regard to the SoC reading on the BMV have a read of this article: http://thunderboat.boards.net/thread/867/battery-state-charge-meters-tell

Really good. Much as I guessed really. Don't believe all the readings. No way my batteries read 90% charge with only 12.2 volts reading. Many thanks

[Rob99fla]

Has anyone had experience with these batteries? Four will fit in my box ok where as Trojan T-105's, the box will need enlarging for them to fit. Not an easy job. I just want decent batteries that will last. Or fit AGM's? Thanks in advance

[Rob99fla]

https://www.tayna.co.uk/30XHS-Trojan-Battery-Deep-Cycle-P7322.html

 

Sorry, forgot link

[system 4-50]

My post above is only relevant if you have a shunt-based battery monitor such as a BMV, NASA, Mastervolt BTM etc. For these, the above applies. The engine battery -ve should be on the other side of the shunt - so they are connected together, but via the shunt. If you don't have a shunt based meter then the engine battery -ve can normally be connected direct to the domestic battery -ve.

I've searched the forum but not found the answer which I am sure is there somewhere to the following:

 

1. What happens if you do have the starter bat neg and domestic bats neg joined on the bat side before the shunt? I know this should not be done but I'd like to understand why.

 

2. Why is it necessary to connect the starter bat neg and domestic bats neg at all?

[cereal tiller]

Has anyone had experience with these batteries? Four will fit in my box ok where as Trojan T-105's, the box will need enlarging for them to fit. Not an easy job. I just want decent batteries that will last. Or fit AGM's? Thanks in advance

Have not used those,have instead the Trojan 27 TMX batteries,12 Volt and 105 A.H.

 

they are now 3 years old and down to 75% capacity

 

CT

[nicknorman]

I've searched the forum but not found the answer which I am sure is there somewhere to the following:

 

1. What happens if you do have the starter bat neg and domestic bats neg joined on the bat side before the shunt? I know this should not be done but I'd like to understand why.

 

2. Why is it necessary to connect the starter bat neg and domestic bats neg at all?

1/ Presuming the alternators are not of the marine isolated ground type (which thy mostly aren't) this means the engine and leisure alternator negatives are connected together at the engine, and of course ditto if there is just one alternator and a split charge system. One normally wants the starter current to not flow through any shunts etc and so typically there is a negative connection between the engine battery negative and the engine starter/ground. This means that current coming from the alternator doesn't flow through the shunt as the alternator negative is connected directly to the leisure battery negatives or, if there are two negative wires (domestic and engine) as we have, roughly half the charging current flows through the shunt, the other half goes direct to the battery. Thus the meter will perhaps measure all the discharge current, and only half the charge current, and thus the indicated SoC heads resolutely downwards over a few cycles.

 

2/ it isn't if there are two alternators, but as I said the battery negatives are effectively connected together via the engine, unless the alternators are isolated ground types. If there is a single alternator /split charge system there has to be a negative path for both sets of batteries and thus their negatives will be connected together somewhere, if not at the batteries then by means of two negative wires and thus at the engine.

 

 

So to summarise the choice is to connect the negatives together at the batteries but via the shunt, or to take two negative leads from the engine, one for the leisure (via the shunt) and one for the engine. The net result is the same. If you draw it out it will be clear!

https://www.tayna.co.uk/30XHS-Trojan-Battery-Deep-Cycle-P7322.html

Sorry, forgot link

I'm sure they would be good batteries but they are pretty expensive. This is why people tend to use T105s, same type of battery but a much more popular size (golf carts) and hence much cheaper due to economies of scale.

Edited December 29, 2016 by nicknorman

[Bod]

Hi. Firstly, we are CC's with no hookup. I have a Victron 12/3000/120 inverter charger, Victron BMV602s battery monitor, 110amp alternator, Honda 1kw generator, Victron 30amp solar controller with 3x 100w solar panels. I have fitted 4x new Yuasa 115amp hr batteries. These are set as first set had faults within a few weeks (from Halfords are the batteries). When I charge the batteries from alternator, the BMV shows about 70amp initially and over a few hours reduces down to about 5-6 amp tail current. Charge voltage is about 14.3 volts. The BMV shows 100%. I always leave the engine running longer to see the tail current low as possible. I sometimes use the Honda generator to top up the batteries making sure they reach float status. Although the BMV shows say 70amps used since 100% charge and SOC still says about 90% charge, the battery voltage is down to below 12 volts. We have a 240v fridge freezer (new) running off the inverter plus some TV, led lights and phone charging, the actual current since last recharge (from the BMV) is correct I assume? Could it just be duff batteries again? Any ideas?

 

How long are you running the engine/ generator on a daily/weekly basis?

Do you have a multi-meter that could take voltage readings directly from the battery terminals?

A battery hydrometer, will show if you have any faulty cells, disregard the little green/red indicators fitted on the batteries, they only show the state of one cell. (maybe the only good cell!)

 

Bod

[Eeyore]

Has anyone had experience with these batteries?

I have a pair of these batteries; they were behaving ok last time I was at the boat. I'll check them in a week or so.

They are on float charge at the moment; I'll take the charger off and monitor the situation.

Bit worrying as there have been several postings on this subject recently. Realy didn't want to concider the possibility of changing batteries at this time of year - ho hum

Edited December 29, 2016 by Eeyore

[Rob99fla]

 

How long are you running the engine/ generator on a daily/weekly basis?

Do you have a multi-meter that could take voltage readings directly from the battery terminals?

A battery hydrometer, will show if you have any faulty cells, disregard the little green/red indicators fitted on the batteries, they only show the state of one cell. (maybe the only good cell!)

 

Bod

Hi Bod

I have tested the batteries today with this hydrometer

 

http://www.ebay.co.uk/itm/322082591860?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

The results are worrying I think. I charged the batteries to show a very low tail current. All batteries show a normal voltage with a meter but the SG readings are as follows.

 

Bat 1

 

1.125, 1.135, 1.120, 1.140, 1.115, 1.142

 

Bat 2

 

1.140, 1.125, 1.140, 1.130, 1.130, 1.125

 

Bat 3

 

1.130, 1.130, 1.127, 1.134, 1.122, 1.135

 

Bat 4

 

1.125, 1.128, 1.130, 1.132, 1.125, 1.131

 

I also smelt sulphur and a bit of black on the battery top up lids. Could the batteries be destroyed in 6 weeks? Or just poor batteries.

 

Many thanks

 

Rob

[MtB]

Those results look to me as though the batteries badly need equalising.

[WotEver]

Those results look to me as though the batteries badly need equalising.

Seconded.

[cuthound]

Thirded.

 

You will need a charging source that the output voltage can be increased to at least 15.5 volts.

 

Charge normally until the tail current has been steady for 30-45 minutes. Then increase the charge voltage to 15.5-16.0 volts and charge for 2-3 hours.

 

Edited for tryping.

Edited December 29, 2016 by cuthound

[WotEver]

And then top up

[nicknorman]

Yes presuming the hydrometer is working correctly, those readings are very low. But of course consistent with the behaviour you are experiencing (ie hardly any capacity). It certainly bears all the hallmarks of very badly sulphated batteries, due to chronic undercharging or some such.

 

As Mike says, you might be able to recover some capacity by doing an equalise charge at 15.5 to 16v. You may be able to coax you Victron into equalise mode and do this using your genny.

 

But it does beg the question "why?". Do you have a hand held clamp meter - or can you borrow one? It could just be that the batteries are not fit for purpose, but first I'd want to be absolutely sure they were being charged properly by looking at the horses mouth rather than some remote reading equipment. So when you next charge the batteries and consider them to be fully charged, can you measure and report the voltage actually on each battery terminal using a hand held meter, and the charge current as measured by the clamp meter? Once you are certain you have been charging them properly and there isn't, for example, a high resistance connection somewhere, then you can go back to Halfords and ask for your money back. Apart from anything else you want to be certain that any new batteries you get will be charged properly.

[Rob99fla]

I can't understand why the batteries need equalising after such a short period in service. I do try to keep the batteries as full as possible using tail current to to make sure the batteries are fully charged and ignoring the SOC displayed. The alternator seems to charge at about 14.5 volts and I see very low tail current before I assume the batteries are fully charged. As I said, I also use the generator to use the Victron charger. I can't alter this (or don't know how to) to charge at 15-16 volts as suggested. I just have a feeling the Halfords batteries are poor quality or stored too long. I had a set of Exide batteries before that seem to work ok before becoming worn through old age. Question is, assuming I can get my money back, what do I fit instead. The battery box needs big modifications to fit Trojan T-105's. Maybe AGM batteries. We live onboard full time so need things to work. I'm prepared to charge well every day and use the generator and charger regularly too. We do have a Zanussi compact washing machine but only run with the engine running and now hot fill to save the water heating. I know batteries are probably the biggest problem but I need to get things working better. Thanks again

Edited December 29, 2016 by Rob99fla