Some Battery Advice Please

[DanLXIX]

So this is the current configuration of the batteries in our new Drabant 38. Now it's been looked after incredibly well, so there are no problems as such, but I want to improve the electrics in a few places this winter. These batteries, 2 x 105aH, are 18 years old, and the voltage still looks good, but I think it's probably sensible to change them (they are sitting so far apart because originally they were separate, one for the fridge and one for the cabin lights). I am thinking we might want to run a 2000w inverter now and then and I don't know if these could cope with that. The old desktop charger that's just wedged in is probably a candidate for replacing as well.

The question is, do I just swap out with new AGM's, so I don't have to rebuild the battery boxes, do I go bigger AGM and just have one battery, or would it be a good idea if the Septor 1275 battery separator would work to go for lithium?

 

[rotrax]

Great service life from your batteries. Lithium might be a step up and will be better for inverter use. Get pro advice unless you are happy to make the neccessary changes yourself.

Good Luck.

 

[PaulRainbow]

So this is the current configuration of the batteries in our new Drabant 38. Now it's been looked after incredibly well, so there are no problems as such, but I want to improve the electrics in a few places this winter. These batteries, 2 x 105aH, are 18 years old, and the voltage still looks good, but I think it's probably sensible to change them (they are sitting so far apart because originally they were separate, one for the fridge and one for the cabin lights). I am thinking we might want to run a 2000w inverter now and then and I don't know if these could cope with that. The old desktop charger that's just wedged in is probably a candidate for replacing as well.

The question is, do I just swap out with new AGM's, so I don't have to rebuild the battery boxes, do I go bigger AGM and just have one battery, or would it be a good idea if the Septor 1275 battery separator would work to go for lithium?

Sorry, but the battery wiring is a mess and is using unsuitable wiring. The crocodile clips need to go too. Not sure that the charger is that good, what make and model is it ?

I assume the Varta battery is for the engine, in which case, move that and put the two domestic batteries together. I would fit leisure batteries, rather and expensive AGMs in this installation.

A 2000w inverter will draw 200a from the batteries at full output, so your batteries will be down to the safe minimum of 50% in 30 mins. You aren't likely to run it for 30 minutes at a time, but if you don't have any charging input it soon adds up.

Would need some more information about your proposed use, equipment onboard and what charging you have to be able to advise on Lithium.

Whatever you decide, the wiring needs replacing. What it needs to be replaced with depends on whether or not you fit the inverter, but i'd suggest it makes sense to fit suitable cable, just in case. Victron recommend 70mm cable for a 2000w inverter and a battery bank of 350-1000 ah.

 

[Alex_Blackwood]

Sorry, but the battery wiring is a mess and is using unsuitable wiring. The crocodile clips need to go too. Not sure that the charger is that good, what make and model is it ?

I assume the Varta battery is for the engine, in which case, move that and put the two domestic batteries together. I would fit leisure batteries, rather and expensive AGMs in this installation.

A 2000w inverter will draw 200a from the batteries at full output, so your batteries will be down to the safe minimum of 50% in 30 mins. You aren't likely to run it for 30 minutes at a time, but if you don't have any charging input it soon adds up.

Would need some more information about your proposed use, equipment onboard and what charging you have to be able to advise on Lithium.

Whatever you decide, the wiring needs replacing. What it needs to be replaced with depends on whether or not you fit the inverter, but i'd suggest it makes sense to fit suitable cable, just in case. Victron recommend 70mm cable for a 2000w inverter and a battery bank of 350-1000 ah.

Paul agree about wiring. Charger appears to be one of these:-
septor 1275 - Google Suche

 

[PaulRainbow]

Paul agree about wiring. Charger appears to be one of these:-
septor 1275 - Google Suche

Morning Alex. That's the "battery separator" the OP mentioned in post #1. Looks like a VSR of sorts to me.

 

[Alex_Blackwood]

Morning Alex. That's the "battery separator" the OP mentioned in post #1. Looks like a VSR of sorts to me.

OK I will be alright when I wake up

 

[DanLXIX]

Sorry, but the battery wiring is a mess and is using unsuitable wiring. The crocodile clips need to go too. Not sure that the charger is that good, what make and model is it ?

I assume the Varta battery is for the engine, in which case, move that and put the two domestic batteries together. I would fit leisure batteries, rather and expensive AGMs in this installation.

A 2000w inverter will draw 200a from the batteries at full output, so your batteries will be down to the safe minimum of 50% in 30 mins. You aren't likely to run it for 30 minutes at a time, but if you don't have any charging input it soon adds up.

Would need some more information about your proposed use, equipment onboard and what charging you have to be able to advise on Lithium.

Whatever you decide, the wiring needs replacing. What it needs to be replaced with depends on whether or not you fit the inverter, but i'd suggest it makes sense to fit suitable cable, just in case. Victron recommend 70mm cable for a 2000w inverter and a battery bank of 350-1000 ah.

Totally agree on the crocodile clips. That charger is an old Danish one, a Dania Electronic 16, and I have no idea how it performs but it must do an okay job to have kept these batteries going for so long.

I understand moving the two batteries closer together, but I'm curious about why you say move the starter battery?

 

[PaulRainbow]

Totally agree on the crocodile clips. That charger is an old Danish one, a Dania Electronic 16, and I have no idea how it performs but it must do an okay job to have kept these batteries going for so long.

I understand moving the two batteries closer together, but I'm curious about why you say move the starter battery?

It's not clear which is the engine battery. If you can move the domestic batteries together without moving it, that's fine. If you can fit more batteries, i would.

But, before you do anything, you need to formulate an overall plan. Without the additional information i previously mentioned, no-one can advise.

 

[William_H]

I would suggest go for similar batteries to what exist. One larger battery will require new battery box and be very heavy to fit. However your old bartteries will need to be replaced only when you find they will not don the job. ie go flat too soon under usual loads. Or will not start the engine. Mean while do get rid of the crocodile clips. ol'will

 

[DanLXIX]

It's not clear which is the engine battery. If you can move the domestic batteries together without moving it, that's fine. If you can fit more batteries, i would.

But, before you do anything, you need to formulate an overall plan. Without the additional information i previously mentioned, no-one can advise.

Ahh okay, the Varta battery is the starter and that Septor separator, from what I've read, prioritises the charging of the starter battery from the alternator.

There is currently the fridge, Webasto heater, water pump, cabin lighting, tiller pilot, nav and deck lights, and instruments, the total consumption of all this I have no idea of!

I will be fitting a new charger as well as new batteries, adding a second portable fridge, and installing LED lighting where it hadn't already been switched. Not planning to install an inverter this winter, but I wanted to make sure I put enough capacity in so I don't have to upgrade again in a year or so.

 

[PaulRainbow]

Ahh okay, the Varta battery is the starter and that Septor separator, from what I've read, prioritises the charging of the starter battery from the alternator.

The Septor device looks like a VSR. It will allow both battery banks to be charged from either bank. Such as, if the engine is running the alternator will charge the domestics too.

There is currently the fridge, Webasto heater, water pump, cabin lighting, tiller pilot, nav and deck lights, and instruments, the total consumption of all this I have no idea of!

I will be fitting a new charger as well as new batteries, adding a second portable fridge, and installing LED lighting where it hadn't already been switched. Not planning to install an inverter this winter, but I wanted to make sure I put enough capacity in so I don't have to upgrade again in a year or so.

I would add a 3rd battery. The battery cables are bad, they should be changed and if you plan to fit a 2000w inverter, change them all for 70mm cables. I'd recommend a Victron Bluesmart IP22 charger.

 

[DanLXIX]

@PaulRainbow One question I forgot to ask - what is the consideration behind not recommending switching to Lithium? One potential challenge I could have is space for more batteries, and I was wondering if lithium would get round this problem because you effectively get double the Ah for about the same physical size don't you?

 

[Tranona]

Lithium starts to make sense if you have higher consumption and wish to spend longer periods of time away from charging sources - that is it gives a larger "buffer" capacity for a given space. However to make use of the properties of lithium (greater capacity and higher charge rates) you need to think carefully about how you are going to charge it. Almost certainly you will need to change charging from your alternator, with either an external regulator or more commonly a DC/DC charger with a controlled output from your engine start battery. However the key really to maximising the use of lithium is adding a solar array sufficient to both help keep up with your consumption and keep the lithium fully charged when you are not there.

With your level of consumption (based on what you say you have) and a pattern of usage that does not stress the buffer capacity, lead acid, particularly AGM is often the best option as adding extra capacity does not require any changes, although adding solar will also help. The key is to always ensure the batteries are fully charged before you go sailing, either using shorepower or solar. A capacity of 250-300Ah (150 usable) is usually adequate for "weekend" sailing. Typical daily consumption (you can do the sums for yourself) with the sort of kit you have is likely to be 70-80Ah, so you have 2 days' buffer, increased by any motoring or solar charge you have.

 

[PaulRainbow]

@PaulRainbow One question I forgot to ask - what is the consideration behind not recommending switching to Lithium? One potential challenge I could have is space for more batteries, and I was wondering if lithium would get round this problem because you effectively get double the Ah for about the same physical size don't you?

From post #3 :

"Would need some more information about your proposed use, equipment onboard and what charging you have to be able to advise on Lithium."