Emergency battery

[slawosz]

Hi,
I have treated my battery not that well for last 2 years, and I am not sure of its condition. I used only 2W maintainer during the season. Now I have 20 W solar panel. Anyway, with 5A load, after the half a year of lying idle, voltage in the system was 11.9 V. Cant really take battery for test now, so I think that I could buy this kind of battery:
Yuasa NP7-12 Battery 12v 7Ah Battery | Hardwarexpress
So it would be an 'emergency' one.

Would this charger be fine for it?
12V 1.3A Mini SLA Battery Charger For 4-14Ah Sealed Lead Acid (SLA) Batteries | eBay

I don't really need much power - mostly for sounder, lights if I mess up tides (which is maybe 0.2 A together), and radio in case of emergency. I use outboard so no startup battery as well.

Thank you.

 

[Refueler]

Similar to the gear I have for starting my model engines .... the charger is stated as for SLA batterys - which that battery you link to is.

Should be fine. I know you will see similar in Emergency Car Start packs - but they really are not designed for high loads ... as backup cabin lights etc. - excellent especially with LED sets.

I know the sales blurb for the battery says good recovery from deep discharge - but I have a few of them on the shelf that have not appreciated it too often ! They appreciate moderate cycling ...

 

[Poey50]

Hi,
I have treated my battery not that well for last 2 years, and I am not sure of its condition. I used only 2W maintainer during the season. Now I have 20 W solar panel. Anyway, with 5A load, after the half a year of lying idle, voltage in the system was 11.9 V. Cant really take battery for test now, so I think that I could buy this kind of battery:
Yuasa NP7-12 Battery 12v 7Ah Battery | Hardwarexpress
So it would be an 'emergency' one.

Would this charger be fine for it?
12V 1.3A Mini SLA Battery Charger For 4-14Ah Sealed Lead Acid (SLA) Batteries | eBay

I don't really need much power - mostly for sounder, lights if I mess up tides (which is maybe 0.2 A together), and radio in case of emergency. I use outboard so no startup battery as well.

Thank you.

That gives you 3.5 usable ah assuming you would only discharge to 50%. And that would be on the first day after full charge. On second or subsequent days it may be a bit slower to get back to full charge because of the internal resistance of lead acid - maybe these would be very overcast days. So that could be only 2 ah.

I'd go larger to give yourself some more headroom.

 

[Refueler]

I have a 7 A/hr actually of same in my 4.5m soviet mobo .... it powers :

1. Auto bilge pump (300gph)
2. Bi-nav light (LED)
3. 3" 'motorcycle' LED spotlight

It sits there with a 5W solar panel happily working ... its in its 3rd year now and fine.

 

[fisherman]

My campervan start battery has disguised its demise because the PV kept it up just enough for a long time. Found it down to 10.5v on a dull day, no start and clock stopped. When I asked the man at the leccy place about checking the leisure battery he said disconnect it and check for voltage drop over two days. 2v drop it's a goner. It showed 13.3, down to 13.02 so OK.

 

[Refueler]

My campervan start battery has disguised its demise because the PV kept it up just enough for a long time. Found it down to 10.5v on a dull day, no start and clock stopped. When I asked the man at the leccy place about checking the leisure battery he said disconnect it and check for voltage drop over two days. 2v drop it's a goner. It showed 13.3, down to 13.02 so OK.

Vans ... I had a 16ft job with Carver Domestic Service panel. Was designed to look after 2 HD 12V ... fridge ... hot water ignition ... as well as the 240V mains breakers etc.
Brilliant concept - but I found that the trickle charge designed for winter storage led to the demise of my 12v HD batterys. All else was great - but thereafter if van was stood - I disconnected the 12v's and put a normal non-smart charger via a timer to 'blip' charge them every few days or so ...

One of the problems I noted was the Leisure batterys and many dealers selling the compromise batterys as full Leisure ... TBH - I reckon half the kids selling gear at Van dealers didn't know the difference between the various Lead Acids.

 

[fisherman]

Daughter works online from her van in France. £700 worth of Li fe plus some intelligent system which seems to be OK, keeps her going all day except she got a non start for unkonown reasons once. My system just charges and uses both batteries until the v goes below 12.9 then the VSR cuts out and isolates the start battery. Clicks in and out all day, so just kept it going. Not what I had on the boat, but heigh ho...

 

[Refueler]

Daughter works online from her van in France. £700 worth of Li fe plus some intelligent system which seems to be OK, keeps her going all day except she got a non start for unkonown reasons once. My system just charges and uses both batteries until the v goes below 12.9 then the VSR cuts out and isolates the start battery. Clicks in and out all day, so just kept it going. Not what I had on the boat, but heigh ho...

Sorry to OP for thread drift .... but I bought some SSC's of ebay (solid state controllers) that do similar ... and are user adjustable. I mean to fit a couple to my boat .... I also want to use for storage of my Lawn Tractors in winter.

12V Battery Low Voltage Cut off Switch Controller Excessive Protection Module | eBay

I also bought a bagful of mains reduction units that protect against overcharge ... so you have 240V input control to charger ... with cut-offs etc.

5pcs XH-M601 12V Battery Charging Module Smart Charger Automatic Charging Power Outage Power Control Board

Idea to have small units tucked away out of sight to control the charge system ..

 

[William_H]

OP might consider setting up set of lithium18650 batteries for his boat power. Get 1,2or3 holders for 3 cells. Typically about 2 AH for each cell. You need 3 in series fro 11 to 12v. then parallel more sets of 3 in series to multiply AH capacity. You need a 3S charge controller like this 12V 3S MPPT Solar Panel Controller Lithium 18650 Battery Pack Charging Module | eBay. NB the Chinese happily throw around the term MPPT when it is certainly not Max power point racking from PV cell. These controllers will cut off charge when cells come up. NB each cell is monitored individually so 4 wires to cell pack. The controller will also cut off output at high current or low cell voltage which is good. However I found with 25w radio I need to connect straight to cells because current drain was too high for controller. See my previous post re 18650 batteries from China (ebay) if they claim 6000 to 10000maH you can expect around 200maH. 18650 at best will do around 3000maH. Just an option to experiment with. ol'will

 

[LiftyK]

I used to have a 35-40Ah battery. Running VHF, depth, plotter and autopilot on a 21’ boat it would drop 50% crossing Lyme Bay. No solar to charge as I went. I’m still obsessive about battery state even after moving to a110Ah house battery on a different boat.

 

[Spirit (of Glenans)]

I have a 7 A/hr actually of same in my 4.5m soviet mobo .... it powers :

1. Auto bilge pump (300gph)
2. Bi-nav light (LED)
3. 3" 'motorcycle' LED spotlight

It sits there with a 5W solar panel happily working ... its in its 3rd year now and fine.

The length of time it would power your bilge pump might be a worry.

 

[fisherman]

For what they cost I would always have an excess of battery, two or three in parallel, good ballast, trickle charge, no worries. Don't like having to eke out the power, worry about will the VHF work if I need help in the end.

 

[Poey50]

Hi,
I have treated my battery not that well for last 2 years, and I am not sure of its condition. I used only 2W maintainer during the season. Now I have 20 W solar panel. Anyway, with 5A load, after the half a year of lying idle, voltage in the system was 11.9 V. Cant really take battery for test now ....

Re-reading your original post it seems to me that you are still optimistic that that your main battery may be OK and that, just in case it isn't, you could buy an emergency battery. Given the few clues above I think if would be reasonable to assume the worst and replace the main battery rather than go down this emergency route. Given your mostly modest loads your 20 watt panel should then be able to maintain it properly.

 

[fisherman]

You are trying to balance long term trickle charge against intermittent higher load use, hence, have more storage capacity....IMO...
120 AH quoted at £105 this week.

 

[Refueler]

The length of time it would power your bilge pump might be a worry.

Yes but so far its more than managed the job and powered the lights. Of course if it was a larger boat or there was a leak to look after - then lets be honest - you could be in situation that no battery is big enough !
Its also to be noted that the pump kicks in when water level is low - so it doesn't have to run for long ... we also have 20 hour daylight this time of year for the solar panel that tops the battery up.

 

[Refueler]

OP might consider setting up set of lithium18650 batteries for his boat power. Get 1,2or3 holders for 3 cells. Typically about 2 AH for each cell. You need 3 in series fro 11 to 12v. then parallel more sets of 3 in series to multiply AH capacity. You need a 3S charge controller like this 12V 3S MPPT Solar Panel Controller Lithium 18650 Battery Pack Charging Module | eBay. NB the Chinese happily throw around the term MPPT when it is certainly not Max power point racking from PV cell. These controllers will cut off charge when cells come up. NB each cell is monitored individually so 4 wires to cell pack. The controller will also cut off output at high current or low cell voltage which is good. However I found with 25w radio I need to connect straight to cells because current drain was too high for controller. See my previous post re 18650 batteries from China (ebay) if they claim 6000 to 10000maH you can expect around 200maH. 18650 at best will do around 3000maH. Just an option to experiment with. ol'will

Just a note of caution .... 18650 cells are in at least two voltage versions ... and if you charge the lower rated to the higher 4.2V standard - they will not last long.
18650's are popular cells for our RC gear and we make sure to get the 4.2V max per cell versions.

18650's are hardy cells and can take abuse - but care in connecting up packs - they can discharge at extremely high rates if a mistake made .. pal of mine blew a pack with just the simplest stupid mishap ... that could have resulted in a fire if he hadn't been there.

 

[Refueler]

I used to have a 35-40Ah battery. Running VHF, depth, plotter and autopilot on a 21’ boat it would drop 50% crossing Lyme Bay. No solar to charge as I went. I’m still obsessive about battery state even after moving to a110Ah house battery on a different boat.

My 25ft Sunrider has two 90 A/hr Car batterys ... yes car batterys ... I can get 2nd hand ones cheap as chips and usually they come from scrapped cars and in as new condition. I can easily get 4 - 5 years out of each ... and at 25 euros a pop .. nice. Even if I have to replace during a trip ... I'm still quids in buying a new one, and easily obtained in any port.
My Baltic cruises are usually of 8 - 10 days duration with about 2hrs motor sailing / 5hrs pure sailing per day. Batterys at end of trip are still at or near full. The engine - Perkins 4107 has the typical 45A car alternator and there is no fancy charge system on board ... that includes running my coolbox which draws up to 8A (its on a relay that only kicks in when engine is on + a manual over-ride switch).

Just remarking ... and before I get advice on what to modify / change ... I have no plan to change it !! Why ?? it works.