wiggy
Well-Known Member
Can I link this small battery to my main batteries with crocodile clips to charge it? Will it make any difference if the solar is charging the domestic bank whilst the little battery is connected?
Dinghy Pump Battery Charging
- Thread starter wiggy
- Start date
Refueler
Well-Known Member
If the SLA you show is lower on charge than your main batterys - the amp flow from your full charged main batterys would be dramatic !!
I seriously suggest you don't do it !
But you could connect your Solar to the SLA with suitable controller to keep the rate down ... you don't say what ouput your Solar is ...
I have an SLA same as yours with a 5W solar panel direct connected without controller and its fine.
I seriously suggest you don't do it !
But you could connect your Solar to the SLA with suitable controller to keep the rate down ... you don't say what ouput your Solar is ...
I have an SLA same as yours with a 5W solar panel direct connected without controller and its fine.
CliveF
Well-Known Member
I agree with refueler. If you connect that direct to the main battery it is going to get very exciting very quick!
There are cheap ( sub £5 ) chargers on EBAY that will do the job safely, I have a couple at different sites and they work very well.
Long Overnight from virtually flat will see it charged.
Portable 12V Car Battery Maintainer Charger Tender Auto Trickle Boat Motorcycle | eBay
Cut off foreign plug, add 3amp UK plug , no earth, either wire to live / neutral it matters not.
Jobs a good un.
There are cheap ( sub £5 ) chargers on EBAY that will do the job safely, I have a couple at different sites and they work very well.
Long Overnight from virtually flat will see it charged.
Portable 12V Car Battery Maintainer Charger Tender Auto Trickle Boat Motorcycle | eBay
Cut off foreign plug, add 3amp UK plug , no earth, either wire to live / neutral it matters not.
Jobs a good un.
Martin_J
Well-Known Member
The problem with a mains type charger is that it won't work keeping the small battery topped up whilst away from shore power.
I wondered similar a few years back when we put a motorcycle battery on board as part of the racing regulations for requiring independent battery source for nav lights. Since then we've had the battery on board and just occasionally top up from shore power with a small car battery charger.
One day I'll put a 12v to 12v charger on board, or maybe I'll look into whether or not the one I used to use to charge radio controlled model batteries from the car would work.
I wondered similar a few years back when we put a motorcycle battery on board as part of the racing regulations for requiring independent battery source for nav lights. Since then we've had the battery on board and just occasionally top up from shore power with a small car battery charger.
One day I'll put a 12v to 12v charger on board, or maybe I'll look into whether or not the one I used to use to charge radio controlled model batteries from the car would work.
andsarkit
Well-Known Member
These gel batteries don't like a high charge rate and will vent and be damaged by too much current. Assuming your main battery charging voltage is suitable you can put a small bulb in series with the connection. Something like a 6V 5W bulb will limit the current to about 1/2 amp and the glow will show that it is charging. When the bulb goes out it is charged and can be disconnected. You may have to experiment to find a suitable bulb and it should not be left permanently connected unless your system voltage is the same as the recommended float voltage. (this is the PBO solution if you don't want to buy a dedicated charger)
I can't find a spec sheet for that battery but the Yuasa version has a maximum charge of 1.75A and charge voltage of 14.5V and float voltage of 13.65V.
I can't find a spec sheet for that battery but the Yuasa version has a maximum charge of 1.75A and charge voltage of 14.5V and float voltage of 13.65V.
Martin_J
Well-Known Member
I've got too many other projects on the go at the moment but a quick search found lots of rather expensive 12v-12v chargers, then this one on 12 bolt planet
Votronic 12V StandBy Charger (DC-DC Trickle Charger)
Looks like it's on the upper limit for charge current into a small battery... I wonder what others think.
Votronic 12V StandBy Charger (DC-DC Trickle Charger)
Looks like it's on the upper limit for charge current into a small battery... I wonder what others think.
Refueler
Well-Known Member
DC - DC charger ... or a small solar panel ..... then its done deal.
A Solar Trickle charge panel of up to 5 to 10W will look after that small battery very nicely .....
A Solar Trickle charge panel of up to 5 to 10W will look after that small battery very nicely .....
andsarkit
Well-Known Member
It may be fine as the lower voltage should limit the current. It doesn't specify a charging voltage - justthat it is 0.6V lower than the system voltage. I wonder what is inside the box? Possibly just a regulator such as this https://docs.rs-online.com/6e4a/0900766b80a13a8a.pdf. It doesn't seem like a proper DC-DC convertor with current limit and fixed output voltage.
wiggy
Well-Known Member
Thanks for all the input, I’ve dug a 5w solar panel out of the garage, can I leave it connected long term and how do I know if it’s doing anything?
Refueler
Well-Known Member
41 quid ?????
I have a Kemo charge monitor that does same and cost me exorbitant sum of a fiver in Maplins .... OK - Maplins has gone ... but there are places like Banggood and so on that can supply splitter monitors to do this job for pennies ...
This could be packaged to do the job ....
LM2596 DC-DC Voltage Regulator Adjustable Step Down Power Supply Module With Display
Refueler
Well-Known Member
Yes it can be left as you will only get over half power when suns shining anyway ... and then night comes along ...
But it would be good if you can disconnect it at reasonable intervals to avoid it being continuously charged ...
Think of it like this : The 7A/hr SLA battery there is same as what gets put into House Burglar Alarms with constant power adaptors on them ...
You could use an auto cut off item ... Banggood has those as well ....
Martin_J
Well-Known Member
As metioned.. I was too busy to look into this years ago... Banggood looks like shipping from Canada with two weeks delivery! UK suppliers have them at £1.99
LM2596 DC-DC 3-35V adjustable step-down power Supply module
Anyway - It would be useful having an auto cut off, which these don't have built in - so there's no chance of faults dragging down the main battery.
I don't want to rely on a small solar panel with that as it's sole purpose but sounds like a plan for Wiggy's .. One day I'll do something for the regulations. I liked the fact that rather than having battery clip on lights, it was nice to be able to say the bow/stern were my reserve lights (with masthead being main lights) and powered independently from the main battery (i.e. the motorbike battery) although it's the keeping of that motorbike battery charged that's the same as Wiggy's project.
Refueler
Well-Known Member
I was only doing a quick search on BG ... there are other items that will auto-cutoff and auto restart when battery level drops. Just a matter of scrolling on through ...
I have a bagful of battery controllers about 4 euros each that control mains chargers to lead acid battery's ... with user settable input / outputs .....
I have a bagful of battery controllers about 4 euros each that control mains chargers to lead acid battery's ... with user settable input / outputs .....
VicS
Well-Known Member
No it wont. The current flow from a fully charged battery at around 12.7 or 12.8 volts will be small compared with the current that it will draw from a battery charger, solar charger or alternator producing perhaps 14.4 volts.
It won't in fact even charge properly until the solar kicks in, the battery charger is switched on or the engine alternator is running
Its an AGM not gel
Put NX AMP9037 into Google and it will soon find all the tech stuff.
andsarkit
Well-Known Member
Thanks, I hadn't spotted that.
It looks like a current limit of 0.7A and a float voltage of 13.5V will get it almost charged in about 12 hours.
Refueler
Well-Known Member
[Inappropriate content removed]
Connecting a low charge battery direct to a full charged battery will be 'dramatic' ... the Solar panel has nothing to do with it ... OP is asking if he can croc clip the SLA direct to the main batterys ... no regulator .. no fuse ... nothing but direct wires ....
First thing I would expect to happen would be wires to get extremely hot before SLA shows its utter contempt for such brutal mishandling.
If you don't believe me - then please go and source items and make a video of you doing it ..... make sure you are well clear when you do.
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Refueler
Well-Known Member
SLA charging ............... 1/10th C = 10hrs .... plus 10 to 20% to finish ...
Standard stuff ... nothing special.
VicS
Well-Known Member
Your language is unacceptable.. and it is against the forum rules to disguise such language using asterisks etc
You are the one claiming that something dramatic will happen. The onus is on you to source the items and make a video .
Refueler
Well-Known Member
My language was based on total disbelief of someone actually suggesting to direct wire SLA to the main battery ..... without any regulator or control ....
Do you honestly think I am so stupid as to connect a low charged SLA to a full charged mains battery ??
The likely result of such is fried wiring that hopefully will fail before the SLA in turn shows you ....
VicS
Well-Known Member
Pathetic excuse! If you cannot keep your posts within forum rules dont try to justify it. Dont post
You just asked me to do it ! .......................... Irresponsible as well
I dont believ it. produce some supporting evidence of your claim
If connecting the battery to a 12.7 ish power supply will be so dramatic connecting to a 14.4 volt source such as an alternator will be even more spectacular.
